Smith, C.A. and J.S. Pepose

Am J Ophthalmol, 1999. 127(1): p. 77-84.

PURPOSE: To determine whether routine office techniques used to disinfect tonometer prisms and trial contact lenses are sufficient to prevent transmission of ocular infections. METHOD: We reviewed the current literature on the efficacy of certain disinfection protocols against commonly encountered viral, bacterial, and fungal pathogens as well as Acanthamoeba. RESULTS: Some commonly used disinfecting solutions and techniques may be inadequate for disinfection of viruses such as hepatitis C virus and organisms such as Acanthamoeba. When used in accordance with guidelines published by the United States Centers for Disease Control and Prevention (CDC) and the American Academy of Ophthalmology (AAO), 3% hydrogen peroxide is a very effective disinfectant against a wide variety of microorganisms. Specifically, tonometer prisms disinfected by a 5-minute soak in 3% hydrogen peroxide (or 70% isopropyl alcohol or a 1:10 dilution of sodium hypochlorite) are adequately disinfected against most ocular pathogens, with the exception of Acanthamoeba. Trial contact lenses that are disinfected with a 2-hour soak in 3% hydrogen peroxide are effectively rid of all pathogens of concern. After disinfection, rigid lenses should be stored dry, and soft lenses should be stored in a sterile, preserved solution. Repeat disinfection should be routinely performed at 1-month intervals to prevent regrowth of organisms. CONCLUSION: A safe office environment can be maintained by following current CDC recommendations for disinfection, as well as instituting some additional procedures.

McLaughlin-Borlace, L., et al.

J Appl Microbiol, 1998. 84(5): p. 827-38.

Bacterial biofilm formation on contact lenses (CLs), and CL storage cases may be a risk factor for CL-associated corneal infection and may explain the persistence of organisms in CL storage cases. This study evaluated biofilm formation on, and microbial contamination of, CLs and CL storage cases from patients with microbial keratitis. Contact lenses and CL storage cases from 20 wearers with microbial keratitis were sampled microbiologically and visualized using scanning electron microscopy (SEM). Culture results from the cornea were also noted. Bacterial biofilm was present more frequently (P 0.05) on CL storage case surfaces (17/20) compared with CL surfaces (11/20) and biofilm density was significantly greater on case surfaces (P 0.05). There was no association between poor compliance and microbial contamination of the CL storage case, nor between poor compliance and biofilm formation or density on the CL or CL storage case. Biofilm formation occurred equally frequently with hydrogen peroxide and chlorine release care systems. Microbial keratitis in CL wearers is frequently associated with bacterial biofilm in the CL storage case. Despite the use of current CL disinfection systems, the CL storage case is a favourable environment for proliferation of certain organisms. Biofilm on CLs may prolong the retention time of organisms at the ocular surface and increase their potential pathogenicity.

Schaumberg, D.A., K.K. Snow, and M.R. Dana

Cornea, 1998. 17(1): p. 3-10.

PURPOSE: To review from a historical perspective the recent epidemic of Acanthamoeba keratitis and its association with the use of contact lenses and to provide a summary of recent techniques that have allowed earlier diagnosis and treatment. METHODS: The authors reviewed available literature on Acanthamoeba keratitis from 1973 to the present, with emphasis on the history of the epidemic and its association with contact lenses, identification of risk factors, preventive measures, and current diagnostic techniques. We also estimated the annual incidence of Acanthamoeba keratitis during 1985 through 1987 from available data. RESULTS: Before the popularization of soft-contact-lens wear, Acanthamoeba keratitis was extremely rare; however, an epidemic began in the early 1980s, and the number of cases increased dramatically beginning in 1984. By 1985, the association of this infection with the use of contact lenses was firmly established, and in 1987, the infection was shown to occur more commonly among men, as well as in contact-lens wearers who failed to disinfect their lenses as frequently as recommended, swam while wearing lenses, or used homemade instead of commercially prepared saline solution. Adoption of "disposable" contact lenses in the late 1980s did not decrease the risk of Acanthamoeba keratitis, and concerns remain regarding the effectiveness of some contact-lens disinfectants; however, recent advances in diagnosis and treatment have improved the prognosis. The annual incidence during 1985 through 1987 was conservatively estimated at 1.65 to 2.01 cases per million contact-lens wearers. It is unclear whether the incidence is declining. CONCLUSION: Acanthamoeba keratitis has now been recognized worldwide, and there are clear associations of this infection with improper contact-lens hygiene, particularly contact with water. Recent methods allow earlier diagnosis and thus improved outcomes. The epidemic provides a valuable lesson on how a new technology can be associated with unforeseen complications and exemplifies how rapid dissemination of epidemiologic information can aid in controlling an emergent epidemic.

Radford, C.F., V. Gastaldo-Brac, and A.R. Hill

Ophthalmic Physiol Opt, 1998. 18(1): p. 63-5.

Contact lens (CL) complications account for 2.2-10.0% of patients attending ophthalmic Accident and Emergency (A&E) units. A survey was conducted to evaluate disease severity among CL wearers attending the Oxford Eye Hospital A&E Unit. CL wearers without a medical indication for CL wear completed a short questionnaire eliciting CL type and wear schedule. Subsequently, A&E Senior House Officers indicated the diagnosis and whether, in their opinion, the patient could have been managed by their optometrist or contact lens practitioner. Approximately half of the CL wearers (321/653, 49%) presented with CL related disorders, but only 16% (53/321) of these had potentially sight- threatening disease. More than a third of these patients were deemed to be inappropriately attending (125/321, 39%), presenting with minor problems such as corneal abrasions, CL handling difficulties and CL solution 'accidents'. Better patient instruction, together with encouragement to consult their optometrist or contact lens practitioner first if problems occur, would greatly reduce the burden of A&E attendance by CL wearers with minor complaints.

Niszl, I.A. and M.B. Markus

Br J Ophthalmol, 1998. 82(9): p. 1033-8.

AIMS: This study was undertaken to investigate the effects of contact lens disinfecting solutions on strains of Acanthamoeba from the United Kingdom and southern Africa and to compare the results with those of other researchers. No information was previously available for southern African isolates. METHODS: 11 contact lens solutions were tested on cysts of 10 strains of Acanthamoeba. RESULTS: Not all solutions used in the study were effective, with some for hard and gas permeable contact lenses being more satisfactory than those for soft contact lenses. The most effective of the gas permeable and hard contact lens solutions tested was Transoak (0.01% (wt/vol) benzalkonium chloride), which killed cysts of all strains within 4 hours of exposure. Oxysept 1 (31 mg hydrogen peroxide/ml) was the best soft contact lens solution tested. It eliminated cysts of certain strains within 4 hours, whereas cysts of other strains were only inactivated within either 8 or 72 hours. CONCLUSIONS: Manufacturers should be aware of the killing time for Acanthamoeba by contact lens solutions and should provide appropriate guidelines for the use thereof. The killing time for cysts of the African and UK isolates studied is, in general, similar. Therefore, it must in the present state of knowledge be assumed that usage guidelines suggested in the UK are also appropriate for travellers to South Africa and for local residents in South Africa.

Lofstrom, T., J.S. Anderson, and A. Kruse

Clao J, 1998. 24(4): p. 210-5.

PURPOSE: The 5-stage scale currently used to grade tarsal conjunctiva is limited with respect to precisely describing the tissue condition and accurately following small changes. We conducted two preliminary studies to evaluate a new 8-stage, photographic tarsal conjunctival grading system. METHODS: We conducted a retrospective review of the records of 145 individuals in Denmark who had successfully worn Acuvue lenses for at least six months on a daily wear basis. Patients wore Acuvue lenses on a two-week replacement schedule and used one of four different care systems (AOSEPT, OPTI-FREE, OXYSEPT, and RENU). Tarsal conjunctiva and lens cleanliness were graded by the investigators. Comfort, vision, and simplicity of care system were rated by the patients. In the second, prospective study, a group of 30 patients who had successfully worn Acuvue lenses and used the OPTI-FREE care system for at least six months were followed for three months to test the repeatability of the new grading system. RESULTS: In the first study, patients using RENU were found to have significantly higher scores than AOSEPT and OPTI-FREE patients when comparing tarsal scores based on the 5-stage scale (P 0.05). When comparing scores based on the 8-stage scale, significant differences were detected between RENU and all three of the other care systems, with RENU scores being higher (P 0.05). Numerous differences were found among care systems in lens cleanliness and subjective patient ratings of comfort, vision, and simplicity of use. In the second study, tarsal scores did not change over time in the patients followed for three months. CONCLUSIONS: These initial studies suggest that the new grading scale may allow for more precise determination of the condition of the tarsal conjunctiva and provide for a greater ability to detect differences among lens care regimens in tarsal conjunctival scores. Early indications are that the scale is reliable and repeatable.

Kidane, A., J.M. Szabocsik, and K. Park

Biomaterials, 1998. 19(22): p. 2051-5.

A technique was developed to accelerate lysozyme deposition on poly(HEMA) contact lenses and measure the amounts of the deposited lysozyme. This technique was for evaluation of bendazac lysine solution, a contact lens cleaning and wetting solution. Effect of temperature on lysozyme deposition on poly(HEMA) contact lenses was examined. Five temperatures ranging from 25 degrees C to 90 degrees C were chosen to examine the temperature effect. The amounts of lysozyme deposited on poly(HEMA) contact lenses at 25 C and 60 C were 0.27 microg/lens and 0.61 microg/lens, respectively. The amount increased sharply to 23 microg/lens at 70 degrees C with the maximum of 31 microg/lens at 90 degrees C. Kinetics of lysozyme deposition on poly(HEMA) contact lenses was examined at 80 degrees C. Lysozyme deposition increased sharply during the first 2 h and reached a plateau after 2 h. Effectiveness of various cleaning procedures was examined using bendazac lysine solution. When the contact lenses were washed without rubbing with fingers, the bendazac lysine reduced the amount of deposited lysozyme by more than 40% from 18.3 microg/lens to 10.6 microg/lens. The effect of bendazac lysine was most prominent when the contact lenses were shaken during storage in the presence of lysozyme in solution. If the contact lenses were cleaned by rubbing with fingers, the effect of bendazac lysine solution on the prevention of lysozyme deposition was negligible.

Alongi, S., et al.

Cornea, 1998. 17(2): p. 146-51.

PURPOSE: This study quantified the bacterial load and protein deposits on 1- and 15-day disposable contact lenses after use in normal wearers. METHODS: Sixteen patients were randomly assigned to a 1-day contact lens (1-Day Acuvue) in one eye and to a 15-day contact lens (Acuvue) in the contralateral eye. Only one specified solution was allowed for the care of 15-day lenses. All patients were evaluated every month for 6 months (at times T1, T2, T3, T4, T5, T6). At times T1, T3, and T5, the lenses were removed in a sterile fashion and sent for laboratory quantification of Staphylococcus aureus and Pseudomonas aeruginosa. At T2, T4, and T6, quantification of protein deposits was determined, and at T0 and T6, impression cytology of the conjunctiva was performed. RESULTS: P. aeruginosa was not identified on any lens. At T1, T3, and T5, S. aureus was significantly greater on the 1-day versus 15-day lenses (p 0.001). In contrast, protein deposits were significantly greater on the 15-day lenses at all time points (T2, T6: p 0.01; T4: p 0.05). Impression cytology of the 15-day lens eyes revealed a worsening trend compared to the 1-day lens; however, no statistically significant differences were found between the two groups (p = 0.29). CONCLUSION: Results of this study suggest that the use of cleaning and preservative solutions can alter the ocular surface bacterial environment of the contact lens wearer and that these changes are not a direct consequence of contact lens wear. The bactericidal activity of these solutions could, with time, also affect ocular surface cells, leading to contact lens intolerance and ocular surface disease.

Gatti, S., et al.

Antimicrob Agents Chemother, 1998. 42(9): p. 2232-4.

Acanthamoeba keratitis is a severe ocular infection secondary to accidental macro- or microscopic trauma of the cornea. Starting in 1985, a dramatic increase of this infection was recorded along with the spread of contact lens use. This protozoal disease is difficult to treat because of the scarcity of efficacious topical and systemic drugs. We evaluated the in vitro effectiveness of povidone-iodine (PVP- I [Betadine]), an agent with broad antibacterial and antiviral activity, compared to that of chlorhexidine (CXD), a cationic antiseptic, on Acanthamoeba isolates from patients with amebic keratitis. The results showed that PVP-I solution from 0.5 to 2.5% has a better antiamebic activity both on trophic and cystic stages of Acanthamoeba spp. than does CXD.

Radford, C.F., O.J. Lehmann, and J.K. Dart

Br J Ophthalmol, 1998. 82(12): p. 1387-92.

AIM: To investigate the frequency, outcomes, and risk factors for acanthamoeba keratitis (AK) in England during the past 4 years. METHODS: An ophthalmologist in 12 of the 14 regional health authorities (RHAs) coordinated identification of patients in their region presenting with AK between 1 October 1992 and 30 September 1996. Clinical and postal patient questionnaire data were analysed. RESULTS: 243 patients (259 eyes) with an AK diagnosis were identified, equating to an annualised incidence of 0.14 per 100,000 individuals. UK resident patients for each year numbered 50, 71, 73, and 32 respectively. Among patients with sufficient data 170/237 (72%) were diagnosed early (within 30 days of presentation), 197/218 (90%) were treated with polyhexamethyl biguanide and/or chlorhexidine, and 40/243 (16%) underwent surgery. Visual acuities of 6/12 or better were achieved by 222/259 (86%) eyes, including 84 eyes of patients under review or lost to follow up. Non-contact lens (CL) wearers were associated with delayed diagnosis, increased need for surgery and a poorer visual outcome (only 10/18 eyes, 56%, achieved 6/12 acuity). 225/243 (93%) patients were CL wearers, and 205/243 (84%) were soft CL (SCL) users. Among SCL user respondents, previously identified risk factors-- swimming with CL (47/138, 34%), non-sterile CL rinsing (11/138, 8%), omitted disinfection (85/138, 62%), and chlorine release disinfection (65/138, 47%)--were identified for 125/138 (91%) patients. CONCLUSIONS: Earlier diagnosis and more effective medical therapy have improved the prognosis for most AK patients. The study demonstrates the highly preventable nature of the disease: 91% of the SCL wearers could have avoided the disease by refraining from inadvisable practices, and a marked fall in frequency was seen after intensive media attention to AK, possibly in conjunction with increasing penetrance of new CL products. Since the frequency of AK appears to be largely determined by the ever changing trends in CL use, continued monitoring is indicated.

Freeman, M.I. and P.C. Donshik

Clao J, 1998. 24(4): p. 194.

Rakow, P.L.

J Ophthalmic Nurs Technol, 1998. 17(2): p. 82-6.

Morris, C.A., et al.

Adv Exp Med Biol, 1998. 438: p. 717-22.

Willcox, M.D., et al.

Aust N Z J Ophthalmol, 1998. 26 Suppl 1: p. S32-5.

PURPOSE: The aim of this study was to test the hypothesis that Pseudomonas aeruginosa that have been internalized in Acanthamoeba are protected against the action of contact lens disinfecting solutions. METHODS: The experiments were divided into two parts. First, five commercially available disinfecting solutions, hydrogen peroxide and non-peroxide based, were tested for their efficacy against four strains of P. aeruginosa and one strain of A. castellanii. Cells were inoculated into working concentrations of disinfecting solutions, incubated for 18 h and the numbers of viable bacteria or amoeba were analysed after appropriate growth on agar plates. Second, two strains of P. aeruginosa were allowed to interact with A. castellanii for 4 h prior to addition to disinfecting solutions. The numbers of P. aeruginosa after incubation with the disinfecting solutions were measured after growth on agar plates. RESULTS: In general, disinfecting solutions containing hydrogen peroxide were most effective against the micro-organisms. Solutions containing only traces of polyaminopropyl biguanide were least effective. CONCLUSIONS: For strains of P. aeruginosa, the presence of the amoebae did not protect the bacteria against the disinfecting agents. The amoeba appeared to kill the bacteria, perhaps using them as a food source.

Christensen, M.T., J.R. Barry, and F.D. Turner

Clao J, 1998. 24(4): p. 227-31.

PURPOSE: Patients who use topical ophthalmic medications and wear soft contact lenses must remove their lenses before drop instillation to prevent absorption of the medication into the lenses. No previous study has examined how long such a patient should wait before reinserting their lenses. This study was designed to test the hypothesis that waiting 5 minutes before reinsertion of lenses would be sufficient to reduce absorption to a level below what is needed to produce a physiological response. METHODS: Naphcon-A was used as the test solution and pupillary dilation was the physiological response measured. The amount of benzalkonium chloride (BAC) extracted from the lenses was also measured. Twenty-three subjects, none of whom had any significant ocular or systemic abnormalities nor showed pupillary dilation to directly applied Naphcon-A, completed this 3-week study. The study used a 2-period crossover design with a 1-week screening phase. Results were analyzed with a repeated-measure analysis of variance. RESULTS: The pupils averaged 0.316 mm larger when subjects instilled Naphcon-A with lenses in place as compared to when dosing with lenses removed for 5 minutes (P = 0.0008). Nine of 23 subjects showed pupillary dilation greater than 0.5 mm when dosing with lenses in place as compared to none when lenses were removed for 5 minutes. Significantly (P 0.01) more BAC was extracted from lenses that had been worn during dosing than from lenses removed for 5 minutes (0.9 microgram/lens as compared to no detectible amount). CONCLUSION: Removing soft contact lenses for 5 minutes was sufficient to prevent absorption of clinically significant amounts of Naphcon-A into the lenses.

Radford, C.F., D.C. Minassian, and J.K. Dart

Br J Ophthalmol, 1998. 82(11): p. 1272-5.

AIMS: A case-control study was performed to evaluate soft contact lens (SCL) wear modality as a risk factor for microbial keratitis. METHODS: Contact lens wearers presenting as new patients to Moorfields Eye Hospital accident and emergency department during a 12 month period completed a self administered questionnaire detailing demographic data and contact lens use habits. Cases were patients with a clinical diagnosis of SCL related microbial keratitis. Controls were SCL users attending with disorders unrelated to contact lens wear. Odds ratios (estimates of relative risks) and 95% confidence limits (CL) were calculated through multivariable logistic regression analysis. RESULTS: There were 89 cases and 566 controls. A substantially increased risk with 1-4 weekly disposable SCL compared with non-disposable SCL was identified among both daily wear (DW) (odds ratio = 3.51, 95% CL 1.60- 7.66, p = 0.002) and extended wear (odds ratio 4.76, 95% CL 1.52-14.87, p = 0.007) users after adjustment for demographic, lens use and hygiene variables. Other significant factors among DW users were "occasional" overnight use, use of chlorine based (as opposed to other chemical) systems in combination with poor storage case hygiene, and irregular disinfection. CONCLUSION: Properties of some disposable SCL may be partly responsible for these excess risks. It is also possible, however, that this finding is largely a reflection of widespread complacency among patients and practitioners with respect to disposable SCL fitting and use.

Illingworth, C.D. and S.D. Cook

Surv Ophthalmol, 1998. 42(6): p. 493-508.

Acanthamoeba species are an important cause of microbial keratitis that may cause severe ocular inflammation and visual loss. The first cases were recognized in 1973, but the disease remained very rare until the 1980s, when an increase in incidence mainly associated with contact lens wear was reported. There is an increased risk when contact lens rinsing and soaking solutions are prepared with nonsterile water and salt tablets. The clinical picture is often characterized by severe pain with an early superficial keratitis that is often treated as herpes simplex infection. Subsequently a characteristic radial perineural infiltration may be seen, and ring infiltration is common. Limbitis and scleritis are frequent. Laboratory diagnosis is primarily by culture of epithelial samples inoculated onto agar plates spread with bacteria. Direct microscopy of samples using stains for the cyst wall or immunostaining may also be employed. A variety of topically applied therapeutic agents are thought to be effective, including propamidine isethionate, clotrimazole, polyhexamethylene biguanide, and chlorhexidine. Various combinations of these and other agents have been employed, often resulting in medical cure, especially if treatment is commenced early in the course of the disease. Penetrating keratoplasty is preferably avoided in inflamed eyes, but may be necessary in severe cases to preserve the globe or, when the infection has resolved, to restore corneal clarity for optical reasons.

Murdoch, D., et al.

Aust N Z J Ophthalmol, 1998. 26(3): p. 231-6.

BACKGROUND: Acanthamoeba keratitis is an uncommon corneal infection that can run a protracted course with, at times, serious visual results. Eighty-five per cent of cases occur in soft contact lens wearers. The first New Zealand case occurred in 1990 and only seven cases have been identified in New Zealand to the end of 1996. METHODS: We surveyed the ophthalmologists looking after these seven cases of acanthamoeba keratitis as to time to diagnosis, treatment and outcome. RESULTS: New Zealand has a low incidence of this disease. All cases were soft contact lens wearers with defective care in every instance. After an initial two late-diagnosed cases, the time to diagnosis for four of the five other cases has been within 2 weeks. Medical treatment has varied over this series, but since the introduction of the cationic antiseptics polyhexamethylene biguanide (PHMB) and chlorhexidine in 1992, the last five cases were all treated with PHMB. One case diagnosed within 2 weeks ran a devastating course, despite intensive PHMB, and a second case remained culture positive after 1 year of PHMB and the late addition of chlorhexidine. Debridement, 0.1% PHMB and hexamidine eventually settled this eye. CONCLUSIONS: For treatment PHMB, hexamidine rather than propamidine and surgical debridement are favoured. While all Acanthamoeba isolates show good in vitro sensitivity to PHMB, the in vivo response is not always proportionate. A bacterial endosymbiont may have been a factor in the favourable outcome of one protracted case.

McArdle, F.A. and C.J. Meehan

Analyst, 1998. 123(8): p. 1757-60.

Tromethamine [tris(hydroxymethyl)aminomethane] is used as an emulsifying agent, alkaliser and buffering agent in pharmaceutical preparations such as eye-care solutions. A new method for the determination of this compound in an eye-care preparation was developed using capillary zone electrophoresis with indirect UV detection. The method displayed linearity between 2.5 and 25 mg l-1 with a correlation coefficient of 0.9992. The limit of detection was 2.5 mg l-1. Precision and accuracy were determined as relative standard deviation and % deviation, and were found to be 0.42% and 1.62%, respectively. Recovery studies of tromethamine in the pharmaceutical preparation gave a 102.98% recovery.

Lin, C.P., J.Y. Chen, and M. Boehnke

Kao Hsiung I Hsueh Ko Hsueh Tsa Chih, 1998. 14(10): p. 639-43.

We studied the influences of hydrogel contact lens care solutions on corneal epithelial wound healing in vitro. The corneal epithelial wounds, 1.5 mm in diameter, 70 microns in depth were created on the pig's eyeballs by the excimer laser. The hydrogen peroxide systems including AOSEPT, Oxysept, Contopharma-peroxide-system were neutralized first, then applied three times on the epithelial wounds. The neutralizing procedures included the agents, duration, doses and containers following the instructions accompanied in the package of the solutions. The multipurpose care solutions including Opti-free, Hexidin, Bausch & Lomb Sensitive Eyes were applied directly as well. The healing scores were ranked 24 hours later with the fluorescin stain. There were no statistical differences between the healing scores of each experiment group and control group performed with Mann-Whitney rank-sum test. None of the lens care solutions retarded the corneal epithelial wound healing when compared with the BSS. The contact lenses treated with above solutions may be safely applied on eye without rinsing.

Tighe, B.J., et al.

Adv Exp Med Biol, 1998. 438: p. 745-51.

Inoue, T., et al.

Am J Ophthalmol, 1998. 125(5): p. 721-3.

PURPOSE: To report a case of severe amebic keratitis in which both Hartmannella and Acanthamoeba were isolated simultaneously from the same lesion. METHOD: Case report. The deep corneal lesion was scraped for cytopathology and isolation of the pathogens. We tested the in vitro sensitivities of the pathogens to several drugs. RESULTS: Cultures of the corneal scrapings and of the solution in the patient's contact lens storage case were positive for Acanthamoeba E9 cysts and trophozoites. Hartmannella ameba coexisted with Acanthamoeba in the cornea. When tested in vitro, Acanthamoeba trophozoites were sensitive to both miconazole nitrate and natamycin, while cysts were sensitive only to natamycin. However, the patient did not respond to these antiamebic drugs. CONCLUSIONS: This case suggests that Acanthamoeba is not the only origin of amebic keratitis. Hartmannella may also cause severe drug-resistant keratitis.

Landa, A.S., et al.

Cornea, 1998. 17(3): p. 293-300.

PURPOSE: To compare the efficacies of two all-in-one contact lens (CL) cleaning solutions and a detergent mixture on the detachment of a pathogenic bacterium adhering to two types of contact lenses in the absence and presence of a tear film. METHODS: Bacterial-detachment studies were carried out in a parallel-plate flow chamber. Rigid gas permeable (RGP) CLs with and without a tear film were fixed on the bottom plate of the flow chamber. After adhesion of Pseudomonas aeruginosa no. 3, bacterial detachment was stimulated by perfusing the system either with an all-in-one CL-cleaning solution, for soft contact lenses (SCL solution) and for rigid lenses (RCL solution), or with a detergent mixture of 0.25% (wt/vol) sodium lauryl sulfate (SLS) and 0.2% sodium methyl cocoyl taurate (Tauranol). In addition, the all-in- one RCL-cleaning solution supplemented with 0.025% (wt/vol) SLS and 0.02% (wt/vol) Tauranol was evaluated. A surface physical-chemical analysis of the lenses before and after application of the solutions was done to determine whether remnants of the ophthalmic solutions or detergents could be found adsorbed to the CL surfaces. RESULTS: Both all-in-one CL-cleaning solutions stimulated minor bacterial detachment from CL surfaces with or without a tear film. The SLS/Tauranol detergent mixture, however, removed or = 95% of the adhering P. aeruginosa cells, whereas the RCL-cleaning solution supplemented with detergents also stimulated significant detachment. Surface physical- chemical analysis clearly demonstrated the presence of a tear film on the CL surfaces, but remnants neither of the ophthalmic solutions nor of the detergents could be found. CONCLUSION: Ophthalmic solutions are not effective in stimulating detachment of adhering bacteria from CL surfaces. Supplementing of an all-in-one CL-cleaning solution with only small amounts of detergents yielded a solution much more effective in stimulating bacterial detachment while leaving no detectable remnants of the ophthalmic solution or of the detergents on the CL surfaces.

van Setten, G.B. and N. Zengin

Adv Exp Med Biol, 1998. 438: p. 537-40.

Sadiq, S.A., et al.

Clao J, 1998. 24(3): p. 155-8.

PURPOSE: The purpose of this study was to evaluate the contamination of used disposable soft contact lenses with Acanthamoeba. METHODS: We evaluated 51 consecutive disposable soft contact lens wearers in a prospective study. Before their check-up visits, patients were offered a free new contact lens in exchange for donating their old one. The used contact lenses (n = 102) were then removed and placed in culture medium for Acanthamoeba. We subsequently investigated patterns of wear and hygiene habits. RESULTS: The mean age of this population was 32.6 +/- 11.0 years. The average time of disposable soft contact lens wear was 13.7 hours per day. The contact lenses were disinfected daily with commercial solutions. Twenty-five (49.0%) subjects did not clean their lens cases properly. Acanthamoeba was not isolated from any of the 102 lenses. CONCLUSIONS: There were no cases of Acanthamoeba contamination in a small population of disposable soft contact lens wearers who regularly disinfected their lenses with standard commercially available contact lens solutions.

Cook, B.E., Jr. and S.B. Holtan

Clao J, 1998. 24(2): p. 72.

Connor, C.G., et al.

Clao J, 1998. 24(2): p. 82-4.

PURPOSE: Fungal contamination of contact lenses is a common occurrence. In this study, we tested the effectiveness of currently used soft contact lens care systems against Aspergillus fumigatus. METHODS: We prepared and added 100 microL inoculums of 1 x 10(6) colony forming units/mL to each test solution. We exposed fungi to disinfectant for 4, 6, and 8 hours or to cleaning solution for 1 minute. We then diluted and plated the samples. After 48 hours, we counted the number of colony forming units. RESULTS: We represented the cleaning agent results as a percentage of the number of colony forming units found in the control at the same exposure period: Quick CARE Starting Solution--0%, MiraFlow- -12%, Opti-Free Daily Cleaner--41%, and PureEyes Cleaner/Rinse--82%. We calculated the percent control for 4, 6 and 8 hour exposures for each disinfecting solution: Opti-One--197%, 163%, and 109%; Quick-CARE Finishing Solution--84.6%, 55%, and 31%; ReNu--97.4%, 17%, and 4%; Complete--10%, 1%, and 0.4%; PureEyes Disinfectant/Soaking Solution-- 0%, 0%, and 0%; and Hydrocare--0%, 0%, and 0%. CONCLUSION: This study of contact lens care systems provides a direct comparison of their effectiveness against the same strain of Aspergillus. The results allow practitioners to select the appropriate care system for each patient.

Durban, J.J., et al.

Optom Vis Sci, 1998. 75(2): p. 126-31.

The antimicrobial efficiency of 20 commercially available solutions for soaking and rinsing soft contact lenses was studied in relation to 5 bacteria (Escherichia coli, Staphylococcus epidermidis, Pseudomonas aeruginosa, Bacillus subtilis, and Serratia marcescens) and 1 fungus (Candida albicans). Each product was separately inoculated with each of six microorganisms, and samples of the inoculated contact lens solutions were taken at predetermined times, placed in a recovery medium, and incubated. Where there was growth, the colonies were counted. There were differences in performance even between solutions labeled as having the same antimicrobial content. One of the solutions marketed in Spain to soak hydrogel contact lenses failed to inactivate all six test strains.

Stapleton, F., et al.

Aust N Z J Ophthalmol, 1998. 26 Suppl 1: p. S44-6.

PURPOSE: This preliminary study evaluated the efficacy of contact lens disinfection systems against Acanthamoeba castellanii, tested with and without co-incubation with Pseudomonas aeruginosa. METHODS: First, disinfection systems containing 3% hydrogen peroxide, 0.00005% polyaminopropyl biguanide or 0.001% polyquaternium were challenged with A. castellanii for 72 h. Surviving cells were enumerated. Second, A. castellanii were co-incubated with P. aeruginosa for 48 h, then exposed to the disinfectants for 6 h. RESULTS: There was zero survival of A. castellanii in hydrogen peroxide and variable survival in multipurpose systems. Following co-incubation, A. castellanii survival increased significantly (P = 0.015). CONCLUSIONS: Multipurpose systems have variable anti-amoeba activity and storage cases contaminated by bacteria may enhance amoeba survival.

Taylor, R.L., et al.

Optom Vis Sci, 1998. 75(1): p. 23-9.

PURPOSE: The purpose of this investigation was to measure the abilities of Pseudomonas aeruginosa and Staphylococcus epidermidis strains to adhere to two hydrogel lens materials and measure the effect of a protein-coated surface on the number of adhered bacteria. METHODS: Proteins absorbed to contact lenses during sleep were extracted, subjected to sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE), and probed for the presence of albumin. Bacterial adhesion was measured by counting bacteria adherent to contact lenses coated in vitro in increasing concentrations of albumin, examining the ability of albumin in solution to prevent adhesion to albumin-coated lenses, and examining the topography of bacterial adhesion by electron microscopy. RESULTS: Albumin adsorbed to lenses during overnight wear. In vitro studies demonstrated that Polymacon lenses adsorbed more albumin than Etafilcon A lenses. In general, the numbers of adherent bacteria increased with increasing concentration of albumin. Bacteria adhered in higher numbers to Polymacon lenses than Etafilcon A (p 0.05). P. aeruginosa showed an increased adhesion as the amount of albumin on Etafilcon A lenses increased. There was a decrease in numbers of bacteria adhering per milligram of albumin as the level of albumin increased on Polymacon lenses. Cells tended to adhere to "deposits" on albumin-coated lenses. DISCUSSION: Albumin adsorbed onto the surface of contact lenses modulated the ability of P. aeruginosa and S. epidermidis to adhere. P. aeruginosa is commonly associated with contact lens-associated microbial keratitis, where bacterial adhesion to contact lenses is believed to be an important first step in the pathogenesis of the disease.

Ky, W., K. Scherick, and S. Stenson

Clao J, 1998. 24(4): p. 216-9.

PURPOSE: Overall, contact lenses provide a safe and effective modality for vision correction. However, problems do occasionally arise. Up to 80% of contact lens complications can be traced to poor patient compliance with recommended lens care guidelines. We conducted a survey to evaluate the level of patient compliance in specific areas of lens care and maintenance and to assess patient knowledge of basic contact lens information. METHODS: Patients were asked to complete an anonymous 15 question survey that focused on lens care--specifically the use of contact lens cleaners, methods of disinfection, enzyme treatments, use of rewetting drops, and the frequency of follow-up exams. In addition, the survey included six true/false questions relating to contact lens care and safety. RESULTS: There were a total of 103 participants in the study. Approximately 24% of patients stated they never cleaned their lenses prior to disinfection, and 5% used saline solutions as their primary mode of disinfection. A sizable portion of those surveyed (43% of soft lens wearers and 71% of rigid gas permeable lens wearers) either never used enzyme cleaners or used them less than once a month. Seventy percent of patients either never used rewetting drops or used them less than once a day. Twenty-nine percent of patients consulted their eye care professionals every 2 years and 6% less often than every two years. Six questions assessed patient knowledge of contact lens care safety. Of a possible six out of six correct answers, the mean number of correct responses was 3.74. CONCLUSIONS: A sizable proportion of contact lens wearers do not adequately adhere to recommended contact lens care, and many have an inadequate understanding of contact lens care guidelines. Therefore, it is important that practitioners place more emphasis on patient education at the time of initial contact lens fitting and reinforce such instruction during follow-up visits.

Monti, P., et al.

Biospectroscopy, 1998. 4(6): p. 413-9.

Disposable soft contact lenses based on HEMA-MAA hydrogels are examined using Raman and ATR/FTIR vibrational spectroscopies and thermal analysis. The main factors dealing with physical, chemical, and biological biocompatibility are evaluated in relation to those of long- wear soft contact lenses with the aim of individuating the most biocompatible lens. The Raman spectra of HEMA-MAA lenses show that some biocompatibility factors are affected by environmental conditions and, in particular, by changes in pH and ionic strength values.

Morlet, N., et al.

Lancet, 1997. 350(9075): p. 414.

Ahearn, D.G. and M.M. Gabriel

Adv Appl Microbiol, 1997. 43: p. 35-56.

Brewitt, H.

Ophthalmologe, 1997. 94(5): p. 311-6.

BACKGROUND: Contact lens wearers are subject to increased risk of infection, and an attempt was made to determine which factors cause the overproportional risk of infection? PATIENTS: The aim of this paper is to explain with appropriate bibliographic support why people who wear contact lenses are at risk of infection. RESULTS: The relative risk of keratitis is a function of the lens material and the wearing time of the contact lenses. Extended wear of hydrogel lenses is associated with an overproportional risk of infection. According to the literature, the frequency of complications in contact lens wearers generally is the result of poor hygiene in 66% of the cases. The general lack of hygiene among contact lens wearers must, therefore, be regarded as one cause among pathophysiological mechanisms of the eye. The microbial spectrum favors gram-negative bacteria living in a wet environment such as Pseudomonas, Serratia and parasites like Acanthamoeba. CONCLUSION: The specific spectrum of pathogens and new problem organisms not only challenge the fitter but also the manufacturers to adapt hygiene (sanitary) measures and products to the new development. Disposable contact lens systems are the first step, but they do not solve all the problems of contact lens wearers. Therefore, the importance of contact lens hygiene must be especially emphasized when the ophthalmologist is giving instructions to the patient. On the other hand, hygiene should also not be neglected by the contact lens fitters since it is part of the whole problem.

Brewitt, H.

Klin Monatsbl Augenheilkd, 1997. 211(2): p. aA7-10.

Contact lens wearers, especially those who wear soft or extended wear contact lenses, are at increased risk of suffering from keratitis. Among the causes of corneal infections, an inadequate hygiene or overextended wear play an important role. An insufficient cleaning and disinfection leads to contamination with pathological germs. Sites of entry for these germs are corneal microlesions, caused by the setting and removal of contact lenses, and epithelial defects, as a result of the wearing of old or defective contact lenses. Primary eye diseases of patients who wear contact lenses can be altered by their wearing, and vice-versa. Even more, miscellaneous infections may lead to infectious corneal ulcerations. Having an adequate hygiene, a proper patient orientation during the medical visit, and a regular control are therefore of great importance for the reduction in the frequency of such infections by patients who wear contact lenses.

Bontempo, A.R. and J. Rapp

Curr Eye Res, 1997. 16(8): p. 776-81.

PURPOSE: To investigate the mechanism of protein-lipid interactions responsible for biofilm formation on the surface of hydrophilic contact lenses in vitro. METHODS: New, never-worn hydrophilic contact lenses were individually incubated in a protein-only, lipid-only, or combination protein-lipid artificial tear solution for 24 hours at 37 degrees C with constant stirring. Deposited lipids were removed with a methanol based extraction procedure, separated using high-performance, thin layer chromatography and quantitatively analyzed densitometrically. Deposited proteins were extracted with 4M urea, separated using gel electrophoresis and quantitatively analyzed densitometrically. RESULTS: The presence of protein in the artificial tear solution has a profound effect on the nature of lipid deposition for each group of hydrophilic lens, whereas the presence of lipid has a significant effect on the nature of protein deposition for only a group IV lens. In addition, the presence of lipid deposits on a group IV lens decreases the adsorption of lysozyme, while the presence of protein deposits reduces the amount of total lipid adhering to a group II lens. CONCLUSIONS: Protein adsorption on a group IV lens renders the lens surface less hydrophilic and, thereby, more susceptible to lipid deposition, which in turn increases surface hydrophobicity and inhibits additional protein deposition. For a group II lens, positively charged protein competes with and replaces some of the polar lipids attached to the lens. Thus, the interaction of protein and lipid on a lens surface most prone to a particular contaminant apparently makes it less likely for that contaminant to bind.

Vaahtoranta-Lehtonen, H.H., O.P. Lehtonen, and O. Peltola

Clao J, 1997. 23(4): p. 270-4.

PURPOSE: We compared Ethyl-6-O-decanoyl-glucoside 0.005% (EDG) combined with 0.00025% chlorhexidine acetate (EDGC) to a commercial polyaminpropylbiguanide (PAPB). METHODS: Fifty-nine subjects wearing both ionic and non-ionic contact lenses for 8-16 hours daily used either EDGC or PAPB as a cleaning and disinfectant agent. Neither mechanical nor separate cleaning agents were employed. The study period was for 8 weeks. The following symptoms were compared for each solution: blurred vision, dryness, foreign body sensation, redness, and dirty lenses. The following signs were also compared for each solution: conjunctival hyperemia, papillary hypertrophy, corneal deposits, purulence, limbal vascularization, subepithelial scarring, visual acuity, bulbar hyperemia, and tear breakup time. RESULTS: After 8 weeks, 52% of the subjects in the EDGC group showed no evidence of corneal or conjunctival abnormalities. In contrast, only 19% of the subjects in the PAPB group showed no abnormalities of the conjunctiva or cornea (P = 0.012). After 8 weeks, 25% of the EDGC group showed evidence of papillary hypertrophy, whereas 50% of the PAPB group showed similar findings (P = 0.007). In addition, after 8 weeks of wear, 21% of the subjects using EDGC had positive conjunctival cultures, whereas the rate of positive cultures in the PAPB group was 50% (P = 0.035). At the conclusion of the study, the protein contents of the lenses were 131 micrograms +/- 48 micrograms (N = 29) in the EDGC group and 185 micrograms +/- 65 micrograms (N = 26) in the PAPB group (P = 0.001). CONCLUSION: Subjects using EDGC had fewer pathological findings than subjects using PAPB as their cleaning and disinfecting agent. The mechanism by which EDGC reduced the rate of papillary hypertrophy needs further investigation.

Brewitt, H.

Klin Monatsbl Augenheilkd, 1997. 211(1): p. aA10-3.

The contactology as frontier between ophthalmology and eye optics requires special attention by part of ophthalmologists. Contact lenses influence the anatomy, the physiology and the immunological responses of the external eye. The corneal metabolic disorders of contact lens wearers are among others, the result of a diminished oxygen supply to the cornea. These disorders are influenced by contact lens deposits, tear film dysfunction and intrinsical characteristics of contact lenses. Sensibilisation and allergic reactions are result of the wearing of contact lenses. Even toxic reactions, as a result of the disinfection systems used, may be observed Ophthalmologists must be able to recognize the contact lens induced diseases and to advice their patients properly. Therefore, regular ophthalmological control examinations are indispensable.

Tan, A., B.K. Milthorpe, and J.W. Huff

Clao J, 1997. 23(3): p. 177-84.

PURPOSE: The purpose of this study was to develop a method for quantitating protein on rigid gas permeable (RGP) lenses and apply it to worn lenses. METHODS: We built a video microscope and wrote software to measure light absorbance by contact lenses before and after protein staining with Coomassie brilliant blue. We corrected for the temporal stability and spatial uniformity of the system, and set the iris aperture so that both lens surfaces could be simultaneously focused. We examined four RGP lens types worn by 22 patients. Standard curves were prepared with plastic discs spiked with dialyzed Coomassie blue-stained bovine serum albumin. RESULTS: The method was linear (R2 = 0.99) from 14 to over 100 microg protein per image and independent of dioptric power from -6 to +14 diopters. Protein quantities on worn Equalens II, Advent, Quantum II, and Fluoroperm 92 lenses were not significantly different (123 +/- 36, 111 +/- 28, 110 +/- 23, and 83 +/- 15 microg/lens; means +/- SEMs, P > 0.7). Patients differed (P 0.05) in protein deposition, independently of lens type, and fit a Poisson distribution. DISCUSSION: The method is adequate for quantitating protein on RGP lenses or for examining the efficacy of cleaning regimens or care systems. However, because of the non-Gaussian distribution of patient protein deposits, paired or cross-over experimental design and testing is recommended for studying protein deposition in clinical trials.

Olveczky, B.P., N. Periasamy, and A.S. Verkman

Biophys J, 1997. 73(5): p. 2836-47.

The decay of evanescent field intensity beyond a dielectric interface depends upon beam incident angle, enabling the 3-d distribution of fluorophores to be deduced from total internal reflection fluorescence microscopy (TIRFM) images obtained at multiple incident angles. Instrumentation was constructed for computer-automated multiple angle- TIRFM (MA-TIRFM) using a right angle F2 glass prism (n(r) 1.632) to create the dielectric interface. A laser beam (488 nm) was attenuated by an acoustooptic modulator and directed onto a specified spot on the prism surface. Beam incident angle was set using three microstepper motors controlling two rotatable mirrors and a rotatable optical flat. TIRFM images were acquired by a cooled CCD camera in approximately 0.5 degree steps for >15 incident angles starting from the critical angle. For cell studies, cells were grown directly on the glass prisms (without refractive index-matching fluid) and positioned in the optical path. Images of the samples were acquired at multiple angles, and corrected for angle-dependent evanescent field intensity using "reference" images acquired with a fluorophore solution replacing the sample. A theory was developed to compute fluorophore z-distribution by inverse Laplace transform of angle-resolved intensity functions. The theory included analysis of multiple layers of different refractive index for cell studies, and the anisotropic emission from fluorophores near a dielectric interface. Instrument performance was validated by mapping the thickness of a film of dihexyloxacarbocyanine in DMSO/water (n(r) 1.463) between the F2 glass prism and a plano-convex silica lens (458 mm radius, n(r) 1.463); the MA-TIRFM map accurately reproduced the lens spherical surface. MA-TIRFM was used to compare with nanometer z- resolution the geometry of cell-substrate contact for BCECF-labeled 3T3 fibroblasts versus MDCK epithelial cells. These studies establish MA- TIRFM for measurement of submicroscopic distances between fluorescent probes and cell membranes.

Ly, V.T., et al.

Optom Vis Sci, 1997. 74(5): p. 288-92.

The effect of various hand washing regimens on transfer of bacterial contaminants from the hands to a hydrogel contact lenses was evaluated. Each of 47 subjects performed 5 different hand washing procedures, and then handled a new, sterile hydrogel contact lens. The lenses were cultured to determine colony-forming units (CFUs) and microbial identity. Median CFUs on lenses handled after washing with water, soap and water, or soap and water followed by towel drying were higher than the median CFU for lenses handled after no hand washing. The median CFU for lenses handled after soap and water washing followed by an alcohol wipe was not different from the no washing group. The majority of the contaminants were identified as Staphylococcus epidermidis. These results show that ordinary hand washing alone does not decrease, and may even increase, the amount of contaminants transferred from the hands to a hydrogel lens. Use of an alcoholic wipe after hand washing reverses this effect. Hand washing is still recommended in contact lens hygiene for removal of more pathogenic contaminants.

Coopersmith, L. and F.J. Weinstock

Clao J, 1997. 23(3): p. 172-6.

PURPOSE: We evaluate contact lens wearers' compliance with practitioner recommendations through the analysis of survey data. Trends in practitioner recommendations on discarding intervals and frequency of disinfection for soft contact lenses are analyzed and compared to actual wearer usage. METHODS: The results of two primary surveys are used. One survey measures fit and wear recommendations for contact lens patients by eyecare providers during 1994 and 1995. The second survey was conducted at the end of 1995 to ascertain contact lens wearers' practices in contact lens wear and care. RESULTS: The general trend in practitioner recommendations is towards either disposable or frequent programmed replacement intervals coupled with daily disinfection. Approximately 15% of the brands marketed for disposable use were recommended for replacement at intervals longer than two weeks--the longest interval associated with disposable lenses. We observe a discrepancy between practitioner recommendations and the lens care provided by patients, noting a tendency to replace lenses at intervals longer than recommended. CONCLUSIONS: Trends in practitioner recommendations are consistent with expectations of providers. However, the observation that patients tend to increase their discarding intervals implies that practitioners could do better in educating their patients as to discarding intervals and in prescribing products that best match patient needs for both convenience and cost. These data should alert contact lens fitters to the importance of giving clear instructions to patients on how they should wear and care for contact lenses.

D'Aversa, G., et al.

Ophthalmology, 1997. 104(6): p. 962-9.

PURPOSE: The purpose of the study is to describe an entity referred to as advancing wave-like epitheliopathy and successful treatment of this keratopathy with 1% silver nitrate solution. METHODS: Eleven eyes of 7 patients were identified with advancing wave-like epitheliopathy. A thorough history and physical examination was performed on each patient, and attempts were made to identify the cause for the epitheliopathy. Six eyes with associated visual loss due to the epitheliopathy involving the visual axis were treated with 1% silver nitrate solution to the superior conjunctival limbus. RESULTS: Possible causes for the epitheliopathy included use of antiglaucomatous medications or contact lens care solutions (6 of 11 eyes), soft contact lens wear (4 of 11 eyes), a history of ocular surgery (3 of 11 eyes), or the presence of an underlying dermatologic or inflammatory disorder (3 of 11 eyes). All patients treated with 1% silver nitrate solution (6 of 6 eyes) experienced resolution of their symptoms with either complete or partial resolution of the epitheliopathy. CONCLUSIONS: Advancing wave-like epitheliopathy is a keratopathy characterized by centripetally advancing waves of coarse, irregular epithelium arising from the superior limbus. The cause appears to be multifactorial. Symptoms include ocular redness, irritation, and a decrease in visual acuity if the visual axis is involved. Application of 1% silver nitrate solution to the superior limbus is well tolerated and effective in treating this condition.

Melgosa, M., E. Hita, and M.J. Velasco

Optom Vis Sci, 1997. 74(4): p. 231-5.

An experimental study of Allergan's Oxysept Comfort system was performed by measuring the slight reddish hue that appears in the disinfecting solution, indicating to the users that their lenses are again ready to be worn. The temporal evolution of the color of the solution has been measured under standardized conditions and analyzed in the CIELAB system, from the perspective of the typical threshold discrimination of the human eye. Color differences between neutralized and non-neutralized solutions occurred in an appropriate direction of the color space to enhance discrimination and were clearly perceptible by normal observers (greater than 9.7 +/- 1.2 CIELAB units). Colorimetric analyses have been used to draw conclusions regarding observers with defective color vision. The color of the solution changes abruptly, approximately 25 min after the neutralization process begins, and remains nearly constant after about 60 min, this agreeing well with the temporal evolution of the hydrogen peroxide concentration.

Claydon, B.E., N. Efron, and C. Woods

Ophthalmic Physiol Opt, 1997. 17(2): p. 137-46.

The contact lens practitioner and patient present a specific case for the study of non-compliance in areas such as hygiene, solution use, appointment attendance and wearing times. Education is one of the factors thought to influence compliance among patients in general health care situations and contact lens practitioners are encouraged to educate patients in the care and maintenance of contact lenses. A prospective, randomized, controlled and double masked study was performed to assess the effect of a 'compliance enhancement strategy' on levels of compliance among contact lens wearers over twelve months. Eighty experienced contact lens patients were randomly allocated to two experimental groups. A standard level of contact lens instruction was applied to the first group and in addition the compliance enhancement strategy was applied to patients assigned to the second group. The strategy consisted of extra education for patients using a video, booklets, posters, a checklist and a health care contract. Patients were given free supplies of ReNu multipurpose solution and Medalist 38 soft contact lenses (Bausch and Lomb, Rochester, New York). Compliance levels were assessed at a twelve month aftercare appointment by demonstration and questionnaire. The results indicate that the compliance enhancement strategy had little significant effect on the compliance levels of the patients to who it was applied. The population of contact lens wearers were generally very compliant and the contact lenses and care regimen were clinically successful. The possibility that the assessment of non-compliance was not adequately sensitive to highlight small differences in non-compliant behaviour is discussed. The standard level of education applied to this sample of contact lens patient were adequate to ensure generally high levels of compliance with the simple care and maintenance regimen recommended.

Prager, M.D. and R.P. Quintana

J Biomed Mater Res, 1997. 37(2): p. 207-11.

Employing an artificial tear preparation composed of six proteins and six lipids as a deposit model, uptake of the lipids 3H-cholesteryl oleate and 14C-dioleoyl phosphatidylcholine was measured on contact lenses representative of the four FDA hydrogel groups and on select RGP lenses. Cholesteryl oleate uptake after 24 h at 37 degrees C generally was less than 1 microgram/lens although occasionally reaching 1-2 micrograms. DuraSoft 3 lenses (Group IV) accumulated the deposits in greater amounts (p = 0.04) with other lens groups not differing significantly from each other. Ionic DuraSoft 2 and 3 lenses bound more phosphatidylcholine (also 1 microgram) than other lens groups, possibly reflecting an interaction between the positively charged choline residue and the negative surface of the lens. Lysozyme deposition, measured simultaneously with cholesteryl oleate, bound to a far greater extent to Group IV lenses (e.g., DuraSoft 3, mean surface deposit 279 micrograms) than to other lens types (p 0.01). Multiple application of the artificial tear solution did not produce a statistically significant increase in cholesteryl oleate accumulation.

Bontempo, A.R. and J. Rapp

Curr Eye Res, 1997. 16(12): p. 1258-62.

PURPOSE: To investigate the mechanism of protein-lipid interactions responsible for biofilm formation on the surface of rigid gas-permeable contact lenses in vitro. METHODS: Two types of new, never-worn rigid gas-permeable contact lenses (siloxanyl alkyl acrylate and fluorosiloxanyl alkyl acrylate) were individually incubated in a protein only, lipid only, or combination protein-lipid artificial tear solution for 24 h at 37 degrees C with constant stirring. Deposited lipids were removed with a methanol based extraction procedure, separated using high performance thin layer chromatography and quantitatively analyzed densitometrically. Deposited proteins were extracted with 4M urea, separated using gel electrophoresis and quantitatively analyzed densitometrically. RESULTS: Lipid deposition on rigid gas-permeable contact lenses is dependent on lens matrix hydrophobicity while protein deposition is minimal and not material- dependent. The presence of lipid in the artificial tear solution enhances protein deposition on both types of rigid gas-permeable materials examined. The presence of protein in the artificial tear solution decreases lipid deposition on a siloxanyl alkyl acrylate lens. CONCLUSIONS: The hydrophobic nature of rigid gas-permeable contact lenses causes them to be more prone to lipid than to protein deposition. When both types of molecule are present in an artificial tear solution, the hydrophobic sites of the lipid molecules are attracted to the lens matrix while the more hydrophilic sites are repelled by the matrix and, thereby, exposed to the aqueous surroundings. Thus, lipid binding to rigid gas-permeable contact lenses reduces the hydrophobicity of the lens surface allowing protein to bind. The bound deposited hydrophilic protein then alters subsequent binding of both protein and lipid.

Lin, C.P. and M. Boehnke

Kao Hsiung I Hsueh Ko Hsueh Tsa Chih, 1997. 13(9): p. 562-5.

To determine the effect of RGP contact lens solution on corneal epithelial wound healing, the following solutions including Soaclens, Contopharma GPHCL-S, Boston condition, Bausch & Lomb condition and Duracare were applied on corneal epithelial wounds of enucleated pig eyes to evaluate possible cytotoxicity of RGP solutions. The wounds, created by excimer laser, were 1.5mm in diameter with 70 microns in depth. The eyeballs were maintained in an incubator using a perfusion system. After twenty-four hours, a score from 3 to 0 was given depending on the size of defect from absence of healing to completely healing. The average scores of the epithelial defect in each group are: Soaclens: 0.38 +/- 0.74; GPHCL-S: 0.63 +/- 0.52; Boston condition: 0.38 +/- 0.52; Bausch & Lomb condition: 0.25 +/- 0.46 and Duracare: 2.38 +/- 0.52. Most of the epithelial wounds healed with one exception, the eyeballs which received Duracare still had large defects. The difference of scores between Duracare and other groups are statistically significant. Duracare, which contains benzalkonium chloride, may be responsible for retarded wound healing.

Donzis, P.B.

Am J Ophthalmol, 1997. 124(3): p. 394-5.

PURPOSE: To report a complication of aerosol saline use in a contact lens wearer. METHODS: Case report. A 57-year-old woman who used soft contact lenses on an extended-wear basis developed a unilateral Pseudomonas corneal ulcer associated with the use of preservative-free aerosol saline. RESULTS: The solution inside the aerosol can was free of microbial contamination. The spray tip, however, was contaminated with P aeruginosa. CONCLUSIONS: Aerosol spray cans may minimize contamination of the solution inside the can. The spray tip is still susceptible to microbial contamination, especially with continued use of the solution over an extended period of time.

Fulk, G.W., R.D. Davis, and M.M. Abbey

J Am Optom Assoc, 1997. 68(5): p. 296-300.

BACKGROUND: The contamination of contact lens storage cases by gram- negative bacteria has been associated with ulcerative keratitis. This study investigated the concentration of endotoxin, a substance produced by gram-negative bacteria, in contact lens cases. METHODS: The limulus amebocyte lysate (LAL) test was used to measure the concentration of endotoxin in the storage cases of 27 contact lens wearers. The units of concentration used were endotoxin units per ml (EU/ml). The type of storage solution used by each patient, as well as other aspects of lens care and use, were recorded. RESULTS: Twenty-one storage cases--78% of those tested--contained measurable amounts of toxin. Two cases contained extremely high concentrations of endotoxin: 60 EU/ml and 300 EU/ml. Both cases were from persons using Opti-Free. Cases from six persons using Opti-Free accounted for five of the top seven endotoxin concentrations when cases were ranked on that basis. Fewer hours of daily lens wear and lower lens age were also possibly associated with higher concentrations of endotoxin, although those associations may have resulted by chance (p = 0.057 and p = 0.095, respectively). CONCLUSIONS: The LAL test was useful in estimating the degree of contamination of cases by gram-negative bacteria. Most cases contained measurable amounts of endotoxin, indicating at least some contamination by gram-negative bacteria. The effectivity of Opti-Free in inhibition of bacterial growth in contact lens cases should be investigated further.

Young, G., et al.

Clao J, 1997. 23(4): p. 226-36.

PURPOSE: We performed a six-month, comparative, contralateral/bilateral study to assess the clinical performance of the Proclear contact lens, which is manufactured from a novel, biomimetic, 59% water content, hydrogel material (Omafilcon A). Omafilcon A is a hydrogel polymer and is based on a new biomimetic approach to the design of biomaterials for biomedical applications. The polymer incorporates a synthetic analogue of the phosphorylcholine (PC) headgroup, an important component found in all human cells. METHODS: Forty-two subjects were fit with the Proclear lens for 6 months of daily wear; 20 subjects wore a Proclear lens in one eye and a Permaflex lens in the fellow as a control, while 22 subjects wore Proclear lenses in both eyes. A one-step hydrogen peroxide system was used for disinfection and no protein remover was used. RESULTS: No subject was required to withdraw due to unacceptable physiological findings with the Proclear lens. At the 3-month visit, corneal staining was present in 33% of the Proclear eyes compared to 72% of the Permaflex-wearing eyes. At one month, the Proclear lens was graded significantly more comfortable than the Permaflex lens (P 0.01), and all 11 of the subjects who expressed a preference did so in favor of the Proclear lens. Overall, the fitting characteristics and visual performance of the Proclear lens did not appear to vary during the study. Spectrofluorimetric analysis of worn lenses confirm that Proclear showed minimal protein and lipid spoliation, which was found to be independent of wear time and subject variations. In contrast, despite the use of a surfactant cleaner, Permaflex lenses showed measurable and significant levels of lipid spoilation. Despite significant differences in average mean thicknesses and the level of bulk water in the lenses, in vivo dehydration of the Proclear lens was significantly lower than that of the Permaflex lens. CONCLUSIONS: The results of this study have confirmed the viability of biomimetic PC- hydrogels in contact lens applications. In vivo and in vitro analyses tended to confirm that Omafilcon A has a number of superior material attributes, as compared to conventional hydrogels when used in contact lens applications.

Momose, T., et al.

Clao J, 1997. 23(2): p. 96-9.

PURPOSE: We evaluated the adsorption of levocabastine (LEV) eye drops onto soft contact lenses in rabbit eyes to confirm the safety of this antihistaminic and antiallergic agent. METHODS: Low- and high- water- content soft contact lenses were placed on the eyes of three rabbits for each type of soft contact lens (total: six rabbits) for 8 hours daily. LEV eye drops and physiological saline solution (used as a control) were instilled into the experimental eye and the fellow eye at a dosage of 0.1 mL per eye, at 1 hour intervals, eight times daily, for 6 consecutive days. Severity of possible eye injury was evaluated before soft contact lens insertion and after removal. RESULTS: After completion of the study, the amounts of LEV and the preservative benzalkonium chloride (BAK) adsorbed onto the soft contact lenses were assayed using high-performance liquid chromatography. There were no significant differences between the experimental solution and the control solution using Draize's method scores or slit lamp evaluation. CONCLUSION: LEV and BAK accumulated only slightly in the soft contact lenses, leading us to conclude that LEV eye drops could be used safely by soft contact lens wearers for about 1 week.

Ramachandran, L., et al.

Clao J, 1997. 23(2): p. 113-6.

PURPOSE: This study was undertaken to determine the extent of adhesion of cysts and trophozoites of Acanthamoeba to worn disposable hydrogel lenses and to study the effect of time, lens material, and washing on the adhesion. METHODS: Etafilcon A (58% water content) and Polymacon (38% water content) lenses worn on a 6 night extended wear basis and collected aseptically in PBS pH 7.2, were used for the study. Unworn lenses of the same materials were used as controls. Segments of lenses were incubated in Acanthamoeba suspension (cysts and trophozoites) and examined at 0, 5, and 24 hours, either washed or unwashed, for adherent Acanthamoeba. The amoebae adherent per square mm surface of the lens were enumerated. Levels of adhesion in various groups were compared using Wilcoxon sign rank test. RESULTS: At 0 hours, unwashed worn Polymacon lenses showed significantly greater adherence than Etafilcon A lenses compared to the controls (P = 0.0469). However, there was no difference at 5 and 24 hours exposure time between the lenses. At 24 hours the adhesion of Acanthamoeba was greater for washed worn lenses of both types compared to washed lenses of controls (P = 0.002, 0.012). CONCLUSIONS: Amoebae adhered with equal affinity to both types of lenses but adhered with greater affinity to worn lenses than unworn lenses. Adhesion of Acanthamoeba to worn disposable lenses may be a factor in the pathogenesis of Acanthamoeba keratitis in disposable lens wearers.

Prager, M.D. and R.P. Quintana

J Biomed Mater Res, 1997. 36(1): p. 119-24.

A systematic study has been made of the uptake of lysozyme by various contact lens materials. Lens uptake of 14C-methylated lysozyme was assessed using simple to complex artificial tear solutions. The data reflect prominent uptake by Group IV (ionic, high-water-content) hydrogel lenses, consistent with the literature. This includes protein on the lens surface and in the lens matrix, the former being estimated at about 33% of the total deposit for the DuraSoft 3 lenses used. Uptake appears to be contingent upon the nature of the lens material, the composition of the deposit model used, and the duration of lens exposure to the artificial tear solution.

Keith, D., B. Hong, and M. Christensen

Curr Eye Res, 1997. 16(5): p. 503-10.

PURPOSE: A quick, simple, and efficient extraction technique was developed for the removal of protein from soft hydrophilic contact lenses. METHODS: An extraction solvent consisting of a 50:50 mix of 0.2% trifluoroacetic acid and acetonitrile was used to remove protein from in vitro laboratory-deposited and human-worn contact lenses. The protein removed was analyzed using HPLC, bicinchoninic acid (BCA) analysis, and SDS-PAGE gel electreophoresis. RESULTS: Extraction efficiency for lysozyme from laboratory-deposited Group IV lenses was determined to be approximately 100%. Group IV human-worn contact lenses were extracted and analyzed for lysozyme by HPLC and total protein by bicinchoninic acid (BCA) analysis. Groups I, II, III, and IV contact lenses deposited with an artificial tear protein solution and human- worn lenses were extracted and analyzed by SDS-PAGE gel electreophoresis and micro-BCA. CONCLUSIONS: The ACN/TFA procedure offers a simple, quick, and efficient extraction technique for removal of protein from contact lenses for subsequent analysis.

Rosenthal, R.A., et al.

Clao J, 1997. 23(1): p. 57-62.

PURPOSE: The purpose of this study was to evaluate the effect of lens storage on the bactericidal activities of disinfecting solutions. METHODS: HYDROCURVEII (55% water content) soft contact lenses were soaked in OPTI-FREE Rinsing, Disinfecting, and Storage Solution (preserved with polyquaternium-1 [PQ-1]) or ReNu Multi-Purpose Solution (polyaminopropyl biguanide [PHMB]). After the lenses were removed, solutions were challenged with Pseudomonas aeruginosa and Staphylococcus aureus. Uptake of the antimicrobial agents by the lenses was evaluated by placing the lenses on plates seeded with S. aureus and observing for zones of growth inhibition. RESULTS: The bactericidal activity of the PHMB preserved solution decreased after 4 hours of storage time and showed no activity after storage for 3 days. Lenses soaked in the PHMB preserved solution produced zones of inhibition. The results suggest that the PHMB in the solution accumulates in the lens. This decreases the levels of preservative in the solution that is no longer available during lens storage. Neither decrease in bactericidal activity nor accumulation of the PQ-1 preservative in the lens occurred during storage with the PQ-1 solution. CONCLUSION: These results demonstrate that PQ-1 preserved solutions maintain bactericidal activity overnight and during prolonged storage without detectable uptake by lenses.

Parment, P.A.

Acta Ophthalmol Scand, 1997. 75(1): p. 67-71.

Serratia marcescens is a Gram negative rod which for a century and a half was considered a harmless saphrophyte. However, medical technology and the use of antibacterial agents have created ecological niches for this bacterium, which is now a medical problem. The bacterium is encountered in connection with contact lens keratitis, often associated with contaminated contact lens solutions. The concentrations of chlorhexidin and thiomersal required in contact lens solution to suppress the bacterium have been proved toxic to the eye. Modern contact lens solutions with biguanids have rapid killing kinetics, while in solutions with polyquaternium S. marcescens can survive in reduced numbers for up to 72 hours. The adherence of a specific isolate of Serratia to hydrogel lenses increased with decreased water content of the lenses. However, there has been no correlation between hydrophobicity markers or hemagglutinins and adherence to contact lenses or urinary tract epithelium. When handling medical plastic devices, such as contact lenses, strictly enforced hygiene remains the most important method to combat environmental bacteria such as Serratia marcescens.

Lee, S.M., et al.

Korean J Ophthalmol, 1997. 11(1): p. 39-50.

We applied ribosomal RNA gene (rDNA) polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) to identify Acanthamoeba isolates from contact lens paraphernalia, and characterized these on the basis of mitochondrial DNA (mtDNA) RFLP and isoenzyme analysis. The 22 Acanthamoeba strains used as reference strains were obtained from the American Type Culture Collection. Twenty- eight isolates were classified into six ribogroups, as follows: Acanthamoeba ribogroup (AcRG) 1 consisted of 18 isolates; AcRG 2, of three, AcRG 3, of three; AcRG 4, of two; AcRG 5, of one, and AcRG 6, of one. AcRG 1, which was the most frequently isolated type, was identified as A. lugdunensis, and AcRG 2 as A. hatchetti. AcRG 4 was identified as A. triangularis, while AcRG 3 and AcRG 5 were closely related to A. triangularis. AcRG 6 was identified as A. castellanii. The mtDNA RFLP patterns and zymograms for five isoenzymes of the isolates belonging to a ribogroup were identical to one another. The mtDNA digestion phenotype and zymogram for acid phosphatase (AcP) of AcRG 1 were identical to those of A. lugdunensis L3a and KA/E2, the type strain and corneal isolates from a Korean keratitis patient, respectively. The mtDNA digestion phenotype and zymogram for AcP of AcRG 6 were identical to those of A. castellanii Castellani and KA/E3, the type strain and another corneal isolate found in Korea, respectively. The mtDNA RFLP and zymogram for AcP of AcRG 2 were very similar to those of A. hatchetti BH-2 and Chang, respectively the type strain and a pathogen. The mtDNA RFLP and zymogram for AcP of AcRG 4 were similar to those of A. triangularis SH621, the type strain. The mtDNA RFLP patterns of AcRG 3 and 5 were unique. These results showed that the riboprints, mtDNA RFLP and zymograms of 22 of 28 Acanthamoeba isolates were the same as or very similar to those of the clinical isolates, which can probably be regarded as keratopathogens. More attention should be paid to the prevention of contamination by Acanthamoeba and to the disinfection of contact lens paraphernalia.

de Faria e Sousa, S.J. and L. Ventura

Ophthalmic Physiol Opt, 1996. 16(2): p. 184-6.

The available methods for the exact calculation of centre thickness presuppose that one knows simultaneously both surfaces of the lens and that the lens' power is determined afterwards. However, this approach is of secondary importance in practical situations. The issue in daily practice is the determination of the centre thickness of lenses that already have explicit vertex powers. In such cases one can set only one surface. The other has to be calculated following the prescription, the known surface and the optical effect of the centre thickness. Exact solution for this problem leads to four expressions, reflecting the number of ways one can treat it. Two of them are complete second-order algebraic equations and the other two, complete third-order algebraic equations. The practical value of the latter is limited by the fact that one cannot always obtain their three roots by pure algebraic procedures.

Sack, R.A., et al.

Curr Eye Res, 1996. 15(11): p. 1092-100.

PURPOSE: This study was designed to determine the effect of overnight eye closure on the rate and composition of protein deposition on high water content ionic matrix soft contact lenses (Group IV SCLs) and to extrapolate from this data information on the probable change in the rate of reflex-type tear secretion associated with eye closure. METHODS: Group IV SCLs were temporally sampled after equivalent periods of wear under closed eye (C) or open eye (O) conditions. Lenses were rinsed in saline and the majority of the tightly bound protein extracted at 90 degrees C in 40% urea, containing 1% SDS, 1 mM DTT, 100 mM Tris-HCl (pH 8.00). Residual protein was determined by Coomassie staining of the extracted lenses and densitometric analysis. Extracted protein was quantitated and separated by SDS-PAGE. Gels were either stained with Coomassie blue or reversibly stained with imidazole-zinc and blotted. Blots were PAS stained, or lectin and antibody probed for glycoproteins, secretory IgA (sIgA), IgG, lysozyme and complement C3. Laboratory simulated deposition studies were carried out on unworn lenses exposed to HPLC purified lysozyme. RESULTS: The protein in the saline rinse, to a large degree mirrored the composition of tear fluid in which the lens had been residing (O or C). This would suggest that the saline wash consists of residual tear fluid and loosely adherent protein. In contrast, the urea extracts were highly homogeneous consisting primarily of lysozyme and to lesser extent lysozyme dimer. This supports the contention that the Group IV SCL functions in the eye much as cationic exchange resin selectively absorbing lysozyme. C extracts also proved relatively enriched in trace amounts of sIgA, IgG and complement C3 and its breakdown products. High levels of C3 and C3 breakdown products were specifically recovered only in the C worn lens extracts from a subject experiencing unilateral contact lens associated corneal infiltrates from the affected eye. In all subjects, markedly less protein (lysozyme) was recovered in urea extracts of lenses exposed to 7-8 h of closed eye as compared to open eye wear (0.20 +/- .08 versus 0.79 +/- .15 mg/lens (n = 6)). Temporal studies further revealed that deposition was linearly related to duration of wear during the initial phase of conditioning film formation giving rise to rate constants for lysozyme deposition of 2.2 +/- 0.29 (n = 5) and 0.20 +/- 0.06 microgram/min (n = 4) under open and closed eye conditions respectively. With further wear, deposition eventually reached a steady state. Under laboratory conditions, lysozyme was much rapidly and quantitatively removed from solution in a manner following a hyperbolic plot. This suggests that during the initial phase of deposition the rate of deposition is limited by the capacity of the tear fluid to deliver lysozyme to the lens surface under these two extremes of conditions. CONCLUSIONS: Eye closure profoundly affects the rate of lysozyme deposition on Group IV hydrogels and the composition of minor biofilm constituents in a manner that could affect biocompatibility. Findings support the contention that eye closure results in a > 90% reduction in the rate of reflex-type tear secretion.

Tang, I., et al.

Optom Vis Sci, 1996. 73(12): p. 746-9.

Contact lens patient discomfort has been linked to the pH of lens care solutions differing from that of tears. To determine if this is a potential problem with multi-purpose soft contact lens solutions, we used a Fisher Scientific Accumet 950 pH/ion meter (accuracy +/- 0.05 pH units) to measure the pH of 3 multi-purpose solutions-Alcon's Opti-One, Allergan's Complete, and Bausch & Lomb's ReNu. The resulting pH values were compared to the threshold for ocular awareness, which is outside the zone of 6.6 to 7.8, and the pH value of tears of 7.45. Each solution was dispensed and measured daily over a 23- to 36-day period using 15-ml increments to simulate the amount used on a daily basis. The average pH of solutions tested were 7.18 +/- 0.02 for ReNu, 6.97 +/- 0.02 for Opti-One, and 7.55 +/- 0.02 for Complete. The highest and lowest pH values of all three multi-purpose solutions were found to be within the zone of ocular comfort and remained within a narrow value range throughout the testing period. Therefore, pH-induced discomfort is unlikely to occur when using these solutions on a daily basis. Nonetheless, practitioners should select lens care products carefully to ensure that the prescribed regimen meets the patient's needs.

Simon, M., et al.

J Fr Ophtalmol, 1996. 19(12): p. 738-42.

PURPOSE: This work aims to characterize products designed for cleaning contact lenses and particularly their physicochemical properties, their efficiency and their ocular irritancy potential compared to the main requirements of eye-washes. MATERIAL AND METHODS: The physicochemical controls include pH determination, viscosity and freezing point depression. In addition, we carried out the hydrogen peroxide assay for products containing this active substance. A microbiological control was performed when opening the product and after simulation of a 21-day aging. We determined the decontaminating efficacy of the products on four bacterial strains and a fungal strain. Finally, we tested their ocular allowance by an in vitro test. RESULTS: The pH values obtained ranged from 3.2 (oxygenated water solutions) to 7.6. The viscosity was close to a water solution one (about 1 centipoise). The different assays showed hydrogen peroxide content similar to that stated on the package: rate averaged to 3% and was negligible after neutralization. At opening and after simulation the bacteriological quality was excellent. Finally, decontaminating efficiency against germs was very good for the products tested. The products were classified as non- irritant by the ocular irritancy test. CONCLUSION: The results obtained show that the products tested met the reference criteria, particularly eye-wash criteria.

Soni, P.S., D.G. Horner, and J. Ross

Optom Vis Sci, 1996. 73(2): p. 70-85.

The purpose of this 3-year prospective study is to compare high school- aged subjects, randomized into wearing soft contact lenses and spectacles, in terms of ocular health, refractive status, and self- esteem. This report focuses on ocular response to the lens care systems used through the first 18 months of the investigation. Eighty-four subjects were randomly fitted with either CibaSoft Visitint or CibaSoft- Standard Visitint contact lenses. Three lens care systems, Ciba Vision AOSept Disinfection/Neutralization Solutions (AOSept), Opti-Free Rinsing, Disinfection, and Storage Solution (Opti-Free), and ReNu Multi- Purpose Solution (ReNu), were randomly prescribed to the subjects wearing contact lenses. Limbal congestion, conjunctival hyperemia, corneal staining with fluorescein, corneal edema, and corneal neovascularization were graded at dispensing and at 6-, 12-, and 18- month visits. There were no significant differences among the groups at baseline. At 6 months statistically significant difference (p = 0.0131, Kruksal-Wallis) was found for fluorescein staining of the cornea among the systems. At 12 months significant differences were found for corneal edema (p = 0.0404, Kruksal-Wallis) and neovascularization (p = 0.0315, Kruksal-Wallis) among the systems. At 18 months generalized conjunctival hyperemia was significantly different (p = 0.0234, Kruksal- Wallis) among the systems along with greater limbal congestion (p = 0.0015, Kruksal-Wallis) and neovascularization (p = 0.0238, Kruksal- Wallis). In conclusion, the cornea, limbal vessels and the conjunctiva respond differently to the lens care systems used in this study. Overall, patients using AOSept showed less corneal staining and inflammatory response than patients using ReNu and Opti-Free.

Liedel, K.K. and C.G. Begley

J Am Optom Assoc, 1996. 67(3): p. 135-42.

BACKGROUND: This investigation compared the efficacy of three widely used contact lens disinfection systems against an ocular isolate of Acanthamoeba polyphaga. METHODS: Twenty-seven worn Ciba NewVues lenses were quartered, heat sterilized and inoculated with Acanthamoeba. Lens quarters were then randomly assigned to three experimental groups, with Group A lenses exposed to cleaner and saline rinse only, Group B to disinfection only, and Group C to both cleaner and disinfection. One quarter of each lens served as a control and the other three quarters were experimental. Quantification of viable Acanthamoeba remaining on the lens was performed after each step of the disinfection process. RESULTS: Group A lenses showed no significant difference between the treatments, or the treatments and the control. Group B lenses demonstrated a significant difference (p = 0.0001) between the treatments and the control. In Group C (cleaning and disinfection), the control lens quarters were significantly different (p = 0.037) from the experimental group, but there was no significant difference between the treatments. CONCLUSIONS: All three disinfection regimens were very effective in reducing the number of viable Acanthamoeba on the contact lens surface. In the absence of proper cleaning (Group B), AOSept was the most effective of the three. These results also show the importance of thoroughly rubbing the contact lens surface to decrease the number of Acanthamoeba.

de Groot, A.C. and J.W. Weijland

Contact Dermatitis, 1996. 35(4): p. 248-9.

Midelfart, J., A. Midelfart, and L. Bevanger

Clao J, 1996. 22(1): p. 21-4.

PURPOSE: We performed a systematic examination of the rate and level of contamination of contact lens cases in a population of asymptomatic contact lens wearers using commercially prepared chemical disinfection solutions. METHODS: Solutions from the lens cases and from the conjunctiva of 21 asymptomatic contact lens wearers were examined. RESULTS: Contamination was found in five (24%) of the lens cases; four of the isolated microorganisms were recognized as potential ocular pathogens, namely Xanthomonas maltophilia, Pseudomonas cepacia, Serratia liquefaciens, and Serratia plymuthica. Serratia organisms have not been previously isolated from lens care solutions preserved with guanide, and, in addition, this was the first time that Serratia plymuthica has been isolated from a lens care system. Acanthamoeba was not detected in any of the examined samples, and no potential pathogens were isolated from the conjunctiva. Among students having contaminated lens cases, all reported problems such as itching, redness, dryness, and coating of the lens. CONCLUSIONS: The percentage of contaminated lens cases in this study was lower than in other studies. However, since the microorganisms identified in 80% of the contaminated lens cases were considered potential ocular pathogens, we feel contact lens wearers should be encouraged to frequently replace their lens cases.

Parment, P.A., B. Colucci, and B. Nystrom

Acta Ophthalmol Scand, 1996. 74(3): p. 235-7.

Samples of five different solutions for disinfection of soft contact lenses were experimentally inoculated with a strain of Pseudomonas aeruginosa or Serratia marcescens. No bacteria could be detected after one hour in solutions with biguanids, while they survived in reduced number up to 72 h in solutions with polyquaternium as active substance. However, prolonged survival after one week could not be detected. Lenses treated with polyquaternium based contact lens disinfectant solutions overnight may still harbour bacteria, which might increase the risk for bacterial complications, such as keratitis.

Garrett, Q. and B.K. Milthorpe

Invest Ophthalmol Vis Sci, 1996. 37(13): p. 2594-602.

PURPOSE: To improve the understanding of the formation of protein deposits on hydrogel lenses. METHODS: A study of protein adsorption on three commercial hydrogel contact lenses of different materials, Etafilcon A (2-hydroxyethyl methacrylate [HEMA] polymer with sodium methacrylate and 2-ethyl-2-hydroxymethyl-1,3-propanediol trimethacrylate), tefilcon (poly[HEMA] cross-linked and copolymerized with ethylene glycol dimethacrylate), and vifilcon A (methacrylic acid polymer with ethylene glycol dimethacrylate, HEMA and N-vinyl pyrrolidone) was undertaken by using a single protein solution, human serum albumin (HSA), and a radiolabel-tracer technique. RESULTS: Static adsorption leading to multilayer adsorption was observed. Complete reversibility for adsorbed HSA on lenses did not exist. Some was tightly bound, whereas most was loosely bound and could be removed easily by rinsing in phosphate-buffered saline. Irreversible adsorption of HSA on the lenses was found to be time dependent and did not reach a maximum value even after 48 hours of adsorption. The amount of HSA adsorbed on the lenses-irreversibly as well as totally adsorbed protein- was in the order of vifilcon A > tefilcon > etafilcon A. Adsorption of HSA on the lenses increases with decreasing pH (range, 7.4 to 4) but always follows the above trend with respect to the different types of lenses. CONCLUSIONS: Irreversible binding of HSA on lenses is governed by the kinetics of protein denaturation. Electrostatic interactions may not play a major role in HSA adsorption on hydrogel lenses. Some other factors, such as hydrophobic dehydration, and special monomer units, such as N-vinyl pyrrolidone in the lens materials, may favor adsorption of HSA.

Sousa, L.B., et al.

Clao J, 1996. 22(2): p. 114-7.

PURPOSE. Microbial keratitis caused by Pseudomonas aeruginosa is the most common contact lens associated corneal infection. Cecropins are microbicidal peptides isolated from the hemolymph of the Cecropia moth. Previous in vitro studies have demonstrated their efficacy against a broad spectrum of ocular pathogens. This study was designed: a) to evaluate the antimicrobial potency of three different contact lens solutions (Renu, Complete, and Opti-Free) against P. aeruginosa, and b) to evaluate the activity of the same contact lens solutions in combination with a synthetic cecropin analog, D5C, against the challenge organism in the presence of a soft contact lens. METHODS. A virulent strain of P.aeruginosa isolated from a case of ulcerative keratitis was used in the study. Three different concentrations of bacteria (10(3), 10(5) and 10(7) CFU/mL) were inoculated into the contact lens solutions and into buffered saline, which was employed as a control. The samples were incubated at 27 degrees C, and at time 0, 30, and 90 minutes, 24, 48, and 72 hours, and aliquots of the test solutions were plated and subcultured on nutrient agar. After 24 hours of incubation at 37 degrees C, colonies observed on the nutrient agar plates were counted. To study the antimicrobial efficacy of D5C (100 micrograms/mL), we used the identical test series and assay, adding a soft contact lens to the solutions and a larger inoculum of bacteria (10(9) CFU/mL). RESULTS. After 72 hours, all of the contact lens solutions tested sterilized 10(3) CFU/mL of P. aeruginosa. At 10(7) CFU/mL, they yielded greater than 2 logs of killing of the bacteria, but the solutions were not sterilized. The addition of D5C (100 micrograms/mL) to the contact lens solutions yielded greater than 3 logs of killing with a larger inoculum of bacteria in the presence of the soft contact lens. CONCLUSION. The contact lens solutions tested were effective against P. aeruginosa at 27 degrees C for up to 72 hours with an inoculum of 10(3) CFU/mL. The addition of D5C augmented their antimicrobial activity in the presence of the contact lens.

Zanen, A.

Bull Soc Belge Ophtalmol, 1996. 260: p. 9-16.

Transmission of infectious agents from a patient to the following one in the medical office may result from infected collyria, from contact to the cornea by infected instruments or simply by the hands of the medical staff if some rules of hygiene are not respected. The prevention comprises the instillation without contact of the collyria, the adequate disinfection of instruments and the frequent hand washing. The disinfection of the tonometers and contact glasses aims particularly the elimination of viruses. If the virus of herpes, hepatitis and acquired immunodeficiency are eliminated by hypochlorite, oxygenated water and alcohol after 10 minutes, the adenovirus which is not coated is on the other hand resistant to alcohol and may survive several days on instruments. Ideally the disinfection would have to be performed between each utilization by soaking in bleach water at 500 ppm, or in chloramine 0.5%, or in hydrogen peroxide 3% (during 10 minutes). The alcohol may damage the glue of diagnostic contact lens. The hypochlorite attacks the metal. In case of possible contact with the blood of the patient, the wear of gloves is counseled (for example for fluorescein angiography) and is of course mandatory for surgical procedures in the office like excision of chalazion or keratotomy. Disposable needles will be thrown in solid wall containers reserved to this aim without being recapped.

Fleiszig, S.M., et al.

Optom Vis Sci, 1996. 73(9): p. 590-4.

BACKGROUND: Staphylococcus epidermidis is a major causative agent of infectious keratitis associated with contact lens wear. Adhesion of this bacterium to contact lenses may contribute to the pathogenesis of infection and could be influenced by lens surface properties, packaging/storage solutions, and vary among different strains according to the level or type of adhesins expressed. METHODS: Adhesion of six clinical isolates of S. epidermidis to three different contact lens materials was tested. Adhesion assays were performed on lenses immediately after removal from their packages, and also after lenses were soaked in sterile phosphate buffered saline (PBS) for 7 days to dilute the packaging solution. RESULTS: For lenses tested immediately upon removal from their packaging, adhesion to polymacon (in PBS with 0.1% polyvinyl alcohol) was significantly greater than to etafilcon A (in borate buffered saline) and vifilcon A (in PBS). After soaking, adhesion to polymacon lenses was significantly less than to the other lens materials. This pattern was consistent for all strains, although major differences in baseline adhesion levels existed between strains, with exopolysaccharide (slime)-positive bacteria being more adherent to lenses. CONCLUSIONS: Properties of contact lens materials were not the sole determinant of viable S. epidermidis adhesion to lenses. Strain variability, including levels of exopolysaccharide expression, and the solution used for lens immersion also influenced adhesion.

Lumbroso, P., et al.

Clao J, 1996. 22(1): p. 61-3.

PURPOSE: We evaluated the adsorption and release of preservatives and a beta-blocking agent (metipranolol) by three different contact lens materials and two collagen shields. METHODS: We recorded the ultraviolet absorption spectra of these materials before, during, and after extended exposure to pharmaceutical preparations of artificial tears, beta-blocking eye drops, and a contact lens cleaning solution. The presence of preservatives and active ingredients was demonstrated by thin layer chromatography. RESULTS: Significant differences were observed depending on the nature of the absorbant materials and the preservatives. Soft lenses showed the greatest affinity for benzalkonium chloride and metipranolol but also readily released them. CONCLUSIONS: This preliminary study points out that rinsing with a sodium chloride isotonic solution without preservatives has an important place in daily contact lens care.

Durban, J.J., et al.

Optom Vis Sci, 1996. 73(8): p. 529-32.

Bacterial contamination of hydrophilic contact lens solutions may play an important role in contact lens-associated ocular infections. This study investigated bacterial contamination in 52 different hydrophilic contact lens solutions marketed in Spain by 12 different companies. We filtered the entire contents of 5 new, factory-sealed bottles from each of the 52 brands and cultured the fitter on a neutralizing broth plate. Bacteria were cultured, isolated, and identified from 29 of the 260 bottles tested (11.15%). Eight of the 52 brands had at least 1 of the 5 bottles contaminated (15.38%). Contaminated solutions originated from four different companies. One manufacturer contributed most of the positive cases due, presumably, to an industrial contamination by Pseudomonas fluorescens. The rest of the culture-positive bottles were contaminated by Bacillus spp. and Oerskovia spp.

Levey, S.B. and E.J. Cohen

Surv Ophthalmol, 1996. 41(3): p. 245-51.

The contact lens industry has grown rapidly over the past four decades due to the wide-spread demands of the American population for a convenient alternative to spectacle wear for the correction of myopia. Unfortunately, many people who wear contact lenses are not aware of the potential risks associated with them, and consumer education about lens care has not been adequate. This article reviews the role of disinfection in contact lens wear, summarizes the current available contact lens disinfection systems, and provides recommendations for safe contact lens use.

Lehtonen, O.J., et al.

Apmis, 1996. 104(7-8): p. 603-6.

Contact lenses with adherent Serratia marcescens and Pseudomonas aeruginosa could not be sterilised either with polyaminopropyl biguanide or with chlorhexidine (CHX) commercial solutions meant for contact lens disinfection, even after treatment lasting 12 h. Ethyl-6-O- decanoyl glucoside (EDG) with chlorhexidine enhanced the killing significantly. The same was also found to be the case for dispersed cells of P. aeruginosa on cellulose acetate filters. EDG enhances the bactericidal effect of 0.00025 CHX by a mechanism not solely due to detergent action and is a potential adjunct to CHX in clinical applications.

Key, J.E. and K. Monnat

Clao J, 1996. 22(2): p. 118-21.

PURPOSE. We compared the disinfecting efficacy of Pure Eyes Disinfectant and Opti-Free Rinsing, Disinfecting and Storage Solution, without recommended daily cleaning steps, against Pseudomonas aeruginosa. METHODS. Vifilcon A soft contact lenses were inoculated with the challenge organism, P. aeruginosa ATCC 15442, at a concentration of 1 x 10(8) colony forming units (CFU/mL) and disinfected with each solution for four and six hours, respectively. RESULTS. Pure Eyes eradicated P. aeruginosa after both four and six hour soak times. With all lots of Opti-Free, colony forming units were too numerous to count (> 200) for both soak times. CONCLUSIONS. We concluded that, because Pure Eyes disinfecting solutions can eradicate P. aeruginosa without the benefit of a daily cleaning step, this disinfecting process may offer protective benefits to noncompliant contact lens wearers.

Pritchard, N., D. Fonn, and K. Weed

Clao J, 1996. 22(1): p. 53-9.

PURPOSE: A significant number of soft contact lens wearers develop complications as a result of lens contamination. We conducted a single- blind 2 year clinical trial to determine if scheduled frequent replacement of lenses decreases complications. METHODS: One hundred nineteen non-contact lens wearers were fit with soft contact lenses and randomly assigned to 1 or 3 month replacement schedules or a non- replacement (control) group. All subjects were fit with 0.04 mm thick HEMA (water content: 38%) lenses to be worn on a daily wear basis only. A single multipurpose solution was prescribed for cleaning and disinfection. RESULTS: The 2-year results showed a significantly greater number of subjects in the non-replacement group exhibited microcysts, infiltrates, clinically significant corneal staining, and limbal and bulbar injection. As a result of lens deposition and damage, approximately twice the number of unscheduled lens replacements per subject were necessary in the non-replacement group compared with the 1 and 3 month replacement groups. Overall subject satisfaction with lens wear decreased in the non-replacement group and increased in the 1 and 3 month replacement groups over the 2-year period. CONCLUSIONS: Frequent replacement of soft lenses for daily wear as compared to non- replacement daily wear: 1) is less likely to cause contact lens induced complications; 2) reduces the number of unscheduled lens replacements; and 3) improves satisfaction with lens wear.

Gorlin, A.I., et al.

Curr Eye Res, 1996. 15(2): p. 151-5.

The numbers of Acanthamoeba binding to new hydrogel contact lenses of different polymer and water content were determined with two quantitative methods, a radiolabeled-cell method and a detaching-fluid method. Numbers of amoebae retained on nonionic lenses increased with increasing water content of the lenses. With both nonionic and ionic lenses numbers of associated amoebae decreased with successive rinsing steps. The retentions of amoebae on unworn hydrogel lenses, in contrast to the irreversible adhesion of bacteria, were tenuous and appeared to be effected mainly by surface tension, surface charge and water content.

Hemenger, R.P.

J Am Optom Assoc, 1996. 67(10): p. 606-9.

BACKGROUND: The superposition of thin sphero-cylindrical lenses with arbitrary angles between cylindrical axes is sometimes required in a clinical setting. For example, it may be useful in some instances to perform an overrefraction which, added to the spectacle or toric contact lens in place on the eye, yields a final correcting lens. METHODS: Computer calculations have been used to create contour graphs allowing a graphical solution to the problem of combining sphero- cylindrical lenses. Although conceptually strightforward, the method has not been presented before. RESULTS: The use of contour graphs to superpose sphero-cylindrical lenses is shown by examples to be accurate and much simpler than calculational methods. CONCLUSIONS: Lacking a pre- programmed computer, the method of contour graphs offers a practical method of combining sphero-cylindrical lenses.

Huang, S.C., N.A. Remeikis, and J.C. Daniel

J Endod, 1996. 22(1): p. 30-3.

Periodontal ligament (PDL) cells cultured from healthy extracted human teeth were exposed to milk, Alcon Opti-Free contact lens solution, K- Mart contact lens solution, saline, and Hank's balanced salt solution. The appearance and rate of loss of the cells from the culture dishes were recorded over time at both room temperature (20 degrees C) and 4 degrees C. The results indicated that saline was superior to either of the contact lens solutions in its ability to maintain the vitality of the PDL cells. Milk at 4 degrees DC provided good short-term viability , but cells did not remain attached after 48 h. At 20 degrees C, however, milk resulted in a 24.4% retention of cells after 72 h. Hank's balanced salt solution was the best storage media, with 46.8% of sells remaining attached after 72 h of exposure.This study supports milk as a good short-term storage medium for maintaining the vitality of PDL cells in vitro.

Sano, K., T. Tokoro, and Y. Imai

Acta Ophthalmol Scand, 1996. 74(3): p. 243-8.

We designed and evaluated a new drug delivery system (DDS) in which a drug plate containing levofloxacin was placed between a hydrophilic soft contact lens (SCL) and a non-hydrophilic SCL. The drug plate (diameter 8.0 mm, thickness 0.2 mm) was prepared by coating and freeze- drying a poly(vinyl alcohol) (PVA) disc containing 20, 30 or 40 wt% levofloxacin with a block styrene-(ethylene/butene)-styrene (SEBS) polymer solution. The release rate of the levofloxacin in vitro reduced with an increase in the concentration of SEBS polymer in solution used for coating. The release rate was well controlled and in zero-order kinetics was observed. The drug release from the drug plate consisting of a PVA disc loaded with 30 wt% levofloxacin and coated with 7.5 wt% SEBS polymer solution was 3.07 +/- 0.39 mg during 8 h. This drug plate was placed on an albino rabbit's eye wearing a hydrophilic soft contact lens (SCL), and then covered with a non-hydrophilic SCL. The drug concentrations in the anterior chamber were 156.0 +/- 133.6 micrograms/ml and 193.2 +/- 136.1 micrograms/ml after 4 and 8 h, respectively. The values obtained with frequent instillation of 0.5% levofloxacin every 30 min were 9.9 +/- 4.3 micrograms/ml and 12.5 +/- 10.0 micrograms/ml after 4 and 8 h, respectively. Therefore a significantly higher drug level was achieved with DDS compared to frequent instillation.

Hu, J., et al.

Clao J, 1995. 21(3): p. 154-5.

We developed a nondestructive, quantitative method for evaluating the cleaning efficacy of rigid gas permeable contact lens care systems. Simulated tears prepared with lysozyme, albumin, and calcium ions were applied to rigid gas permeable lenses as a protein soiling model, and a mixture of grease and unsaturated fat was applied as a lipid soiling model. The ComfortCare system (Pilkington Barnes Hind) and the Boston Cleaner and Boston Conditioning Solution (Polymer Technology) were evaluated for their efficacy in removing protein deposits; water was used as a control. The ComfortCare system and the Boston Advance Cleaner and Boston Advance Conditioning Solution were evaluated for their effectiveness in removing lipid deposits; saline was used as a control. Protein deposit level was detected by a densitometer at the absorbance of 280 nm. The lipid deposit level was evaluated by the absorbance of the fluorescence at 430 nm using the same densitometer with a fluorescence accessory. The two test systems demonstrated a significantly higher cleaning efficacy than the control for both soiling models. The methods provide quantitative measurements and therefore can be analyzed statistically for screening or comparison purposes.

Sivak, J.G., K.L. Herbert, and D. Fonn

Clao J, 1995. 21(3): p. 169-74.

We measured the potential toxicity of four contact lens solutions using an in vitro approach in which the optical quality of the cultured bovine lens was measured as a function of exposure to each substance tested. This approach uses an automated scanning laser to measure the focal variability of lenses contained in special culture cells and maintained under long-term culture conditions. The products tested included three rigid gas permeable contact lens conditioning solutions (Boston Conditioning Solution, Boston Advance Conditioning Solution, and a new formulation of Boston Advance Conditioning Solution [Polymer Technology]) and one soft contact lens disinfecting system (OptimEyes; Core Technologies). The results indicate a wide range of toxicologic potential that corresponds, on a relative basis, with published in vivo evaluation of the same substances. Moreover, the results demonstrate that this in vitro system can be used to evaluate the potential for recovery from damage caused by the four solutions tested.

Gray, T.B., et al.

Br J Ophthalmol, 1995. 79(6): p. 601-5.

BACKGROUND--Microbial corneal infection is the most serious complication of contact lens wear. Contact lens cases are a recognised potential source of pathogens associated with corneal ulcers. METHODS-- This survey established the incidence of protozoal, bacterial, and fungal contact lens case contamination in 101 asymptomatic daily wear cosmetic contact lens wearers from a domiciliary contact lens practice. RESULTS--Eighty two (81%) contact lens cases were found to be contaminated, with 19 (19%) sterile. Of all contact lens cases, 78 (77%) grew bacteria, 24 (24%) fungi, and 20 (20%) protozoa. Acanthamoeba spp were isolated from eight (8%) contact lens cases. Fifty six (55%) contact lens cases yielded mixed bacterial contamination. This is the first contact lens case survey in which hydrogen peroxide disinfection was the major method of contact lens disinfection (75% of subjects) and no home made saline was used. All the contaminating organisms were shown to possess the enzyme catalase that breaks down hydrogen peroxide to oxygen and water. The polymicrobial nature of the biofilms found in many contact lens cases is illustrated electron micrographically. CONCLUSION--Based on data from this and previous studies, the authors conclude with recommendations for contact lens wearers: (1) regular scrubbing of contact lens case interior to disrupt biofilms; (2) exposure of contact lens case to very hot water (> or = 70 degrees C) will kill Acanthamoeba contaminants; (3) allow contact lens case to air dry between uses; (4) if hydrogen peroxide disinfection is preferred, use a two step system; (5) replace contact lens case regularly.

Giasson, C. and J.A. Bonanno

Curr Eye Res, 1995. 14(4): p. 311-8.

Contact lens wear causes significant epithelial and stromal acidosis. In this study, we tested whether lens wear can cause endothelial acidosis as well. Rabbit corneas were isolated and perfused in vitro. The endothelial intracellular pH (pHi) was measured with a pH sensitive fluorescent probe (BCECF). Three conditions were examined: 1) Polymethylmethacrylate (PMMA) and rigid gas-permeable (RGP) contact lens wear using a range of oxygen transmissibility (Dk/L) from 0 to 121, 2) epithelial hypoxia produced by exposure to oligomycin/sodium azide solution or epithelial perfusion with 100% N2 equilibrated Ringer's solution, and 3) epithelial exposure to Ringer's equilibrated with 5% CO2, balance air. PMMA and RGP contact lens wear acidified endothelial cells by 0.23 +/- 0.01 (n = 23) and 0.11 +/- 0.01 pH units (n = 23), respectively, within twenty min of lens insertion. Epithelial hypoxia, induced by sodium azide and oligomycin, reversibly acidified the endothelium by 0.04 +/- 0.01 pH units (n = 4). However, epithelial hypoxia induced by perfusion with 100% N2 equilibrated Ringer's did not have a significant effect on endothelial pHi. Introduction of 5% CO2 to the epithelium, acidified the endothelium by 0.15 +/- 0.02 pH units (n = 7) within 10 min. We conclude that contact lens wear can significantly acidify corneal endothelial cells. The endothelial pHi change is caused almost exclusively by a build up of CO2 behind the lens; hypoxia having very little contribution. As expected, RGP contact lenses induced less endothelial acidosis than PMMA controls.

Fonn, D., C.A. Gauthier, and N. Pritchard

Optom Vis Sci, 1995. 72(12): p. 857-63.

Patient preferences and ocular responses were compared between rigid and soft contact lenses by randomly fitting 32 neophyte subjects with a rigid lens in 1 eye and a soft lens in the contralateral eye. Twenty- seven of 32 subjects completed the 3-month study and 16 subjects were willing to continue for an additional 3-month extension. Subjects preferred the comfort and handling of the soft lens but preferred the vision provided by the rigid lens and initially its ease of maintenance. There was also a marked preference for the soft lens when all aspects of lens wear were compared. Objectively, the rigid lenses were responsible for more ocular changes than the soft lenses. Palpebral aperture sizes of the rigid gas permeable (RGP) wearing eyes decreased significantly (0.5 mm; p 0.05) compared to the soft lens wearing eyes. The incidence of corneal staining was significantly greater in the rigid lens wearing eye (50% RGP vs. 22% soft) but limbal injection was greater in the soft lens wearing eye (18% soft vs. 6% RGP). Refractive sphere, cylinder, and corneal astigmatism decreased in the rigid lens wearing eye after 3 months. This daily wear clinical trial has shown a marked subjective preference for wearing soft lenses with fewer short-term ocular effects.

Farber, B.F., et al.

Ophthalmology, 1995. 102(5): p. 831-6.

PURPOSE: Nonsteroidal anti-inflammatory drugs, including sodium salicylate, inhibit extracellular bacterial biofilm production. The authors studied the effect of the addition of sodium salicylate on bacterial adherence and biofilm formation on contact lenses and cases and commonly used medical polymers. METHODS: The study was done in vitro with bacterial adherence and biofilm measured on lenses and cases that were exposed to saline contaminated with Staphylococcus epidermidis and Pseudomonas aeruginosa with and without 1 and 3 mm sodium salicylate. Bacterial adherence to contact lenses was quantitated by a vortex assay and by scanning electron microscopy. Biofilm formation on contact lens cases and other polymers was measured by an optical density assay and a radiolabeling assay. RESULTS: Inhibition of biofilm formation was demonstrated on plastic contact lens cases in a dose-related manner with 1 and 3 mm sodium salicylate. A dose-related decrease in bacterial adherence also was noted. Assays with contact lenses also demonstrated less adherence in the presence of sodium salicylate. Electron micrographs of the contact lens showed less biofilm, most noticeable with 3 mm salicylate. Other studies demonstrated decreased adherence of S. epidermidis to polyethylene and polystyrene. Sodium salicylate also decreased biofilm on plastic tissue culture wells, but sorbic acid paradoxically increased deposition. CONCLUSION: The authors found that the addition of low-dose sodium salicylate to saline decreased the adherence of S. epidermidis and P. aeruginosa to contact lenses and lens cases. Biofilm production also was decreased on the lens cases and on medical polymers used to make plastic cases. These studies suggest that sodium salicylate deserves additional study to determine its use in contact lens solutions.

Hay, J. and D.V. Seal

J Hosp Infect, 1995. 30 Suppl: p. 275-81.

Microbial keratitis can occur in association with contact lens wear. The absolute risk of infection is low but may be enhanced as a consequence of increased exposure to potentially pathogenic microbes in a hospital setting. There is variation in risk depending on type of lens worn and its modality of use. Extended-wear lenses carry the greatest risk. Pseudomonas aeruginosa and Acanthamoeba are causes of potentially devastating ocular infections in contact lens wearers. The risk of these infections could be reduced by fastidious hygiene practice. Hydrogen peroxide disinfection is recommended when a storage case is included in the care regimen. This should be cleaned thoroughly and dried prior to disinfection and never exposed to tap water. Daily wear of one-day 'disposable' soft contact lenses or use of rigid gas permeable lenses is recommended for hospital staff. Contact lenses should be removed immediately and discarded or disinfected if the eye becomes contaminated and/or use of an eyewash is required.

Soni, P.S., et al.

Clao J, 1995. 21(2): p. 86-92.

We fit eighty-five children between the ages of 11 years and 13 years, 11 months with soft contact lenses to study safety of soft contact lens wear in children. We report the results at 6 months of a 3 year longitudinal study. Contact lens care compliance, a critical factor in successful lens wear, was evaluated using a questionnaire. The questionnaire was completed by 74 subjects at dispensing and at 1-week and 6-months post-dipensing visits. Subjects found contact lens removal to be the easiest and lens insertion the most difficult procedures. After 6 months, 85% of the children correctly identified the purpose of lens care solutions, 90% knew that daily cleaning was necessary, 96% understood lens disinfection, and 99% expressed confidence in their ability to care for their lenses.

Rosenthal, R.A., et al.

Clao J, 1995. 21(2): p. 99-110.

We evaluated the antimicrobial activity of chemical and hydrogen peroxide-neutralizer contact lens disinfection systems. The acute activity, storage, and recontamination potential of the two disinfection methods were compared by challenging the disinfectants with Staphylococcus spp., Pseudomonas aeruginosa, Serratia marcescens, Candida spp., and Aspergillus fumigatus. Chemical disinfectants preserved with polyquaternium-1 and polyhexamethylene biguanide and hydrogen peroxide-neutralizer systems with no additional preservatives were tested. Additionally, lens cases from patients using both systems were evaluated. Lens cases from patients using peroxide-neutralizer systems tended toward heavier contamination (31.8%) than the cases disinfected with a chemical system (20.3%, P = 0.16). The laboratory results showed that the differences in activity of chemical and peroxide-neutralizer systems was not statistically significant at the disinfection times against Staphylococcus epidermidis, S. marcescens, Candida parapsilosis, and A. fumigatus (P = 0.1037 to P = 0.5412). A statistical difference was shown against C. albicans (P = 0.0176) in favor of the peroxide-neutralizer systems. The reverse was true during storage. Although the chemical disinfectants maintained the population of microorganisms, the bacteria and yeast increased to over 10(7) CFU/mL in neutralized peroxide systems. Overall, the results emphasize the importance of contact lens products containing preservatives for lasting protection from microorganisms.

Slonim, C.B.

Clao J, 1995. 21(4): p. 233-5.

The probability of the ophthalmologist and office personnel coming into direct contact with a patient infected with the human immunodeficiency virus (HIV) is extremely high. HIV has been recovered from the ocular tissues, tears, and soft contact lenses of patients with acquired immunodeficiency syndrome. All ophthalmic offices, especially those with a contact lens practice, must be aware of any potential risk of transmission of HIV to both the office staff and to other patients from HIV-infected patients through the use of trial contact lenses. To date, there has been no documented case of HIV transmission through human tears or contact lenses, and the risk of such a transmission is extremely low.

Guthrey, P., J.D. Bartlett, and K.P. Singh

J Am Optom Assoc, 1995. 66(6): p. 334-7.

BACKGROUND: Pharmacists' recommendations on selection and proper use of eye care products are important in terms of patient compliance with therapy. A questionnaire was designed to determine if educational differences exist between North Carolina and Alabama pharmacists with regard to ophthalmic drugs and procedures. METHODS: Pharmacists in Raleigh, North Carolina and Birmingham, Alabama were surveyed since these areas have similar populations and demographic characteristics but differed in the prescriptive authority accorded optometrists. RESULTS: Relative to familiarity, dispensing experience, and patient instruction on proper use, North Carolina pharmacists seem to have a statistically significant (p 0.05) better educational preparation and experience with three ophthalmic drugs and procedures: OTC decongestants, ointments, and eyedrop instillation procedures. Pharmacists of both cities felt they had insufficient knowledge and experience with numerous ophthalmic drug products, including antiglaucoma cap color codes, C-cap compliance caps, eyelid scrubs, contact lenses, and nasolacrimal occlusion procedures. CONCLUSIONS: Pharmacists appear to need more post-graduate education relative to ophthalmic drugs and procedures and could benefit from additional training on these subjects while in pharmacy school. Optometrists and ophthalmologists should educate patients about ophthalmic drug delivery, including eyedrop instillation procedures.

Nao, N., et al.

Acta Ophthalmol Scand, 1995. 73(6): p. 521-4.

The effects of intraocular irrigating solutions on electroretinography have been extensively studied in animal models, but effects on human electroretinography have not been reported. This study examined the effects of two commercially available irrigating solutions, S-MA2 (Opeguard MA) and DE-057 (BBS-Plus) on 30-Hz flicker electroretinography during closed vitrectomy in humans. Eight eyes of 8 patients were examined. All patients underwent a simple vitrectomy without treatment of proliferative membrane. For 30-Hz flicker electroretinography recording, a contact lens with a built-in light- emitting diode was sterilized and used as both a stimulus source and a recording electrode. Replacing S-MA2 with DE-057 decreased the electroretinography amplitude from 55.8 +/- 15.2 to 45.5 +/- 13.2 microV (mean +/- SEM). Changing the irrigation solution from DE-057 back to S-MA2 increased the amplitude from 45.5 +/- 13.2 to 59.9 +/- 17.3 microV. However, these changes were not statistically significant. Replacing S-MA2 with DE-057 significantly increased the peak time from 50.1 +/- 1.5 to 57.6 +/- 1.3 msec (p 0.001). This change was reversible; after changing from DE-057 back to S-MA2, the peak time of flicker electroretinography significantly decreased from 57.6 +/- 1.3 to 49.0 +/- 2.1 msec (p 0.01). Thus intraoperative 30-Hz electroretinography showed delayed peak time during irrigation with DE- 057, as compared with S-MA2. The lower potassium concentration and higher glucose concentration of S-MA2, as compared with DE-057, may be the cause of such electroretinography changes.

Semes, L.

Optom Vis Sci, 1995. 72(5): p. 296-8.

The Occupational Safety and Health Act empowers the Occupational Safety and Health Administration (OSHA) to establish a standard when it determines that a significant risk to employees exists. Leading to the OSHA bloodborne pathogen Standard were the following events: recognition of Hepatitis B virus as an occupational hazard where blood and body fluids are handled. Similarly, the human immunodeficiency virus (HIV) had been shown to infect those exposed to blood and body fluids, and OSHA was petitioned by two unions to require employers to require Hepatitis B vaccine free of charge and to mandate general infection control practices as recommended by the Centers for Disease Control (CDC) as early as 1983. OSHA determined that the risk of contracting Hepatitis B virus and HIV was significant and that the final bloodborne pathogens Standard would substantially reduce that risk.

Roth, H.W.

Med Monatsschr Pharm, 1995. 18(1): p. 3-12.

Illingworth, C.D., et al.

Br J Ophthalmol, 1995. 79(12): p. 1078-82.

AIMS/BACKGROUND--This study was initiated to investigate risk factors for and outcome of Acanthamoeba keratitis. METHODS--Results of treatment were studied in 22 patients (23 eyes) presenting to Bristol Eye Hospital between 1985 and February 1995. Details related to the use and disinfection of contact lenses were also obtained. An additional two patients who were seen at Bristol but mainly treated elsewhere were surveyed for contact lens related information only. RESULTS--The incidence of Acanthamoeba keratitis rose substantially in the 1990s: three patients presented before 1990, while the remaining 21 presented between January 1990 and February 1995. Eleven patients have presented since january 1994. All of the patients in this series were contact lens wearers, 16 (67%) using daily wear disposable contact lenses. Contact lens disinfection data were available in 22 patients of whom 11 (50%) were using chlorine disinfectant. Other types of disinfection were much less common. Four patients (18%) had not used any disinfectant. During the course of the series the average diagnostic delay has fallen markedly, although in 77% of patients a diagnosis of a viral keratitis, most commonly herpes simplex, was made on first presentation. All but three of the series were treated with a combination of polyhexamethylene biguanide and propamidine isethionate. Penetrating keratoplasty was performed in 9/23 eyes (39%); in all of these eyes diagnosis was delayed for at least 6 weeks. All but one of the eyes in the series achieved a visual acuity of 6/9 or better after treatment, and 18 eyes (78%) saw 6/6 or better. CONCLUSIONS--Most patients with Acanthamoeba keratitis can now expect a good visual result and cure by medical therapy alone is favoured by early diagnosis.

Dorigo, M.T., R. De Natale, and P.A. Miglioli

Chemotherapy, 1995. 41(1): p. 1-4.

Collagen shields have been used as therapeutic contact lenses to promote corneal epithelial healing and to deliver hydrosoluble drugs. In albino rabbits, we studied the ocular pharmacokinetics of netilmicin, an aminoglycoside antibiotic, released by a 24-hour collagen shield immersed for 10 min in commercially available eye solution of netilmicin, at the standard concentration of 3 mg/ml. The animals were sacrificed after 0.5, 1, 6 and 18 h. The antibiotic concentrations were measured by the microbiological method. The drug levels remained above the MIC for the usual pathogens for 18 h in the cornea and for 6 h in the aqueous humor. In the iris and ciliary body the peak concentration was reached 1 h after shield application, netilmicin concentration decreased thereafter rapidly. The lens and the vitreous did not appear to be permeated by the drug. In the conjunctiva, drug concentrations were low, showing a negligible lateral diffusion of netilmicin released by shields. In conclusion, our findings show, that if the collagen shields are used as delivery systems, a very concentrated drug solution is not required to obtain high and persistent levels of netilmicin in cornea.

Stapleton, F., et al.

Epidemiol Infect, 1995. 114(3): p. 395-402.

This study evaluated the epidemiology of Pseudomonas aeruginosa keratitis in contact lens (CL) wearers; the relationships between CL storage case contamination and CL hygiene practice and between CL hygiene and the development of keratitis. Sixteen CL wearers with keratitis were compared with 44 asymptomatic controls. Lens hygiene practice was assessed and CL care materials, domestic water sites and endogenous sites were evaluated microbiologically. Poor CL hygiene was not associated with Ps. aeruginosa keratitis. There was an association between keratitis and bacterial contamination of the CL and storage case (P 0.0005). Lens and storage case contamination were not significantly associated with poor hygiene. No domestic or endogenous source for Ps. aeruginosa was found. Causative organisms may be derived from other sources, but CLs and CL storage cases provide a favourable environment for Ps. aeruginosa colonization. Changing the CL care environment to one less favourable for Ps. aeruginosa may help to eliminate this problem.

Dart, C.R., S.V. Goddard, and R.P. Cooke

J Hosp Infect, 1995. 29(4): p. 297-300.

A survey of ophthalmic decontamination protocols in eight district hospitals was undertaken. Procedures differed widely. A literature search revealed only four publications on the subject, all of which dealt with tonometer head disinfection only. After discussion with several manufacturers, whose advice was restricted largely to acrylic lens disinfection and which varied considerably, a local policy for ophthalmic decontamination was established. Nationally agreed disinfection guidelines for high risk ophthalmic instruments are needed.

Coiffard, L., P. Rivalland, and Y. De Roeck-Holtzhauer

J Fr Ophtalmol, 1995. 18(1): p. 33-9.

OBJECTIVE OF THE STUDY: We characterized some market products designed for cleaning contact lenses and we compared their properties to the main requirements of eye-washes. MATERIAL AND METHODS: We performed several physicochemical controls including pH determination, viscosity with a Baume apparatus and the decreasing of the freezing point following the method described by the French Pharmacopea. In addition, we carried out certain analytical controls, concerning three active principles (thiomersal, chlorhexidin digluconate, hydrogen peroxide), at the opening of the different package and after accelerated aging. A microbiological control was performed when opening the product and after a simulation of a 5-day aging. We finally determined the efficacy of the products on four bacterial strains for tests and of deproteinizing products on artificial dust. RESULTS: The pH values obtained ranged from 4.0 (oxygenated water solutions) to 7.8. The viscosity was close to a water solution one. Contents in active substances were usually similar to those stated on the package. At opening, the bacteriological quality was excellent. But, the multidose package were highly contaminated when used. Finally decontaminating efficacy against some germs was very good for the products tested. CONCLUSION: The results obtained show that the rincing products best answer the eye-wash criteria taken as references. Their main disadvantage is their contamination in the case of multidose packaging.

Chowhan, M.A., B. Asgharian, and F. Fontana

Clin Ther, 1995. 17(2): p. 290-5.

The comfort of rigid gas-permeable contact lenses is influenced by multiple factors, including the composition of lens material and the presence of surface deposits and/or cleaning solution residues on the lens, as well as the direct effect of lens care solutions on the lens and eye. This study was designed to examine the comparative properties of several soaking solutions with respect to wettability, viscosity, and substantivity, which are essential to maintaining patient comfort. Solutions included in this trial were: OPTI-SOAK Conditioning Solution, Boston Advance Conditioning Solution, Boston Advance Conditioning Solution, Boston Conditioning Solution, Barnes-Hind Wetting and Soaking Solution, Duracare Conditioning, and Total Cleaning, Wetting & Soaking Solution. Wettability, as indicated by mean wetting angle, was determined and OPTI-SOAK Conditioning Solution, followed by Boston Advance and Boston Conditioning solutions, respectively, yielded superior results. For viscosity, OPTI-SOAK Conditioning Solution again provided the most favorable (highest) viscosity, followed by Boston Conditioning and Barnes-Hind solutions. With regard to substantivity, a measure of sustained wettability, Boston Conditioning Solution achieved the highest measurement, followed by OPTI-SOAK and Boston Advance solutions. On the basis of this in vitro evaluation, OPTI-SOAK Conditioning Solution provided the highest potential for patient comfort based on a combination of wettability, viscosity, and substantivity.

Chiselita, D., et al.

Oftalmologia, 1995. 39(3): p. 205-13.

The retrospective analysis of the postoperative course in 204 traumatic cataracts (140 isolated, simple cataracts and 64 aggravated ones) showed an apparent functional improvement in the simple cases (preoperative and postoperative visual acuity 0.0139 and 0.8520, respectively); the incidence of postoperative detachment of retina was of 4.9%, that of postoperative endophthalmitis that of cystoid macular edema of 3.2%; complications more commonly occurred in aggravated traumatic cataracts and partially accounted for the poorer functional results. During the investigated interval (1988-1992) a rapid shift to extracapsular cataract extraction and posterior chamber lens implants was made. The crystalline grafts preserved binocular vision in 92% of the cases and contact lens in 50% of the cases. Lens implant remains a matchless solution for the visual rehabilitation of the patients with aphakia.

Bergmanson, J.P. and R. Barbeito

Ophthalmic Physiol Opt, 1995. 15(6): p. 535-44.

The issue of possible adverse effects of contact lens care solutions on ocular health has been raised in the literature. Possible effects of a multipurpose contact lens care solution (Bausch & Lomb ReNu) on eight measures of ocular function were evaluated relative to the effects of physiological saline (Bausch & Lomb Sensitive Eyes). In a randomized, two-treatment, crossover design, all subjects were treated with each of the two solutions on successive weeks. In 73 subjects, comprised of contact lens and non-lens wearers, tear break-up time was measured using the keratometer mire and fluorescein techniques. Measures of autonomic function were vertical palpebral aperture size, amplitude of accommodation, intraocular pressure, pupil size, conjunctival injection, and pupil reactivity. The results indicated that this multipurpose solution provoked no adverse ocular response as determined by the tear break-up time and autonomic functions, and the multipurpose solution was clinically equivalent to physiological saline. These results apply to both contact lens wearers and non-lens wearers. Additional findings speak of the unreliability of the fluorescein method for measuring tear break-up time.

Aswad, M.I., J. Baum, and M. Barza

Am J Ophthalmol, 1995. 119(6): p. 738-43.

PURPOSE: Bacterial contamination of previously worn soft contact lenses, especially at sites of lens deposits, might play a role in the pathogenesis of lens-associated bacterial keratitis. We studied the effects of three commercial contact lens cleaners and disinfectants in a rabbit model to determine whether cleaning and disinfection reduced infectivity. METHODS: Duragel 75 soft contact lenses, designed to fit the eyes of rabbits, were worn by rabbits under tarsorrhaphies, then were removed and cleaned in one of three cleaner and disinfectant solutions according to the manufacturers' instructions. The lenses were contaminated by overnight incubation in a suspension of 10(8) Pseudomonas aeruginosa/ml and were placed under tarsorrhaphies on the eyes of fresh rabbits. The rabbits were observed for two weeks for signs of infection. Control rabbits wore new, uncleaned but contaminated lenses or worn, uncleaned but contaminated lenses. RESULTS: The rates of infection with the three commercial cleaner and disinfectant solutions ranged from 18% (two of 11) to 31% (four of 13); these incidences were not significantly different from one another or from the 19% (three of 16) incidence with new, contaminated but uncleaned lenses. By contrast, when worn, uncleaned but contaminated lenses were placed in rabbits' eyes, seven of eight were infected, a rate that is significantly higher than that of the other four groups (P = .0003). CONCLUSIONS: These data indicate that the three commercial lens cleaner and disinfectant solutions were of similar efficacy in reducing the infectivity of contaminated contact lenses to a level similar to that of new, unworn lenses.(ABSTRACT TRUNCATED AT 250 WORDS)

Radford, C.F., et al.

Bmj, 1995. 310(6994): p. 1567-70.

OBJECTIVE--To investigate reasons for an increase in cases of Acanthamoeba keratitis related to contact lenses. DESIGN--Case-control study. Cases were contact lens related acanthamoeba keratitis patients treated between 1 September 1989 and 31 August 1992. Controls were lens users without lens related disease who presented as new patients to the casualty department from 1 March 1992 to 31 August 1992. All subjects completed a questionnaire detailing lens use and hygiene practices. SETTING--Eye hospital. SUBJECTS--35 cases with acanthamoeba keratitis and 378 controls. MAIN OUTCOME MEASURES--Relative risks comparing different contact lens types, socioeconomic classification, age, sex, lens use, lens wearing experience, hygiene compliance, and hygiene systems. RESULTS--The crude relative risk for developing acanthamoeba keratitis with the use of daily wear disposable lenses was 49.45 (95% confidence interval 6.53 to 2227; P 0.001) compared with conventional soft lenses (the referent). Multivariable analysis showed that this increased risk could be largely attributed to lack of disinfection (relative risk 55.86 (10 to 302); P 0.001) and use of chlorine based disinfection (14.63 (2.8 to 76); P = 0.001) compared with other chemical systems (the referent). None of the other outcome measures showed a significant association. CONCLUSIONS--Both failure to disinfect daily wear soft contact lenses and the use of chlorine release lens disinfection systems, which have little protective effect against the organism, are major risk factors for acanthamoeba keratitis. These risks have been particularly common in disposable lens use. Over 80% of acanthamoeba keratitis could be avoided by the use of lens disinfection systems that are effective against the organism.

Itoi, M., et al.

Clao J, 1995. 21(4): p. 261-4.

We evaluated the efficacy of sodium hyaluronate ophthalmic solutions on 3 and 9 o'clock staining with rigid contact lens wearers in a double masked multicenter study involving four institutions and 43 patients. Both sodium hyaluronate (0.1%) and control ophthalmic solutions (artificial tears) without preservative were used. Patients were randomly divided into two groups. The test group received sodium hyaluronate ophthalmic solution, and the control group received artificial tears as a control ophthalmic solution. The agents were instilled six times per day for 2 weeks while patients wore contact lenses. Although subjective symptoms improved similarly in the two groups, slit lamp observation, corneal staining, and anterior segment photography demonstrated improved results in eyes having received sodium hyaluronate ophthalmic solutions. We conclude that sodium hyaluronate ophthalmic solution is effective and safe for treating 3 and 9 o'clock staining in rigid contact lens wearers.

Jarkman, S. and R. Bragadottir

Doc Ophthalmol, 1995. 89(3): p. 251-66.

This study was undertaken to investigate further the responsiveness of the albino rabbit retinal pigment epithelium and the inner retina to adrenergic agents as reflected in changes of the direct-current electroretinogram and of the standing potential of the eye. After unilateral vitrectomy on albino rabbits, a continuous intraocular perfusion with a reference solution was established. The reference solution was then alternated with the test solution. The direct-current electroretinogram and the standing potential were recorded from both eyes with a scleral contact lens and a reference electrode connected to matched calomel half-cells. An in vivo experimental technique that allows intraocular perfusion of a test substance and simultaneous intraretinal microelectrode measurements was also used. The alpha- adrenergic agonist phenylephrine (0.04 microM, n = 8) produced a reversible increase in c-wave amplitude (48%, p 0.001) and also a small increase in b-wave amplitude (12%, p 0.002). There was no significant influence on the a-wave amplitude. The standing potential was elevated at 1694 +/- 362 microV (mean +/- SEM) (p 0.002). The alpha 2-adrenergic agonist clonidine caused similar effects on the electroretinogram, although at a higher concentration (40 microM, n = 5), with an elevation of the c-wave (25%, p 0.001) and a small b-wave increase (12% p 0.002). No significant influence on the a-wave or on the standing potential was found. Intraretinal direct-current electroretinogram-recordings during intraocular perfusion with phenylephrine showed an increase in transepithelial potential (p 0.004; n = 6), accompanied by a reduction of the slow PIII (p 0.0035; n = 6). The c-wave increase resulting from alpha-adrenergic stimulation seems to be generated partly across the retinal pigment epithelium, with an increase in transepithelial potential, combined with a reduction of the slow PIII. The elevation of the b-wave amplitude, together with the influence on the slow PIII, suggests alpha-adrenergic effects also on the inner retina. The experimental technique used in this study with intraocular perfusion after vitrectomy and simultaneous intraretinal direct-current recordings seems to be a practicable method for studies of the influence of pharmacologic agents on the retina and the retinal pigment epithelium.

Seal, D.V. and J. Hay

Bmj, 1995. 311(7008): p. 808.

Zabel, R.W.

Can J Ophthalmol, 1995. 30(1): p. 33-4.

Zanetti, S., et al.

Antimicrob Agents Chemother, 1995. 39(7): p. 1596-8.

A corneal isolate of Acanthamoeba castellanii was exposed to commercial contact lens disinfecting solutions containing hydrogen peroxide, benzalkonium chloride, polyaminopropyl biguanide, polyquaternium 1, and chlorhexidine-thimerosal. The minimum trophozoite amebicidal concentration and exposure times required to kill trophozoites and cysts were determined. Solutions containing hydrogen peroxide or chlorhexidine-thimerosal were active against both trophozoites and cysts. The benzalkonium chloride-based solution was effective only against trophozoites. Solutions containing polyaminopropyl biguanide or polyquaternium 1 were completely ineffective. The need for adequate exposure times must be stressed.

Hu, J., et al.

Clao J, 1995. 21(2): p. 93-5.

We investigated the ability of the Gentle Touch, a non-ionic contact lens material containing 35% netrafilcon A and 65% water, to repel protein deposits. Studies were conducted in vivo (lenses worn by patients) and in vitro (lenses coated by artificial tears). Acuvue soft contact lenses, an ionic lens material containing 42% etafilcon A and 58% water, were used as controls. After 1 to 2 weeks of wear, protein deposits on Gentle Touch lenses averaged 1.5-2.8 micrograms per lens versus 338-444 micrograms per lens for Acuvue. Gentle Touch lenses that were heat-coated with an FDA tear solution recommended for testing protein deposition averaged 6.5 micrograms of protein deposits per lens, whereas almost 100 micrograms of protein was deposited on each Acuvue lens. Lenses treated with an artificial tear solution deposited a non-detectable amount of protein on each Gentle Touch lens versus more than 358 micrograms on each Acuvue lens. These studies demonstrated that Gentle Touch lenses are highly resistant to protein deposits.

Golding, T.R., et al.

Acta Ophthalmol Scand, 1995. 73(2): p. 139-44.

Hydrogel contact lenses require a settling period before lens fit stabilizes, but the process underlying the initial reduction in lens mobility is poorly understood. Explanations for this phenomenon include base curve steeping with dehydration, expulsion of postlens tear fluid, and osmotic flow of hypotonic tears into the cornea. We conducted two randomized, single-masked interocular comparisons for ten subjects wearing HEMA lenses for 1 h. We investigated potential mechanisms of dehydration-dependent lens tightening, by limiting dehydration in one eye using a high humidity environment (experiment 1), and of a hypotonic lacrimation-dependent decrease in lens movement, by presoaking lenses in isotonic (0.9%) or hypertonic (1.5%) saline (experiment 2). Lens mobility profiles were not significantly affected by modification of environment; lenses in both normal and high humidity environments displayed a significant reduction in lens movement during the first 15 min of wear (ANOVA, p = 0.0001), and no change in lens mobility thereafter. Lens mobility profiles were identical for lenses presoaked in isotonic and hypertonic saline, with initial lens movement being significantly greater than for subsequent measurements (ANOVA, p 0.05). These studies find no evidence to support dehydration- dependent steepening of base curve, or osmotic-dependent binding from hypotonic lacrimation as mechanisms for the initial postinsertion decrease in lens movement.

Keeven, J., et al.

Clao J, 1995. 21(4): p. 238-41.

We examined the antimicrobial preservative efficacy of nine rigid gas permeable (RGP) contact lens care solutions by challenging them in a laboratory study with both standard test organisms and preservative- resistant strains. Solutions containing polyhexamethylene biguanide (PHMB), such as Boston Advance (15 ppm) and a Boston Advance Enhanced Comfort Formula (5 ppm PHMB + 30 ppm chlorhexidine gluconate [CHG]) were most effective at rapidly killing vegetative cells, killing all bacteria and yeast by 6 hours. Boston Advance only slightly reduced the number of Aspergillus niger spores during the 28 day study, but Boston Advance Enhanced Comfort Formula reduced the spores by almost 3 logs by 14 days and by 4 logs by 21 days. Thimerosal-preserved Soaclens only reduced Staphylococcus aureus by 1 log at 6 hours, but at 1 day all tested organisms including S. aureus and A. niger were killed. Barnes Hind Gas Permeable Wetting and Soaking Solution, containing 50 ppm CHG, had little effect on adapted Serratia marcescens or Pseudomonas cepacia during the 28 day study. Allergan Wet-N-Soak Plus, containing 30 ppm benzalkonium chloride (BAK), was also unable to kill adapted S. marcescens or P. cepacia. CIBA Vision Premus (40 ppm BAK) was unable to kill adapted S. marcescens. Alcon Opti-Free, with 50 ppm polyquaternium- 1 (polyquad), did not kill P. cepacia. Sherman Stay-Wet 3, containing 0.1% benzyl alcohol, was not effective against S. marcescens (adapted or unadapted), P. cepacia, or A. niger. Sherman DeStat 3, which contains 0.1% benzyl alcohol plus surfactants and five times the concentration of EDTA as in Stay-Wet 3, was able to kill all the vegetative cells by 7 days but did not significantly reduce A. niger.

May, L.L., et al.

Clao J, 1995. 21(4): p. 242-6.

We examined eight conditioning or disinfecting solutions recommended for use with rigid gas permeable (RGP) or hard contact lenses for their efficacy against planktonic and attached cells of bacteria and Candida albicans. Most solutions, particularly those containing phenylmercuric nitrate and polyaminopropyl biguanide, gave marked inhibition (99.99% reduction within 4 hours) of planktonic cells of bacteria. Planktonic cells of Serratia marcescens and C. albicans survived in certain solutions containing chlorhexidine and benzalkonium chloride. In contrast, cells of all test microorganisms adhered to wells of polyethylene contact lens cases showed various degrees of survival after 4, 6, and 12 hours of exposure to most contact lens solutions. Drying of the lens case with adhered cells for 10 hours prior to addition of the lens solution usually reduced the incidence of recovery. Studies demonstrated that biofilms developed in cases with solutions of low and high efficacy. The enhanced resistance of adhered cells requires the periodic disinfection or replacement of lens cases used with RGP lenses.

Modi, P., W. Gresh, and K. Shih

Clao J, 1995. 21(1): p. 24-6.

We compared the antimicrobial activities of two rigid gas permeable (RGP) lens care systems, a one-step wetting and soaking system (0.005% chlorhexidine gluconate, 0.02% EDTA) and a conditioning solution (0.006% chlorhexidine gluconate, 0.05% EDTA). The formulations were individually inoculated with approximately 10(6) CFU/mL of a pathogenic organism. Both the one-step wetting and soaking system and the conditioning solution demonstrated good antimicrobial efficacy against Pseudomonas aeruginosa, Staphylococcus epidermidis, Serratia marcescens, and Aspergillus fumigatus. However, the one-step wetting and soaking system provides better disinfection against Candida albicans (1.2 log reduction in 4 hours) than the conditioning solution (0.39 log reduction in 4 hours). The one-step system also reduced S. marcescens by 5 logs in 1 hour, whereas the conditioning solution reduced S. marcescens by about 2 logs only in the same time interval. Although both RGP lens care systems use the same active preservative (chlorhexidine digluconate), the variation in disinfecting activities may be attributed to differences in formulation and buffer systems.

Lipener, C., et al.

Clao J, 1995. 21(2): p. 122-4.

We prospectively analyzed bacterial contamination in 15 soft contact lens wearing subjects. Contact lenses, cases, tips of saline solution bottles, and conjunctiva were cultured. Cultures were positive for 13 subjects (86.6%). Contamination was present in 13 contact lens cases (86.6%), 12 contact lenses (80.0%), nine saline solution bottles (60.0%), and in the conjunctiva of three patients (20.0%). Gram- negative bacteria (Pseudomonas aeruginosa and Proteus mirabilis) were the most frequently isolated organisms. Staphylococcus aureus was the only gram-positive organism isolated. We discuss the possible sources of contamination, and emphasize the importance of contact lens care instruction.

Niszl, I.A., M.B. Markus, and J.M. van Deventer

Antimicrob Agents Chemother, 1995. 39(10): p. 2364-6.

The effects of eight contact lens solutions on a Mastigina sp., which was associated with the infected eye of a patient, were studied. The solutions which killed the organism promptly were those which are used for gas-permeable and hard contact lenses. Some solutions for soft contact lenses were more effective than others.

LaMotte, J., G. Smith, and A. Chang-Smith

Optom Vis Sci, 1995. 72(9): p. 605-7.

Few studies have been done on the absorption and release of chemical vapors by high water content hydrogel lenses. In this study we investigated the absorption of ammonia vapors by this type of contact lens (CL). Ten high water content hydrogel lenses were exposed to vapor generated in a cuvette by 1 drop of aqueous ammonia. The contact lens was transferred to a 0.9% saline solution containing a colorometric indicator for ammonia and the amount of ammonia released into the saline was measured. We found that significant quantities of ammonia were absorbed into the lenses and the relation between average concentration of ammonia vapor and amount absorbed per contact lens was nearly linear from 50 parts per million (ppm) to 250 ppm ammonia vapor. For concentrations greater than 250 ppm there appears to be a saturation effect. Our findings indicate that high water contact lenses will absorb ammonia and release it into a solution similar to tears.

Little, S.A. and A.S. Bruce

Ophthalmic Physiol Opt, 1995. 15(2): p. 117-24.

The determinants of postlens tear film (PTF) composition in hydrogel lens wear are poorly understood, although this layer has important roles in lens movement and corneal integrity. We investigated the hypothesis that the PTF could be depleted by instillation of hypotonic saline, using a randomized, double masked, placebo controlled study design. Solutions of 0.90, 0.60 and 0.45% NaCl were instilled into the eyes of 12 subjects wearing ionic and non-ionic high water content hydrogel lenses. Postlens tear film appearances in specular reflection were categorized as amorphous, faint coloured or coloured, where the coloured patterns represent a progressive thinning of the PTF. With instillation of the hypotonic solutions (0.60 and 0.45% NaCl), the appearance of the PTF in specular reflection changed to a faint coloured or coloured pattern in at least 67% of subjects for each lens type (Friedman ANOVA, P 0.002). For the 0.45% NaCl solution, median lens movement decreased from 0.50 to 0.10 mm (Friedman ANOVA, P = 0.02); however, there were no significant changes in measured lens parameters and no difference between lens types. Postlens tear film depletion due to a hypotonic shift in tear osmolality, as demonstrated here, may explain the clinically observed phenomenon of lens binding.

Collins, M., et al.

Clao J, 1994. 20(1): p. 32-6.

We investigated the contamination of disinfection solution bottles after 2 weeks of patient use. Forty-four subjects participated in the study and each used three soft lens care systems (cross-over study). The order in which the three care systems were dispensed was randomized to eliminate systematic bias. Sixteen subjects used only one of the systems (disinfection solutions) over three consecutive 2-week periods (reliability study). Contamination of the disinfection solution bottles occurred in 12 of the 180 bottles sampled (7%), and the level of contamination of these bottles ranged up to 10(5) colony forming units per milliliter. A wide range of microorganisms was identified in these positive samples, many of which were potential ocular pathogens. None of the subjects in the study (n = 60) showed contamination in more than one of the three solution bottles sampled, suggesting that the phenomenon was not strongly patient specific. The rate of contamination of disinfection solution bottles was not influenced by contact lens wearing experience (i.e., familiarity with care procedures), by the time of year (season) at which the samples were collected, or by the subjects' compliance with hand washing. However, among the 44 subjects in the cross-over study, the rate of contamination of disinfection solution bottles was influenced by the type of disinfection solution.

Hay, J. and D.V. Seal

Br J Hosp Med, 1994. 51(10): p. 538-41.

The increasing use of contact lenses means that some hospital staff wear them at work. Yet hospitals inevitably contain populations of pathogens. This article reviews the risks of microbial keratitis faced by contact lens wearers, and suggests ways to avoid them.

Gower, L.A., J.M. Stein, and F.D. Turner

Optom Vis Sci, 1994. 71(10): p. 629-34.

Noncompliance is an important health care issue. This report presents results of assessments of three different lens care systems and directly compares compliance with each and the potential impact on patients' safety and comfort. Methods involved trained interviewers, patient demonstrations, a panel of experts, statistical analyses, and an assessment of the clinical significance of patients' noncompliant behaviors. These methods were able to discriminate among the levels of compliance with the lens care systems assessed. The three regimens were comparable regarding steps significant to lens wearing comfort with approximately one-third of all patients noncompliant with at least one of these steps. The same cannot be said regarding safety, however, with the incidence of noncompliance at 55, 84, and 91% for the three regimens. These findings indicate that simplicity alone cannot overcome noncompliance and the design of the system is an important consideration when making recommendations regarding lens care.

Gopinathan, U., et al.

Indian J Ophthalmol, 1994. 42(2): p. 65-70.

Ocular infection associated with microbial contamination of contact lens care products is a major problem in contact lens wearers. The sterility and the antimicrobial activity of contact lens care systems reflect their suitability for disinfection of contact lenses. These factors remain to be evaluated for the various newer contact lens care products manufactured in India. In this study, 35 bottles of contact lens solutions marketed by different manufacturing units in India were tested for sterility. Seven solutions were tested for antimicrobial effectiveness employing the D value method of analysis. The D value is defined as the time required to reduce a population of organisms by 90% (one log unit). A standard inoculum of the ocular isolates of Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens, Aspergillus fumigatus, Fusarium solani, and Acanthamoeba castellanii were used as challenge organisms. Bacterial contamination was detected in 20 (57.1%) solution bottles and none yielded fungus or Acanthamoeba. Pseudomonas species were the most commonly encountered contaminant (11/20; 55%). Only sterile solutions were analyzed for antimicrobial activity. D values ranging between 12 and 20 minutes were demonstrated by six of the seven solutions against bacterial challenge. Good antifungal activity was noticed in five solutions against Fusarium solani though results varied with Aspergillus flavus and Candida albicans. All solutions were adequately effective against Acanthamoeba.

Schein, O.D., et al.

Arch Ophthalmol, 1994. 112(2): p. 186-90.

OBJECTIVE: To assess the relative risk of contact lens-associated ulcerative keratitis by lens type and related lens-wearing behavior. DESIGN: Case-control study. SETTING/PARTICIPANTS: Forty practice-based case patients with contact lens-associated ulcerative keratitis and 180 control patients matched to the case patients' dispensing practitioner and date of contact lens prescription. RESULTS: Compared with users of daily-wear soft lenses, users of disposable soft contact lenses had a 13.33-fold (95% confidence interval [CI], 5.35 to 33.20) excess risk of ulcerative keratitis. However, after adjusting for overnight wear, the excess risk associated with disposable contact lenses is reduced to 3.21 (95% CI, 1.22 to 14.36). Overall, overnight wear of contact lenses conferred an 8.25-fold excess risk (95% CI, 3.33 to 25.58) of ulcerative keratitis after controlling for lens type. No protective effect of standard compared with substandard lens hygiene was found. The risk of ulcerative keratitis attributable to overnight wear was estimated at 49% for users of daily-wear lenses and 74% for users of lenses approved for overnight wear. CONCLUSION: Overnight wear of contact lenses is the overwhelming risk factor for ulcerative keratitis among contact lens users. We estimate that 49% to 74% of cases of contact lens-associated ulcerative keratitis could be prevented by eliminating overnight wear.

Roth, H.W.

Fortschr Med, 1994. 112(4): p. 33-6.

Hard and soft contact lenses are not always well tolerated--a certain percentage of lens wearers develop eye complications, which may be either mechanical toxic, metabolic, or allergic in nature and are caused by sensitization of the anterior part of the eye by cleaning/disinfecting media or the material of the lens. Inadequate cleaning or disinfection of the lens can also lead to eye injury, as can leaving the lens in the eye for too long. Only thorough patient instruction on the handling and care of the lenses, coupled with regular visits to the ophthalmologist can avoid the development of complications in contact lens wearers.

Imayasu, M., et al.

Clao J, 1994. 20(3): p. 183-8.

We evaluated the effects on the rabbit cornea of daily wear of rigid gas permeable (RGP) contact lenses treated with preserved care solutions by measuring concomitant tear lactate dehydrogenase (LDH) activity followed by in vivo tandem scanning confocal microscopy (TSCM). In vivo morphologic changes were confirmed by in vitro scanning electron microscopy (SEM). Two standard commercial RGP lens wetting and soaking solutions from the same manufacturer were tested: solution A with 0.004% benzalkonium chloride (BAK) and solution B with 0.003% chlorhexidine digluconate (CHX) and 0.002% thimerosal. Two experimental PBS-based wetting and soaking solutions were also tested: solution C with 0.005% BAK and 2% hydroxypropylmethylcellulose (HPMC) and solution D with 0.005% BAK without HPMC. Instillation of solution A without contact lens wear caused significant (P 0.01) increases in desquamation of the superficial corneal epithelium and tear LDH activity compared with control eyes. After 3 weeks of RGP contact lens daily wear (8 hours/day), modified Draize scores of ocular surface lesions on the eyes wearing RGP lenses treated with solution A increased according to the duration of lens wear. Solution B did not produce significant change. With daily wear for 4 days (8 hours/day), RGP lenses treated with solution C and solution D produced increased corneal epithelium desquamation and an increase of LDH activity in tears. These effects were greater with HPMC (solution C) than without HPMC (solution D).(ABSTRACT TRUNCATED AT 250 WORDS)

Larragoiti, N.D., et al.

J Am Optom Assoc, 1994. 65(3): p. 161-3.

BACKGROUND: Contact lens storage cases may harbor a variety of pathogenic organisms, and are a potential source of ocular infection. In this study, we evaluated the anti-microbial efficacy of several methods of rinsing of contact lens storage cases. METHODS: Lens cases were inoculated with Pseudomonas aeruginosa and then 1) rinsed with hot tap water and closed without drying, 2) rinsed with hot tap water followed by air drying, 3) rinsed with 3% hydrogen peroxide followed by air drying, or 4) left closed and undisturbed (control condition). After 24 hours, the cases were cultured to determine the rate of disinfection. RESULTS: The hydrogen peroxide rinse was the most effective (99.5 percent of cases disinfected), followed by hot water with air drying (94.7 percent) and hot water without drying (51.1 percent). Significant residual hydrogen peroxide was detected in the cases rinsed with peroxide. CONCLUSIONS: Therefore, we recommend that patients be instructed to rinse their cases with hot water and allow them to air dry after use, as well as replace their cases on a regular basis.

Donshik, P.C.

Trans Am Ophthalmol Soc, 1994. 92: p. 687-744.

Giant papillary conjunctivitis is a syndrome found frequently as a complication of contact lenses. Many variables can affect the onset and severity of the presenting signs and symptoms. Rigid gas permeable contact lenses appear to result in less severe signs and symptoms, with a longer time before the development of giant papillary conjunctivitis. Nonionic, low-water-content soft contact lenses tend to produce less severe signs and symptoms than ionic, low-water-content soft contact lenses. Enzymatic treatment appears to lessen the severity of signs and symptoms. The association of an allergy appears to play a role in the onset of the severity of the signs and symptoms but does not appear to affect the final ability of the individual to wear contact lenses. Using multiple treatment options, such as changing the polymer to a glyceryl methyl methacrylate or a rigid lens, or utilizing a soft lens on a frequent-replacement basis, can result in a success rate of over 90%. In individuals who still have a return of symptoms, the use of topical mast cell stabilizers or a nonsteroidal anti-inflammatory drug as an adjunctive therapy offers the added possibility of keeping these patients in contact lenses.

Bergenske, P.D.

Optom Clin, 1994. 4(1): p. 47-60.

Contact lens disinfection plays an important role in both patient education and office management. Several methods of disinfection are available for protecting the contact lens wearer from contamination by a variety of organisms, but no one system is best suited to all lenses, patients, or situations. Furthermore, these disinfection agents are only one component in an effective lens care system. Essential also is thorough lens cleaning and rinsing as well as preventing lens case contamination. The practitioner needs to educate each patient for optimal lens care compliance at home, and to instruct staff on maintaining safe trial lenses in-office.

Claydon, B.E. and N. Efron

Ophthalmic Physiol Opt, 1994. 14(4): p. 356-64.

Non-compliance is emerging as a critical issue in the contact lens field. This problem has been studied at depth in general health care situations and is seen as the responsibility of both practitioner and patient (client) working in a health care partnership. The contact lens practitioner and patient present a specific case for the study of non- compliance in areas such as hygiene, solution use, appointment attendance and wearing times. From 40 to 91% of contact lens patients have been reported as non-complaint in the use of recommended care and maintenance regimens and many of these are confused or ignorant about their behaviour. In order to arrive at a general set of conclusions from the studies published to date, it is important to understand the methodology of each study, it purpose, the definition of non-compliance used and the way the results were analysed and described. This review summarizes the research into non-compliance in the contact lens field to data. A set of general conclusions is drawn and a model for compliance in the context of contact lens practice is proposed.

O'Donnell, J.J., Jr.

J Am Optom Assoc, 1994. 65(11): p. 772-3.

BACKGROUND: The tendency for rigid gas permeable contact lenses to suffer parameter changes is well known. The following case report identifies an infrequently reported instance of marked power change associated with inappropriate abrasive cleaning. METHODS: A patient presented to our clinic with contact lens-related decrease in vision that was determined to have been the result of a patient-induced lens power change. A review of the literature uncovered similar reported cases. Further evaluation revealed the existence of common etiological factors. RESULTS: Consideration of elements common to this particular case and the available literature allows for the construction of a profile of a patient at risk for this lens complication. These include prior history of PMMA wear, use of an abrasive cleaner, silicone- acrylate lenses, and digital cleaning. CONCLUSIONS: Contact lens patients may present with complaints of decreased vision that are secondary to a number of different causes. One potential problem identified in this report is that of lens power change induced by inappropriate patient cleaning. It is hoped that this will serve to alert other practitioners to patients who correspond to this profile.

Kalso, S., et al.

Duodecim, 1994. 110(13): p. 1256-61.

Watanabe, R., et al.

Nippon Ganka Gakkai Zasshi, 1994. 98(5): p. 477-80.

Acanthamoeba keratitis seems to be associated with wearing contact lenses. As controls, we surveyed contact lens wearers without keratitis. Contact lens solutions of 93 persons were examined in order to identify risk factors for contamination by Acanthamoeba. Therefore, the contact lens disinfection system and storage schedules were studied in each case. Acanthamoeba organisms were isolated from 4 specimens (4.3%). The incidence of Acanthamoeba was higher in specimens of soft contact lens solution than in those of hard contact lens solution, and all the Acanthamoeba positive cases had been using tap water.

Clark, B.J., et al.

J Infect, 1994. 28(3): p. 293-304.

A survey of the hygienic practices of 178 contact lens wearers in west central Scotland was conducted along with assessment of microbial contamination of their lens storage cases. Multivariate analysis indicated that in some subgroups of lens wearers, the method of disinfection used, the use of unmodified tap water and the age of the lens, were significantly associated with microbial contamination of storage cases. In addition, statistical analysis suggested that features other than those commonly considered as important in contact lens hygiene, and therefore included in this study, may be more significant predictors of contamination of cases. Instruction of patients, patient compliance and simplicity of the regimen for the care of contact lenses may be important for achieving their safer use.

Bontempo, A.R. and J. Rapp

Clao J, 1994. 20(4): p. 242-5.

Never-worn hydrophilic contact lenses (from each of the four FDA- classified groups) and rigid gas permeable (RGP) lenses were individually incubated for 24 hours at 37 degrees C with constant stirring in a mixture of 992 microL of 0.9% saline and 8 microL of a 1:1 chloroform:methanol solution of lipids (20 mg each of cholesterol, free fatty acid, triglyceride, fatty acid methyl ester, and cholesteryl ester, representative of lipids commonly found in the tear film). The lipid material deposited onto each lens was then extracted and its components separated using high performance thin layer chromatography. The chromatograms were analyzed by densitometry. Results indicate significant lipid deposition onto all lens types, with the siloxanyl alkyl acrylate RGP-type lenses accumulating two to three times as much total lipid as any of the other lenses. This suggests that hydrophobic RGP lenses, which also have lipophilic character, are most prone to develop lipid deposits. Among the hydrophilic lenses, nonionic polymer matrices and higher water content tended to increase lipid deposition.

Boets, E.P., M.J. Kerkmeer, and J.A. van Best

Ophthalmic Res, 1994. 26(3): p. 129-36.

The aim of the study was to evaluate the effect of residual concentrations of two contact lens care solutions (hydrogen peroxide and polyaminopropyl biguanide) on corneal barrier function in vivo. The barrier function was determined by fluorophotometric measurement of corneal epithelial permeability in 30 contact lens wearing healthy subjects after 1 month's use of each of the solutions. All participants except one had corneal epithelial permeability values within the range for non-contact lens wearing healthy volunteers (0.011-0.061 and 0.008- 0.090 nm/s, respectively). The deviating value (0.14 nm/s) was due to improper use of the contact lens care system. No statistical significant difference between the permeability values after use of the two contact lens care solutions was found (Wilcoxon ranked paired test: p = 0.2). It can be concluded that both solutions do not have harmful effects on corneal epithelial barrier function, provided the handling instructions are followed.

Bartolomei, A., et al.

Clao J, 1994. 20(1): p. 23-6.

Purilens is a new contact lens care system that uses ultraviolet light and subsonic turbulence for lens cleaning and disinfection. In a single hands-off process using only preservative-free sterile saline, the lenses are ready to wear after a 15-minute cycle. This study was designed to test the safety of this contact lens care system. A total of 84 contact lens wearers from six centers were enrolled in the 3- month study, which comprised an initial visit and follow-up visits at 1, 2, 4, 8, and 12 weeks. At the end of the study, lenses and units were collected and a questionnaire was completed. Seventy-six of the 84 subjects (168 eyes) completed the study. No severe eye complications were reported, and no patients were removed from the study because of ocular problems or complications associated with the device or its use. Four patients were removed from the study for noncompliance with follow- up. Another four patients were active for 2 months, but were requested by the sponsor to complete the study 1 month early to complete data collection. Patient satisfaction was high. The study suggests that Purilens may be considered as an alternative for contact lens cleaning and disinfection.

Batterbury, M., et al.

Eye, 1994. 8(( Pt 5)): p. 547-9.

During combined cataract extraction and intraocular lens insertion in eyes undergoing removal of silicone oil, we noted that oil became adherent to the implant. This adhesion persisted post-operatively. Although patients seemed not to be symptomatic as a result of this effect, the oil interferes with the fundal examination. Since heparin- coated intraocular lenses are more hydrophilic than unmodified lenses, oil should spread less well on these lenses and therefore be less adherent. This study was conducted to test this hypothesis. Heparin- surface-modified and unmodified polymethylmethacrylate (PMMA) lenses were immersed in 1000 centistoke neat silicone oil and in an emulsion of silicone oil taken from a patient. The lenses were washed with saline solution in an attempt to remove adherent oil. The lenses were photographed for examination and qualitative comparison. It was found that both neat and emulsified silicone oil was strongly adherent to both surface-modified and unmodified lenses, and could not easily be washed off. The heparin-coated lenses showed a tendency for adherence of emulsified oil. It is concluded that heparin coating of intraocular lenses does not prevent, though may reduce, oil adherence. We recommend that care be taken to avoid contact between oil and implant during combined oil removal and cataract extraction.

Wang, J.M., R.Y. Chu, and Y.T. Li

Chung Hua Yen Ko Tsa Chih, 1994. 30(2): p. 131-3.

The author reports that enhancement by the native made collagen-shield on the permeation of cephradine into the eye is 1.5 times and 1.3 times versus controls when the corneal epithelium is intact or defect, and is 10 times versus frequent eyedrops instillation. On the other hand, the enhancement of the collagen-shield is about the same as that of the soft contact lens impregnated with cephradine solution, but the drug concentration in aqueous humor is increased by collagen-shield 1-2 times than that by the wet soft contact lens. These results indicate that the collagen-shield can effectively increase the drug concentration in aqueous humor.

Admoni, M.M., et al.

Clao J, 1994. 20(4): p. 246-8.

We evaluated a new integrated contact lens care system that combines fluid turbulence for lens cleaning with ultraviolet (UV) light for solution sterilization. The ultraviolet light system was used to clean and disinfect 42 soft contact lenses (water contents: 38.6%, 43%, 55%, and 70%) and two rigid gas permeable lenses. Test lenses were contaminated with 10(6) cells/mL of Bacillus pumilus, Aspergillus niger, Pseudomonas aeruginosa, and Acanthamoeba castellanii and subjected to a 15-minute cleaning-disinfection cycle. Bathing solutions and contact lenses were cultured at various time intervals and at the end of the cycle. All bathing solutions and all lenses but one were found to be sterile after one cycle. All units effectively disinfected solutions and contact lenses. This device may be an effective alternative to existing contact lens care systems.

Begley, C.G., et al.

Clao J, 1994. 20(1): p. 52-8.

This investigation compared the effects of three commercial soft contact lens solutions on the rabbit corneal epithelium. Fifteen rabbits wore lenses soaked in ReNu multi-purpose disinfecting solution, Opti-Free rinsing, disinfecting and storage solution, and neutralized AOSEPT for a period of 30 minutes. Control eyes wore lenses soaked in unpreserved saline for the same time period. Corneas were photographed by scanning electron microscopy and graded in random locations across the corneal surface. Slides of these photographs were projected at a magnification of x3000 and graded according to two scales by an observer unaware of the treatment used. The results showed a significant treatment effect, with all three experimental solutions scoring higher than controls. When the three experimental solutions were compared, corneas exposed to ReNu multi-purpose disinfecting solution showed a significantly increased effect by contingency table analysis of data from the adapted Burstein's scale.

Seal, D.V., et al.

Br J Ophthalmol, 1993. 77(2): p. 128.

Bruce, A.S. and N.A. Brennan

Clao J, 1993. 19(4): p. 211-6.

Corneal epithelial, stromal, and endothelial edema were assessed in 19 subjects before and after a 4-month period of hydrogel contact lens extended wear. A thick hydrogel lens was worn under closed-eye conditions for 3 hours to induce stromal edema and endothelial edema (blebs), and eye bathing with a hypotonic solution was used to induce epithelial edema. Initial central stromal edema (corneal thickness) was 14.4 +/- 0.6% in response to the stress lens compared with 2.1 +/- 0.4% in the control eye (mean +/- SE). After 4 months of lens extended wear, stromal edema was significantly reduced (P 0.0001) to 12.3 +/- 0.6% and 0.5 +/- 0.2% in test and control eyes, respectively. Adjustment of the stromal edema response at the second visit for residual edema from the extended wear accounted for some of the reduction, but the edema response remained significantly decreased (stress lens: 13.6 +/- 0.7%; and control eye: 1.2 +/- 0.4%). Endothelial edema response to the stress lens, as measured on a scale of 1 to 7, decreased from 4.6 +/- 0.3 to 2.8 +/- 0.3 over the period of extended wear. The final level was indistinguishable from that of the eye not wearing the stress lens. The epithelial edema response to hypotonic exposure was not altered with extended wear. These findings indicate that the stromal and endothelial edema responses may be unreliable diagnostic signs of the physiologic impact of hydrogel extended wear.

Vanhakendover, C.

Bull Soc Belge Ophtalmol, 1993. 247(1): p. 8-11.

Though there is a large variety of lens care systems, the following steps are always required: clearing, disinfection and rinsing. The goal to reach is removing of deposits and microorganisms to prevent infections.

Turner, F.D., et al.

Clao J, 1993. 19(2): p. 108-13.

Failure to comply with contact lens care instructions is a conspicuous finding among both symptomatic and asymptomatic patients. We used a new methodology to quantify the extent of noncompliance and its clinical significance among 170 soft lens wearers. All patients were interviewed and asked to demonstrate their lens care practices. The significance of deviations from package insert instructions was assessed by 22 ophthalmologists and optometrists with regard to potential impact on safety and comfort. Virtually all patients were noncompliant with at least one required procedure. Noncompliant behavior that could significantly affect safety was more common and judged by practitioners to be of more concern than deviations that could affect comfort. Fifty- seven percent of the patients used disinfection procedures that could seriously affect safety. Overall, the study methodology was found to be very effective both for quantifying noncompliance and for evaluating its clinical significance.

Sher, N.A., et al.

Refract Corneal Surg, 1993. 9(6): p. 425-36.

BACKGROUND: Following excimer laser photorefractive keratectomy, patients experience significant ocular pain until corneal reepithelialization. Despite the use of cold compresses, bandage soft contact lenses, cycloplegics, narcotics, and topical corticosteroids, the pain has not been adequately controlled in many patients. METHODS: A randomized, double-masked, parallel-group study of diclofenac sodium 0.1% ophthalmic solution and its placebo vehicle was evaluated. Patients undergoing excimer myopic photorefractive keratectomy on their second eye were admitted overnight. Postoperative procedures included two drops of diclofenac or placebo immediately after surgery and then qid until reepithelialization, topical tobramycin (qid), 0.1% fluorometholone (q2h), cycloplegics, and a disposable soft contact lens. Thirty-two patients (diclofenac = 16, placebo = 16) were evaluated from +30 minutes to +96 hours by several types of questionnaires. RESULTS: Most patients who received placebo experienced pain, starting within 1 hour, peaking at 4 to 6 hours and lasting 36 to 48 hours. The diclofenac-treated patients rarely experienced the early peak in pain, had less pain overall until 72 hours postoperatively, and experienced significantly less photophobia and burning/stinging. Significantly fewer patients on diclofenac required oral narcotics. Three patients (diclofenac = 2, placebo = 1) developed corneal infiltrates, the etiology of which is not known. In a separate study we conducted, there was no difference in epithelial healing times between the diclofenac-treated eyes and those not receiving the drug. CONCLUSIONS: Diclofenac appears to significantly reduce the ocular pain following excimer photorefractive keratectomy.

Phillips, L.J. and S.L. Prevade

J Am Optom Assoc, 1993. 64(3): p. 201-5.

Three-hundred and seven contact lens wearers in a planned replacement program were evaluated to determine compliance with scheduled replacement, yearly evaluation, and lens care. Patients studied were wearing soft lenses and replaced them every 6 months or less but were not using disposable lenses. Those involved were in this program for more than 24 months. The results show a 97.1 percent compliance with lens replacement and a 94.7 percent compliance with scheduled annual visits. The 32.4 percent lens care compliance rate for a single solution system was lower than expected.

Stapleton, F., J.K. Dart, and D. Minassian

Clao J, 1993. 19(4): p. 204-10.

Risk factors in contact lens related suppurative keratitis were investigated. Over 12 months, sixty contact lens wearers presented with presumed microbial keratitis and 147 presented with presumed sterile keratitis. The control group consisted of contact lens wearers without lens related disorders (n = 507). The relative risk of microbial keratitis for extended wear soft contact lens users were 36.8 times (12.6-107.6) that of rigid gas permeable (RGP) contact lens users; while the relative risk of sterile keratitis among extended wear soft lens users was 4.6 times (2.2-9.9) that of RGP lens users. For daily wear soft contact lens users, the relative risk of microbial keratitis was 4.2 times (1.1-16.0) that of RGP lens wearers; for sterile keratitis the relative risk was 2.3 times (1.3-4.3) greater than RGP contact lens users. A multivariable logistic regression analysis was used to examine associated risk factors for daily and extended wear soft lens users. The type of disinfection system and its frequency of use were associated with both microbial keratitis and sterile keratitis in daily wear users. Duration of overnight wear and gender were associated with microbial keratitis, while a patient's age and socioeconomic class were associated with sterile keratitis. Different relative risks and risk factors for microbial keratitis and sterile keratitis support the use of a clinical definition to differentiate the diseases.

Shimizu, A., et al.

Nippon Ganka Gakkai Zasshi, 1993. 97(9): p. 1047-52.

Tear volume and turnover rate were measured in 31 normal eyes using a newly designed objective fluorophotometer. After instillation of 1 microliter of 50,000 ng/ml fluorescein solution, its concentration in the lower marginal strip was measured every minute for 10 minutes after instillation. The tear volume and the tear turnover rate were determined using the method of Mishima et al. (Invest. Ophthalmol. Vis. Sci., 1966). The tear volume in this study was 12.4 +/- 6.2 microliters, initial turnover rate was 31.5 +/- 14.4%/min., and basal turnover rate was 24.0 +/- 14.2%/min. (Mean +/- SD). There were no significant differences in sex, age or use of contact lens. We also measured the tear volume and turnover rate using 5 microliters of 10,000 ng/ml fluorescein solution in the same way. The result turned out to be significantly higher, suggesting that minimal irritation is required for evaluating the tear flow.

Richardson, L.E., C.G. Begley, and G.K. Keck

J Am Optom Assoc, 1993. 64(3): p. 210-4.

The efficacies of five FDA-approved soft contact lens disinfecting solutions and heat disinfection were evaluated against the mold, Beauveria bassiana. Beauveria bassiana is a ubiquitous soil fungus with a demonstrated ability to grow into a soft contact lens matrix. A stock solution of the fungus was prepared and aliquots were added to each of the following disinfection solutions: ReNu Multi-Purpose Disinfecting Solution, Opti-Free, AOSEPT Disinfection/Neutralization Solution, Lens Plus Oxysept 1, UltraCare, and a Softmate Thermal Disinfecting Unit. Hydrogen peroxide systems were neutralized immediately using the manufacturer's recommended method. After 1 min, 5 mins, 15 mins, 30 mins, 1 hour, 4 hours, and 8 hours; samples were removed, added to neutralizing broth, and streaked onto Sabouraud's Dextrose Agar plates. Our results showed that hydrogen peroxide and heat disinfection were much more effective against Beauveria bassiana than Opti-Free or ReNu.

Zandvoort, S.W., J.H. Kok, and H. Molenaar

Int Ophthalmol, 1993. 17(6): p. 305-11.

Many people of the so-called 'baby-boom' of 1945, nowadays require presbyopic correction. A lot of them choose for multifocal contact lenses, but this is not the perfect solution. Decreased visual acuity and contrast sensitivity, and appearance of haloes, 'ghosting' and glare are a problem. In this pilot study, with ten randomly, selected, consecutive patients, a newly designed soft aspheric multifocal contact lens was tested for visual performance and comfort on day 1 and after six months' wear. Success rate was 80% after six months. Visual acuity was good with exception for near vision under low illumination conditions. Two patients mentioned haloes. A statistical significant loss of contrast sensitivity was recorded on day 1 for the spatial frequencies 6.0, 12.0 and 18.0 cpd (cycles per degree) under high and low illumination. As well as for the spatial frequencies 12.0 and 18.0 cpd under high illumination and 6.0 cpd under low illumination (p = 0.05) after six months' wear. Mean overrefraction was limited. All patients recorded good comfort.

Turner, F.D., et al.

Optom Vis Sci, 1993. 70(12): p. 998-1004.

We propose a new method for assessing and quantifying compliance with contact lens care regimens. We recommend two separate procedures: one in which trained interviewers examine the actual lens care techniques used by typical, experienced patients and another in which clinicians rate each step in a lens care regimen as to the level of risk to the patient's comfort and safety if noncompliance with that step occurs. When combined, these steps quantify compliance with the regimen under investigation. The method can be used to assess the incidence of compliance with the regimen in question, and to compare compliance across dissimilar care systems. In our investigation, we applied the method to a multi-purpose solution regimen which has been marketed as being simple to use and, therefore, the correct care procedures are more likely to be complied with. However, we found that patient compliance with this regimen was equivalent to that found in an earlier study of an oxidative (hydrogen peroxide) care system, with noncompliance posing significant risks to both safety and comfort. The results indicate that 91% of patients were noncompliant with one or more of the steps in the lens care regimen that were judged to be clinically significant safety risk factors. Factors which posed significant risks to comfort were less likely to induce noncompliance. Only 34% of patients failed to follow one or more of the steps judged to provide clinically significant risks to comfort. The authors conclude that multi-purpose or simplified regimens are not acceptable substitutes for careful patient training and frequent follow-up.

Kiel, J.S.

Clin Ther, 1993. 15(1): p. 30-5.

The purpose of this study was to determine whether protein deposits on soft contact lens could be removed without digital or enzymatic cleaning. Group IV soft contact lenses were incubated in an artificial tear solution of lysozyme, albumin, mucin, calcium chloride, and sodium phosphate. The amount of protein on the lenses was determined using a total protein assay with ninhydrin derivation. Mean (+/- SD) protein levels were significantly higher on untreated lenses (598 +/- 184 micrograms) than on lenses treated with hydrogen peroxide and a catalytic disc (360 +/- 51 micrograms). These findings are discussed in light of the finding that one third of contact lens wearers do not digitally clean their lenses after each use and one half do not use an enzymatic cleaner at least once a week. It is concluded that hydrogen peroxide/catalytic disc-based soft contact lens disinfection can remove up to 40% of the protein deposited on soft contact lenses.

Devonshire, P., et al.

Br J Ophthalmol, 1993. 77(1): p. 41-5.

A cross-sectional study of 178 asymptomatic contact lens wearers attending 10 contact lens practices in the west of Scotland was conducted over a 4 month period. The aims of the study were to identify specific microbial contaminants in lens cases, to determine the rate of contamination of such containers and to assess the value of the steps involved in different lens care regimens in the prevention of case contamination. Microbial contamination affected 53% of lens cases. Cases used with conventional wear and disposable systems were contaminated at similar rates and, therefore, the advantage of regular lens replacement may have been lost if these lenses were stored in contaminated cases. Four percent of lens cases were contaminated with amoebal species and all of these showed concomitant bacterial colonisation. These findings imply that case hygiene is probably as important as lens hygiene if new or disinfected lenses are not to be immediately re-contaminated by storage in dirty cases. Unfortunately simple and effective methods of lens and case disinfection, which would be suitable for use in the average home environment, are not yet available. It follows that frequent and regular disposal of lens cases may prove to be a necessary measure to prevent the build-up of microbial colonisation in such containers.

Harris, M.G., et al.

Optom Vis Sci, 1993. 70(9): p. 739-42.

Ultraviolet (UV) radiation has been proposed as an alternative method for contact lens disinfection. In order for UV radiation to be considered a viable contact lens disinfection method, its effects on lens polymers and parameters must be minimal. To evaluate this, soft contact lenses from each of the four FDA categories, soft lenses with handling tints, and rigid gas permeable (RGP) lenses were exposed to UV radiation in a controlled laboratory setting and their parameters measured. After 20 h of UV exposure, we found statistically significant changes in at least one parameter for each lens type evaluated. Most of these changes were small and within the error of measurement and, therefore, were not considered clinically significant. However, the group 2 soft lenses showed an increase in all four measured parameters-- power, center thickness, diameter, and water content. These changes may have an impact on lens fitting characteristics and performance. Other than these changes for group 2 soft lenses, 20 h of UV exposure appeared to have little clinical effect on the contact lenses evaluated. This suggests that UV radiation may prove to be a feasible alternative method of disinfection for most types of contact lenses.

Kim, J.K., J.C. Haselgrove, and I.M. Shapiro

J Histochem Cytochem, 1993. 41(5): p. 693-702.

We developed a technique to map the distribution of selected metabolites in the growth cartilage in situ using luciferase- NAD(P)H:FMN oxidoreductase. Chick tibial epiphyses were freeze-trapped, sectioned, and freeze-dried. For evaluating lactate, luciferase was suspended in a buffer containing polyvinylalcohol, gelatin, NAD, FMN, and lactic dehydrogenase (LDH). The buffer was frozen into a layer 800 microns thick and placed in contact with the tissue section. The temperature of the frozen reagent mixture was then allowed to increase; the emitted light was focused through a photographic lens and collected on film. We found that lactate was synthesized by cells in all regions of the growth plate. The highest concentration of the metabolite was observed in the calcified hypertrophic region. Substantial levels of lactate were also present in articular cartilage. By modifying the composition of the buffer solution, we were able to map the distribution of glucose and glucose-6-phosphate and the activity of LDH. Maximal levels of each of the three components were present in hypertrophic cartilage. Chemical analysis of the tissue section confirmed the luminographic studies and provided further evidence that there was reliance on glycolytic metabolism in terminally differentiated chondrocytes. Use of enzyme couples similar to those described above should permit the technique to be used to study most, if not all, of the major metabolic components of cartilage.

Harris, M.G., et al.

Optom Vis Sci, 1993. 70(10): p. 839-42.

To evaluate the efficacy of ultraviolet (UV) radiation as a method of disinfecting contact lenses and their storage solutions, we contaminated soft lenses (Bausch & Lomb Optima 38), rigid gas permeable (RGP) lenses (Oxyflow F-30), and their storage solutions with three common bacteria. Escherichia coli (E.c.), Staphylococcus epidermis (S.e.), and Serratia marcescens (S.m.). The storage solutions used were saline solution and RGP conditioning solution. We determined the exposure times to 253.7-nm wavelength UV radiation necessary to disinfect the contact lenses and solutions. The decimal reduction values (D values) found for UV radiation were 10 to 200 hundred times shorter than reported for currently available disinfection systems. For E.c., sterilization was attained after 100 s of exposure. For S.e. and S.m., sterilization occurred after 300 s of exposure. Different contact lens solutions transmit UV radiation to various degrees, with saline solution passing more than 90% of the UV radiation. Thus, our results indicate that UV radiation is an effective and rapid method of disinfecting contact lenses and their storage solutions.

Andenmatten, R. and M. Gonvers

Graefes Arch Clin Exp Ophthalmol, 1993. 231(9): p. 495-9.

Forty-four patients who had undergone successful vitreoretinal surgery were included in a retrospective study intended to evaluate the real benefit of surgery in each case. All patients presented with a retinal detachment complicated by proliferative vitreoretinopathy in one eye, the fellow eye being healthy. The number of operations undergone by each patient and the total operating time per patient were carefully recorded. Objective parameters such as visual acuity, visual field and stereoscopic function were monitored. Visual comfort and subjective complaints were graded by means of a questionnaire given to the patients. Any severe event occurring in the fellow eye during the follow-up period was also registered. Sophisticated vitreoretinal surgery in patients with a good fellow eye is useful to the patient if binocular function can be restored at least partially. Correction of unilateral aphakia by a contact lens should not be considered an acceptable solution.

Harris, M.G., et al.

Optom Vis Sci, 1993. 70(10): p. 843-8.

We evaluated the effect of repeated microwave irradiation on soft contact lens parameters to determine if microwave disinfection affects soft lens polymers or parameters. Ten factory-sealed lenses from each of the four FDA categories were placed in Ciba AOsept cases which were filled with 13 ml of sterile unpreserved saline. The cases were placed in a 10-cm diameter circle on the rotating plate of a standard 2450 MHz 650 W microwave oven and exposed to repeated 5-min cycles of microwave irradiation. The lens parameters, including back vertex power, back optic zone radius, diameter, thickness and water content, were measured over a period of 200 cycles to simulate over 6 months of daily disinfection. The postirradiation measurements were compared to baseline measurements taken before microwave exposure. We found statistically significant changes in many lens parameters, but all were small and few were clinically significant. These findings indicate that microwave disinfection does not have a clinically significant effect on the parameters of most unworn soft contact lenses. Further studies are needed to determine the long-term effects of microwave disinfection on worn soft contact lenses.

Gehlbach, P.L. and R.L. Purple

Invest Ophthalmol Vis Sci, 1993. 34(8): p. 2596-9.

PURPOSE: To examine a photoelectric artifact associated with the ERG- jet corneal contact lens electrode (Universe SA, La Chaux-de-Fons, Switzerland). METHODS. An artifact associated with the ERG-jet, gold foil corneal contact lens electrode was reproduced in vitro and in vivo using 50 msec light flashes. In vitro responses were examined using light flashes that varied in intensity, duration, and wavelength. Ionic strength of the bathing solution and temperature dependence were also examined. In vivo responses were compared to similarly recorded signals using the Burian-Allen bipolar electrode. RESULTS. The artifact is not apparent with microsecond light flashes, as with the Grass PS22 Photo- stimulator connected to a Ganzfeld. Longer light flashes and increasing light intensities, however, elicit graded responses that may resemble the late PIII component of the ERG in profile and in magnitude. The artifact varies with temperature, ionic concentration of the bathing medium, and wavelength of stimulating light. The artifact also varies in magnitude and polarity from one disposable electrode to the next. Light flashes of shorter wavelengths elicit greater responses than light flashes of equal radiant energy but of longer wavelengths. CONCLUSIONS. The artifact derives from electrode polarization occurring at the interface between the gold foil and its ionic medium. Caution is required when using light stimuli longer than 2-3 msec with this and similar types of intrinsically polarizable metal electrodes.

Gandhi, P.A., et al.

Appl Environ Microbiol, 1993. 59(1): p. 183-8.

Serratia marcescens (11 of 12 strains) demonstrated an ability to grow in certain chlorhexidine-based disinfecting solutions recommended for rigid gas-permeable contact lenses. For a representative strain, cells that were grown in nutrient-rich medium, washed, and inoculated into disinfecting solution went into a nonrecoverable phase within 24 h. However, after 4 days, cells that had the ability to grow in the disinfectant (doubling time, g = 5.7 h) emerged. Solutions supporting growth of S. marcescens were filter sterilized. These solutions, even after removal of the cells, showed bactericidal activity against Pseudomonas aeruginosa and a biphasic survival curve when rechallenged with S. marcescens. Adaptation to chlorhexidine by S. marcescens was not observed in solutions formulated with borate ions. For chlorhexidine-adapted cells, the MIC of chlorhexidine in saline was eightfold higher than that for unadapted cells. Cells adapted to chlorhexidine showed alterations in the proteins of the outer membrane and increased adherence to polyethylene. Cells adapted to chlorhexidine persisted or grew in several other contact lens solutions with different antimicrobial agents, including benzalkonium chloride.

Jung, J. and J. Rapp

Clao J, 1993. 19(1): p. 47-9.

New, never-worn, individual hydrophilic contact lenses were incubated in an artificial tear solution (containing lysozyme, albumin, lactoferrin, and glycoprotein) for 24 hours at 37 degrees C with constant stirring. These lenses were then cleaned following the manufacturer's instructions with one of six commercial cleaning systems: AOSEPT, CONSEPT, Oxysept, ReNu, Opti-Free and thermal disinfection in conjunction with the Allergan Enzymatic Contact Lens Cleaner. The protein remaining on each lens after cleaning was removed and then quantified by the Bio-Rad Protein Assay. High resolution gel electrophoresis was used to assess the individual protein profile patterns. We found that only one-third to one-half of the protein deposited on a lens is removed by the above cleaning systems. Of the proteins in the artificial tear solution only lysozyme is removed by cleaning, while lactoferrin, albumin, and glycoprotein tend to remain on the lens. Since many of the complications experienced by contact lens wearers are thought to be related to protein deposits on their lenses, our results suggest the need for more effective contact lens cleaning solutions.

Bergmanson, J.P. and R.N. Ross

J Am Optom Assoc, 1993. 64(5): p. 308-14.

The purpose of this study was to challenge the cornea in vivo with a lens care solution (ReNu Multi-Purpose Solution, Bausch & Lomb) formulated with polyaminopropyl biguanide at a higher than standard concentration of 1.0 ppm (1.0 x 10(-6) percent) rather than the marketed 0.5 ppm (0.5 x 10(-6) percent) and to evaluate any cytotoxic epithelial response. Test solutions included the modified formulation of Bausch & Lomb ReNu Multi-Purpose Solution (poloxamine, EDTA, borate buffer, and polyaminopropyl biguanide) and Bausch & Lomb Hypo-Clear unpreserved, isotonic saline. A dose of 50 microL of each solution was administered to the superior limbus of 10 pigmented rabbits free of anterior segment disease. Neither the unpreserved saline solution nor the more highly concentrated multipurpose solution produced significant toxic effects on the corneal epithelial cells and compared favorably with previously reported incidences of desquamating cells in the normal corneal epithelium.

Evans, T.C., B. Levy, and J. Szabocsik

Optom Vis Sci, 1993. 70(3): p. 210-5.

Bendazac Lysine (BZL), a nonsteroidal anti-inflammatory drug (NSAID), prevents denaturation of proteins secondary to chemical and physical activity. The major protein deposited on soft contact lenses is lysozyme, derived from the preocular tear film. We evaluated the effectiveness of eye drops formulated with BZL for in vivo prevention of proteinaceous deposits on contact lenses and found them to be useful in inhibiting protein deposition during a 6-month clinical trial.

Masters, B.R.

Scanning Microsc, 1993. 7(2): p. 645-51.

A chamber is described for maintaining the mechanical and physiological stability of the ex vivo eye during observation with confocal microscopy. The mechanical stability is provided by a plastic ring situated on the limbal region of the eye. The ring and supporting chamber are designed to reduce mechanical motion of the specimen. The ring and chamber size vary with the species and size of the eye under examination. The physiological stability over a period of approximately one hour is provided by immersing the eye in a bicarbonate Ringer's solution that is exchanged every five minutes. This fluid exchange is made between periods of microscopic observation. The suggested method for confocal microscopic observation of cornea and ocular lens in an ex vivo eye is to use a non-contact water immersion microscopic objective with a high numerical aperture. This is a non-invasive, non-applanating system for the confocal microscopical observation of ex vivo rabbit or human eye. Sample preparation and the specimen chamber are described. Optical sections of the cornea and lens obtained with a confocal microscope from a freshly removed ex vivo rabbit eye are presented as examples of applications of this technique.

Hart, D.E., et al.

Clao J, 1993. 19(3): p. 169-73.

We used electron spectroscopy for chemical analysis (ESCA) to examine the surface chemistry of polymacon, tefilcon, and bufilcon hydrogel contact lenses. Worn and unworn water-cleaned and surfactant-cleaned lenses were compared. The surface chemistry of unworn lenses, which were used as controls, consisted of approximately 70% carbon, 25% oxygen, and 10% other elements (i.e., silicon, sulfur, sodium, nitrogen, and zinc). In general, surfactant cleaning removed silicon contamination, but left a residue containing sulfur and zinc. The increase in the nitrogen/carbon (N/C) ratio for worn bufilcon and polymacon lenses was significantly greater than the N/C ratio for unworn bufilcon and polymacon lenses. As a group the worn ionic lenses (bufilcon) showed a greater N/C ratio than the worn nonionic lenses (polymacon, tefilcon). The nitrogen that appears on all worn lenses probably represents adherent as well as adsorbed surface proteins. The highest N/C ratios were found on a pair of pathologically deposited lenses and on the lens with the longest wearing time (2 years). For the bufilcon and polymacon lenses, the differences observed in the ESCA data for the unworn and worn lenses suggest that contact lenses begin interacting with the tear film within 1 minute (the shortest wearing time in this study).

Lawin-Brussel, C.A., et al.

Cornea, 1993. 12(1): p. 10-8.

Pseudomonas aeruginosa adherence in vitro to perfilcon A (ionic, 71% H2O) extended wear soft contact lenses--both new and after 7 days of continuous wear on closed rabbit eyes--was found to be related directly to the bacterial concentration in the contaminating solution. Thirty rabbits wore perfilcon A lenses for 7 days with complete lid closure to mimic contact lens overwear. After 7 days, conjunctival cultures showed no growth of pathogens, but all corneas had developed epithelial cell exfoliation and/or epithelial defects and stromal edema. The lenses were then incubated in various concentrations (10(7), 10(6), 10(5), 10(4), and 10(2) colony-forming units per milliliter or saline control; n = 5/group) of P. aeruginosa suspensions and replaced on their respective corneas with tarsorrhaphies for an additional 48 h. By day 9, corneal thickness had increased significantly, and P. aeruginosa keratitis had developed in 13 of 25 bacterially exposed eyes but not in 5 control eyes. Although with decreasing P. aeruginosa concentration the prevalence of ulcerative microbial keratitis also decreased, the initial concentration of bacteria or the initial extent of soft contact lens-induced corneal damage had no influence on the ultimate clinical severity of the disease.

Bartov, E., et al.

Ann Ophthalmol, 1993. 25(5): p. 167-9.

When silicone oil, a hydrophobic agent, is injected into the vitreous cavity during the course of vitrectomy operations, often some escapes outside the eye, and a mixture of oil and water forms under the infusion contact lens, markedly interfering with visibility. We found that a viscous solution of methylcellulose 1.75% in saline used as the infusion contact lens irrigant, instead of a saline solution alone, can prevent silicone oil from entering under the contact lens, thus avoiding this difficulty.

Compan, V., et al.

Optom Vis Sci, 1992. 69(9): p. 685-90.

We studied the passage of oxygen through some commercially available contact lenses. Oxygen diffusion coefficients were determined by the time-lag method and a 201T Redher permeometer was used to measure the oxygen permeability and transmissibility by the polarographic method. The measurements were carried out at room temperature with 0.09% sodium chloride physiologic solution. The following types of lenses were tested: (1) 12 lenses of cellulose acetate butyrate (CAB) of a mean thickness of 0.194 mm (observed Dk approximately 6.3 barrers) (1 barrier is equivalent to 10(-11) cm3 of O2 (STP).cm2/cm3.s.mm Hg). (2) 13 lenses of a cross-linked polyhydroxyethyl methacrylate (2-HEMA), manufactured by Lenticon and Bausch & Lomb, with 40 and 38.6% water content, respectively. The mean thicknesses were 0.160 and 0.148 mm, respectively (observed Dk approximately 12 to 13.5 barrers). (3) Finally 10 lenses of a copolymer of 2 HEMA with N-2-vinylpyrrolidone (2- HEMA/VP), manufactured by Bausch & Lomb under the name Hydrocurve II, with 55% water content and a mean thickness of 0.138 mm (observed Dk approximately 24.5 barrers). For a given lens thickness, the transmissibility and permeability of lenses whose main material is 2- HEMA are found to be equivalent. This fact suggests the use of such material as a standard in the study of diffusion processes in contact lenses of low oxygen permeability (Dk approximately 12 to 13.5 barrers). We studied the boundary layer effects and found significant discrepancies between true and apparent oxygen permeabilities. The apparent transmissibility decreased with increasing lens thickness, this effect being more apparent for lenses with low water content. Oxygen permeability is found to be exponentially dependent on water content rather than on the chemical composition of the hydrogel.

Ann Ophthalmol, 1992. 24(9): p. 352-7.

Mowrey-McKee, M.F., H.J. Sampson, and H.M. Proskin

Clao J, 1992. 18(4): p. 240-4.

We cultured Soflens (polymacon) contact lenses to determine the number of microorganisms present after patient handling and the number present after patient handling and 5 hours of lens wear. Twenty adapted contact lens patients were each dispensed two pairs of new sterile Soflens contact lenses. Both pairs of lenses were handled by the patients during a single experimental session. Prior to handling lenses, patients were instructed to wash their hands with soap and water, rinse with tap water, and dry with a paper towel. One pair (handled-only) was cultured immediately after handling. The second pair (handled-and-worn) was placed on the eyes by the patient, removed aseptically following 5 hours of wear, and then cultured. All 40 handled-only lenses had viable microorganisms associated with them (mean: 653 colony forming units (CFU) per lens). Bacteria were isolated on all of these lenses and fungi were detected on six. The mean bacterial count for the handled- and-worn lenses was 30 CFU/lens; fewer than half exhibited handled-and- worn lenses was 30 CFU/lens; fewer than half exhibited bacteria and no fungi were isolated. These data suggest that patient handling is a highly significant source of microbial contamination of hydrophilic contact lenses. Also, the number of microorganisms on lenses is significantly reduced (P 0.0001) after the lens has been worn on the eye.

Begley, C.G., et al.

Optom Vis Sci, 1992. 69(5): p. 347-53.

In this investigation, the effects of three rigid gas permeable (RGP) contact lens wetting and soaking solutions, Boston Advance Conditioning Solution, Boston Conditioning Solution, and Allergan Wet-N-Soak Plus, were tested on the human corneal epithelium. Thirty subjects participated in three experimental sessions, during which one eye received three drops of one of these RGP solutions, while the other eye served as a control. After 10 and 30 min, corneal staining was graded in 5 areas and the eyes were photographed for a digitized analysis of staining. Our results indicate that corneas exposed to Boston Advance Conditioning Solution demonstrated significantly more fluorescein staining than control eyes at both 10 and 30 min by both methods of analysis, whereas corneas treated with the other two solutions were not significantly different from controls. The increased corneal staining noted with Boston Advance Conditioning Solution may be caused by the presence and concentration of the preservative, 0.0015% polyaminopropyl biguanide. An unforeseen result of this experiment was the relatively large number of subjects exposed to Boston Conditioning Solution and Allergan Wet-N-Soak Plus who had more corneal staining in the control eye. This may suggest that the two RGP solutions served as a barrier to fluorescein, protecting the epithelial cells from staining.

Hasebe, S.

Nippon Ganka Gakkai Zasshi, 1992. 96(1): p. 102-8.

The authors developed a real-time measurement system to analyze torsional eye movements using video-based technique with two small dots on a soft contact lens as the targets. The lens, saturated with physiological saline solution, was made to adhere to the eye by dropping distilled water on it, according to Edelman's method. It was demonstrated that the clear image of the lens marker was sufficient to extract torsional eye information without using complex image processing technique and that the lens attached firmly to the eye during recordings. An engineering work station (Hewlett Packard Inc, HP9000/350) was used for hardware implementation, which required only 15 milliseconds to process one frame of a video image and the torsional angle was able to record and display in real-time rate. The accuracy (precision error) of this measurement, evaluated by simultaneous recordings with dyed dots on the conjunctiva and an error propagation analysis, was better than delta = 0.08 degrees.

Huang, Z.P. and J.A. Wu

Chung Hua Yen Ko Tsa Chih, 1992. 28(3): p. 170-2.

Collagen corneal shields immersed in 13.33 mg/ml gentamycin solution for 5 minutes were placed in rabbit eyes and the gentamycin concentrations in the cornea and aqueous humor were determined with radioimmunoassay. The results were compared with those achieved by soft contact lens, subconjunctival injection, and frequent instillations. It was found that (1) 1 and 3 hours after application, the collagen corneal shield produced significantly higher concentration of gentamycin in the aqueous than did the other methods, and in the cornea than did the contact lens or instillations; and (2) 6 hours after application, the antibiotic level in the cornea dropped lower than that by subconjunctival injection, but still 15-30 times higher than the bactericidal concentration.

Mowrey-McKee, M.F., et al.

Clao J, 1992. 18(2): p. 87-91.

We cultured Soflens (polymacon) contact lenses to determine the number of microorganisms present following normal patient wear and handling just prior to disinfection. Total protein deposited was determined for the companion lens from each patient. A random population of 109 adapted soft contact lens patients participated in the study. Some patients participated more than once, resulting in a total of 196 lenses being cultured and 195 lenses analyzed for total protein. The left lens was cultured immediately. The right lens was extracted at 70 degrees C in sodium hydroxide, and the total protein in the extract determined using a modified Lowry protein assay. The mean protein deposition per lens was 3.4 micrograms (median 2 micrograms per lens; range less than 1 to 78 micrograms/lens). Microorganisms were cultured from 95% of the lenses. The mean bacterial count (in colony forming units per lens) was 2,482 (median: 123; range less than 3 to 150,000). Fungal contamination was found on 11% of the lenses at very low levels (3-9 yeast/lens and 3-18 mold/lens). Statistical analysis found no significant relationship between bacterial bioburden and any of the study parameters, including total protein, lens age, or subjective evaluation of lens cleanliness.

Cejkova, J., et al.

Histochemistry, 1992. 97(1): p. 69-76.

Plasmin activity in the tear fluid of the rabbit eye was examined during the wearing of soft contact lenses (SCL) and compared with the occurrence of corneal disturbances assessed in cryostat sections. Plasmin activity was determined with a semiquantitative method using dry punches of filter paper previously soaked in 0.1 M Tris-HCl buffer solution containing mmol/l D-Val-Leu-Lys-FCA (trifluoromethylaminocoumarine), pH 7.2. Punches were applied to the corneal surface for 5 s (tear collection) and incubated in wet chamber. The time of appearance of the bright yellow fluorescence in UV light was recorded and taken as a measure of plasmin activity. For calibration punches soaked in solutions containing plasmin in various concentrations, and processed in the same manner were used. Changes in the cornea were examined histochemically using methods of choice for acid glycosidases, proteases, dehydrogenases, and Na(+)-K(+)-ATPase. SCL with high and low water content were worn in rabbits in 1, 2, 4, 7, 14, 21 and 28 days. Decreased activity of Na(+)-K(+)-ATPase, GGT, and SDH in the corneal endothelium and epithelium were not accompanied by detectable plasmin activity in the tear fluid. Pronounced damage of the corneal epithelium (increased activities of acid glycosidases, acid proteases, LDH, markedly decreased activity of SDH) was accompanied by low concentration of plasmin (0.4-1.0 micrograms/ml) in the tear fluid. Middle activity of plasmin (1.0-2.0 micrograms/ml) was detectable when PMNs were present in the corneal stroma. High plasmin activity (2.0-3.0 micrograms/ml) correlated with corneal ulceration and vascularization.(ABSTRACT TRUNCATED AT 250 WORDS)

Reuber, H. and J.M. Koch

Klin Monatsbl Augenheilkd, 1992. 200(1): p. 48-50.

A 68 year old female with aphakic soft lenses on an extended wear basis developed an Acanthamoeba-keratitis. The diagnosis could be confirmed by a positive culture of a corneal smear, the contact lens and the care solution. Immediate antibiotic therapy including aminoglycosides and cephalosporines topically showed response with clearing of the stromale infiltrates and, as a residuum, the development of small stromal scars at the former site of inflammation. An Acanthamoeba-keratitis should be considered in the differential diagnosis of all cases of keratitis in contact lens wearers that are unresponsive to topical medical therapy and without bacterial growth on routine cultures.

Fleiszig, S.M. and N. Efron

Optom Vis Sci, 1992. 69(5): p. 354-7.

A longitudinal study was performed to examine the effect of rigid gas permeable (RGP) contact lenses (Boston Equalens II and Quantum II) on the conjunctival flora of 45 young healthy subjects. Microbial flora were determined before delivery of lenses. Subjects wore lenses on an extended wear basis, removing them every 7 days for cleaning and disinfection. Cultures were repeated after 2 months of lens wear and the microbial flora were found to be significantly altered compared to the prelens wear results (0.05 greater than p greater than 0.02). Changes to conjunctival flora included an increase in the number of eyes from which potentially pathogenic microorganisms were isolated, an increase in the number of eyes that were culture-negative, and a decrease in the number of eyes harboring only normal conjunctival flora. The increase in potentially pathogenic flora was not specific for Gram-negative bacteria, which are most often associated with infectious keratitis during contact lens wear.

Bottone, E.J., R.M. Madayag, and M.N. Qureshi

J Clin Microbiol, 1992. 30(9): p. 2447-50.

We encountered a patient with Acanthamoeba keratitis whose contact lens care solution contained numerous trophozoites and cysts admixed with Xanthomonas maltophilia organisms, many of which were adherent to the trophozoite surface and internalized within endocytic vacuoles. Because of this finding, we investigated the role of bacterial cocontaminants in contact lens care systems as substrates for the growth of Acanthamoeba spp. Individual cocultivation of Acanthamoeba castellanii and A. polyphaga with X. maltophilia, Flavobacterium breve, and Pseudomonas paucimobilis showed better enhancement (1.5x) of ameba growth after 96 h than that obtained in the presence of Staphylococcus aureus, S. epidermidis, and Escherichia coli, the standard cocultivation species used for isolation of amebae from clinical specimens. Our data suggest that contamination of contact lens care systems with Acanthamoeba spp. and a bacterial species capable of supporting amebic growth may be the first step in the pathogenesis of ameba-induced keratitis by the provision of large inocula of amebae.

Fleiszig, S.M. and N. Efron

J Clin Microbiol, 1992. 30(5): p. 1156-61.

Microbial flora from the right eye conjunctival sac of 84 consecutively presenting contact lens patients were compared with cultures from both surfaces of their lens after aseptic removal and with the flora of their storage cases. Similar results were obtained from contact lens and conjunctival cultures of each individual; however, there was no correlation between storage case isolates and lens or conjunctival flora, suggesting that in uncomplicated lens wear, the eye is highly efficient in eradicating microorganisms introduced via handling. Conjunctival flora during daily contact lens wear was similar to the conjunctival flora of a matched control group of non-lens wearers. However, bacteria that are considered to be part of the normal ocular flora were isolated significantly more often from former contact lens wearers. The data also indicated that the use of nonperoxide chemical lens disinfection was associated with a higher proportion of positive cultures for pathogenic microorganisms than the use of other forms of disinfection, for both current and former contact lens wearers. The isolation of potential pathogens was particularly common among elderly subjects using thick contact lenses for extended wear. These changes to conjunctival flora may contribute to the increased risk of ocular infection associated with contact lens wear.

Fleiszig, S.M., N. Efron, and G.B. Pier

Invest Ophthalmol Vis Sci, 1992. 33(10): p. 2908-16.

Extended wear of soft contact lenses is associated with an increased risk of Pseudomonas aeruginosa infection of the cornea. To assess the role of bacterial adherence in the pathogenesis of these infections, superficial corneal epithelial cells and leukocytes from ten patients who use extended-wear soft lenses and ten control eyes were compared for their propensity to attach P. aeruginosa in vitro. Cells were washed from the cornea by saline irrigation, incubated with a 10-ml solution containing 10(7) colony-forming units/ml of bacteria at 35 degrees C for 30 min, collected on a filter, and prepared using a modified acridine orange staining method. Fluorescence microscopy showed bacterial adherence to corneal epithelial cells, leukocytes, and ocular mucus. The mean number of bacteria adhering to epithelial cells was 2.6 for control eyes and 6.6 for the lens-wearing eyes (P = 0.002). The percentage of epithelial cells attaching greater than or equal to four bacteria was higher for lens-wearing eyes than control eyes (57.4% versus 26.0%, P = 0.0005). There was no significant difference between contact lens-wearing eyes and control eyes in the number of leukocytes collected or in the number of bacteria attached to these cells. These results show that P. aeruginosa adherence to epithelial cells is enhanced in those who use extended-wear soft contact lenses, and this may contribute to the increased incidence of P. aeruginosa keratitis for this population.

Sutton, S.V., et al.

Clao J, 1992. 18(3): p. 155-60.

The Multi-item Microbial Challenge Test (MIMCT) is a stringent, carrier assay of the disinfecting efficacy of a contact lens care regimen. The test involves four steps: 1) in vitro contamination of contact lenses in the presence of organic load; 2) cleansing the contact lens by mechanical rubbing and subsequent rinsing; 3) disinfection of the cleansed lens; and 4) assaying the contact lens and the disinfecting solution for viable microorganisms. The variability of the individual steps was evaluated in this study by the Contributions of Elements protocol. The efficacy of the cleansing step, while reputed to be highly variable, was found to be reproducible and dependent upon the formulation under test. A contact lens disinfecting regimen must reduce the level of contaminants to approximately 10(-4) CFU/lens to enjoy a 95% chance of passing the MIMCT. This reflects a 10-log unit reduction from the initial inoculum of approximately 10(6) CFU/lens. The stringency of the MIMCT depends on the ability of the recovery system to allow the growth of low numbers of residual challenge microorganisms in the presence of the disinfecting solution. Neutralizers included in the recovery system to inhibit the disinfectant are therefore critically important to the stringency of the assay. The design of experiments to evaluate neutralizers specifically for the MIMCT is discussed with suggestions for an improved procedure.

Marshall, E.C.

J Am Optom Assoc, 1992. 63(1): p. 28-34.

The wearing of contact lenses is not without some risk. When prescribing contact lenses, several decisions must be made regarding the type of lens; for example, daily wear vs. extended wear and disposable or frequent replacement lenses vs. non-disposable or traditional (reusable) lenses. Often the decisions are based on issues of comfort, cost and/or the ability to fit the patient with one type or another. Consideration of a possible increase in the risk of ocular infection from contact lens wear is not necessarily a variable in the selection process, but maybe it should be. From the aspect of provider liability and as a public health issue, this paper will attempt to explore the relative risk of ocular infection associated with the wearing of disposable and traditional contact lenses.

MacMillan, T.F. and W.J. Benjamin

J Am Optom Assoc, 1992. 63(5): p. 333-42.

Most care regimens used with rigid contact lenses are composed of three solutions: 1) a "cleaning" solution; 2) a "combination" solution intended for storage, disinfection, and wetting prior to placement of rigid lenses on the eye; and 3) an in-eye "rewetting" or "lubricating" solution. While solutions (1) and (3) have only single functions, solution (2) must fulfill three fairly disparate functions. A "2- solution" care regimen is offered by Sherman Pharmaceuticals and consists of (a) a solution for cleaning, storage, and disinfection; and (b) a "wetting" solution that doubles as an in-eye lubricant. Through a more compatible and efficient matching of multiple functions within solutions, Sherman Pharmaceuticals claims to more adequately clean and prepare rigid gas-permeable (RGP) lens surfaces for wear. We investigated this strategy in terms of in-eye wettability of initially "ill-prepared" RGP lens surfaces, as measured with the in vivo contact angle technique. For this study, lenses were intentionally not cleaned of residues or solvents by the manufacturer at the end of production so as to create the well-known "first-day non-wetting syndrome." The ability of the 2-solution care regimen to even then provide wettable surfaces was compared to that of a saline control "regimen" and the most popular competing "3-solution" care system. We concluded that use of both care regimens dramatically enhanced in-eye wettability and, therefore, reduced the incidence of the "first-day non-wetting syndrome". However, the 2-solution care regimen provided significantly better wettability overall, lower incidence of functionally non-wetting surfaces, and more consistently wettable RGP lenses.

Parment, P.A., et al.

Curr Microbiol, 1992. 25(2): p. 113-8.

The capacity of 59 isolates of Serratia marcescens, obtained from urinary tract infections, wounds, and contact lenses or their paraphernalia, to agglutinate erythrocytes from different animal species was tested. Three main patterns were found: mannose-sensitive agglutination of guinea-pig, fowl or horse erythrocyte; mannose- resistant agglutination of chicken or pigeon erythrocytes alone or in combination with mannose-sensitive agglutination; and no agglutination. Hemagglutination capacity was associated with isolates from urinary tract infection, but not with isolates associated with contact lenses. Adherence to human urinary tract epithelium did not correlate with the hemagglutination patterns nor with the origin of the isolates. Some strains of different hemagglutination pattern were selected for the study of hydrophobicity and adherence to contact lens polymers. Hydrophobicity, as determined by degree of partition in hexadecane and water (BATH-values), correlated neither with degree of adherence to contact lens polymers nor with the hemagglutination pattern. For a representative strain there was an excellent correlation (r2 = 0.98) between adherence and the water content (hydrophobicity) of the lens polymers. These results suggest that, as with tissues, other factors interact with hydrophobicity in causing adherence to plastics.

Goodenough, D.A.

Semin Cell Biol, 1992. 3(1): p. 49-58.

The vertebrate eye lens is a solid cyst of cells which grows throughout life by addition of new cells at the surface. The older cells, buried by the newer generations, differentiate into long, prismatic fibers, losing their cellular organelles and filling their cytoplasms with high concentrations of soluble proteins, the crystallins. The long-lived lens fibers are interconnected by gap junctions, both with themselves and with an anterior layer of simple cuboidal epithelial cells at the lens surface. This network of gap junctions joins the lens cells into a syncytium with respect to small molecules, permitting metabolic co- operation: intercellular diffusion of ions, metabolites, and water. In contact with nutrients at the lens surface, the epithelial cells retain their cellular organelles, and are able to provide the metabolic energy to maintain correct ion and metabolite concentrations within the lens fiber cytoplasms, such that the crystallins remain in solution and do not aggregate (cataract). Gap junctions are formed by a family of integral membrane channel-forming proteins called connexins. Gap junctions between lens epithelial cells are composed of a connexin which is common between many different cell types, notably myocardial cells and connective tissue fibroblasts. The gap junctions between epithelial cells and lens fibers have not yet been biochemically characterized. The gap junctions formed between lens fibers are composed of at least two different connexins, one of which has not been detected between other cell types. The unusual physiology and longevity of the lens fibers may require the special set of connexins which are found joining these cells.

Frucht-Perry, J., et al.

Cornea, 1992. 11(5): p. 393-7.

Treatment of bacterial keratitis requires frequent application of topical antibiotics. We studied the efficacy of a single topical administration of tobramycin incorporated in large multivesicular liposomes and enmeshed in a fibrin sealant on rabbit corneas infected with Pseudomonas aeruginosa. One cornea each of 25 New Zealand albino rabbits was infected with P. aeruginosa. Twenty-four hours later, the animals were randomly divided into five groups of five. Group A received single hourly drops (50 microliters) of fortified tobramycin (14.5 mg/ml, total of 17.4 mg). Group B received a single topical application of 3.5 mg tobramycin, in 0.1 ml multivesicular liposomes, enmeshed in a fibrin sealant with an overlaying bandage contact lens. Group C was treated in the same manner as group B without the addition of fibrin sealant. Groups D and E served as nondrug-treated controls, with group D receiving topical fibrin-enmeshed liposomes devoid of tobramycin and group E receiving hourly topical balanced salt solution (BSS) drops. All animals were killed 24 h after initiation of therapy. Significantly fewer colonies of Pseudomonas were present in corneas of all three treated groups, as compared with the two nondrug-treated control groups (p less than 0.02). There were significantly fewer colonies of Pseudomonas in groups A and B as compared with group C (p less than 0.02). No significant difference was noted between a single administration of topical fibrinen-meshed tobramycin-encapsulated liposomes (group B) and 24 doses of hourly fortified topical tobramycin (group A, p greater than 0.05). Tobramycin-encapsulated megaliposomes may serve as a useful adjunct in treatment of Pseudomonas keratitis.

Kanpolat, A., et al.

Clao J, 1992. 18(2): p. 105-7.

We studied the rate of contamination in the contact lens care systems and conjunctivas of 30 asymptomatic cosmetic soft contact lens wearers. In caring for their lenses, 23 patients used chemical disinfection systems (quaternary ammonium solutions), six patients used hydrogen peroxide, and one used heat. Eighteen patients used unpreserved intravenous saline solution, and only seven patients used commercially prepared preserved saline solutions. Cultures were obtained from lens cases, lens care solutions, and conjunctivas. Contamination was found in 70% of the lens care systems. Fifty-seven percent of the patients had lens case contamination, and 17% had conjunctival contamination. The most frequently isolated bacteria in the lens care systems were Pseudomonas, Staphylococcus epidermidis, and Escherichia coli. We suggest the development of more effective systems for disinfection.

Callender, M.G., A.M. Charles, and R.L. Chalmers

Optom Vis Sci, 1992. 69(9): p. 678-84.

A combined prospective and retrospective study was conducted to evaluate the efficacy of in-office disinfection methods for hydrogel trial contact lenses. Two hundred and twenty-one trial contact lenses, disinfected by four different disinfection methods, were collected from seven Study Centers and cultured for microbial contamination after various storage periods. Negative and positive control lenses were included as an additional Center in this double-masked study. There was a significant difference in the incidence of microbial contamination among the Centers for all storage times (chi 2 p 0.001). Contamination of trial lenses in Centers using thermal disinfection with preserved saline (SoftWear Saline) was negative and thermal disinfection with nonpreserved saline (LensPlus Saline) was 8.7%. Lens contamination in Centers using chemical disinfection was 13.6% with ReNu and 40.7% with OptiFree. The degree of contamination ranged from 90 colony forming units (CFU)/ml to over 10 million CFU/ml. Among the microorganisms isolated after the different disinfection methods were Alcaligenes xylosoxidans, Serratia marcescens, Moraxella phenylpyruvica, Enterobacter agglomerans, Pseudomonas stutzeri, and various gram-positive organisms. This study suggests that practitioners should redisinfect all inventory trial lenses at least once a month to minimize the risk of patient infection.

Lowe, R., V. Vallas, and N.A. Brennan

Clao J, 1992. 18(1): p. 34-40.

Using the D value method of analysis, we evaluated the relative antimicrobial effectiveness of eight contact lens disinfection solutions against a standard population of challenge organisms as defined in the Microbiological Guidelines proposed by the Food and Drug Administration (FDA). Six bacteria (Escherichia coli, Staphylococcus aureus, S. epidermidis, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Serratia marcescens) and two fungi (Aspergillus fumigatus, Candida albicans) were investigated. The disinfectants included hydrogen peroxide (AOSept, MiraSept, Oxysept), chlorine-based solutions (Aerotab and Softab), soaking solutions containing synthetic, high molecular weight preservatives (ReNu and Opti-Free) and a thimerosal preserved soaking solution (Hydrocare Cleaning and Soaking Solution). The one-step hydrogen peroxide system (AOSept) was evaluated both with and without the catalytic disk. To facilitate comparison of the disinfecting solutions, we defined a new measure of performance, namely "power" of solution. This has an advantage over the "safety factor" because the solution power is independent of the size of the initial inoculum. Because different approaches to analysis may yield a wide range of D values for one set of survival data we call for adoption of a standardized approach. Our results suggest that one of the chlorine-based solutions fails to meet the FDA recommendations for bacterial challenge. Most solutions performed poorly against mycotic challenge. However, when used over longer disinfecting periods, 3% hydrogen peroxide and the Hydrocare solution gave adequate performance against fungi.

Fresco, B.B. and G.R. Trope

Optom Vis Sci, 1992. 69(8): p. 656-7.

Although a laser-produced iridotomy effectively controls angle-closure glaucoma the iridotomy can cause annoying visual effects. One solution is to fit a toric contact lens with an opaque portion to cover the iridotomy.

Kaplan, E.N., et al.

Clao J, 1992. 18(3): p. 149-54.

Recently there has been considerable attention given to the possible deleterious effects of residual hydrogen peroxide on both the cornea and the crystalline lens of the eye. We measured residual hydrogen peroxide levels of the AOSept disinfection system at regular intervals over a 4 month period. By 1 month the residual hydrogen peroxide level was 21 ppm +/- 9.4 (mean +/- standard deviation); at the end of 2 months it was 36 ppm +/- 17.6. At 3 months, when disc replacement is recommended, the residual hydrogen peroxide level was 43 ppm +/- 4.7 (range: 17-98 ppm). At 4 months the residual hydrogen peroxide level rose to a mean of 48 ppm +/- 18.2. The increase in measured residual hydrogen peroxide between month 1 and each successive month was found to be statistically significant. However, these levels failed to induce an increase in symptomatology or slit lamp findings. As determined by scanning electron microscopy there was an erosion of the platinum coating with time that appeared to coincide with the measured residual peroxide level. Cultures of randomly selected platinum discs at the end of 4 months failed to reveal more than isolated positive findings of Staphylococcus epidermidis. While an increase in residual peroxide with time may lead to greater disinfecting capabilities of this system, the possibility of corneal damage as a direct result of high peroxide levels is of concern.

Gundel, R.E., E.N. Kaplan, and J.S. Rosen

Optom Vis Sci, 1992. 69(12): p. 948-52.

Discoloration of hydrogel contact lenses is frequently encountered in clinical practice and often precipitates lens replacement. This investigation sought to determine if lens discoloration was associated with a compromise in low or high contrast, high illumination visual acuity. This association would lead to a more scientific rationale for lens replacement. Amber lens discoloration was achieved using human- worn 55% water hydrophilic contact lenses (Methafilcon-A) heated in a 1% potassium sorbate, low pH saline solution. A spectrum of 6 discolored lenses was obtained with a peak absorbance at 320 nm. Fifteen subjects, between the ages of 22 and 38 years, were tested wearing each of the discolored lenses. None of the differences in high or low contrast acuity between our discolored and nondiscolored lenses were found to be statistically significant using a paired t-test at the 99% significance level.

Sassani, J.W. and G.O. Rosenwasser

Clao J, 1991. 17(3): p. 205-6.

Ponte, F., et al.

J Cataract Refract Surg, 1991. 17(6): p. 785-9.

Intraocular dapiprazole for reversing mydriasis during extracapsular cataract extraction with intraocular lens (IOL) implantation has been compared to intraocular acetylcholine. Ninety patients were enrolled in a double-blind study and divided into three groups of 30 eyes; each group received balanced salt solution (control), 0.25% dapiprazole, or 1% acetylcholine. Pupillary diameter recordings were performed immediately before and a few minutes after drug injection, and two, four and eight hours after surgery. Goldmann tonometry was performed the day before and 6 and 24 hours after surgery. Contact endothelial cell count was performed before and one and four months after surgery. The results indicated a slower starting but longer lasting effect with dapiprazole than with acetylcholine and a significant reduction of the postoperative intraoperative pressure rise with both drugs. No significant difference in reduction in the endothelial cell count was seen between dapiprazole and acetylcholine groups and the control group.

Begley, C.G., et al.

Optom Vis Sci, 1991. 68(3): p. 189-97.

This investigation was designed to compare the effects of three rigid gas permeable (RGP) contact lens solutions on the rabbit corneal epithelium. Boston Advance Conditioning Solution, Boston Conditioning Solution, and Allergan Wet-N-Soak, which are preserved with 0.0015% polyaminopropyl biguanide, 0.006% chlorhexidine gluconate, and 0.003% benzalkonium chloride, respectively, were evaluated by scanning (SEM) and transmission electron microscopy (TEM). Our results show that Boston Advance Conditioning Solution is significantly more toxic to the corneal epithelium than either Boston Conditioning Solution or Allergan Wet-N-Soak Plus. This is presumably due to the presence and concentration of the preservative, 0.0015% polyaminopropyl biguanide. Although this study was conducted using rabbits, the results raise clinical concerns for human RGP contact lens wearers.

Vilaplana, J., C. Romaguera, and F. Grimalt

Contact Dermatitis, 1991. 24(3): p. 232-3.

Tomlinson, A. and G.R. Trees

Ophthalmic Physiol Opt, 1991. 11(1): p. 48-52.

It has been suggested that certain preservatives in artificial tears may affect the stability of the tear film lipid layer. In the present study, tear film evaporation rate (TER) was measured with a modified Servomed Evaporimeter to determine whether preservatives affected tear stability. Two solution combinations were compared in a cross-over study of eight non-contact lens wearers. These combinations consisted of identical solutions, one preserved with either benzalkonium chloride (0.004%) or chlorobutanol (0.5%), the other non-preserved. Grouped data analysis showed no significant difference in TER with either solution combination. Individuals showed differences, but these were not related to the preservative. It is suggested that these concentrations of chlorbutanol and benzalkonium chloride did not affect the stability of the tear film lipid layer as indicated by an altered TER.

Brod, R.D. and D.A. Lightman

Ophthalmology, 1991. 98(4): p. 532-4.

To study the effect of contact lens fundus biomicroscopy on the clarity of subsequent fluorescein angiography, the authors compared the fluorescein angiogram from 20 eyes recently examined using a fundus contact lens with fellow control eyes. Saline solution was used to couple the lens to the cornea. In 15 (75%) of the 20 pairs of eyes studied, there was no difference in the fluorescein angiogram clarity between examined and control eyes. In five (25%) patients, there was a slight asymmetry in clarity between the examined and control eyes, but this did not affect the ability to interpret the angiogram. The results were verified by comparing the overall quality of the transit phase of the angiograms. The application of a fundus contact lens to the cornea using saline solution as a coupling agent does not adversely affect the clarity of subsequent fluorescein angiography.

Thornley, D.

Can J Infect Control, 1991. 6(2): p. 52.

Cameli, N., et al.

Contact Dermatitis, 1991. 25(4): p. 261-2.

Lowther, G.E.

Optom Clin, 1991. 1(3): p. 63-78.

The clinical properties of hydrogel and rigid gas-permeable contact lenses for extended wear are examined, with emphasis on oxygen permeability and transmissibility, so that clinicians may select lenses likely to minimize corneal edema or may predict the amount of edema likely with a given lens. Lens deposit formation and related problems are also described, as are lens care systems, particularly their limitations with respect to preventing infections. The advantages, disadvantages, and limitations of lens cleaners are discussed, and recommendations for use are provided.

Connor, C.G., S.L. Hopkins, and R.D. Salisbury

Optom Vis Sci, 1991. 68(2): p. 138-41.

Thirteen commercially available contact lens solutions were tested for their ability to kill the cysts of Acanthamoeba culbertsoni. Miraflow, which contains 20% isopropyl alcohol, was the most effective at killing the cyst (94%), followed by solutions containing thimerosal (89%). The rigid gas permeable lens solutions in general were more effective than soft lens solutions. None of the solutions tested were completely cidal, but our data do suggest a combination of a good daily cleaner and disinfecting solution may be effective in reducing acanthamoeba exposure. These findings should provide guidelines for the practitioner in selecting the best disinfection system for the contact lens patient.

Sutton, S.V., T. Wrzosek, and D.W. Proud

J Appl Bacteriol, 1991. 70(4): p. 351-4.

A quantitative assay for the demonstration of neutralizer efficacy was developed to monitor contact lens disinfecting solutions. Adequate neutralization of disinfecting agents is essential to the accurate determination of disinfecting activity with time. This method employed the recovery of small numbers of micro-organisms from neutralizing medium containing a disinfectant. A statistical estimation of significance between treatments demonstrated that Dey-Engley medium (DE; Difco) was generally effective when tested as an agar growth medium with several bacterial test organisms. DE medium from another vendor was less effective, underscoring the need for laboratory quality control and monitoring. DE agar (Difco) adequately neutralized all solutions tested at a 1:20 dilution. The solutions included those containing Dymed (polyaminopropyl biguanide, 0.00005%), chlorhexidine (0.005%), Polyquad (0.001%), chlorhexidine (0.005%) and thimerosal (BP, 0.001%), thimerosal (BP, 0.002%) and Tris(2-hydroxyethyl) tallow ammonium chloride (0.013%), and a solution preserved with 115 ppm benzalkonium chloride (BAK). A modification of this medium was developed which retained virtually all of the neutralizing efficacy for the solutions tested while allowing the use of automated testing procedures.

Heinrich, T., et al.

Klin Monatsbl Augenheilkd, 1991. 198(5): p. 433-4.

Acanthamoeba keratitis was seen in two contact-lens wearers. In both cases, this finding was verified by microbiological examination of conjunctival swabs and of the lens solution. One patient had perforating keratoplasty. While neither vital amoebae nor cysts could be detected in the host corneal explant, immunohistochemical examination revealed fluorescence-positive fragments which probably correspond to incomplete cycstic walls.

Sutton, S.V., et al.

Appl Environ Microbiol, 1991. 57(7): p. 2021-6.

Determination of a D value for specific test organisms is a component of the efficacy evaluation of new contact lens disinfecting solutions. This parameter is commonly defined as the time required for the number of surviving microorganisms to decrease 1 logarithmic unit. The assumption made in establishing a D value is that the rate of kill exhibits first-order kinetics under the specified conditions. Such exponential kill rates are seen with thermal contact lens disinfection system. A comparison of the death rate kinetics for a variety of chemical contact lens disinfecting solutions was undertaken to ascertain the suitability of D-value determination for these chemical disinfectants. The active agents of these different solutions included hydrogen peroxide, thimerosal, chlorhexidine, tris(2- hydroxyethyl)tallow ammonium chloride, thimerosal, polyaminopropyl biguanide, and polyquaternium-1. The solutions were challenged with 10(6) CFU of either Pseudomonas aeruginosa, Serratia marcescens, or Staphylococcus hominis per ml, and survival rate was determined. This study clearly demonstrates the nonlinear nature of the inactivation curves for most contact lens chemical disinfecting solutions for the challenge organisms. D-value determination is, therefore, an inappropriate method of reporting the biocidal activity of these solutions.

Wilson, L.A., A.D. Sawant, and D.G. Ahearn

Arch Ophthalmol, 1991. 109(8): p. 1155-7.

Biofilms of Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus epidermidis, Streptococcus pyogenes, and Candida albicans, established in the wells of a polyethylene contact lens case, retained viability to certain soft contact lens disinfectant solutions after exposure for the manufacturer's minimum recommended disinfection times. The relative order of resistance of bacterial biofilms was as follows: S marcescens was greater than P aeruginosa, which was greater than S epidermidis, which was greater than S pyogenes. Air drying of biofilms for 10 hours increased the efficacy of the disinfectant solutions, but drying was not enough to decrease the incidence of recovery to 0% for all solutions. Hydrogen peroxide was more effective against biofilms than disinfectant solutions formulated with chlorhexidine gluconate or polyquaternium-1 or polyaminopropyl biguanide. We recommend that determination of efficacy of contact lens disinfectant solutions should include challenges against biofilms.

Brennan, N.A., et al.

Clao J, 1991. 17(3): p. 169-72.

Stipulation of the oxygen transmissibility (Dk/L) of a contact lens based upon oxygen permeability (Dk) and nominal lens thickness (L) can be misleading since center thickness, average thickness, and hence Dk/L of a contact lens vary with lens power. While earlier confusion regarding determination of Dk has now been resolved, this data has yet to be fully incorporated into a clinically applicable model. We developed a graphical solution describing variations in Dk/L with power for a representative sample of currently available hydrogel and rigid contact lenses. The Dk/L is found to be optimal for lenses of low minus power (approximately -2.50 D). The model presented here will assist practitioners in assessing the potential oxygen performance of different lens designs with respect to a given power. We advocate that lens manufacturers print the average Dk/L on lens packaging, according to the model described in this paper, along with the parameters that are usually stated.

Myers, R.I., et al.

Optom Vis Sci, 1991. 68(10): p. 776-82.

The purposes of this study were to determine if the quantity of protein deposited (QPD) upon hydrogel lenses was affected by enzymatic cleaning and to test the potential relation between QPD and visible protein deposition (VPD) and change. Seventy-four contact lens patients classified as "heavy depositors" wore new lenses for an average of 80 (SD = 32) days. Cleaning and disinfection solutions varied. One lens was cleaned weekly by a papain enzymatic treatment. The distribution of QPD measurements was bimodal and was related to the FDA material for nonionic, low water content lenses (FDA Materials Group no. 1). The mean deposition was 45 micrograms/cm2 (N = 112) compared with that of ionic, high water content lenses (FDA Materials Group no. 4), which was 1010 micrograms/cm2 (N = 30). VPD distributions were the same for the FDA Group no. 1 and no. 4 lenses. Enzymatic treatment did not significantly reduce QPD; however, enzymatic treatment did reduce VPD. Thus QPD and VPD are independent phenomena and possible reasons for this are given.

Meisler, D.M. and I. Rutherford

Rev Infect Dis, 1991. 13 Suppl 5: p. S410-2.

The association between acanthamoeba keratitis and the use of soft contact lenses is firmly established. Despite alerts and warnings, education of eye-care professionals and patients, and identification of risk factors that are associated with the use of soft contact lenses, acanthamoeba keratitis remains a threat. It is presumed that in some cases, the soft contact lens is the vector by which Acanthamoeba is introduced to the cornea. This presumption has spurred concern regarding the efficacy of systems used for the disinfection of soft contact lenses in killing the organism. Many questions have been raised regarding the proficiency of disinfection. These have stemmed from a poor understanding of the interactions among soft contact lenses, soft contact lens paraphernalia, and Acanthamoeba. Another issue to be addressed is the need for standardized testing of the efficacy of contact lens disinfection systems against Acanthamoeba. Only through a concerted and focused effort by eye-care and other concerned health care professionals can these questions be answered.

McLaughlin, W.R., K.B. Hallberg, and O.H. Tuovinen

Optom Vis Sci, 1991. 68(9): p. 721-7.

The efficiency of four contact lens disinfectant formulations was tested against three types of bacteria (Pseudomonas aeruginosa, Staphylococcus aureus, and Serratia marcescens) and one fungus (Aspergillus niger). The bacteria were tested both as free suspensions and after attachment on surfaces of rigid gas permeable contact lenses (RGPCL). The disinfection data were used to calculate the death rates and decimal reduction times for the test organisms. P. aeruginosa was the most sensitive and A. niger was the most resistant organism to the disinfectants. Scanning electron micrographs showed that P. aeruginosa occurred mostly as single cells, with little extracellular material, on the lens surface. In contrast, S. marcescens produced copious amounts of capsular material layered on the lens surface, promoting cell aggregation. Transmission electron micrographs revealed that bacterial cells were physically separated from the lens surface by a space barricaded with capsular material.

Stevenson, R.W. and R.O. Ansell

Clao J, 1991. 17(1): p. 36-40.

A polarographic method of oxygen determination across contact lenses has been developed. A custom designed polarographic cell, with a platinum cathode and a silver anode was used to measure a series of specially prepared contact lens samples made from four gas permeable contact lens materials currently commercially available. On a series of measurements the polarographic current was shown to be highly repeatable without the need for a wet membrane between the lens and the cathode. A layer of solution was adequate. The greatest variability was found with the thinnest sample of the highest oxygen permeable material. The results were plotted using the resistance (L/Dk) of the readings against sample thickness. Three of the four examples showed a curvilinear function and the other a linear relationship relative to sample thickness. From these graphs the reciprocal of the slope of the curve at zero thickness gave the measured oxygen permeability of the material. The significance of this system towards setting up a standard for the measurement of oxygen permeability of contact lens materials is discussed.

Lopez Bernal, D. and J.L. Ubels

Curr Eye Res, 1991. 10(7): p. 645-56.

The effect of artificial tear solutions on the corneal epithelial barrier was evaluated by measuring corneal uptake of 5, 6 carboxyfluorescein (CF) after exposure of rabbit corneas to various formulations in a conjunctival cup. Four tear solutions containing 0.01% benzalkonium chloride (BAC), a formulation containing 0.001% Polyquad, a contact lens re-wetting solution containing 0.004% thimerosal, and each of the above preservatives in balanced salt solution (BSS) were evaluated. Four non-preserved solutions were also tested. After treatment with the solutions corneas were exposed to the CF, removed from the eyes and dialyzed in balanced salt solution. The CF concentration in the dialysate was measured by fluorometry. Solutions containing 0.01% BAC caused a 9.24 to 99.28 fold increase in CF uptake as compared to control. Solutions preserved with Polyquad or thimerosal caused only a 0 to 4 fold increase in CF uptake while non- preserved solutions caused no change compared to control. Corneas prepared for transmission electron microscopy using fixative containing ruthenium red exhibited damage which correlated well with CF uptake; the ruthenium red penetrated the epithelium to the basal cell layer after corneal exposure to solutions containing BAC while only superficial cell layers were stained after exposure to the other test solutions. The method used in this study allows statistical comparison of artificial tear formulations. The data show that patients with severe dry-eye who use artificial tears frequently should avoid tear solutions containing BAC and that non-preserved solutions are preferable for treatment of these patients.

Mirejovsky, D., et al.

Optom Vis Sci, 1991. 68(11): p. 858-64.

An artificial tear solution containing the major types of proteins, glycoproteins, and lipids represented in human tears has been developed. The adsorption of lipids onto various hydrogel lens materials (polymacon, lidofilcon A, phemfilcon A, etafilcon A) was examined by exposing the lenses to our artificial tear solution for 18 h. The adsorbed lipids were detected using Nile red stain. The patterns of deposits obtained in vitro were similar to those obtained with human worn lenses. The Nile red stain appeared far more sensitive in detecting lipids adsorbed to hydrogel lenses than the oil red O stain. It was found that lipids adsorb to hydrogel materials quite readily either in a pure state or combined with mucin or other proteins. In view of this work more attention should be given to the role of lipids in the etiology of various contact lens wear complications.

Huff, J.W.

Invest Ophthalmol Vis Sci, 1991. 32(2): p. 346-53.

The effects of physiologic and pharmacologic manipulations on contact lens-induced edema were studied. In isolated superfused rabbit corneas bathed in Ringer's solution and covered with large-diameter polymethylmethacrylate (PMMA) lenses, corneal swelling rates of 17-26 microns/hr (versus -5-5 microns/hr in paired controls) were observed. Neither the calcium antagonist diltiazem (10(-4) M), the glucocorticoid dexamethasone (10(-7) M), the glucose substitute fructose (20 mM), nor 0.5 mM adenosine and 0.3 mM reduced glutathione mitigated the edema. Lens-induced edema was 25 microns/hr in corneas bathed at pH 8.2 and decreased to 9 microns/hr at pH 7.0. In corneas without lenses, however, decreasing the pH from 7.4-7.0 caused significant swelling (P less than 0.05). The pyruvate dehydrogenase stimulant sodium dichloroacetate (3.2 mM) on the tears side ameliorated the edema, and its congener, 3.2 mM 2-chloropropionate, was less effective. These latter agents are known to relieve lactic acidosis systemically and had no significant effect on corneas without lenses. In tissues bathed with 20 mM lactate Ringer's, normal thickness was maintained in both control and PMMA-treated corneas throughout the 3-hr period. These findings suggest that the contact lens-induced edema does not involve the acute cytotoxic mechanisms seen in severe tissue ischemia or hypoxia. The edema appears to result in part from acidosis but mainly from stromal lactate accumulation.

Franklin, V., et al.

Clao J, 1991. 17(4): p. 244-8.

One of the problems with hydrophilic contact lenses is that they are susceptible to spoilage. This study investigated the degree of spoilage associate with lenses of various surface changes during the early stages of wear and the effect of surfactant cleaning of lenses at this stage. Ten patients wore a control HEMA lens on one eye and either an ionic (Bufilcon A) or non-ionic (Tetrafilcon A) lens on the other for one week and used a peroxide system for disinfection. The lenses were then replaced with identical lenses, which were also worn for 1 week, with surfactant cleaning added to the care regimen. The lenses then were examined by fluorescence spectroscopy in order that the extent of lipid and protein deposition could be assessed. The results indicate that protein accumulation is highly material dependent, whereas lipid deposition is primarily patient dependent. Also the term "ionic" does not necessarily indicate equally enhanced deposition in all lenses so termed. Surfactant cleaning appears to be of little benefit in reducing deposits during the early stages of wear, its benefit in the long-term being of much greater significance.

Silvany, R.E., J.M. Dougherty, and J.P. McCulley

Ophthalmology, 1991. 98(6): p. 854-7.

Single preservatives used in contact lens solutions were evaluated for their effectiveness in killing Acanthamoeba castellanii and Acanthamoeba polyphaga trophozoites and cysts. Preservatives were tested against amoebae at intervals varying from 30 minutes to 24 hours. The preservatives were tested with axenically and nonaxenically grown organisms. Chlorhexidine (0.001% and 0.005%), polyaminopropyl biguanide (0.0015%), benzalkonium chloride (0.001% and 0.004%), and hydrogen peroxide (3%) were very effective preservatives. Lower concentrations of these same preservatives were less effective. Thimerosal (0.001% and 0.004%), sorbic acid (0.1%), potassium sorbate (0.13%), EDTA (0.1%), polyaminopropyl biguanide (0.00005%), and polyquaternium-1 (0.001%) were not effective as tested. However, thimerosal 0.004% when combined in solution with EDTA was effective. Preservatives were more effective when tested against axenically prepared organisms than when tested against co-cultured organisms.

Efron, N., T.R. Golding, and N.A. Brennan

Clao J, 1991. 17(2): p. 114-9.

In order to establish the efficacy of soft lens lubricants and their mode of action, we conducted a controlled, double-masked, randomized study. Symptoms of dryness as well as lens water content were assessed in 30 symptomatic hydroxyethylmethacrylate (HEMA) contact lens wearers who each applied either saline or one of two soft lens lubricants every 2 hours over a 6-hour wearing period. Short- and long-term symptomatic relief from ocular dryness was provided by both lens lubricants (ANOVA, P less than .05). However, neither lubricant was found to be significantly superior to saline. Contact lens dehydration was not significantly reduced by the instillation of any solution. A psychological rather than a physical (lens hydration) or physiological basis to the symptomatic relief provided by soft lens lubricants cannot be discounted.

Mirejovsky, D., A.S. Patel, and D.D. Rodriguez

Curr Eye Res, 1991. 10(3): p. 187-96.

The effect of adsorbed substances on the properties of the water in various hydrogel contact lens materials was examined by exposing contact lenses (Hydron Zero 4, B&L 70, DuraSoft 3, Vistamarc, and Acuvue) to an artificial tear solution for various periods up to 14 days. The only materials affected were the high-water/ionic lenses which adsorbed a large amount of protein, predominantly lysozyme. In the DuraSoft 3 lenses the equilibrium water content (EWC) dropped from 49% to 46% and the freezing water from 28% to 21%. Similar changes were seen with the Vistamarc lenses. After a 10-day exposure of the Acuvue lens to artificial tears, the EWC decreased from 53% to 47% and the amount of freezing water from 33% to 23%. The decrease in the permeability of water seen with these materials was consistent with the decrease of the freezing water, i.e., the water able to participate in diffusion. Since the content of freezing water determines the transport through hydrogels it can be expected that any lens characteristics that depend upon the amount of this portion of water would be affected by the presence of proteins inside the polymer matrix. We extrapolated that an absolute change of 10% in the amount of freezing water could lead to a decrease in oxygen permeability of as much as 7 Dk units. In view of this work more attention should be given to changes in the properties of lenses during wear, in particular, in the high- water/ionic lenses.

Shih, K.L., et al.

Clao J, 1991. 17(3): p. 165-8.

The antimicrobial activities of three non-peroxide soft contact lens chemical disinfection systems--ReNu Multi-Purpose Solution (0.00005% polyaminopropyl biguanide), Opti-Soft Disinfecting Solution (0.001% polyquaternium-1), and Opti-Free Rinsing, Disinfecting & Storage Solution (0.001% polyquaternium-1)--were compared to Soft Mate Disinfecting Solution (0.005% chlorhexidine digluconate). Each product was separately inoculated with each of five microorganisms at approximately 10(6) microorganisms per mL. All of the solutions demonstrated excellent disinfecting activity against Pseudomonas aeruginosa and Staphylococcus epidermidis, with complete disinfection occurring within 4 hours. Only Soft Mate disinfected Serratia marcescens within 4 hours. ReNu reduced the microorganisms to 10-100 cells/mL and Opti-Soft and Opti-Free reduced the number to 10(2)-10(3) cells/mL. For the fungal species, Soft Mate showed excellent activity against Candida albicans (disinfection in 4 hours) and reduced Aspergillus fumigatus to 10(3) spores/mL in 4 hours. After 4 hours ReNu, Opti-Soft, and Opti-Free had reduced C. albicans only slightly, to 10(5) cells/mL and displayed virtually no disinfecting activity against A. fumigatus. For these newer chemical disinfection systems, diligent cleaning and rinsing of the soft contact lenses are the most important steps in the patient care regimen.

Rakow, P.L.

J Ophthalmic Nurs Technol, 1991. 10(4): p. 178-80.

Hugo, E.R., et al.

Invest Ophthalmol Vis Sci, 1991. 32(3): p. 655-7.

A simple, quantitative plate assay has been developed for use in the enumeration of Acanthamoeba. The technique uses an agarose overlay and low-nutrient medium to support the growth of amoebae on a bacterial lawn. The authors found that in this assay, individual trophozoites or dormant cysts will cause plaques to form in an Enterobacter aerogenes lawn. With the assay, it is possible to quantitatively assess the effects of various disinfectant compounds on the viability of Acanthamoeba. The authors used this assay to enumerate Acanthamoeba cyst viability after chemical disinfection in contact lens care solutions. The inactivation data indicated major differences among the four test solutions evaluated.

Missiroli, A., et al.

Clao J, 1991. 17(2): p. 126-8.

We used the heat denaturation of lysozyme to induce the in vitro formation of protein deposits on 60 poly-HEMA contact lenses (38.6% water). Each lens was individually placed in 20 mL of a 0.04% lysozyme solution. The lenses were divided into two equal groups. In the first group (30 lenses), bendazac lysine (100 mg) was added to the lysozyme solution. The second group of lenses was used as control. Quantitative analysis of protein deposits on the lenses of both groups was carried out by a colorimetric test. In the lenses where deposit formation occurred in the presence of bendazac lysine, a mean protein level of 7.17 +/- 3.42 micrograms per lens was found; in the control group the mean value was 30.6 +/- 8.22 micrograms per lens. Student's t-test showed this difference to be significant (P less than 0.001).

Izquierdo, N., et al.

Bol Asoc Med P R, 1991. 83(3): p. 96-8.

The prevalence of microbioogic flora was determined in a convenience sample of contact lens wearers at the Puerto Rico Medical Center, ophthalmology clinics obtaining cultures from the conjunctival fornices. Gram positive bacterial prevalence was 100% in the control group, as well as in rigid gas permeable lens wearers. In the soft contact lens group, gram positive bacterial prevalence was 94.7%. On the other hand prevalence of Gram negative bacteria is null in the soft contact lens wearer population, being only 2.5% in control group, and 45.5% for Rigid Gas Permeable wearers. These contact lens wearers were using different disinfection systems.

Sibley, M.

Int Ophthalmol Clin, 1991. 31(2): p. 13-6.

Farris, R.L.

Cornea, 1990. 9(Suppl 1): p. S44-6; discussion S47.

The practitioner's office can be an unsafe environment for fitting contact lens (CLs), owing to numerous reservoirs of microbial contamination. These include sinks, trial lenses, solutions, lens cases, multidose dropper bottles, and storage trays. Microbes may also be introduced to the eyes via the practitioner's fingers, the patient's lashes or lids, or cosmetic residues on the ocular adnexa. Because sterility is difficult to achieve in an office, CL fitters must accept the more realistic goal of disinfection. Periodic cultures are necessary to monitor the effectiveness of office hygiene and disinfection. Cultures are especially important, considering that the panel of organisms routinely used to test lens care solutions may not reflect those in office settings, which may become resistant to preservatives. It has been shown, for example, that 50% of chlorhexidine-preserved solutions used in offices can become contaminated with Serratia marcescens within 7 days of bottle opening. At present, it appears that contamination is best avoided by using solutions containing 15 ppm of polyaminopropylbiguanide (PAPB). Frequent replacement of solutions, trial lenses, and lens cases may also help to reduce the likelihood of microbial contamination in the office.

McNally, J.J.

Clao J, 1990. 16(1 Suppl): p. S46-51; discussion S51-2.

Because hydrogen peroxide (H2O2) is a widely used microbicidal agent for contact lens disinfection, it is important to assess its effect on ocular tissues at the levels that can be associated with the use of these systems. Three recently reported clinical studies provide new information on this subject: In the first study, the discomfort threshold for a range of H2O2 concentrations administered to the eye was explored. The mean thresholds for 10 subjects were 267 ppm H2O2 for 55% water content contact lenses soaked in the solution and 282 ppm for 38% water content contact lenses. Hydrogen peroxide disinfection systems are designed to have residual H2O2 concentrations in the eye of no more than 50-60 ppm, allowing for an adequate safety margin. The stinging occasionally reported after lens disinfection may be due to factors other than residual H2O2. In the second study, the rate of in vivo neutralization of H2O2 administered to the eye was studied. Removal of 50 ppm H2O2 from a hydrogel lens was completed within the first 30 seconds of human wear when the eyelids were held closed, and within 60 seconds during wideopen gaze, with blinking every 5 seconds. In the third study, the corneal permeability to fluorescein was determined in 10 subjects after dosing with 50 ppm H2O2, 500 ppm H2O2, as well as negative and positive controls. There was no significant difference between the negative control and the two H2O2 concentrations, whereas the positive control was different from all other treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Stulting, R.D.

Clao J, 1990. 16(2): p. 82-3.

Kita, M., et al.

Nippon Ganka Gakkai Zasshi, 1990. 94(5): p. 480-3.

A transparent polyvinyl alcohol (PVA) hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water miscible organic solvent by cooling. The physical properties were evaluated in comparison with commercially available soft contact lens materials, such as polyhydroxyethyl methacrylate (PHEMA) and copolymers of methyl methacrylate (MMA) and N-vinyl pyrrolidone (VP). The PVA hydrogel showed higher tensile strength and elongation at break than the other materials, while it had high water content and oxygen permeability the latter being comparable to those of PMMA/VP copolymers. The protein adsorption of the PVA hydrogel was much less than those of the other materials. The PVA hydrogel soft contact lenses were applied on rabbit eyes for 12 weeks. The influence on the cornea was studied by biomicroscopy, ultrasonic corneal pachymetry and histopathological examination. These examinations revealed no abnormal findings in the cornea. These results suggest that the PVA hydrogel may be promising as a new soft contact lens material.

Larkin, D.F., S. Kilvington, and D.L. Easty

Br J Ophthalmol, 1990. 74(3): p. 133-5.

In order to identify possible risk factors for microbial keratitis the storage cases for contact lenses of 102 asymptomatic lens wearers were tested for contamination by bacteria and free-living amoebae. Of this group 43 had significant counts of viable bacteria and only 40 had negligible counts. Seven had contamination by acanthamoebae, of whom six also had significant bacterial counts. These results were categorised according to the type of contact lens worn and the lens disinfection method. The high rates of contamination by apathogenic and pathogenic organisms, in particular Acanthamoeba, and the probable support by contaminating bacteria of Acanthamoeba, are discussed.

Lattimore, M.R., Jr.

Aviat Space Environ Med, 1990. 61(10): p. 946-9.

The military aviation communities have benefitted from the development of advanced electro-optical avionics systems. One drawback that has emerged is an increasing system incompatibility with traditional spectacle visual corrections. An alternative solution to the refractive error correction problem that some services have been investigating is that of contact lens wear. Since this much-debated topic is currently of command interest, a general overview of contact lens issues is presented as a framework for future discussions.

Key, J.E.d.

Cornea, 1990. 9(Suppl 1): p. S9-11; discussion S15.

The overriding consideration in choosing between soft contact lenses (SCLs) and rigid gas-permeable (RGP) lenses is the severity of the changes each induces in the corneal epithelium, endothelium, and conjunctival structures. Lens-related epithelial changes are largely the consequence of relative oxygen deprivation and consequent corneal edema. Factors such as lower oxygen transmissibility, minimal tear exchange capacity, and large diameters may explain why SCL wearers show a higher rate of corneal infiltrates, sterile ulcers, and irregular staining patterns than users of RGP lenses. The greater association of hydrogels with infectious keratitis may reflect their tendency to accumulate proteinaceous deposits, harbor bacteria in the polymer matrix, and resist easy disinfection. SCL wear has been linked to endothelial polymegethism, a largely irreversible condition that may cause more rapid corneal swelling and slower deswelling after periods of hypoxic stress. Among the conjunctival problems more often seen in SCL wearers are superficial neovascularization, contact lens-related superior limbic keratoconjunctivitis, and giant papillary conjunctivitis. Mechanical irritation from large-diameter lenses, a tendency to build up mucoproteinaceous deposits, corneal draping, and hypersensitivity to preservatives in SCL care products may play a role in these problems.

Chandler, J.W.

Clao J, 1990. 16(1 Suppl): p. S43-5.

Critical factors of soft contact lens care include adequate disinfection and neutralization of the chemical constituents of the disinfecting system before reinsertion. Three cases of microbial keratitis are described that exemplify the critical nature of disinfection with adequate antimicrobial activity. Disinfection rates are described for a 3% solution of hydrogen peroxide (H2O2) against multiple microorganisms. The results indicate that H2O2 is equivalent to heat disinfection when used for appropriate lengths of time. Problems associated with chemical disinfection include lens fit alterations, which may lead to epithelial trauma. However, unless antimicrobial chemicals can be rinsed, neutralized, or degraded, they can also injure the corneal and conjunctival epithelium. Repeated exposure of the corneal epithelium to oxidizing agents renders it vulnerable to complications.

Burns, F.R., et al.

Antimicrob Agents Chemother, 1990. 34(11): p. 2065-9.

Pseudomonas aeruginosa elastase is a zinc metalloproteinase which is released during P. aeruginosa infections. Pseudomonas keratitis, which occurs following contact lens-induced corneal trauma, can lead to rapid, liquefactive necrosis of the cornea. This destruction has been attributed to the release of both host-derived enzymes and the bacterial products P. aeruginosa elastase, alkaline protease, exotoxin A, and lipopolysaccharide endotoxin. A synthetic metalloproteinase inhibitor, HSCH2 (DL)CH[CH2CH(CH3)2]CO-Phe-Ala-NH2, which we previously showed to be a potent inhibitor of corneal collagenase and alkali- induced corneal ulceration, was tested as a potential inhibitor of P. aeruginosa elastase. Inhibition constants (Kis) for the resolved diastereomers were determined with the chromogenic substrate furylacryloyl-glycyl-L-leucyl-L-alanine. One isomer had a Ki of 0.3 microM, while the other had a Ki of 0.4 microM. The more potent diastereomer was evaluated in vivo in experimentally induced Pseudomonas keratitis in rabbits. Following inoculation of one cornea of each rabbit, topical treatment with a 1 mM solution of the inhibitor significantly delayed the onset of corneal melting and perforation, as compared with the results for the control and gentamicin-treated groups. This protective effect suggests that the inhibitor may have a therapeutic application by delaying the progression of corneal destruction in Pseudomonas keratitis.

Lund, O.E., V. Klauss, and O.F. Scheiffarth

Fortschr Ophthalmol, 1990. 87(Suppl): p. S94-100.

Seventy percent of patients with AIDS have AIDS-related ocular involvement. This is a special challenge for the ophthalmologist which requires specific knowledge. The nature and frequency of the ocular involvement as well as the time of manifestation during the HIV-disease are discussed. The potential therapy for such opportunistic infections is discussed. Furthermore, the HIV-specific aspects for disinfection procedures in the office (tonometry, three-mirror lens, contact lenses) are also elucidated.

Kita, M., et al.

Graefes Arch Clin Exp Ophthalmol, 1990. 228(6): p. 533-7.

We prepared a transparent polyvinyl alcohol (PVA) hydrogel from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent by cooling. The physical properties of the hydrogel were evaluated in various mixed solvents and compared with those of commercially available soft contact lens materials, such as polyhydroxyethyl methacrylate (PHEMA) and copolymers of methylmethycrylate (MMA) and N-vinyl pyrrolidone (N-VP). The PVA hydrogel showed higher tensile strength and elongation before breaking than did the other materials. Also, the PVA hydrogel was comparable in its high water content and its oxygen permeability with the MMA/VP copolymers. The protein adsorption of the PVA hydrogel was much lower than that of the other materials. Soft contact lenses of PVA hydrogel were applied to rabbit eyes for 12 weeks. The effects of the lenses on the cornea were studied by biomicroscopy, ultrasonic pachymetry, and histopathologic examination. No abnormal findings were noted, suggesting that the PVA hydrogel may be promising as a new material for use in soft contact lenses.

Sokol, J.L., et al.

Clao J, 1990. 16(3): p. 209-13.

The incidence of corneal infections among the almost 20 million Americans who wear contact lenses, while still small, is rising rapidly. Patient non-compliance with instructions for proper lens care is partly at fault. The general phenomenon of patient non-compliance has been widely studied, most often by using the Health Belief Model (HBM). We report here on 50 consecutive patients fit with contact lenses by one ophthalmologist who were questioned by telephone regarding their lens care practices and beliefs. Forty-four percent of this group wore contact lenses for therapeutic reasons; the remainder wore them for either cosmetic reasons (34%) or convenience (22%). Adherence to published lens care guidelines was used as a basis for segregating patients into a compliant and a non-compliant group. By the criteria selected, 46% of the sample was non-compliant in their lens care. An analysis of responses from each group was structured in terms of HBM dimensions. Our aim was to determine whether there were differences in the beliefs held by compliant vs. non-compliant patients. Age under 30 and obtaining lenses for cosmetic or convenience reasons were the two variables statistically associated with non- compliant behavior. At least one undesirable belief representing each of the four HBM dimensions was found to be positively correlated with non-compliant lens use. The HBM is an effective model with which to investigate the relationship between non-compliant behavior and the rise in contact lens-related complications.

Moore, M.B.

Cornea, 1990. 9(Suppl 1): p. S33-5; discussion S39-40.

The avoidance of nonsterile solutions is important to curtailing Acanthamoeba keratitis, a serious infection that has been found to occur with all types of contact lens (CL) wear. Increased patient education, revised recommendations regarding the use of tap and distilled water, and improved disinfecting systems are vital to preventing infection. These precautions are particularly important since it appears that Acanthamoeba, unlike Pseudomonas, may not require an epithelial defect to establish corneal infection and, once in the cornea, may not respond to drug therapy or surgical extirpation. Unfortunately, many patients receive poor lens care instructions or cannot be relied on to follow appropriate routines. Finding a foolproof means of lens disinfection for them is critical. Recently, several disinfection systems were tested against Acanthamoeba castellanii and Acanthamoeba polyphaga cysts and trophozoites to see which might prove most effective. Effective systems included heat disinfection at 70 to 80 degrees C for 10 min, 3% hydrogen peroxide for 2-3 h, 0.001% thimerosal with edetate for 4 h, 0.005% benzalkonium chloride with edetate and reagent for 4 h, and either 0.001% chlorhexidine for 4 h or 0.004% chlorhexidine for 1 h. Thus, for patients who are careless or persist in using nonsterile rinsing solutions, it appears that at least some methods of disinfection will help prevent Acanthamoeba infection.

Piccolo, M.G., N.E. Leach, and R.L. Boltz

Optom Vis Sci, 1990. 67(1): p. 19-21.

Because of the possibility of transmitting communicable diseases, in particular the HIV virus, it has been recommended that all diagnostic contact lenses, including rigid lenses, be disinfected after each use. Hydrogen peroxide is a recommended disinfection agent, but its effect on rigid lens polymers is relatively unknown. We soaked 50 lenses of 5 different polymers in 3% hydrogen peroxide for 10 min and measured the base curves to determine if any changes occurred. Our results showed no statistically significant change in base curve for the lenses measured, but 22% of the lenses did exhibit a small amount of warpage (mean 0.0382 mm) of the base curve. We were not able to determine what caused these lenses, and not all the lenses, to warp. Under the conditions of this study, hydrogen peroxide does not appear to cause clinically significant parameter changes, but lenses should be checked for warpage before use.

Garcia, G.E., J. Aucoin, and G. Gladstone

Clao J, 1990. 16(3): p. 195-9.

A study of extended wear rigid gas permeable lenses in aphakic patients was started in 1975. We present an analysis of 186 patients (274 eyes) with from 1 to 194 months (average: 88 months) of extended wear. Patients wore their lenses 24 hours per day, only removing the lenses for periodic cleaning. Approximately one-third of the patients removed their lenses at least once per week; roughly another one-third wore lenses for up to a month between cleanings; and one-third cleaned lenses at intervals up to 6 months. All of the patients in the study achieved vision with their contact lenses comparable to their best spectacle correction without an overcorrection. None of the patients experienced a permanent loss of vision as a result of this mode of contact lens wear.

Bachman, W.G.

J Am Optom Assoc, 1990. 61(3): p. 203-10.

Aviation systems incorporating sophisticated electro-optical displays frequently are designed without provision for use by spectacle-wearing pilots. Contact lenses offer a solution to the compatibility problems experienced by Army aviators, approximately 18% of whom wear corrective lenses. Under a waiver from The Surgeon General, 44 helicopter pilots performed flying duties while wearing extended-wear soft and rigid lenses. Pilots remained in the study for a minimum of 6 months and a maximum of 24 months. Six experienced temporary discontinuance of wear (4-19 days); and six withdrew from the study. An overall wearing success rate of 86% was achieved. No pilot was grounded due to contact lens-related problems. Subjectively, extended wear contact lenses favorably affected job performance. This is the first major field evaluation of contact lens use by U.S. Army aviators while flying military aircraft.

Wilson, L.A., et al.

Am J Ophthalmol, 1990. 110(2): p. 193-8.

We compared microbial contamination of contact lens storage cases of asymptomatic contact lens wearers (Group 1; No. = 118; sampled once) and of contact lens wearers with manufacturer's lens-care instructions reinforced (Group 2; No. = 62; sampled three, six, 12, and 20 weeks after initial advisement). A significantly higher incidence of contamination of contact lens storage cases and solutions was observed among samples from Group 1 (132 of 247 samples) as compared to samples from Group 2 (30 of 500 samples; P = .000). Contact lens storage cases of individuals in Group 2 who used hydrogen peroxide systems (four of 78) showed a significantly lower incidence of contamination as compared to individuals who used other chemical disinfection (11 of 62 soft lens users; 10 of 59 rigid gas-permeable lens users; P = .041). Biofilms, adhered microorganisms embedded in a glycocalyx, in contact lens storage cases were not always inactivated by the addition of fresh solutions. Cleaning and periodic replacement of contact lens storage cases is recommended.

Golding, T.R., N. Efron, and N.A. Brennan

Optom Vis Sci, 1990. 67(6): p. 461-5.

Soft contact lens wearers complaining of "dry eye" are frequently prescribed rewetting drops, although the mode of action and efficacy of this treatment have not been established. Enhancement of prelens tear film (PLTF) stability could provide a basis for symptomatic relief with solution instillation. Thirty symptomatic hydroxyethyl methacrylate (HEMA) lens wearers participated in 4 separate trials of no solution (baseline), saline, and 2 soft lens lubricants. Solutions were applied for a 6-h adaptation period, and PLTF noninvasive break-up time (NIBUT) was monitored for 1 h after a final instillation. PLTF NIBUT was significantly elevated 1 min after instillation of all solutions (p less than 0.001, logrank test) but this effect persisted for less than 5 min. The transient enhancement of PLTF stability arising from the instillation of these rewetting solutions is unlikely to provide a basis for prolonged symptomatic relief.

Janoff, L.E.

Clao J, 1990. 16(1 Suppl): p. S36-42.

The discovery of hydrogen peroxide (H2O2) by Thenard in 1818, and the early phase of its development, are discussed. A brief description is given of the uses of this compound for purposes other than contact lens care. A detailed description of the first application of H2O2 to hydrophilic contact lenses is provided. A review of toxicologic and microbiologic issues and concerns follows, with specific emphasis on the decimal reduction rate (D-value) for H2O2 and the contribution of elements test as applied to any disinfection system. The role of pH and increasing concentrations of H2O2 in inducing ocular discomfort is described. After the introduction of the first H2O2 system, a number of competitive methods reached the marketplace. The unique qualities of one neutralization technique are noted. Hydrogen peroxide will continue for some time as a popular contact lens disinfection mechanism.

Clao J, 1990. 16(1 Suppl): p. S1-68.

Silvany, R.E., et al.

Ophthalmology, 1990. 97(3): p. 286-90.

Contact lens disinfection systems were evaluated for their effectiveness in killing Acanthamoeba castellanii and Acanthamoeba polyphaga trophozoites and cysts. Amoebae were inoculated into commercially available contact lens cleaning and soaking solutions. At intervals varying from 30 minutes to 24 hours, solutions were filtered. The filters were removed and cultured for Acanthamoeba organisms. Striking differences were observed in the abilities of the different disinfecting solutions to kill the organisms. Solutions containing chlorhexidine were effective at very short exposure times. Solutions containing benzalkonium chloride required slightly longer exposure times but were faster than solutions containing only thimerosal. Solutions containing sorbate, polyaminopropyl biguanide, or polyquaternium-1 were not effective at killing Acanthamoeba organisms in the time allotted for the experiment. Solutions containing hydrogen peroxide were quite effective if the agent was not prematurely catalyzed. A. polyphaga generally required longer exposure to disinfectants than did A. castellanii for complete inhibition to occur.

Bartlett, J.D.

J Am Optom Assoc, 1990. 61(3): p. 159-60.

Bergen, G. and C.B. Slonim

Clao J, 1990. 16(2): p. 114-6.

We incubated ten different hydrogel lens materials in nine different artificial tear preparations and in cromolyn sodium (Opticrom) 4% at 35 degrees C for a period of 6 months. The subsequent ability of these hydrogel materials to transmit visible light was analyzed spectrophotometrically as a measure of each solution's compatibility with the different hydrogel materials. Ultra Tears solution was found to be significantly incompatible with four of the hydrogel materials: tetrafilcon A, deltafilcon A, phemfilcon A, and polymacon. Seven other solution/hydrogel combinations had relatively high absorbance readings that were not statistically significant. These combinations should probably be avoided. Cromolyn sodium 4% was found to be compatible with all hydrogel lens materials tested, as were the majority of artificial tear solution/hydrogel combinations. We believe that the use of the compatible solution/hydrogel combinations should produce no alteration in the ability of the hydrogel lens to transmit visible light (400-700 nm).

Kasparov, A.A., et al.

Vestn Oftalmol, 1990. 106(1): p. 37-41.

The authors analyze the efficacy of microdiathermocoagulation (MDC) in 126 patients with herpetic keratitis. Combined use of MDC and soft contact highly hydrophilic lenses preimpregnated with poludan, an interferon inductor solution, has helped reduce almost twofold the mean period of treatment of 80 patients with dendritic keratitis as compared to idoxuridine monotherapy. The study has shown the advantages of a soft contact lens over ointment dressing prescribed after such microsurgical manipulations to patients with superficial herpetic keratitis. A special microelectrode scarifier is suggested. The efficacy of MDC in the treatment of herpetic stromal keratitis with ulceration has been demonstrated, as well as in the management of superinfection manifestations (purulent ulcer, abscess of the cornea). The technique and the results of MDC are discussed and compared to mechanical abrasion and argon laser coagulation in herpetic keratitis.

Schein, O.D. and E.C. Poggio

Cornea, 1990. 9(Suppl 1): p. S55-8; discussion S62-3.

A case-control study of ulcerative keratitis in soft contact lens (CL) users compared three groups of daily wear or extended wear patients: (a) 86 patients with ulcerative keratitis, (b) 61 hospital-based controls, and (c) 410 population-based controls. Overnight lens use, whether regularly with extended wear lenses or occasionally with daily wear lenses, emerged as the preeminent risk factor for ulcerative keratitis. It increased risk by 10 to 15 times in users of extended wear lenses and by 9 times in users of daily wear lenses when these groups were compared with subjects engaged in strict daily wear of daily wear lenses. Even when actual overnight wear was not taken into account, the relative risk was four times greater in users of extended wear lenses than in users of daily wear lenses. The study found a marginal association (p = 0.056) between lens care frequency in general and ulcerative keratitis in comparing ulcerative keratitis cases with population controls. Of the individual hygiene-related measures, evidence of a protective effect was strongest for cleaning the lens case. Smokers showed a threefold greater risk than nonsmokers, regardless of the type of lens worn. An incidence study found the rate of ulcerative keratitis to be approximately 1 in 2,500 daily wear lens users and 1 in 500 extended wear lens users per year. This finding was statistically consistent with the risk ratio noted in the case-control study. Extrapolations suggest that 4,000 of the 9 million U.S. users of daily wear soft lenses develop ulcerative keratitis annually. Among the 4 million U.S. extended wear soft lens users, 8,000 may do so per year.

Stern, G.A.

Cornea, 1990. 9(Suppl 1): p. S36-8; discussion S39-40.

Microbial keratitis with Pseudomonas aeruginosa is the most common corneal infection associated with contact lenses (CLs). Pseudomonas organisms are ubiquitous in nature, and can colonize CLs without a prior breach in lens care or hygiene. Although poor lens care is often found in affected patients, lens contamination and traumatic epithelial defects are more relevant. Hydrophilic lenses, particularly extended wear lenses, have been associated with a greater frequency of Pseudomonas keratitis. The polymer matrix of these lenses is apparently suited to the avid adherence of Pseudomonas organisms. Adherence is promoted by the presence of lens coatings, which begin to accumulate upon lens insertion and whose level mounts over time. Evidence suggests that infection is more common with mucin-coated contaminated CLs than with noncoated contaminated CLs. In general, lens wear can promote bacterial adherence to the ocular surface by shielding the cornea from the wiping action of the eyelids and immune components in tears. Still, experimental models have shown that keratitis develops regularly (84%) only in corneas that have been traumatized. Trauma may arise through lens insertion or removal, deposits or debris entrapment, hypoxia, or toxic reactions to solution preservatives. Extended wear is believed to facilitate the infectious process because of the chronic accumulation of coatings, the chronic exposure of CLs to potentially adherent bacteria, the continuous presence of irritating lens deposits, the prolonged entrapment of debris beneath the lens, and the relative infrequency of lens cleaning and disinfection.

Cohen, E.J.

Cornea, 1990. 9(Suppl 1): p. S41-3; discussion S47.

Contact lens (CL) fitting carries the risk of transmitting infectious agents, including adenovirus and Pseudomonas. Therefore, a number of precautions must be observed to ensure safety in the office. Paramount among these is hand washing, both immediately after contact with a patient's eyes and again between patients. Equally important is that all trial lenses and CLs removed from patients be disinfected before reuse. Low-water-content soft CLs can be heat disinfected; high-water- content CLs require chemical treatment. A combination of surfactant cleaning with a chlorhexidine-containing agent and hydrogen peroxide disinfection is preferred for rigid lenses to guarantee destruction of human immunodeficiency virus (HIV). The proper use of lens care solutions is also necessary to minimize the risk of their becoming contaminated with pathogenic organisms. Only commercially prepared solutions should be used, preferably in small-volume bottles that are frequently replaced. Preservative-free solutions should be discarded after 1 day's use, whereas preserved solutions may be used for up to 2 weeks. Sterile saline rather than tap water is recommended for rinsing rigid lenses. Finally, part of the clinician's responsibility in running a safe office is to educate patients about these hygienic practices.

Huff, J.W.

Invest Ophthalmol Vis Sci, 1990. 31(7): p. 1288-93.

The relationship of contact lens-induced edema to epithelial and endothelial function was determined in isolated superfused rabbit corneas. Placement of a polymethyl methacrylate (PMMA) contact lens on the cornea caused swelling rates of 15-28 microns/hr compared to 0-6 microns/hr in paired control corneas. The edema increased with temperature (P less than 0.01). PMMA-induced swelling was significant in: 1) bicarbonate-free Ringer's solution; 2) chloride-free Ringer's; 3) 0.3 mM furosemide-treated corneas; and 4) deepithelialized corneas. The swelling did not occur in corneas with silicone oil replacing the endothelium to block fluid uptake. The effluent aqueous bathing fluid from edematous corneas did not induce edema in normoxic corneas. These studies demonstrate that contact lens-induced edema depends on metabolism, involves a significant stromal contribution, and requires fluid absorption across the endothelial layer, but is not a direct result of epithelial and endothelial ion transport inhibition.

Huff, J.W.

Invest Ophthalmol Vis Sci, 1990. 31(5): p. 942-7.

Corneal stromal lactate accumulation may result from epithelial hypoxia and contact lens wear, but the possible corneal toxicity of lactate has not been reported. Isolated superfused whole rabbit corneas were examined for thickness changes during exposure to neutral sodium lactate (NaL) or excess sodium chloride (NaCl) in Krebs-bicarbonate Ringer's solution for a 3-hr period. Placed in the tears side bath, 5 mM NaL significantly thinned corneas (swelling rates of 1 +/- 1 micron/hr in Ringer's controls vs -11 +/- 1 micron/hr in lactate- treated corneas; mean +/- SD). Excesses of 5 mM NaCl had essentially identical effects (0 +/- 1 micron/hr in controls vs -13 +/- 3 micron/hr in experimentals). When placed on the aqueous side of normal-thickness corneas, neither 20 mM NaL nor 20 mM excess NaCl affected corneal thickness, but both solutions stimulated endothelium-mediated deswelling in preswollen deepithelialized corneas. When "loaded" into the stroma of deepithelialized corneas, Ringer containing 20 mM lactate caused more swelling than Ringer's alone (491 +/- 18 microns in controls vs 558 +/- 20 microns in loaded corneas; mean +/- SEM). A similar swelling occurred when 20 mM excess NaCl was loaded into the stroma (483 +/- 15 vs 565 +/- 20 microns in controls and loaded corneas, respectively), due to fluid uptake into the hypertonic stroma across the endothelium from the aqueous side (Ringer's) bath. Corneas both loaded and superfused with either NaL or excess NaCl swelled and subsequently deswelled similar to controls swollen and superfused in Ringer's.(ABSTRACT TRUNCATED AT 250 WORDS)

Harris, M.G., et al.

Optom Vis Sci, 1990. 67(2): p. 129-32.

We evaluated the effectiveness of an in-office microwave disinfection procedure which allowed for the disinfection of up to 40 soft contact lenses at one time. Ciba AOSept cases filled with sterile unpreserved saline were contaminated with one of six FDA test challenge microorganisms at a concentration of approximately 10(3) colony forming units per milliliter (CFU/ml). Twenty cases were placed on the rotating plate of a standard 2450 MHz 650 W microwave oven in a 10-cm diameter circle. The cases were exposed to high intensity microwave irradiation for periods of 0 to 15 min. None of the 6 microorganisms evaluated survived 2 min or longer of microwave exposure. Our findings indicated that microwave irradiation can be a convenient, rapid, and effective method of disinfecting a number of soft contact lenses at one time and thus adaptable as an in-office soft contact lens disinfection procedure.

Starr, M.B.

N Y State J Med, 1990. 90(1): p. 12-6.

Kilvington, S., et al.

J Clin Microbiol, 1990. 28(12): p. 2722-5.

Following the diagnosis of Acanthamoeba keratitis in a contact lens wearer, the antimicrobial susceptibility of the clinical isolate and the environmental source of the infection were investigated. Contrary to previous reports, in vitro antimicrobial testing showed that the infecting strain was inherently resistant to propamidine isethionate. Restriction endonuclease digestion analysis of Acanthamoeba whole-cell DNA of strains isolated from the patient's cornea, contact lens storage container, saline rinsing solution, and kitchen cold-water tap showed that the isolates were identical. This implicates, for the first time, domestic tap water as the source of Acanthamoeba sp. in this infection. It is therefore recommended that the use of homemade saline solutions and the rinsing of contact lenses in tap water be strongly discouraged.

Harris, M.G., et al.

Optom Vis Sci, 1990. 67(2): p. 84-8.

We evaluated the pH of eight brands of aerosol saline solution to determine if there is a change in pH during the normal usage of an aerosol canister. The pH measurements were taken over a period of 14 to 24 days with a Corning model 10 pH meter (accuracy +/- 0.05 pH units). The saline was expelled and measured daily in 15-ml increments, the approximate volume used each day by soft lens wearers. We found no significant change in pH within each brand evaluated over the test period. However, there was a statistically significant difference in the median pH of the buffered and the unbuffered aerosol saline solutions. The mean pH of the buffered aerosol saline solutions, which averaged 7.30 pH units, was within the ocular comfort range. The mean pH of the unbuffered aerosol saline solutions, which averaged 5.79 pH units, was outside the ocular comfort range. This indicates that all aerosol saline solutions should be buffered.

Harris, M.G.

Clao J, 1990. 16(1 Suppl): p. S53-60.

Three studies were conducted to evaluate the effectiveness of hydrogen peroxide (H2O2) neutralization in returning the pH of the soft contact lens soaking solution to that of tears (pH 7.4). In the initial study, we evaluated seven different brands of H2O2 disinfection systems. The final pH of the seven systems ranged from 6.15 to 7.74, with two systems having values outside the threshold for ocular discomfort. The final residual H2O2 concentrations ranged from 0 to 70 ppm (parts per million), five of the seven having residual concentrations of 0 to 3 ppm. In the second part of the study, we evaluated the pH of four H2O2 systems over 4 weeks of daily use. The end-point pH of the H2O2 systems did not change significantly over the 4-week period, although two of the systems were consistently closer to the physiologic pH of tears than were the other two. In the third part of the study, four brands of over-the-counter (OTC) 3% H2O2 were substituted into six different H2O2 disinfection systems. The manufacturer's recommended H2O2 was used as a control. There were wide variations in initial pH and significantly lower end-point pH levels with the OTC preparations.

Harich, I., M. Bohnke, and J. Draeger

Fortschr Ophthalmol, 1990. 87(5): p. 475-8.

We investigated the protective effect of the high-viscosity substances sodium hyaluronate (1%) and methylcellulose (2%) on corneal endothelium in the face of severe mechanical insult. An intraocular lens was drawn across the endothelium of porcine corneas with standardized conditions. We used different compression forces. Methylcellulose and sodium hyaluronate were used as lubricating substances in the experimental groups, while balanced salt solution (BSS PLUS) was used in the control group. In this study no significant protective effect of high-viscosity substances against strong direct mechanical damage was generally demonstrable. Only one group in which a moderately strong compression force was applied showed significantly less smaller endothelial cell loss when methylcellulose was used. The most important function of viscous substances is therefore to prevent a collapse of the anterior chamber and to prevent any contact of the intraocular lens or of instruments with the endothelium. Any mechanical contact with the endothelium means an irreversible endothelial cell loss.

Wilson, G.S. and R.L. Chalmers

Optom Vis Sci, 1990. 67(4): p. 252-5.

The corneal epithelium can be affected adversely by some preservatives used in contact lens solutions. To test the effect of H2O2 at the epithelial surface, the rabbit cornea was perfused with various concentrations of H2O2, and the effect on stromal and Anterior Bright Band (ABB) thickness measured for 150 min. The study compares stromal swelling and ABB swelling for a single 10-min pulse with that for a 150- min sustained dose. With the 10-min pulse dose there was no significant swelling up to 235 ppm H2O2, the highest dose tested. With the sustained dose, significant stromal swelling began between 72 and 153 ppm H2O2. These results indicate that residual H2O2 present at the epithelial surface after neutralization in current contact lens disinfection systems does not have a high enough concentration to affect corneal function adversely.

Holden, B.A.

Cornea, 1990. 9(Suppl 1): p. S69-71.

Although most contact lens (CL) patients prefer the convenience of extended wear lenses, 85% of consumers worldwide use their lenses on a daily wear basis. This disparity between preference and practice is due largely to the association of extended wear lenses with a high rate of both short- and long-term problems. Up to 26% of hydrogel extended wear patients cease lens wear because of chronic hypoxia or ocular inflammation. Among patients using extended wear rigid gas-permeable (RGP) lenses, discomfort causes 18% of all discontinuations. These problems must be addressed and solved before extended wear can truly become a viable option for CL patients. One possible solution is the development of hydrogel materials that have high gas permeability (100 Dk), minimal water loss, and deposit resistance. In the event that such materials are not forthcoming, the use of currently available extended wear lenses on a daily wear, regular replacement basis offers the greatest chance of success for hydrophilic lenses. Finally, the discomfort associated with rigid lenses may be reduced by developing more flexible RGP materials with an optimum design.

Holden, B.

Clao J, 1990. 16(1 Suppl): p. S61-4.

Hydrogen peroxide (H2O2) is one of the best disinfectants for contact lenses. Despite the fact that hydrogen peroxide challenges microorganisms of all kinds, issues such as time of exposure, post- neutralization residuals, and lens stability remain. Data indicate that the currently recommended short exposure time (10 to 15 minutes) in inadequate for protection against fungi and Acanthamoeba and that at least 2 hours is necessary. The addition of weekly enzyme for lens cleaning is also essential in decreasing the incidence of contact lens- related conjunctivitis when lenses are not replaced frequently. In studies at the Cornea and Contact Lens Research Unit (CCLRU) of the University of New South Wales, daily wear of "disposable" lenses, mechanical cleaning, an H2O2 system, and lens disposal on a monthly basis resulted in an adverse response rate of almost zero over the first year of use. Residual H2O2 levels are of concern with some systems. Although data indicate that 100 ppm of H2O2 is the threshold for ocular awareness in many individuals, post-neutralization pH at the end of the neutralization cycle plays an important role in the occurrence of residual effects. Lens material composition also may play a role in determining the rate and degree of post-neutralization parameter recovery. These issues underscore the need for continued clinical research of H2O2 to update our understanding of the best methods of use for this valuable disinfection regimen.

Heidemann, D.G., et al.

Am J Ophthalmol, 1990. 110(6): p. 630-4.

Two patients developed Acanthamoeba keratitis associated with the use of disposable extended-wear hydrogel contact lenses. Both patients removed, irrigated, and reinserted the contact lenses without disinfecting them. One patient wore the lenses on a daily basis, rinsed the lenses in tap water, stored them overnight, and discarded them weekly. Both infections were treated successfully. In a third patient, Acanthamoeba species was cultured from two pairs of disposable lenses that had been stored in cases rinsed with well water. Potential benefits from disposable contact lens wear are negated when patients do not comply with a continuous wearing schedule.

Roth, H.W. and J. Teuchert

Fortschr Ophthalmol, 1990. 87(4): p. 369-73.

In a clinical long-term study over a period of 10 years with 3850 patients wearing hard and soft contact lenses, unusual reactions of the cornea and perilimbal conjunctiva have been observed in 3% of all cases. Mainly corneal abrasions, cracks, clouds and mosaics have been observed, which were analyzed as being rare contact lens complications. The causes were lack of proper maintenance of the contact lenses, such as mistakes in cleaning and disinfecting the lenses, mishandling or toxic and allergic reactions due to cleaning and disinfection solutions. Only exact ophthalmological monitoring of the anterior parts of the eye and laboratory tests on the worn lenses permit differentiation between primary eye diseases and contact lens-induced complications.

Clin Pediatr (Phila), 1990. 29(4): p. 233.

Friedlander, P. and M.L. Zimny

Invest Ophthalmol Vis Sci, 1989. 30(10): p. 2138-47.

This study was undertaken to determine the effects of thin (60 microns) and thick (240 microns) soft contact lenses of equal water content (70%) and power on nonlesioned and lesioned rabbit corneas. In one group of animals, corneas were not lesioned. Thin lenses were placed on left corneas and thick lenses on right corneas. In a second group, lesions were made in both corneas. Left corneas were covered with thin lenses and right corneas with thick lenses. Post-treatment times were 8 hr and 24 hr. At sacrifice, one-half of the cornea was fixed in 4% buffered glutaraldehyde for SEM study. The other half was cut into segments, fixed in a buffered glutaraldehyde-ruthenium red (RR) solution post-osmicated in osmium containing RR and prepared for TEM. At both 8 hr and 24 hr SEM showed cell migration in lesioned corneas covered with thin lenses but not in lesioned corneas covered with thick lenses. At 8 hr, TEM of nonlesioned and lesioned corneas showed no changes in the thickness of the corneal epithelium or the RR staining of the surface. At 24 hr, in nonlesioned corneas covered with thick lenses, the RR staining of microvilli and the height of the corneal epithelium were less than in nonlesioned corneas covered with thin lenses. In lesioned corneas covered with thick lenses, the thickness of the cornea was markedly reduced, the RR staining of microvilli was less and basal cells were more compressed than in lesioned corneas covered with thin lenses. The results of this study indicate that the thickness of a soft contact lens is important in treating corneal trauma.

Podmore, P. and F.J. Storrs

Contact Dermatitis, 1989. 20(2): p. 98-103.

20 patients complaining of contact lens intolerance were patch tested to a contact lens solution and a contact lens components battery. Contact urticaria testing was also carried out. 8 patients had positive delayed reactions on patch testing, 6 patients had positive contact urticaria reactions, and 9 patients had no reactions. These results are discussed and possible alternative diagnoses for the 9 undiagnosed patients are proposed.

Lea, P.J. and M.J. Hollenberg

Am J Anat, 1989. 184(3): p. 245-57.

Mitochondrial structure has been examined in three dimensions using high-resolution scanning electron microscopy in cells from rat liver, retina (photoreceptors and retinal pigment epithelium), and kidney (proximal convoluted tubular cells and podocytes). Tissues were prepared by aldehyde-osmium fixation and freeze cleavage using a cryoprotectant, followed by removal of the cytosol by immersion in a dilute osmium tetroxide solution. The microscope used (Hitachi S-570) was equipped with a secondary electron detector located in the column above the specimen, situated within the objective lens. Mitochondria in all tissues examined were found to have only tubular cristae, which in some instances could be seen to span the entire diameter of the organelle. The walls of the tubular cristae, when unfractured, were in contact with the inner mitochondrial membrane; and their lumens were open to the intermembranous space. We hypothesize that in cells of many, perhaps most tissues, mitochondrial cristae are not shelf-like but are, in fact, tubes which span the mitochondrial matrix and are continuous with the inner mitochondrial membrane at both ends.

Penley, C.A., S.W. Willis, and S.G. Sickler

Clao J, 1989. 15(4): p. 257-60.

Ten soft contact lens cleaners, three rigid gas permeable contact lens (RGP) disinfecting-soaking solutions, and four hydrophilic contact lens disinfecting solutions were evaluated by laboratory challenge procedures for their antimicrobial efficacy against trophozoites and cysts of Acanthamoeba polyphaga and Acanthamoeba castellanii. MiraFlow was the only cleaner that killed trophozoites and cysts on all lenses during the cleaning step. A disinfecting solution preserved with chlorhexidine and one preserved with benzalkonium chloride killed trophozoites of A. polyphaga within 4 hours, but cysts persisted in both solutions for at least 2 days. Cysts of A. polyphaga survived in three disinfecting solutions up to one week, whereas those of A. castellanii were recovered from six disinfecting solutions at 7 days. An RGP solution that is marketed only in Japan was effective against trophozoites and cysts of both species within 30 minutes.

Rabinowitz, S.M., S.C. Pflugfelder, and M. Goldberg

Arch Ophthalmol, 1989. 107(8): p. 1121.

Rakow, P.L.

J Ophthalmic Nurs Technol, 1989. 8(2): p. 67-8.

Pinzauti, S., et al.

J Pharm Biomed Anal, 1989. 7(12): p. 1611-6.

Under positive-ion fast atom bombardment (FAB) mass spectrometric conditions, benzalkonium chloride (BAK) afforded intense peaks at m/z 304 and 332, corresponding to the intact cations [M--Cl]+ of C12 and C14 homologues, respectively. The use of benzethonium chloride as an internal standard and thioglycerol as a FAB matrix allowed the direct and specific determination of the BAK content (0.004-0.020%) in commercial hard contact lens solutions through the individual assay of the two alkyl homologues. A linear relationship between the homologue concentration and the peak-area ratio was observed over the concentration range 3-180 micrograms ml-1.

Gobbels, M., A. Wahning, and M. Spitznas

Fortschr Ophthalmol, 1989. 86(5): p. 448-50.

Deep stromal and preendothelial corneal opacities have been described to be a problem of growing importance in contact lens wearers, above all in those with a more than ten-year-old history of contact lens wearing. In the present study the corneal endothelial permeability of 21 patients with a more than ten-year-old history of contact lens (HEMA 38%) wearing has been determined and compared with that of an age- matched group of 8 healthy individuals without ocular disease. The corneal endothelial permeability has been measured by a computerized automated fluorophotometer (Coherent Radiation Fluorotron Master) after topical application of a Na-fluorescein solution according to the method described by Jones and Maurice. The corneal endothelial permeability of contact lens wearers with deep corneal opacities has been found to be significantly (p = 0.05) increased when compared with contact lens wearers without corneal opacities. Contact lens wearers without corneal opacities showed no significant increase of their endothelial permeability in comparison to the control group.

Barr, J.T., et al.

Optom Vis Sci, 1989. 66(3): p. 133-40.

Soft contact lenses worn by six patients (12 eyes) diagnosed as having contact lens-induced superior limbic keratoconjunctivitis (SLK) and from four patients (5 eyes) with giant papillary conjunctivitis (GPC) were analyzed for protein concentration and for elemental content. Fifty-five percent water content, ionic lenses containing methacrylic acid had high protein concentration. Calcium was not a common element found on protein-coated lenses. Sulfur and iron were found on used and new lenses. An elevated level of mercury was detected in one gray lens that had been disinfected in thimerosal-preserved saline with a high heat disinfection unit by a patient with SLK.

Bates, A.K., et al.

Eye, 1989. 3(( Pt 6)): p. 803-10.

Ninety four patients with 'sterile' keratitis presenting consecutively over a nine month period to the Accident and Emergency Department of Moorfields Eye Hospital were studied. This condition was found to account for 0.49% of all new casualties. A significant association was found in these patients, compared with controls, with contact lens hygiene, particularly for daily wear soft contact lenses, and contact lens case contamination by bacteria suggesting that these may be important factors in the aetiology of 'sterile' keratitis. Compared to gas permeable hard contact lenses the relative risk of developing 'sterile' keratitis in our patients was found to be 2.3 times higher with extended wear soft contact lenses, 1.56 times higher with daily wear soft contact lenses and 0.509 with polymethylmethacrylate lenses (test of trend p-value less than 0.05). The results indicate that 'sterile' corneal infiltrates are related to contact lens hygiene and in part to contact lens case contamination by bacteria and also to the type of lens worn.

Bowden, F.W.d., et al.

Clao J, 1989. 15(1): p. 49-54.

A prospective study of 24 contact lens patients with culture- or histopathology-proven microbial keratitis was performed between July and December 1987 to determine associated lens care practices and patterns of lens care product contamination. A questionnaire was used to document methods of lens care. Bacterial cultures were performed on all available contact lenses, lens cases, and solutions (including saline, disinfectant, daily cleaner and wetting agents), in addition to standard smears and cultures of the corneal ulcer. Failure to follow standard recommendations regarding contact lens care was widespread (21 of 24, 88%). In the majority of patients (20 of 24, 83%) bacterial contamination of the contact lens, case, and/or solutions was present. Almost two-thirds (15 of 24, 62%) of patients used solutions that were more than 3 months old. Cosmetic extended wear lens patients were most likely (7 of 8, 88%) to use solutions that were more than 3 months old and very likely (6 of 8, 85%) to have contaminated solutions. Efforts to improve lens care and decrease lens product contamination are necessary to prevent contact lens associated corneal ulcers.

Brandt, F.H., D.A. Ware, and G.S. Visvesvara

Appl Environ Microbiol, 1989. 55(5): p. 1144-6.

Acanthamoeba keratitis is a chronic infection of the human cornea. Many people who have this infection wear soft contact lenses. Usually lens wearers clean and maintain their lenses with various ophthalmic solutions including homemade saline. Recently it has been shown that homemade saline solutions play a role in lens contamination and thus in Acanthamoeba keratitis. We therefore evaluated the viability of cysts of three species of Acanthamoeba by exposing them for various time periods to saline, cleaning, and disinfectant solutions generally used to care for these lenses. We found that the viability of the cysts in saline solutions ranged from a minimum of 14 days to 90 days of exposure. In cleaning solutions, the survival times ranged from a minimum of 1 day to 90 days of exposure. Disinfectants, as expected, were the most effective of all tested solutions in killing Acanthamoeba cysts. The survival times ranged from 6 h to 14 days. None of these products were effective in destroying Acanthamoeba cysts in less than 6 h of exposure, which exceeds the suggested time that any given solution should be used for lens care.

Bruce, A.S.

J Am Optom Assoc, 1989. 60(8): p. 581-2.

Some hydrogel contact lenses are susceptible to changes in hydration when soaked in hydrogen peroxide solutions of acidic pH. This study uses a hand refractometer to assess the water content of four Hydrocurve Elite hydrogel contact lenses during prolonged hydrogen peroxide disinfection. A 3-week period of soaking in peroxide solution lead to a decrease in contact lens water content from 50% to approximately 30%. Full rehydration of the lenses occurred over a period of 2 days, using one rinse and two changes of the recommended sodium thiosulfate neutralizing solution.

Cejkova, J., et al.

Cesk Oftalmol, 1989. 45(6): p. 408-11.

The authors investigated on the rabbit eye the effect of long-term continuous wearing (14, 21, 28 days) hydrophilic contact lenses (h. c. l.) with varying degrees of hydration (37%, 55%, 65% water). Long-term wearing of the lenses caused disorders in all corneal layers. These changes are identical in all types of contact lenses, only their onset is earlier and the extent is more marked in contact lenses with a low hydration (37% water). Contrary to epithelial changes in the corneal stroma, the changes are qualitatively different depending on the degree of hydration of the contact lens. Prolonged application of contact lenses with 37% water leads to infiltration of the stroma by inflammatory cells which carry the activities of destructive lysosomal enzymes. The latter are gradually released into tissues and local degenerative processes develop which in some instances culminate by ulceration. Other corneas are vascularized. The described changes in stroma were not found in hydrophilic contact lenses with 55% and 65% water. After prolonged application of highly hydrated contact lenses (65% water) the authors, however, observed uptake of liquid from the upper third of the stroma due to the contact lens which dried on the eye and acted on the cornea as a hypertonic solution. In this subepithelial zone the staining of glycosaminoglycans was reduced, similarly as the enzymatic activities in keratocytes which suggests serious degenerative processes, i. e. disorders in the synthesis of components of the ground substance of the corneal stroma.

Chalmers, R.L.

Optom Vis Sci, 1989. 66(11): p. 796-803.

The role of hydrogen peroxide when it is physiologically produced or when it is applied externally to the eye is examined in this review. Three enzymes deal with the endogenously produced H2O2. They are catalase, superoxide dismutase, and glutathione peroxidase. These enzymes are present at different concentrations in ocular tissues and function most efficiently at different concentrations of H2O2. For H2O2 which contacts the external surface of the eye, the same enzymes also seem to act to metabolize the H2O2. In general the eye is more sensitive to changes in pH than to low concentrations of topically applied H2O2 at concentrations less than about 400 ppm. So, the small amounts of residual H2O2 which remain on contact lenses after disinfection in H2O2 solutions do not pose a great risk to the eyes.

Harris, M.G., et al.

Optom Vis Sci, 1989. 66(2): p. 82-6.

We evaluated the effectiveness and convenience of microwave irradiation as a method of disinfecting soft contact lenses. Soft contact lenses from each of the four Food and Drug Administration (FDA) categories were placed in sterile vials and immersed in 2 ml of saline which had been contaminated with one of three common species of bacteria. The contaminated lens vials were placed in a standard 600 W microwave oven and exposed to microwave irradiation times ranging from 30 to 180 s. Significant reductions in bacteria colony counts were found after 30 s of microwave irradiation. Few of the bacteria survived 60 s of microwave exposure and none survived 90 s. Our findings indicate that microwave disinfection can be an effective and rapid means of killing bacteria on soft lenses and in the storage solution. However, further studies are necessary to determine the minimum exposure time required, the effect of microwave disinfection on other microorganisms, and the effect of microwave irradiation on contact lens polymers and lens dimensions.

Harris, M.G., et al.

Optom Vis Sci, 1989. 66(12): p. 839-42.

We evaluated the pH of six hydrogen peroxide (H2O2) soft lens disinfection systems which had over-the-counter (OTC) H2O2 substituted for the manufacturer's recommended H2O2. Substitution of four brands of OTC H2O2 into the five two-step disinfection systems resulted in a pH after neutralization which ranged from 6.70 to 7.55 pH units. There was a small but statistically significant difference in the pH after neutralization when OTC H2O2 was substituted for the manufacturer's recommended H2O2. There was a significantly lower pH after neutralization when the same brands of OTC H2O2 were substituted for the manufacturer's recommended H2O2 in a one-step H2O2 disinfection system. The pH after neutralization for the manufacturer's recommended H2O2 was 6.50 pH units. The pH after neutralization for the OTC H2O2 ranged from 3.35 to 4.77 pH units. This range is below the ocular comfort range of 6.6 to 7.8 pH units. These findings, along with other possible differences between OTC H2O2 and the manufacturer's recommended H2O2, indicate that OTC H2O2 should never be substituted for the manufacturer's recommended H2O2 in any H2O2 soft lens disinfection system.

Connor, C.G., Y. Blocker, and D.G. Pitts

Optom Vis Sci, 1989. 66(10): p. 690-3.

Acanthamoeba culbertsoni was used in this study inasmuch as its susceptibility to disinfection has not been examined. Although heat was found to be the most effective means of disinfection some cysts survived this procedure. Chlorhexidine exhibited a dose-response kill curve but the most effective concentrations are also corneo-toxic. Polyaminopropylbiguanide (0.00005%) has good effectiveness against the cyst but was not completely cidal at the dose tested. Thimerosal (0.002%) and hydrogen peroxide (3%) were found to be without effect. These findings should give contact lens practitioners guidelines for selecting a disinfection system for their patients.

Tripathi, B.J. and R.C. Tripathi

Arch Ophthalmol, 1989. 107(10): p. 1516-9.

We investigated the cytotoxicity of hydrogen peroxide by exposing primary cell cultures of human corneal epithelium to a single dose of this agent at concentrations ranging from 30 to 100 ppm. Hydrogen peroxide, at a concentration as low as 30 ppm, caused cell retraction as well as cessation of cell movement and mitotic activity. Formation of membranous vesicles preceded cell death that occurred by 7 to 8 hours after exposure to 30 ppm. With a concentration of 50 ppm, normal cell activity ceased almost instantaneously. Numerous surface vesicles formed by 1.5 hours of exposure, and the cells died by 4 to 5 hours. Higher concentrations of hydrogen peroxide (70 to 100 ppm) caused cell death within a few minutes. Because neutralization of hydrogen peroxide and patient compliance are critical in the proper use of hydrogen peroxide-based contact lens disinfection systems, users will be well served if the long-term effects of residual peroxide on the cornea are subjected to continued study.

Dolman, P.J. and M.J. Dobrogowski

Am J Ophthalmol, 1989. 108(6): p. 665-9.

A 253.7-nm ultraviolet light with an intensity of 1,100 microW/cm2 was tested for its germicidal activity against contact lenses and storage solutions contaminated with various corneal pathogens. The exposure time necessary to reduce a concentration of organisms from 10(6)/ml to less than 10/ml was 30 seconds for Staphylococcus aureus, 60 seconds for Pseudomonas aeruginosa, and 84 seconds for Candida albicans. The time necessary to sterilize a suspension of 10(4)/ml Acanthamoeba polyphaga was less than three minutes with this technique. Four brands of soft contact lenses were exposed to ultraviolet light for over eight hours without changing their appearance, comfort, or refraction.

Cotgreave, J.T., et al.

Prof Nurse, 1989. 4(9): p. 446-9.

Hardman Lea, S.J., J. Loades, and M.P. Rubinstein

Acta Ophthalmol (Copenh), 1989. 67(4): p. 441-6.

The interaction between sodium fluorescein dye and hydrophilic contact lenses was assessed quantitatively by spectrophotometry. Absorption of dye into he lens matrix was found to be proportional to the exposure time and also depends on the optical power and water content of the lens. 0.9% saline appeared preferable to oxidising agents as a rinsing solution in decontamination procedures. 3% hydrogen peroxide solution affects the nature of fluorescein such that it becomes colourless and also absorb less incident light, whilst still being retained within the lens. The implications of our findings for practical lens decontamination and theoretical fluorescein/polymer binder are discussed.

Demas, G.N.

J Am Optom Assoc, 1989. 60(10): p. 732-4.

The pH of contact lens solutions has been implicated in the comfort of contact lenses on insertion. The pH of five samples each of 11 different products available for the rinsing and wetting of contact lenses was measured over a 4-month period. Buffered solutions were initially neutral to slightly basic (mean pH 7.03-7.83) and remained relatively close to their original pH throughout the study. The unbuffered solutions tested were initially acidic (5.81 and 5.46). One unbuffered solution rapidly became even more acidic (5.01) before rebounding slightly toward its original value. The difference in the mean pH between all the buffered solutions and the unbuffered solutions was found to be statistically significant. This study indicates the use of buffered solutions unless otherwise contraindicated.

Driebe, W.T., Jr.

Surv Ophthalmol, 1989. 34(1): p. 44-6.

Disposable soft lenses are now available for extended wear. These lenses were designed to provide a more acceptable margin of safety than conventional extended wear soft lenses. Disposable lenses, which are intended to be discarded after 1-2 weeks of continuous wearing time, do offer a number of theoretical advantages. The short wearing schedule minimizes deposit formation which has been implicated in the development of giant papillary conjunctivitis and infectious keratitis. Lens disinfection systems, which are expensive and time consuming, and may become contaminated, are rarely needed if the manufacturer's guidelines are followed. Careful longterm follow-up of disposable soft lens patients will be needed to establish actual patient compliance and the safety of these lenses.

Dunn, J.P., Jr., et al.

Am J Ophthalmol, 1989. 108(2): p. 113-7.

Four patients developed corneal ulcers associated with the use of disposable extended-wear hydrogel contact lenses. Bacteria were recovered from corneal ulcers in three of the patients. Three patients discarded their contact lenses after ten or more days of extended wear; the corneal ulcers in these patients developed toward the end of the wearing cycle. The fourth patient removed her contact lenses every two days for cleaning and disinfection and discarded them for a new pair on a weekly basis. Improper lens hygiene was noted in only one patient. All corneal ulcers responded to antibiotic treatment. In three patients visual acuity returned to normal, but scarring of one patient's cornea resulted in a visual acuity of 20/60.

Sack, R.A., H. Harvey, and I. Nunes

Clao J, 1989. 15(2): p. 138-45.

Chemical analysis was carried out on clinically obtained hazy white hydrogel lenses that had been exposed to hydrogen peroxide disinfection. Analysis revealed that hazing was a surface phenomenon limited to high water content ionic matrix hydrogels (type IV), the type associated with the deposition of large amounts of lysozyme. We subjected unworn lenses to cycling studies involving doping in a variable artificial tear solution followed by exposure to disinfectant; this allowed us to duplicate the clinical situation and to derive a mechanism for this phenomenon. Hazing proved independent of the presence of hydrogen peroxide but dependent on the interaction of lens- bound lysozyme and stannate anion, the latter derived from sodium stannate present in the disinfectant as a stabilizing agent. Hazing is restricted to the type IV hydrogels because only these polymers have a sufficient number of anionic binding sites and are of sufficient porosity to allow the penetration and binding of a thick layer of lysozyme. Lysozyme is essential to hazing. No other tear protein is small enough to penetrate the hydrogel matrix or basic enough to have a marked affinity for the lens and to provide binding sites for stannate anion. These findings highlight the unique vulnerability of the type IV hydrogel to interaction with trace or transient ionic constituents in tears and lens care solutions.

Donzis, P.B., et al.

Am J Ophthalmol, 1989. 108(1): p. 53-6.

We analyzed bacterial and fungal contamination within the contact lens care systems of ten patients who had Acanthamoeba detected within their care systems. Seven patients had Acanthamoeba keratitis, one had Pseudomonas keratitis, and the remaining two were asymptomatic. Gram- negative bacteria were found in all ten care systems, and Pseudomonas was found in six. Bacillus species, the only gram-positive bacteria isolated, were found in five systems. Fungi were isolated in six care systems. The use of homemade saline and the two-cup method of peroxide disinfection were associated with microbial contamination. Acanthamoeba organisms were found only in contact lens cases or solutions that also had bacterial and in many cases fungal contamination, suggesting that the presence of bacterial and fungal contamination within the contact lens care system may be an important element for the survival and growth of Acanthamoeba.

Grutzmacher, R.D.

Postgrad Med, 1989. 86(4): p. 90-2, 97-100.

Because of the continued popularity of contact lenses in the United States, ocular inflammatory diseases are being encountered with increasing frequency by both ophthalmologists and primary care physicians. Distinction between minor noninfectious inflammation and serious, sight-threatening infection is crucial to the proper management of these patients. Symptoms of infectious keratitis are pain and loss of vision. Signs include infiltration or loss of clarity of the cornea, eyelid swelling, and purulent discharge. If an infectious process is suspected, the patient should be referred to an ophthalmologist immediately. If this is not possible, the contact lens should be removed and a culture performed, if possible. Aminoglycoside antibiotic drops should be applied frequently until ophthalmologic consultation is obtained. Patients should be reminded of the need for strict adherence to disinfection techniques and avoidance of homemade saline preparations. They should also be told to discontinue use of contact lenses at the first sign of ocular irritation or inflammation and to report to their physician if inflammation persists.

Wood, T.S., et al.

Ophthalmology, 1988. 95(6): p. 822-6.

This multicenter study of patients with contact lens-associated giant papillary conjunctivitis (GPC) was a randomized, double-masked comparison of a 1.0% suprofen solution versus the suprofen vehicle solution (placebo). Patients were given two drops of medication four times daily for up to 28 days and were clinically examined on days 0, 2, 7, 14, 21, and 28. The physicians' clinical judgments of the patients' responses to therapy significantly favored suprofen over placebo at day 21 (P = 0.02), while strongly favoring suprofen at day 14 (P = 0.057) and at day 28 (P = 0.067). The patients' opinions of their response to therapy significantly favored suprofen on day 14 (P = 0.03); a trend for suprofen was evident on day 28 (P = 0.1). Treatment with suprofen led to a greater overall reduction in ocular signs and symptoms than with placebo. Strong trends approaching statistically significant levels were found for reductions in the principal ocular sign, papillae, at day 28 (P = 0.068) and in mucus strands at days 14 and 28 (P = 0.09), which also favored suprofen.

Hall, L. and L. Takahashi

J Pharm Sci, 1988. 77(3): p. 247-50.

A specific and sensitive HPLC method has been developed for the quantitative determination of disodium edetate (1) in a variety of ophthalmic and contact lens care solutions. Using this method, a common contaminant, nitrilotriacetic acid (2), is easily separated from 1. Sample preparation involves a single dilution step prior to mixing with an aqueous cupric nitrate solution to form a copper:EDTA complex for analysis. An aliquot of the resulting mixture is analyzed by HPLC using either a 10-microns styrene divinyl benzene column or, for separations requiring greater selectivity and resolution because of interfering components in the sample matrix, a 5-microns octadecyl column with a mobile phase of acetonitrile:0.006 M aqueous tetrabutylammonium phosphate, pH 6.5 (20:80). The column effluent is monitored by UV detection at 254 nm. The method is linear, quantitative, and reproducible for a wide variety of formulations. Using this method, the average recovery of 1 from spiked samples was 100%, with a relative standard deviation of less than 2%. The minimal quantifiable level of 1 was approximately 2.8 ng (equivalent to an analytical concentration of 1.5 microgram/mL).

Harris, M.G., J. Torres, and L. Tracewell

Am J Optom Physiol Opt, 1988. 65(7): p. 527-35.

Hydrogen peroxide disinfection has caused discomfort for some soft contact lens wearers even though the solution was neutralized properly. The discomfort could be due to the endpoint pH of the system used or the residual H2O2 concentration. Using a digital pH meter and H2O2 concentration detection strips, we measured the pH and H2O2 concentration of seven different hydrogen peroxide disinfection systems over their recommended disinfection and neutralization cycles to determine their time courses and endpoint values. The final pH of the seven systems varied from 6.15 to 7.74 pH units. All systems resulted in residual H2O2 concentrations below threshold values. These findings indicated that the final pH may be the cause of patient discomfort after hydrogen peroxide disinfection and neutralization.

Gordon, A.

Am J Optom Physiol Opt, 1988. 65(3): p. 147-50.

This pilot study was conducted to determine if prospective patch-test screening could predict ocular tolerance to a thimerosal-preserved chemical disinfection system. Thirty patients were patch tested for thimerosal hypersensitivity before beginning soft contact lens wear. Only one patient exhibited a positive prospective patch test and subsequently developed an ocular thimerosal hypersensitivity. Two other patients with negative patch tests developed thimerosal hypersensitivity reactions over the 1-year study duration. Prospective patch testing for thimerosal hypersensitivity was neither clinically valuable nor sensitive in this particular sample.

Pepose, J.S.

Clao J, 1988. 14(3): p. 165-8.

Current FDA standards for contact lens disinfecting systems require that viricidal activity be demonstrated against just one strain of herpes simplex virus, type 1. Small and nonenveloped viruses (e.g., adenoviruses) may be more resistant to disinfection than herpes simplex virus (HSV); however, the efficacy of disinfection systems against these other agents is not routinely tested. Currently approved methods of chemical and thermal lens disinfection do appear to be efficient means to inactivate HSV and the human immunodeficiency virus, both of which have lipid envelopes.

Clao J, 1988. 14(1): p. 55-6.

White, G.L., Jr., S.M. Thiese, and M.K. Lundergan

Am Fam Physician, 1988. 37(4): p. 187-92.

In the past 20 years, great strides have been made in contact lens technology, but this progress has been accompanied by a multitude of lens-related problems. Bacterial keratitis may be the most significant problem, but reports of Acanthamoeba keratitis, a parasitic corneal infection, are increasing. Infectious complications may be lessened by proper lens care. Thermal disinfection is recommended for soft lenses with a low water content; chemical decontamination is preferred for soft contact lenses with a high water content.

Bohnert, J.L., et al.

Invest Ophthalmol Vis Sci, 1988. 29(3): p. 362-73.

A series of polymers and copolymers of 2-hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) were synthesized in order to find surfaces that would adsorb minimal amounts of protein. The adsorption of albumin, lysozyme and immunoglobulin G from a three-way mixture of these proteins in isotonic buffered saline to the polymers was measured using 125I-labeled proteins. Apparently high protein uptake on copolymers rich in HEMA was found to be due to sorption of unbound 125I by the polymers. 125I sorption by the polymers was minimized by dialysis of the protein solution to remove unbound 125I iodide and inclusion of 0.01 M sodium iodide to block uptake of residual 125I iodide. Using these improved protocols, minimal total protein uptake was observed on copolymers containing 50% or more HEMA. The majority of adsorbed protein on all p(MMA-HEMA) polymers was albumin. Total protein uptake was greatest on pMMA. Commercial contact lenses composed of copolymers of HEMA and N-vinyl pyrrolidone (NVP) or acrylamide (AAm) adsorbed small amounts of all proteins whereas copolymers of methacrylic acid (MAAc) and HEMA adsorbed much larger quantities of lysozyme. These results indicate that protein uptake by contact lens materials varies greatly with polymer composition. Artifactually high "adsorption" can occur if precautions are not taken to prevent uptake of unbound 125I.

Mauger, T.

Arch Ophthalmol, 1988. 106(8): p. 1037.

Nilsson, S.E. and H. Lindh

Acta Ophthalmol (Copenh), 1988. 66(1): p. 15-8.

In a group of 66 daily hydrogel contact lens wearers, all lenses were cleaned and disinfected daily using a regular daily cleaner and a 3% hydrogen peroxide system. In addition, one of the lenses for each subject was subjected to weekly enzymatic cleaning with a multi-enzyme pancreatin preparation. After 6 months there were highly significant differences (P less than 0.001) between the lenses, the enzymatically cleaned ones showing less deposits and longer break-up time (BUT) on the lens. Also, comfort was significantly (P less than 0.05) better for these latter lenses. No adverse reactions that could be attributed with certainty to the preparations used were observed. The effectiveness of the pancreatin preparation employed in this study is of interest, since it has been demonstrated that enzymatic removal of deposits from hydrogel lenses reduces complications such as acute red eye reaction, contact lens-induced papillary conjunctivitis, and presumably also corneal ulceration because of decreased bacterial adherence to the lenses.

Tripathi, R.C., B.J. Tripathi, and C.B. Millard

Clao J, 1988. 14(1): p. 23-32.

Donzis, P.B., B.J. Mondino, and B.A. Weissman

Am J Ophthalmol, 1988. 105(2): p. 195-7.

We examined two soft contact lens wearers who developed keratitis associated with Bacillus contamination of their contact lens care systems. Patient 1 developed a corneal ulcer caused by B. subtilis, and Patient 2 demonstrated multiple, diffuse, punctate corneal epithelial opacities associated with B. cereus contamination in the contact lens and lens case compartment. The contact lens cases of both patients contained Bacillus spores that survived multiple heat disinfection treatments. Three different contact lens chemical disinfection systems used for the minimum recommended time failed to kill the Bacillus organisms.

Tosti, A. and G. Tosti

Contact Dermatitis, 1988. 18(5): p. 268-73.

We report 36 patients with thimerosal-induced follicular allergic contact conjunctivitis. 18 patients had follicular conjunctivitis without eyelid involvement, while 5 patients had follicular conjunctivitis associated with an allergic contact dermatitis of the eyelids; all these patients had been using thimerosal-containing eye drops. A further 13 patients were soft contact lens wearers who became sensitized to their own thimerosal-containing lens solutions. All 36 patients showed a positive patch test reaction to thimerosal, while only 1 of them reacted to an ophthalmic solution. Thimerosal sensitization appears to be clinically relevant in ophthalmic patients.

Josephson, J.E. and B.E. Caffery

J Am Optom Assoc, 1988. 59(3): p. 219-20.

The reports of serious corneal infection associated with hydrogel lens wear prompted us to explore the level of sterility of the distilled water used by lens wearers in our practice. Fifty patients supplied samples of their partially-used distilled water for testing. Of the samples, 12% were found to be contaminated. Five samples of previously unopened distilled water were tested and no growth was found. We recommend that patients do not use distilled water for the care of hydrogel contact lenses. Rather, sterile unit dose or multi-dose (aerosol) nonpreserved, or preserved salines can be used.

Lindquist, T.D., et al.

Cornea, 1988. 7(4): p. 300-3.

Acanthamoeba keratitis has frequently been associated with contact lens use. In this study, contaminated hydrogel contact lenses of patients were subjected to disinfection by thermal hydrogen peroxide and chemical (quaternary ammonium) systems. New hydrogel contact lenses contaminated by incubation on Acanthamoeba polyphaga plates were similarly subjected to the disinfection systems described above. Thermal disinfection was universally effective in eradicating acanthamoeba, whereas hydrogen peroxide and quaternary ammonium disinfection were ineffective. Scanning electron microscope photomicrographs suggest that acanthamoeba may adhere to surfaces of hydrogel contact lenses. These findings have significant implications for soft contact lens users.

Paugh, J.R., N.A. Brennan, and N. Efron

Am J Optom Physiol Opt, 1988. 65(2): p. 91-8.

A controlled, randomized, double-masked study was conducted on eight human subjects to determine the threshold level of hydrogen peroxide, which is toxic when introduced into the eye via a high water content (75%; Durasoft 4) hydrogel contact lens. Subjective comfort, conjunctival hyperemia, corneal and conjunctival epithelial staining, and corneal oxygen uptake were assessed in response to 5-min wear of lenses that were presoaked in isotonic saline solutions of physiologic pH containing 0, 25, 50, 100, 200, 400, and 800 parts per million (ppm) hydrogen peroxide. Higher levels of hydrogen peroxide were associated with greater discomfort (p less than 0.05) and increased conjunctival hyperemia (p less than 0.001). The highest level of hydrogen peroxide tested (800 ppm) did not induce significant corneal or conjunctival epithelial staining or alter the corneal aerobic response. We conclude that residual concentrations of hydrogen peroxide in contact lens care systems should not exceed 100 ppm. Practitioners can use these data to estimate the level of residual hydrogen peroxide to which a patient may have been exposed upon lens application after neutralization.

Diefenbach, C.B., et al.

Am J Optom Physiol Opt, 1988. 65(9): p. 710-6.

On site swimming pool studies have indicated that soft contact lenses adhere to the cornea when exposed to swimming pool water. It was the aim of this investigation to study, under controlled laboratory conditions, both the adherence of hydrophilic extended wear lenses and any changes in lens movement with exposure to swimming pool water. Normal saline and a hypotonic solution having a pH and osmolality identical to the pool water served as controls. Exposure to both swimming pool water and the hypotonic solution promptly caused both lenses to stop moving and adhere to the cornea. Notably, the instillation of normal saline also caused a dramatic decrease in lens movement for some subjects.

Dart, J.K.

Br J Ophthalmol, 1988. 72(12): p. 926-30.

Fifty-three patients consecutively admitted to Moorfields Eye Hospital for treatment of suspected microbial keratitis were examined to identify predisposing factors. The principal associations were pre- existing corneal disease (22 patients (41.5%] and contact lens wear (22 patients (41.5%]. In 13 cases (25%) contact lens wear was the only factor in patients with otherwise healthy eyes using contact lenses as an alternative to spectacles. Gram-negative keratitis was more frequent in the lens wearers, with the exception of therapeutic lens users, than in other patients (p = 0.0006) and Pseudomonas aeruginosa caused keratitis in cosmetic soft lens users more frequently (p = 0.001). There was no correlation between lens handling or solution contamination in three extended wear soft-lens users. This implies that some soft-lens wearers may be infected by Gram-negative organisms from environmental sources other than contaminated lens care materials. Gram- negative keratitis is strongly associated with contact lens wear, and the diagnosis must be considered in any contact lens user with an acutely painful red eye.

McMonnies, C.W. and A. Chapman-Davies

Am J Optom Physiol Opt, 1987. 64(4): p. 251-5.

A photographic reference scale has been used to grade conjunctival hyperemia in contact lens wearers. A sample of hard lens wearers, included as a control, has been found to have significantly less conjunctival hyperemia (p less than 0.01) than either of two soft lens wearing groups (one using preserved storage solutions and the other using unpreserved storage solutions). Because both soft lens samples were found to have more hyperemia, it is concluded that factors other than storage solution preservative contribute to increase conjunctival hyperemia in soft lens wearers. However, the preserved storage soft lens wearers had significantly more hyperemia than the unpreserved storage solution group (p less than 0.01). The conclusion is that, apart from acute and subacute responses, there may be a relatively benign chronic response to soft lens storage solution that is associated with minimal symptoms.

Sertoli, A., et al.

Contact Dermatitis, 1987. 16(2): p. 111-2.

Goldstein, J.

J Ophthalmic Nurs Technol, 1987. 6(2): p. 70-2.

Olcerst, R.B.

Am Ind Hyg Assoc J, 1987. 48(5): p. 425-31.

Environmental microbial assays of industrial microscope eyepieces were conducted following reports of multiple intershift ocular infections. Pathogenic Staphylococcus aureus was identified among the microorganisms cultured. This paper suggests that direct contact with industrial microscope eyepieces provides a potentially significant route of transmission of both bacterial and viral ocular infections. An industrial hygiene ocular health questionnaire was distributed to a first and second shift manufacturing operation to assess the incidence of ocular infections. These data were compared to the questionnaire responses of 122 control manufacturing workers who did not use microscopes. Based on self-reporting by employees, those who used microscopes were found to have statistically significant incidence of sites and conjunctivitis that was 8.3 times that of the control group. Sterilization of eyepieces by ethylene oxide, formaldehyde and isopropyl alcohol were considered, but ultimately rejected. These biocides were found respectively to damage ocular lens coatings, contribute to volatile organic emissions, or be ineffective against spore-forming bacteria. This article presents a detailed evaluation of a commercially available ultraviolet sanitization unit (manufactured by the King Bactostat Corp., 7115 Armistad Street, El Paso, TX 79912). This ultraviolet disinfection process proved to be rapid and emission free; it also yielded eyepieces free of residual chemical biocides that have the potential for ocular irritation. Field tests involving 60 eyepieces demonstrated effective disinfection by a Chi-Square statistical comparison, at values greater than 95% confidence level, as compared to unirradiated eyepieces.

Cohen, E.J., et al.

Am J Ophthalmol, 1987. 103(5): p. 615-25.

We examined seven patients with Acanthamoeba keratitis. All patients had a history of soft contact lens use. Predisposing factors included use of homemade saline, hydrogen peroxide disinfection, a history of improper lens care, and swimming with contact lenses. Currently recommended medical therapy, including topical propamidine isethionate and dibromopropamidine isethionate, miconazole, Neosporin, corticosteroids, and systemic ketoconazole, was used in all patients. Five patients have undergone penetrating keratoplasty for progressive primary Acanthamoeba keratitis (four patients) or recurrent infection (one patient) after maximal medical therapy. Two patients who began medical therapy less than three weeks after the onset of symptoms have done well. Early diagnosis of Acanthamoeba keratitis appears critical for successful medical therapy. Penetrating keratoplasty continues to have a central role in the management of more advanced cases that are unresponsive, or only transiently responsive, to medical therapy.

Bergmanson, J.P., P.G. Soderberg, and P. Estrada

Acta Ophthalmol (Copenh), 1987. 65(4): p. 417-23.

Eighty-two hydrogel extended wear contact lenses (EWCL) from four brands were tested for overall quality and variations in specified parameters. Two of the EWCL brands were approved by the United States Food and Drug Administration (FDA) for wear by the public, while two of the brands were uninvestigated. In addition, the packaging solution was examined for osmolarity and pH. All brands were delivered with solutions that had estimated means of pH and osmolarity departing from what may be considered ideal physiologically. The EWCLs all had a consistent power and an acceptable thickness reproducibility. One of the FDA approved brands, demonstrated diameter variations of a magnitude that may produce an unpredictability in the lens fit. Several lenses of one brand suffered from edge quality deficiencies. Although the FDA clinical trial is designed to control the clinical performance of contact lenses prior to the market entry, the results of the present investigation indicate that an authority independent of the manufacturer should regularly sample the lens quality. It is for this purpose imperative that standards for contact lenses are established.

Harris, M.G., et al.

Am J Optom Physiol Opt, 1987. 64(5): p. 321-3.

The Blairex Water Purifier is designed to make tap water into purified water that can be used to make saline solution for soft contact lens disinfection and rinsing. The micropore filters of eight Purifiers were perforated to allow a controlled contamination by either Pseudomonas aeruginosa or Serratia marcescens. The bacterial growth was evaluated in these altered Blairex Water Purifiers under refrigerated and unrefrigerated conditions. Those Purifiers that were refrigerated showed significantly less bacterial growth than those Purifiers that were kept at room temperature between samplings. Our findings imply that soft contact lens wearers may reduce the level of microbial growth in undamaged Purifiers by refrigerating the Purifiers between uses.

Moore, M.B., et al.

Ophthalmology, 1987. 94(12): p. 1654-61.

Eleven contact lens-wearing patients presented with Acanthamoeba keratitis. Eight cases were culture- and/or stain-positive for Acanthamoeba and three were presumed to have Acanthamoeba keratitis based on history and clinical findings. Six wore daily wear soft contact lenses, two wore extended-wear soft contact lenses, one wore a polymethylmethacrylate hard contact lens, one wore a gas-permeable hard contact lens, and one wore a Saturn lens (combined hard and soft lens). Four patients used distilled water and salt tablet saline, three used tap water and salt tablet saline, two used tap water rinse, two used well water rinse or storage, and one used intravenous (IV) saline. It is apparent that all contact lens wearers are at some risk for Acanthamoeba keratitis developing if proper contact lens care is not maintained. Of great concern is the inability of most current chemical sterilization methods to kill the organism if the lens becomes contaminated. Heat disinfection will kill Acanthamoeba trophozoites and cysts but the lens must not be placed into contaminated solutions afterward. Prevention is very important because medical and surgical treatment failures are frequent. Eye care practitioners who fit contact lenses are advised to use heat disinfection for low-water content stock soft contact lenses, and to use hydrogen peroxide without a catalyst for a minimum of 6 hours for all other stock lens fitting sets, to specifically inquire about contact lens care habits used by their patients, and to discourage the use of homemade saline solutions.

Stehr-Green, J.K., et al.

Jama, 1987. 258(1): p. 57-60.

Acanthamoeba keratitis is a rare, serious protozoal infection of the cornea associated with wearing contact lenses. To identify risk factors in soft contact lens wearers, we interviewed 27 patients with Acanthamoeba keratitis and 81 uninfected matched controls to compare contact lens care practices, brands of contact lenses and associated solutions, and behavioral activities. Patients were significantly more likely than controls to use homemade saline instead of commercially prepared saline (21/27 [78%] vs 14/81 [17%]; odds ratio [OR], infinity), and wear their lenses while swimming (17/27 [63%] vs 24/81 [30%]; OR, 6.2). Contact lens disinfection schedules could be determined for 25 of the patients and all of the controls. Patients were significantly more likely than controls to disinfect their lenses less frequently than recommended by lens manufacturers (18/25 [72%] vs 26/81 [32%]; OR, 5.8). Microbiologic assay of contact lens solutions from controls showed frequent contamination with high levels of bacteria. Acanthamoeba species were isolated from homemade saline solutions from two controls. These findings emphasize adherence to recommended methods of soft contact lens care, especially when using nonsterile lens care solutions.

Lapple, W.J., A.C. Snyder, and O.H. Tuovinen

J Am Optom Assoc, 1987. 58(3): p. 216-21.

Microbial bioburden of contact lenses was evaluated in connection with lens care by refrigeration. Subjects wore new hydrogel contact lenses for approximately 8 hours. The microbial bioburden initially and after an overnight refrigeration of the lens was evaluated with the use of viable counts on three different media. No major changes in viable counts were observed resulting from this method of storage. Scanning electron microscopy indicated the presence of foreign material on both new and worn lenses, presumed to be debris from lens manufacture and mucoid deposits from daily wear. Microbial colonization was not apparent and single bacterial cells could not be discerned on the micrographs.

Moore, K.B.

J Am Optom Assoc, 1987. 58(3): p. 180-6.

This paper reviews and analyzes the sensitivity of HTLV-III to various agents. The finding of HTLV-III in tears, the conjunctiva, and the cornea indicates the remote possibility that acquired immunodeficiency syndrome (AIDS) can be spread by instruments in contact with the eye, specifically trial contact lenses. Common contact lens disinfection systems are compared to agents known to inactivate HTLV-III. Recent studies reveal that heat disinfection may not be adequate, thereby, leaving only H2O2 systems as a potentially effective method of inactivating large titers of the virus. Other possible disinfection methods are proposed based on known sensitivity of HTLV-III but are awaiting further investigation.

Stern, G.A. and Z.S. Zam

Ophthalmology, 1987. 94(2): p. 115-9.

Previous studies have demonstrated that Pseudomonas aeruginosa adheres more readily to soft contact lenses with a mucin coating than to unworn contact lenses. The mucin coatings that develop on soft contact lenses may, therefore, play a significant role in the pathogenesis of contact lens-associated Pseudomonas corneal ulceration. We tested the ability of a variety of enzymatic contact lens cleaners and other enzyme solutions to decrease the adherence of Pseudomonas to mucin-coated soft contact lenses. Of the commercially available solutions that were tested, cleaning with Optizyme and Extenzyme significantly reduced the adherence of Pseudomonas to the lenses, whereas cleaning with the Softmate Weekly Cleaning System had no effect. Optizyme and Extenzyme were as effective as a 10% solution of acetylcysteine and more effective than a 0.25% trypsin solution. Neuraminidase at pH 5 was the most effective solution at reducing the adherence of Pseudomonas to the lenses, supporting the finding that sialic acid is a specific receptor for Pseudomonas aeruginosa. Soft contact lenses should be cleaned frequently with an effective enzymatic cleaner to reduce the likelihood of Pseudomonas adhering to the lens and thereby reduce the incidence of Pseudomonas corneal ulceration in soft contact lens wearers.

Tse, L.S., M.G. Callender, and A.M. Charles

Am J Optom Physiol Opt, 1987. 64(11): p. 824-8.

A study of the antimicrobial effectiveness of three soft contact lens care systems, In-A-Wink, Oxysept, and Hydrocare revealed that viable microorganisms are less likely to be present in the storage solution of the Hydrocare system than in either the Oxysept or In-A-Wink systems after lenses are removed by patients. The limited antimicrobial activity of sorbic acid in the In-A-Wink neutralizing solution could be attributed to the pH of the formulation. It is recommended that the neutralizing solution be discarded after the lenses are removed from the case, as microorganisms transferred by the hands to the solution in the case could remain viable, thus increasing the risk of eye contamination.

Callender, M.G., et al.

Am J Optom Physiol Opt, 1986. 63(3): p. 177-80.

Bacteriological comparisons between the tear fluids of soft contact lens wearers and noncontact lens wearers indicate that there is an increase in the bacterial population in contact lens wearers but not a significant change in the varieties present. Differences between groups of contact lens wearers appear to depend on the method of disinfection used.

Simmons, R.B., et al.

J Clin Microbiol, 1986. 24(1): p. 21-5.

Filamentous fungi of the genera Acremonium, Aspergillus, Alternaria, Cladosporium, Curvularia, and Fusarium penetrated the matrix of soft contact lenses both during normal usage and in laboratory studies. Growth of the fungi within the lens matrix increased with increasing water content of the lens. Hyphae within the lens were coiled. Some species penetrated completely through the lens within 96 h. More frequent cleaning and disinfection of extended-wear soft contact lenses is recommended.

Moore, M.B., et al.

Ophthalmology, 1986. 93(10): p. 1310-5.

Three myopic patients who wore soft contact lenses developed unilateral Acanthamoeba keratitis that presented with unusual infiltrates that appeared to be located along the corneal nerves. These infiltrates were found in the midstroma, beginning paracentrally, and extending to the limbus in a radial pattern. The epithelium overlying these infiltrates was intact. In two patients, the central epithelium had a stippled, almost dendritiform appearance leading to the misdiagnosis of herpes simplex keratitis. Cultures from corneal scrapings of two patients and cultures of a corneal biopsy from one patient, which included an area of presumed neural involvement, grew Acanthamoebae. All three patients used homemade saline solutions (salt tablets dissolved in distilled water). In one patient, Acanthamoebae were found in the contact lens case solution. In our recent experience, Acanthamoebae have also been found in the distilled water bottle and the saline solution made from distilled water and salt tablets in two additional patients with A. keratitis. Distilled water, which is not sterile, has proven to be one potentially avoidable source of A. keratitis in contact lens wearers.

Findley, H.M.

J Am Optom Assoc, 1986. 57(5): p. 392-6.

Sharp pain, profuse tearing, and photophobia, usually upon awakening, are the hallmark symptoms of recurrent corneal erosions (RCE). The underlying histopathology of RCE is an abnormal basement membrane with loss of adherence of the overlying epithelium. RCE is associated with trauma, corneal dystrophies, and other miscellaneous conditions. Treatment includes patching, hypertonic preparations, epithelial debridement, and use of a bandage soft contact lens when necessary.

Faulborn, J.

Klin Monatsbl Augenheilkd, 1986. 188(4): p. 322-4.

Problems during a pars plana vitrectomy, such as infusion terminal within a detached choroid or behind the retina, and opacities of the cornea and lens may be prevented by simple means. These include introduction of the infusion terminal using a trocar; using a scleral ring for miniature contact lenses, which is fixed by sutures to the four rectus muscles; and in incipient opacification of the corneal epithelium, irrigation of the cornea with a solution of 50% glucose may render removal of the corneal epithelium unnecessary. Opacification of the cornea and lens can also be prevented by using glucose (500 mg/100 ml) in the intraocular irrigation solution.

Epstein, R.J., et al.

Arch Ophthalmol, 1986. 104(9): p. 1318-21.

Two soft contact lens wearers using a homemade saline solution developed corneal stromal inflammation and epithelial ulceration and were both treated for months with a presumptive diagnosis of herpes simplex keratitis. Subsequently, corneal scrapings revealed refractile, cystic structures consistent with the appearance of Acanthamoeba. This was rapidly confirmed by indirect fluorescent antibody studies, and Acanthamoeba castellani was later identified by growth in culture in both cases. Acanthamoeba is being reported with increasing frequency as a pathogen responsible for chronic stromal keratitis and ulceration in contact lens wearers. Since specific therapy is required to control this organism, rapid diagnosis is essential. Indirect fluorescent antibody staining of corneal scrapings provides a simple means of accomplishing this goal with a high degree of accuracy.

Wilson, L.A. and D.G. Ahearn

Am J Ophthalmol, 1986. 101(4): p. 434-6.

Fungi were isolated from 11 extended-wear soft contact lenses. In two cases, fungi had penetrated through the contact lens and the same fungus was cultured from corneal ulcers. In four cases, fungal growth on and in the soft contact lens matrix was associated with conjunctivitis and punctate fluorescein staining of the corneal epithelium.

Butrus, S.I. and S.A. Klotz

Curr Eye Res, 1986. 5(10): p. 745-50.

The adherence of microorganisms to contact lenses may be an important initial step in the pathogenesis of contact lens-associated infectious keratitis. Using a strain of Candida albicans whose interaction with various polymers has been well characterized we systematically investigated the adherence of this pathogen to hard hydrophobic and soft hydrophilic extended-wear contact lenses. Yeasts adhere to the hydrophobic lenses in direct proportion to the wetting angle of the lens whereas yeasts adhere to the hydrophilic lenses in direct proportion to the water content of the lens. Tear proteins such as albumin, lactoferrin, and lysozyme in addition to fibronectin enhance yeast adherence to both types of lenses (P less than 0.01). Concanavalin A reduces adherence of yeasts to both lens types (P less than 0.01). Among tear components however, only mucin (0.5%) consistently reduced yeast adherence to both lens types. Hydrophilic extended wear lenses worn for at least 28 days by normal patients consistently had greater adherence of yeasts than unworn lenses of the same type, often as much as ten-fold or greater yeasts/mm2 of lens surface area (P less than 0.05). These investigations indicate that tear components both in solution and adsorbed to the lens surface enhance microorganism adherence to contact lenses.

Mayo, M.S., et al.

J Clin Microbiol, 1986. 24(3): p. 372-6.

Pseudomonas aeruginosa was isolated from the corneal scrapings of 11 of 14 patients with gram-negative corneal ulcers and from salt tablet- prepared saline solutions from 6 of these patients wearing soft contact lenses. Comparison of physiological properties, antibiograms, serotypes, and plasmid profiles for five of the patients indicated that the isolates from the ulcer and the saline solution of a given patients were of the same strain. Improper hygienic practices of contact lens wearers appeared to be a major factor in the epidemiology of pseudomonad corneal ulcers.

Vogt, M.W., et al.

Ophthalmology, 1986. 93(6): p. 771-4.

The human T-lymphotropic retrovirus type III (HTLV-III), the etiological agent of AIDS, has recently been detected in tears, cornea, and conjunctiva, raising the possibility of transmission of HTLV-III via contact lens trial sets used in routine fitting. We evaluated the ability of several contact lens cleaning solutions, with or without conditioning or disinfecting solutions, to disinfect contact lenses experimentally contaminated with HTLV-III. Following attempted disinfection, the lenses were cultured for residual HTLV-III on Hg cells for 28 days. Cultures without characteristic cytopathic effects, reverse transcriptase activity, and HTLV-III-specific antigen expression were considered negative. We found that all commercially available cleaning solutions tested were able to disinfect contact lenses exposed to HTLV-III.

Simitzis-Le Flohic, A.M., et al.

J Fr Ophtalmol, 1986. 9(4): p. 305-9.

A first study was conducted on 243 hydrophilic contact lenses: 65 were macroscopically abnormal and 100 were infected with fungi. Moreover on Sabouraud's medium with chloramphenicol, 30 bacterial strains were isolated of which 25 Pseudomonas sp. (10 Ps. cepacia) and 1 Serratia liquefaciens. Then a second study was conducted on 107 among the 243 lens solutions: the 50 of the B trade mark were spoiled with 12 X 10(7) bacteria/ml and the 57 of the C trade mark with 5 X 10(7) bacteria/ml. This quantitative bacterial difference was confirmed with a qualitative one: from B trade-mark 6 Pseudomonas aeruginosa strains were isolated and from C only one. The authors emphasize the importance of Ps. aeruginosa in corneal ulcers associated with contact lenses, of lens solution composition, and of preservative usefulness.

Weissman, B.A. and T.R. Pearson

J Am Optom Assoc, 1986. 57(6): p. 448-50.

Fifteen patients discontinued use of extended-wear hydrogel contact lenses. The primary cause was neovascularization (60%), although lens soilage, giant papillary conjunctivitis and ulceration were factors in several patients each. All patients were successfully refitted with daily-wear rigid or thin, hydrogel contact lenses following simple clinical techniques.

Ludwig, I.H., et al.

Invest Ophthalmol Vis Sci, 1986. 27(4): p. 626-8.

Members of the genus Acanthamoeba are increasingly recognized as agents of indolent, chronic, infectious keratitis. Recently, Acanthamoeba corneal infection has been reported in some persons who wear soft contact lenses. In this study, three "heat" and three "cold" soft contact lens disinfection systems were tested according to the manufacturers' instructions against Acanthamoeba castellanii and Acanthamoeba polyphaga in separate trials, and with appropriate controls. Suspensions of Acanthamoeba cysts or trophozoites of each species were tested individually. Each of the three heat disinfection units killed all acanthamoebae in one cycle in all trials. A chlorhexidine 0.005%/thimerosal 0.001% solution killed A. castellanii trophozoites and cysts, but those of A. polyphaga survived. Trophozoites and cysts of both species survived an alkyl triethanol ammonium chloride 0.013%/thimerosal 0.002% solution and a hydrogen peroxide 3% preparation. Heat disinfection overall appears to be more effective in killing Acanthamoeba trophozoites and cysts as compared to cold disinfection methods.

Mondino, B.J., et al.

Am J Ophthalmol, 1986. 102(1): p. 58-65.

Over a 21-month period, we treated corneal ulcers in 11 patients using daily-wear contact lenses and 29 patients using extended-wear contact lenses. Since more patients use daily-wear than extended-wear lenses, this suggests that patients using extended-wear lenses are at greater risk for the development of corneal ulcers. Positive bacterial cultures were obtained from the corneal scrapings of nine of 11 patients using daily-wear lenses and 20 of 29 patients using extended-wear lenses. In the daily-wear group, all 11 patients failed to exercise satisfactory care in using and disinfecting their contact lenses: three did not wash their hands before manipulating the contact lenses, eight wore them overnight, two did not use any disinfecting system, and four had contaminated contact lens cases, solutions, or drops. In the extended- wear group, 17 patients failed to exercise satisfactory care in using and disinfecting their contact lenses: 12 had contaminated contact lens care systems, two did not use any disinfection system, five reported not washing their hands before contact lens manipulation, and two disinfected their contact lenses at intervals of more than a month. We were unable to identify any defect in the way 12 patients took care of their extended-wear lenses, suggesting that there may be a problem with these contact lenses even when care is satisfactory.

Parment, P.A., R. Ronnerstam, and M. Walder

Acta Ophthalmol (Copenh), 1986. 64(4): p. 456-62.

Twenty-four different brands of contact lens solutions were experimentally inoculated with strains of S. marcescens, S. liquefaciens and E. coli. Only flexol and hexidin could sufficiently suppress the growth of Serratia strains. If a soaking agent is to be effective in suppressing S. marcescens it must have a chlorhexidine concentration of at least 50 micrograms/ml and a thiomersal concentration of 10 micrograms/ml.

Wardlaw, J.C. and M.D. Sarver

Am J Optom Physiol Opt, 1986. 63(6): p. 403-8.

Four types of hydrogel contact lenses (N = 164) were subjected to in vivo and in vitro standard care regimens for a period of six months. Lens care variables included: heat disinfection in Bausch and Lomb Sensitive Eyes saline solution; heat disinfection in Cooper Unisol 4 sterile, nonpreserved saline solution; American Optical/Reichert Lensept disinfection and storage in Sensitive Eyes saline; and Lensept disinfection and storage in Unisol 4 saline. The study was conducted to determine the conditions under which lens discoloration occurs. The 45% Bufilcon A (55% water) lens showed significant discoloration in vivo with both heat and Lensept disinfection when rinsed and soaked in sorbate-preserved saline, and in vitro when heat disinfected in sorbate- preserved saline.

Rohde, M.D. and J.W. Huff

Curr Eye Res, 1986. 5(10): p. 751-8.

Isolated rabbit corneas bathed in Krebs-bicarbonate Ringer solution were observed for thickness changes after a 90 minute equilibration period. Control corneas swelled an average of 0.5 micron/hr, and placement of a polymethylmechacrylate (PMMA) contact lens on the epithelial surface caused the corneas to swell 24.5 microns/hr, an effect similar to 0.5 mM epithelial cyanide exposure. The pronounced swelling induced by PMMA lens placement was much less however, in the epithelial presence of 3.2 mM sodium oxalate (3.22 microns/hr) or 3.2 mM sodium oxamate (5.38 microns/hr). An equiosmotic excess of 4.8 mM NaCl was least active (15.89 microns/hr). On normal isolated corneas (without contact lenses), the Ringer containing an excess of 4.8 mM NaCl significantly deswelled the corneas (-13.44 microns/hr), which contrasted with oxalate and oxamate containing Ringer solutions (1.17 and 1.33 micron/hr respectively). The present study supports the notion that contact lens-induced edema results from stromal lactate accumulation, and suggests a potential alternative to osmotic therapy for its amelioration. These LDH inhibitors, in the concentrations used, have no acute osmotic or toxic effect on normal corneas in vitro.

Aiello, J.P. and M.S. Insler

Am J Ophthalmol, 1985. 99(5): p. 521-3.

Twenty healthy volunteers were fitted with a Bausch & Lomb plano O4 bandage contact lens (center thickness, 0.06 mm; water content, 38.6%) in one eye and a CooperVision therapeutic bandage Permalens (center thickness, 0.24 mm; water content, 70%) in the other eye. Ten received eyedrops every hour for six hours of a solution of 224 ml Osmol and the other ten received a solution of 670 ml Osmol. At the end of the examination period water loss was 21.05% and 20.36% in the Permalens group with the hypertonic and hypotonic solutions, respectively, and 8.86% and 10.74% in the Bausch & Lomb lens groups with the hypertonic and hypotonic solutions, respectively. These values were not significant when compared to those for five control patients (13.75% water loss for the Permalens and 7.28% for the Bausch & Lomb contact lens), suggesting that other factors may be more significant in controlling hydrogel contact lens dehydration.

Moore, M.B., et al.

Am J Ophthalmol, 1985. 100(3): p. 396-403.

Three patients (a 13-year-old girl, a 25-year-old man, and a 22-year- old woman) who used daily-wear soft contact lenses, sterilized with saline made from distilled water and salt tablets, developed Acanthamoeba keratitis. Acanthamoeba was cultured from the contact lens solution of one patient. This patient, in whom the diagnosis was made by corneal biopsy early in the clinical course, was successfully treated with topical neomycin-polymyxin, miconazole, and propamidine isethionate. The other two patients underwent penetrating keratoplasty. One of these patients, who received a graft early in the clinical course, developed a recurrence of disease in the graft, whereas the other, who received the graft 18 months after the initial symptoms, has maintained a clear corneal transplant with useful vision.

Santucci, B., A. Cristaudo, and M. Picardo

Contact Dermatitis, 1985. 12(4): p. 233.

Udell, I.J., et al.

Clao J, 1985. 11(1): p. 51-3.

Rakow, P.L.

J Ophthalmic Nurs Technol, 1985. 4(5): p. 36-8.

Elie, G.

J Fr Ophtalmol, 1985. 8(4): p. 349-52.

The authors reviews his experience during a period of six years with permanent wear gas-permeable hard contact lenses. Problems with dislocation of the lens during sleep was solved by using a diameter of 11 mm. Corneal respiration was maintained due to the oxygen permeability of the new material. A new fitting technique was developed advising daily wear for 8 days post-operatively, extended wear at the 15th day, and the final lens given after 45 days. The results obtained suggests that the technique is a very real alternative to intraocular lens implantation.

Hewett, T.T.

Am J Optom Physiol Opt, 1984. 61(2): p. 73-9.

A mail survey of several hundred hard and soft contact lens wearers was conducted focusing upon demographic characteristics of wearers, factors involved with purchasing, wearing and caring for lenses, and the attitudes, perceptions, and anxieties which wearers have about lenses. The results are presented in two papers. This paper reports on wearer behaviors, experiences, attitudes, and expectations. A number of differences were found between hard and soft lens wearers and between the regular and the occasional and former wearers. For example, occasional and former wearers in general were considerably more likely than regular wearers to express anxieties about several aspects of lens wear and care. Some implications of the data are discussed and suggestions for future research are outlined.

Coward, B.D., R. Neumann, and M. Callender

Am J Optom Physiol Opt, 1984. 61(8): p. 523-7.

The incidence of solution intolerance in 161 soft contact lens patients was about 33% in those using chlorhexidine plus thimerosal chemical disinfecting systems. Those who disinfected their lenses with systems based primarily on thimerosal developed intolerance in 5 to 8% of cases. A family history of allergy appears not to be significant.

Weissman, B.A., et al.

Am J Ophthalmol, 1984. 97(4): p. 476-81.

We treated nine myopic and nine aphakic eyes in patients who developed corneal ulcers while wearing extended-wear soft contact lenses. Bacteria were recovered from the corneal ulcers of 13 of 18 patients with Pseudomonas aeruginosa being the pathogen most frequently isolated. Chemical disinfection was used by seven of the nine patients with myopia and eight of the nine with aphakia. Two of nine patients in the myopic group had visual loss to 20/200 and hand movements; five of nine patients in the aphakic group had visual loss to 20/50 or worse. Invasion of the corneal stroma by bacteria may occur after breakdown of the epithelial barrier by contact lens manipulation or after chronic overnight anoxic stress. Thus, the use of soft contact lenses on an extended-wear basis may be complicated by the development of corneal ulcers. Both aphakic and myopic eyes are at risk.

Houlsby, R.D., M. Ghajar, and G. Chavez

J Am Optom Assoc, 1984. 55(3): p. 205-11.

Several chemical disinfecting solutions for soft contact lenses were evaluated according to the tests suggested by FDA in the May 1983 revision of the Microbiological Guidelines. It was experimentally determined that cleaning and rinsing lenses remove 3.5 to 3.9 logs of microorganisms. Furthermore, it was determined that only 3% hydrogen peroxide had a rapid enough disinfection rate to meet the safety factor requirement within four hours as suggested in the "D-value test.' when contaminated lenses were cleaned, rinsed, and disinfected with commercially available solutions, all failed to disinfect the lenses within the minimum time specified on the label. These results were used to recommend significant changes in the Microbiological Guidelines. These changes include (1) limiting the rechallenge requirement during preservative effectiveness testing to only disinfecting solutions, (2) using the death rate kinetic profile of any approved chemical disinfecting solution as a basis for comparison of a new chemical disinfecting solution, and (3) using the results of the multi-item test for any approved chemical disinfecting solution as a basis for comparison of a new, proposed chemical disinfecting solution.

Billig, H., et al.

Clao J, 1984. 10(4): p. 341-5.

Bernstein, D.I., et al.

J Allergy Clin Immunol, 1984. 74(3 Pt 1): p. 258-60.

This is a case report of a patient who developed IgE-mediated sensitization and subsequently ocular angioedema and conjunctivitis from papain contained in a commercial contact lens cleansing solution. Serum-specific IgE and positive cutaneous prick tests to papain and chymopapain were detected. When the lens solution containing papain was stopped, there was resolution of her allergic symptoms. Recognition of this route of papain-induced sensitization may be important in those patients undergoing chemonucleolysis with chymopapain who may be at greater risk to develop a systemic allergic reaction after injection of this enzyme.

Katz, H.R., D.H. Aizuss, and B.J. Mondino

Cornea, 1984. 3(1): p. 65-72.

Cellulose acetate butyrate contact lenses were fitted for extended wear on 28 rabbits 6 weeks after radial keratotomy. Fourteen rabbits received 0.03% flurbiprofen to one eye and vehicle solution to the contralateral control eye, while the other 14 received 1% prednisolone acetate to one eye and vehicle solution to the contralateral control eye four times each day in a double-blind fashion. The eyes were photographed and graded weekly with a standardized slit-lamp grading method. After 6 weeks, inhibition of corneal neovascularization was found with flurbiprofen (p = 0.001), while there was a trend toward inhibition of corneal neovascularization with prednisolone acetate (p = 0.076). We also found a significant vehicle effect, with hydroxypropyl methylcellulose, the more viscous vehicle, suppressing corneal neovascularization more than polyvinyl alcohol (p = 0.004).

Flynn, W.J. and R.M. Hill

J Am Optom Assoc, 1984. 55(3): p. 221-2.

Even without a contact lens, the cornea can suffer adverse physiological changes from hypotonic exposure, as well as the associated subjective phenomena (e.g., halo and rainbows). The contact lens adds a dimension to this problem that should be viewed against a background of normal (non-wearing) susceptibilities.

Lubert, G.P. and L. Caplan

Am J Optom Physiol Opt, 1984. 61(11): p. 683-8.

Several high water content lenses (greater than or equal to 55%) have been approved for either thermal or chemical disinfection. Thermal disinfection has been reported to be contraindicated for higher water content lenses, yet no studies have been performed to show this with a high water content daily or extended wear lens approved for thermal disinfection. A three-phase clinical study was initiated in which eight previously successful soft contact lens wearers were fitted with etafilcon A lenses. The subjects were placed on an approved thermal disinfection regimen for the lens on the right eye, and on an approved chemical disinfection regimen for the lens on the left eye. Results show that thermal disinfection of the etafilcon A lenses results in lens discoloration and reduced lens performance over a short period of time, as compared to the chemically disinfected lenses which showed no compromise in fit or any discoloration. Possible causes of the poor performance and appearance of the thermally disinfected lenses are discussed.

Jenkins, J.T. and M. Shimbo

J Biomech Eng, 1984. 106(1): p. 62-5.

We determine the pressure distribution behind a soft contact lens that is necessary to keep the lens in conformity with an axisymmetric substrate. The substrate consists of two regions: a central portion, the cornea, supposed to be an ellipsoid; and a peripheral region, the sclera, taken to be a sphere. The pressure is obtained as part of a numerical solution of the axisymmetric equilibrium equations for an initially curved, linearly elastic membrane. The relaxed shape of the lens is assumed to be an axisymmetric ellipsoid with a central curvature and a shape factor different from those of the cornea. The variation in the thickness of the lens from its center to edge is approximated by a polynomial. Pressure distributions are obtained for several typical soft contact lens fittings.

Pinzauti, S.

Farmaco [Prat], 1983. 38(1): p. 21-42.

Flach, A.J. and J.A. Sorenson

Am J Ophthalmol, 1983. 95(6): p. 850-1.

Sendele, D.D., et al.

Ophthalmology, 1983. 90(6): p. 616-22.

Forty patients with daily wear, cosmetic contact lenses (CL) presented with symptoms of ocular irritation and a keratoconjunctivitis clinically resembling superior limbic keratoconjunctivitis (SLK). Typically the patients were either successful hard CL wearers who changed to soft lenses and used a chemical aseptisizing solution or preserved saline solution, or successful soft CL wearers using salt tablets who switched to a preservative-containing system. In all cases, exposure to thimerosal-preserved solutions was documented. Upon discontinuation of lens wear, all signs and symptoms slowly resolved without permanent sequelae. Positive skin and ocular sensitivity reactions to thimerosal were present in one-third (5/15) of patients tested. Light and transmission electron microscopic examination of conjunctival specimens disclosed intercellular epithelial edema, pseudoepitheliomatous hyperplasia, acute and chronic inflammation, and decreased numbers of goblet cells. Exposure to thimerosal is implicated in the etiology of contact lens-superior limbic keratoconjunctivitis (CL-SLK).

Crook, T.G. and J.J. Freeman

Am J Optom Physiol Opt, 1983. 60(9): p. 759-61.

We examined the reaction to thimerosal which occurred when patients were prescribed tetracyclines simultaneously. Nine patients were identified who had been using a 0.004% thimerosal-containing contact lens solution for over 6 months. All had developed varying degrees of ocular reaction (red eye, irritation, blepharitis) apparently as a result of taking tetracyclines concurrently. The reaction disappeared upon discontinuance of either the thimerosal or the tetracyclines. The hypothesis that the reaction was due to an interaction between thimerosal and tetracyclines was confirmed in rabbits.

Needham, D. and D.A. Haydon

Biophys J, 1983. 41(3): p. 251-7.

A method is described for the accurate measurement of the interfacial tension of lipid bilayer membranes containing little or no solvent. The tensions were obtained from the interfacial tensions of the equilibrium film-forming solution in the Plateau-Gibbs border, measured by conventional techniques, and the contact angle between the border and the bilayer. The contact angles in these systems are large (greater than 10 degrees) and were estimated by a new method that involved the injection of small known volumes of lipid solution into the bilayer so as to form a lens. Results have been obtained for monoolein-triolein, monoolein-squalene, and monoolein-squalene-decane systems. Half bilayer tensions in these systems were up to approximately 1 mN m-1 less than the single interface tensions. Although bilayer tension tended to increase with bilayer thickness, the interdependence of these quantities varied with the alkane solvents present. In the monoolein- squalene-decane systems, small concentrations of decane have a larger effect on tension than on thickness. Free energies of formation of the near-solventless bilayers were much greater than estimated from the simple application of Lifshitz theory.

Arthur, B.W., et al.

Arch Ophthalmol, 1983. 101(10): p. 1607-10.

Corneal epithelial erosions developed in two patients wearing gas permeable contact lenses (Boston) soon after commencing topical timolol maleate therapy. This prompted the following investigation. Forty rabbit corneas were examined by scanning and transmission electron microscopy after treatment for one month with one of the following: timolol ophthalmic solution, preservative-free timolol, contact lens, contact lens and timolol, contact lens and preservative-free timolol, contact lens and saline, or no treatment. Corneas treated with either timolol or contact lens alone showed mild to moderate edema or degeneration of epithelial and endothelial cells. However, the combined use of a contact lens and timolol produced marked alterations in both the corneal epithelium and endothelium.

Klein, P.

Am J Optom Physiol Opt, 1983. 60(9): p. 783-7.

A study was conducted to determine the efficacy of low water content, hyper-thin lenses for extended wear by myopic patients. Patients selected had from 1 to 7 D of simple myopia or myopia with up to 2 D of astigmatism. Patients were either first time wearers or previously successful soft lens wearers. All patients were fitted with Bausch & Lomb O3 or O4 series lenses and were evaluated for 6 months. Either heat or a chemical disinfection system was used. The study shows that Bausch & Lomb O Series lenses may be used successfully for up to 1 week of continuous wear. Visual acuity, patient comfort, lens life, and physiological tolerance compared favorably with those achieved when the currently available high water content lenses were used for extended wear.

Driebe, W.T., Jr., C.G. Rabell, and W.L. Houde

Surv Ophthalmol, 1983. 27(4): p. 259-63.

Molinari, J.F.

J Am Optom Assoc, 1983. 54(11): p. 1007-9.

A case of transient ptosis due to GPC in a 14-year-old white female was presented. The hydrogel contact lenses were removed and after 3 days of cold compress management, the ptosis disappeared. After two months of spectacle wear the patient was refitted with hydrogel lenses made from a different material in a different design. In addition the solution regimen was changed to non-preserved saline and thermal disinfection. A review of the GPC literature and pathophysiological mechanism were presented.

Belmont, J.B., et al.

Am J Ophthalmol, 1982. 93(3): p. 338-41.

Ring-shaped keratitis appeared in the left eye of a 37-year-old woman who had worn soft contact lenses for more than five years. The corneal ring began to appear within seven days of a central corneal abrasion. Gram staining of the patient's contact lens cleaning solution showed many gram-negative rods, and microbiologic investigations of the patient's soft contact lens and contact lens case disclosed Pseudomonas aeruginosa. There was no clinical or laboratory evidence of an infectious process. Prompt treatment with polymyxin B-bacitracin ointment and prednisolone acetate 1% eyedrops led to resolution of the opacity and a return to the patient's normal visual acuity. The P. aeruginosa endotoxin may have been transferred through the epithelial break into the superficial corneal stroma, leading to ring formation via endotoxin-initiated, properdin-mediated, antibody-independent complement activation.

Duffin, R.M., et al.

Am J Ophthalmol, 1982. 93(5): p. 607-14.

Cellulose acetate butyrate extended-wear contact lenses were fitted bilaterally on ten New Zealand albino rabbits. We administered flurbiprofen 0.03% solution topically to the experimental eyes and vehicle solution to the contralateral control eyes four times a day in a random, masked fashion beginning 24 hours before the contact lens was fitted. Corneal neovascularization, which developed in all eyes by the 25th day of contact lens wear, was significantly suppressed by flurbiprofen treatment (mean vessel length was 1.5 +/- 0.4 mm for the treated eyes and 3.0 +/- 0.3 mm for the control eyes; P less than .005). Topical administration of a noncorticosteroidal anti- inflammatory agent may be an effective treatment for corneal neovascularization induced by contact lenses.

Jira, T., B. Panzig, and R. Pohloudek-Fabini

Pharmazie, 1982. 37(8): p. 587-90.

To assess the suitability of benzalkonium chloride as a preserving agent for potential contact lens fluids, the authors tested its antimicrobial efficiency at various pH values, in the presence of viscosity modifiers (hydroxyethylcellulose, polyvinylpyrrolidone, polyacrylamide) and also in combination with other preserving agents. The diffusion test and the suspension test were used as test methods. The efficiency of benzalkonium chloride depends upon the pH value of the solution and upon the concentrations of the viscosity modifiers. No better results were achieved by combination with phenylethanol and chlorobutanol. Formulations for potential contact lens fluids were indicated, the appropiateness of which is viewed in microbiological perspective.

Mondino, B.J., S.M. Salamon, and G.W. Zaidman

Surv Ophthalmol, 1982. 26(6): p. 337-44.

The allergic and toxic effects of preservatives found in soft contact lens solutions are reviewed. Thimerosal, a preservative commonly found in soft contact lens solutions, may cause ocular delayed hypersensitivity. Patients with delayed hypersensitivity to thimerosal may develop conjunctival hyperemia, corneal infiltrates and intolerance to lens wear with the use of soft contact lens solutions containing thimerosal. Delayed hypersensitivity to thimerosal can be demonstrated by an occlusive patch test or intradermal injection. Discontinuation of chemical disinfection with substitution of thermal disinfection using unit-dose, non-preserved saline causes resolution of signs and symptoms. Another cause of lens wear intolerance is contact lens- associated giant papillary conjunctivitis. Protein deposits on the lens may act as antigens and initiate an allergic condition which disappears when the lens is discontinued. Alternatively, the giant papillae may be the result of mechanical irritation induced by the contact lenses. The chemical preservatives that are found in soft contact lens solutions cause epithelial toxicity when applied to isolated rabbit corneas. However, corneal toxicity toxicity in a clinical setting has not been demonstrated.

Dixon, J.M.

Contact Intraocul Lens Med J, 1982. 8(3): p. 168-72.

Eng, W.G., L.K. Harada, and L.S. Jagerman

Aviat Space Environ Med, 1982. 53(3): p. 235-8.

The increasing use of hydrophilic (soft) lenses in the United States hs prompted interest in the clinical investigation of these lenses under various wearing conditions. Any factor causing lens dehydration during wear may affect lens performance and ultimately cause eye discomfort. The purpose of this study was to evaluate the environmental conditions in the aircraft cabin and to observe any changes in the fit of the hydrophilic lenses that might occur during flight. A "laboratory" for testing was set up aboard a World Airways DC-10 on a scheduled round trip between Oakland, California and Honolulu, Hawaii. A keratometer was used to assess lens fit of seven subjects who were wearing hydrophilic lenses. The efficacy of using a soft lens hydrating solution on the fit of the lens was evaluated, but will also be evaluated in a future paper. Atmospheric pressure, humidity, and temperature measurements were recorded throughout the inflight study. The results showed that a decline in cabin humidity from at least 47% to 11% occurred within 30 min of takeoff. Although previous reports have indicated that there are a number of environmental factors in the aircraft that contribute to eye discomfort for lens wearers, this study indicates that low cabin humidity is possibly the most significant factor.

Wright, P. and I. Mackie

Trans Ophthalmol Soc U K, 1982. 102(Pt 1): p. 3-6.

Details of 61 patients are presented who, having worn soft contact lenses for many months, developed red eyes, conjunctival irritation with minimal discharge, and progressive loss of tolerance of the lenses. Investigations revealed an absence of infective agents and the clinical course after treatment with preservative-free solutions strongly suggested that preservatives, especially organic mercurials, were responsible for the changes. The corneal signs were slow to clear but after resolution the majority of patients were able to return to soft contact lens wear using a heat disinfection system with preservative-free solutions. Skin testing to a wide range of substances, including preservatives, contact lens solutions, and common sensitizers, revealed only one responder to Thiomersal out of 21 tested. However a rapid response followed conjunctival challenge with 0.005 per cent Thiomersal in normal saline in all subjects tested.

Nizami, R.M.

Ann Allergy, 1981. 47(1): p. 5-7.

Previous studies have shown the effectiveness of topical cromolyn solution in the treatment of allergic conjunctivitis. However, the preservative, phenylethanol, produces an immediate burning or stinging sensation when the drops are first instilled in the eye. A double- blind, crossover, placebo controlled study using 2% cromolyn solution was conducted, without the preservative and supplied in unit doses. Twenty six patients took part in the trial. They had ragweed pollen- induced conjunctivitis. The results of the trial indicate that the active drug was effective in controlling the signs and symptoms of allergic conjunctivitis in 22 of the 26 patients, i.e., 84.6% (p less than 0.001). Two patients preferred the placebo. There were no complaints of stinging or burning sensation after the instillation of the drops in the eyes. There were no cases of infection of the eye. Without the preservative, the cromolyn solution does not damage the soft contact lens.

Wilson, L.A., R.L. Schlitzer, and D.G. Ahearn

Am J Ophthalmol, 1981. 92(4): p. 546-54.

Seven Pseudomonas corneal ulcers in six patients were associated with soft contact-lens wear and use of saline solutions prepared from distilled water and sodium chloride tablets. The same species of Pseudomonas isolated from the corneal ulcers were also isolated from the home-prepared saline and in one instance from the water used to prepare the saline solution. In three of the six patients, the pseudomonad isolated from the corneal ulcer was of the same serotype and biochemically identical to the pseudomonad from the patients' saline solution. Commercially available distilled water, even brands recommended for use with soft contact lenses, was found to be contaminated with gram-negative bacteria before use. Clinical histories disclosed that all patients inappropriately used the home-prepared saline as a wetting agent, or eyedrop, or bath, after thermal disinfection of the contact lens. Self-inoculation of the eye with contaminated saline is a hazard for soft contact-lens wearers who use home-prepared saline solution.

Refojo, M.F.

Contact Intraocul Lens Med J, 1981. 7(2): p. 172.

Josephson, J.E. and B.E. Caffery

J Am Optom Assoc, 1981. 52(3): p. 227-34.

The selection of the appropriate hydrogel lens care system must incorporate an understanding of the properties and actions of cleaning, disinfecting and rinsing solutions; the characteristics of the lens; and the ocular characteristics of the patient. When changes in a care system are required, reselection involves recognizing: the nature of adverse ocular responses; the nature of deposits; any changes in patient characteristics; the characteristics of potential new products. These factors are considered and used to create an approach to selecting the initial care system and to reselecting an alternate care system.

Hovding, G.

Acta Ophthalmol (Copenh), 1981. 59(3): p. 387-401.

The conjunctival bacterial flora in wearers of hydrophilic, hard and silicone lenses and in a non-lens control group has been studied. Cultures were also taken from the posterior surface of the various contact lenses. Coagulase negative staphylococci were the most commonly occurring microorganisms both on the conjunctiva and on the lenses. Further identification of these bacteria showed Staph. epidermidis to be the predominant species. Compared with control group a significantly increased frequency of negative conjunctival cultures was found among the lens wearers (P = 0.020). The occurrence of coagulase negative staphylococci was reduced, but the difference was not statistically significant (P = 0.08). Gram-negative bacilli were more frequently found during lens wear (P = 0.012), but were mainly species which are traditionally regarded as apathogenic. The possible influence of lens disinfection, duration of lens wear and eye/lid hygiene on the conjunctival bacterial flora is discussed.

Ruben, M.

Ann Ophthalmol, 1981. 13(3): p. 289-95.

Binder, P.S., D.M. Rasmussen, and M. Gordon

Arch Ophthalmol, 1981. 99(1): p. 87-90.

Three patients with soft contact lenses had acute onset of a red eye that clinically appeared consistent with an adenoviral keratoconjunctivitis. The signs and symptoms cleared within five to ten days in all three patients. When the patients reinserted their lenses after their initial episodes, the same signs and symptoms again developed, including follicular conjunctivitis, punctate keratitis, and subepithelial infiltrates. All three were using preserved solutions for soft lens disinfection, and when switched to thermal disinfection with saline tablets, a recurrence of the syndrome did not develop when the lenses were replaced. This syndrome seems related to a toxic or allergic reaction to the preservatives in the contact lens disinfecting solutions. Similar patients who have an acute or chronic, red, irritated eye should stop their lens wear and later should change their disinfection technique to one that uses unpreserved saline solution to eliminate the problem.

Spizziri, L.J.

Ann Ophthalmol, 1981. 13(11): p. 1277-8.

A case is presented of small, round, discrete, stromal corneal opacities resulting from the use of preserved saline solution with cosmetic soft contact lenses. The lesions completely cleared with cessation and recurred with resumption of use of saline solution.

Wilson, L.A., J. McNatt, and R. Reitschel

Ophthalmology, 1981. 88(8): p. 804-9.

Thirty-eight patients were examined because of ocular redness, irritation, and corneal changes apparently related to soft contact lens wear. The corneal changes were transient and ranged from faint epithelial opacities to a coarse, punctate epithelial keratopathy. Solutions containing thimerosal had been used by all of the patients for lens care, and 31 responded to an ocular challenge with a thimerosal-preserved lens lubricant. Twenty-seven of these 31 also reacted to thimerosal patch testing. The 31 resumed lens wear with relief of symptoms by using unit-dose, preservative-free saline for lens storage and thermal disinfection. A hypersensitivity to thimerosal was assumed responsible for the clinical findings.

Monno, R. and C. Balacco-Gabrieli

Boll Ist Sieroter Milan, 1981. 60(5): p. 446-7.

Farris, R.L., R.N. Stuchell, and I.D. Mandel

Ophthalmology, 1981. 88(8): p. 852-7.

Minimally stimulated, retained "basal' tears and stimulated reflex tears were collected from normal controls, keratoconjunctivitis sicca (KCS) patients, and contact lens (CL) wearers. Basal tear samples were collected on small filter paper strips (Periopaper) over a five-second period, and volume was measured by means of an electronic device (Periotron). Collected basal tear volumes for KCS patients (0.84 +/- 0.42 mul) were significantly lower (P less than 0.01) than normal controls (1.18 +/- 0.36) and CL wearers (1.24 +/- 0.27). Reflex tear flow rates were measured over a five-minute period on Schirmer strips. Volume was calculated by comparison of wet length with known volumes of 1% egg white lysozyme solution. The reflex tear flow rates in KCS patients (3.29 +/- 3.57 mul/minute) were significantly lower than normal controls (5.71 +/- 5.86) and CL wearers (6.96 +/- 6.07). The elevation in CL wearers was not statistically significant when compared to normals. KCS patients are deficient in both basal and reflex tears compared to normals but have a more significant deficiency of basal tears. Female normals and CL wearers over 40 years of age have a higher tear osmolarity than those under 41 years of age. Female KCS patients over 40 years of age have a tear osmolarity that is not significantly different from female KCS patients under 41 years of age.

Plaut, B.S., et al.

J Pharm Pharmacol, 1981. 33(2): p. 82-8.

The extent of the interaction between chlorhexidine digluconate and poly(2-hydroxyethyl methacrylate), (PHEMA), is independent of temperature between 22-50 degrees C which is consistent with an ion-ion interaction mechanism. Different contact lens materials exhibit different affinities for chlorhexidine digluconate, the extent of uptake correlating in rank order with the number of free carboxylic acid sites in the polymers. Esterification of the carboxyl groups with diazomethane, resulted in a reduction in the affinity of the treated polymers for chlorhexidine to a near basal level. The uptake of chlorhexidine in soaking solution experiments involving lenses made from PHEMA and the more ionic material, poly(2-hydroxyethyl methacrylate-co-isobutyl methacrylate-co-methacrylic acid), was consistent with their carboxylate content. However, the fraction of bound disinfectant released was lower from the terpolymer, suggesting there are differences in bonding strengths between chlorhexidine and different contact lens hydrogels.

Contact Intraocul Lens Med J, 1981. 7(2): p. 89-100.

Wechsler, S. and N.C. George

J Am Optom Assoc, 1981. 52(3): p. 179-86.

The cleaning and disinfection of hydrogel lenses has been discussed in the optometric literature by a number of authors. Although significant differences exist among authors regarding the disinfection method of choice, there is reasonable agreement that lenses that are carefully cleaned and rinsed are advantageous from the standpoint of both safety and lens longevity. Chemical disinfection with the soaking solution changed daily is a fail-safe method, while thermal disinfection may be less safe, perhaps due to ineffective lens case construction or thermal unit breakdown.

Unlu, N., Y. Capan, and N. Yulug

Mikrobiyol Bul, 1981. 15(3-4): p. 179-87.

The purpose of this study was to develop hard contact lens wetting solutions which would contain suitable and sufficient antimicrobial agents for preventing contamination. In the first part of the formulation studies, microbiological methods were employed to determine the adequate antibacterial concentrations of benzalkonium chloride and disodium EDTA.

Myrowitz, E., P. Pearlman, and H.K. Goldberg

Contact Intraocul Lens Med J, 1981. 7(4): p. 337-8.

Carlson, M. and L.E. Habeger

J Pharm Sci, 1980. 69(7): p. 826-8.

The quantitative analysis of edetate disodium in nonprescription eyewash and ophthalmic solutions is described. The method involves differential pulse polarography using a dropping mercury electrode. A known concentration of cadmium or zinc is added to a buffer in a polarographic cell. The sample solution is incremented into the cell with a micropipet. The peak current decreases because the resulting chelate is not reducible at the potentials used. The quantity of edetate disodium in the sample then is determined graphically. Some contact lens cleaning and wetting solutions containing polymeric compounds are amenable to assay to edetate disodium if extraction, precipitation, centrifugation, or dilution steps minimize the maximum suppressor effect of the additives. These steps are very effective with cellulose ether compounds but are ineffective with polyvinyl alcohol.

Sorensen, T., F. Taagehoj, and U. Christensen

Acta Ophthalmol (Copenh), 1980. 58(2): p. 182-7.

Tear flow was determined in 14 persons before and after one month of adaptation to a soft contact lens, (Soflens, Bausch & Lomb), by means of a radioactive tracer (technetium, Tc99m, as pertechnetate), a gamma camera and a computer system. The elimination of the radioisotope from the conjunctival sac was diphasic with a significant increase of the fractional turnover rate after the adaptation period in the initial phase with a rapid elimination, but no change in the basal phase with a slower elimination. The fractional turnover rate was also determined with the soft contact lens placed on the cornea after having been pre- soaked in the technetium solution resulting in a value of 0.021 +/- 0.003 min-1 (mean +/- SEM, n = 12). The fractional turnover rate resulting from instillation of the radioisotope on the non-pre-soaked soft contact lens placed in the eye was found to 0.020 +/- 0.004 min-1 (mean +/- SEM, n = 6). In the studies with the soft contact lens in the eye the elimination curves was monophasic and not diphasic as in normal tear flow studies.

Olson, R.J., et al.

Arch Ophthalmol, 1980. 98(10): p. 1840-2.

Sixty-eight intraocular lenses were implanted in cats to compare the efficacy of a new polyvinyl alcohol coating in protecting the corneal endothelium from lens-cell contact damage. The mean endothelial density after implantation of the coated lens was significantly higher than the cell density in those eyes receiving the uncoated lens. We saw no clinical signs of unusual inflammation; whole-eye histopathologic study disclosed no signs of inflammation or toxicity related to the coating. Ten coated lenses were placed in balanced salt solution or perfused with balanced salt solution at 0.5 mL/min. The coating remained intact for 60 minutes, affording corneal endothelial protection for this period. In a rabbit anterior chamber toxicity study, using balanced salt solution as a control, no differencs in reaction in the anterior chamber or intraocular pressure were noted.

Sorensen, T., F.T. Jensen, and J. Marqversen

Acta Ophthalmol (Copenh), 1980. 58(4): p. 576-87.

Elimination of technetium (pertechnetate in normal saline solution) was studied from various types of contact lenses placed on normal human eyes by means of computer assisted gamma camera using "region of interest technique" with the designated area corresponding to the conjunctival sac. An elimination 4 times slower was found from a highly hydrophilic lens (Scanlens) than from a HEMA-lens (Softlens), 0,5% min and 2.0% min, respectively. From an ultrathin lens (U3-Softlens) was eliminated 2.4% min. Hard lenses did not absorb the isotope. In a laboratory study the lenses were pre-soaked in pertechnetate, blotted and washed at 2 min intervals in 0.5 ml saline. By this procedure 3% min of the technetium was eliminated from Scanlens, 16% min from Softlens and 28%/min from a thin, therapeutic lens (Plano-T). The ratio Softlens/Scanlens was in the human study 4.0 and in the laboratory study 4.9. Radioactivity was very rapidly eliminated from CAB-lenses. A similar study was carried out with radioactive water. More than 100% min was eliminated in the first 10 min followed by a slower elimination from 10-20 min. Then an increased elimination was seen for a few min. This increased elimination was in repeated studies constantly found after 20 min. It was not found in the studies with technetium and labelled leucine.

Candia, O.A., et al.

Biochim Biophys Acta, 1980. 602(2): p. 389-400.

The effects of serotonin and five other indoles were tested on the electrical parameters and ionic transport in the isolated toad lens. Serotonin, tryptophan and 5-hydroxy-L-tryptophan did not affect the electrical parameters of the lens at concentrations as high as 1 mM. Tryptamine, 5-methyltryptamine and 5-methoxytryptamine had dual effects: 1 mM in the posterior bathing solution depressed the potential difference of the posterior face of the lens, which resulted in an increase in the translenticular potential difference and short-circuit current; 1 mM in the anterior solution (in contact with the lens epithelium) produced a quick and pronounced reduction of the potential difference of the anterior face. This resulted in a 90-100% decline of the translenticular short-circuit current. Serotonin and tryptamine were then tested for their effect on the ATPases of lens epithelium. Both amines inhibited the enzymes with tryptamine at 5 mM completely inhibiting all ATPase activity. Since tryptophan is transported from the aqueous humor into the lens and may be converted by lens enzymes to serotonin and tryptamine, these findings may have physiological implications in cataractogenesis.

van Ketel, W.G. and F.A. Melzer-van Riemsdijk

Contact Dermatitis, 1980. 6(5): p. 321-4.

In cases of conjunctivitis associated with the use of soft lenses, delayed hypersensitivity to disinfecting components of the used soft lens liquids has to be considered. In 7/15 patients, positive patch test reactions to merthiolate, chlorhexidine or the soaking solutions were observed. The significance of these findings is discussed.

Puffer, M.J., R.W. Neault, and R.F. Brubaker

Am J Ophthalmol, 1980. 89(3): p. 369-76.

We studied 51 normal subjects with a simple method that permits measurement of the rate of fluorescein loss from the central precorneal tear film. In 15 (29%), no measurable dye remained 30 minutes after application of 1 microliter of a 10% solution of sodium fluorescein into the lower culde-sac. In 31 (61%) of the subjects, an exponential decay of the dye was observed between 15 and 30 minutes after application. In 5 (10%) of the subjects, a prolonged increase in dye concentration was observed, followed by a steady decrease that began 30 to 45 minutes after application. One eye of one subject had a steady increase in dye concentration for over an hour, and this eye was excluded from the analysis. The mean value for the tear elimination coefficient in all subjects analyzed was 15%/min. The logarithm of the tear elimination coefficient appeared to be normally distributed within the population sample. Analysis of the frequency distribution permitted an estimate that the 95% confidence limits for the tear elimination coefficient, as measured by this method, was 5 to 30%/min. No statistically significant correlations were found between tear elimination coefficient and sex, eye color, or contact lens use.

Green, K., et al.

Arch Ophthalmol, 1980. 98(7): p. 1273-8.

Chlorhexidine digluconate, a soft contact lens disinfectant, was perfused over rabbit corneal peithelial and endothelial surfaces under a variety of concentrations and conditions. Without protein in the bathing solutions, the cornea swelled when chlorhexidine concentrations of 20 microgram/mL or greater were perfused over the endothelium. Scanning electron microscopy demonstrated rounded, swollen cells with loss of microvilli. Perfusion of the epithelium with chlorhexidine in protein-free Ringer's solution resulted in a dose-dependent sloughing of cells and loss of microvilli, which resulted in little or no swelling when the endothelium was concomitantly bathed with oil. Corneal swelling followed at concentrations of 500 and 1,000 microgram/mL when both corneal surfaces were bathed with protein-free Ringer's solution and the epithelium was perfused with chlorhexidine. With protein included in the bathing solution, no swelling occurred when separate chlorhexidine (500 microgram/mL) and albumin (1%) solutions were applied simultaneously to the epithelial surface of corneas, with the endothelial surface bathed in Ringer's solution.

Mondino, B.J. and L.R. Groden

Arch Ophthalmol, 1980. 98(10): p. 1767-70.

For three cosmetic soft contact lens wearers who chemically disinfected their lenses, conjunctival hyperemia and anterior stromal infiltrates of the cornea developed. When the conjunctival hyperemia and corneal infiltrates resolved, two of the three patients were challenged with their chemically disinfected soft contact lenses, with reappearance of the conjunctival and corneal reactions. Bacterial cultures of the conjunctiva, lids, lens cases, lens solutions, and eye cosmetics were not helpful. Conjunctival cultures for adenovirus and chlamytdial titers were negative. Giemsa stain of conjunctival scrapings showed a few mononuclear cells, polymorphonuclear leukocytes, and rare eosinophils but no inclusion bodies. Occlusive patch tests and intradermal tests showed positive delayed hypersensitivity reactions to the chemical disinfectants in all three patients. Occlusive patch tests with thimerosal suggested that this preservative was responsible for the reactions. Delayed hypersensitivity to thimerosal may play a role in the development of the conjunctival hyperemia and corneal infiltrates described in these patients.

Pitts, R.E. and J.H. Krachmer

Arch Ophthalmol, 1979. 97(3): p. 470-2.

Recent reports of bacterial corneal ulcers in cosmetic soft contact lens wearers prompted an evaluation of one possible source of contamination, inadequate home disinfection of the lenses. Twenty-nine patients were asked to come for an early morning examination. They were told not to wear their lenses so their usual home disinfection procedure could be observed. On arrival, extensive bacterial and fungal cultures were taken of the solution in the previously unopened cases. Ten of the 29 patients (34.5%) had contaminated cases. Some patients did not follow the manufacturer's disinfection guidelines. The current disinfection procedure has repeatedly proven adequate in the laboratory. However, the practical fact is that a substantial percentage (34.5% in this study) of soft lens wearers are inadequately disinfecting their lenses. This serves as a possible source of contamination leading to bacterial corneal ulcers.

Hirji, N.K. and J.R. Larke

Br J Ophthalmol, 1979. 63(4): p. 274-6.

The continual wearing of a soft contact lens for a period of 20 weeks is shown to produce no significant evidence of corneal swelling, although the use of soft lenses in conjunction with a topically applied solution is shown to produce evidence of transient swelling. The extent of corneal thinning during waking hours is also shown to be reduced among wearers of contact lenses for long periods.

Baldone, J.A.

Ophthalmology, 1979. 86(3): p. 403-8.

Because of their size and mass, weight is a major concern in the fitting of soft gel lenses. Lenticular design is necessary, and there are essentially two lens designs for aphakia: the spin-cast lens of Bausch & Lomb and the lathe-cut lenses of the other manufacturers. A solution to the problem of weight in a single cut soft contact lens is presented.

Morgan, J.F.

Ophthalmology, 1979. 86(6): p. 1107-19.

The complications that have been seen when hydrophilic lenses are cared for by chemical decontamination are reviewed. The findings that help to differentiate lens-induced changes from chemical-care-produced changes are presented. Incompatibilities between care methods are illustrated. The complications are discussed in terms of changes produced in the cornea, conjunctiva, flora of the cul-de-sac, and lens.

Hathaway, R.A. and G.E. Lowther

J Am Optom Assoc, 1978. 49(3): p. 259-66.

The useful life of a hydrophilic lens is often reduced by deposits forming on or within the polymeric structure of the lens. To eliminate this problem, several cleaning agents have been formulated to prevent and/or remove these deposits. The efficacy of these agents in cleaning heavily deposited lenses is the topic of this investigation.

Davies, D.J.

J Appl Bacteriol, 1978. 44(3): p. Sxix-Sxxviii.

Richardson, N.E., et al.

J Pharm Pharmacol, 1978. 30(8): p. 469-75.

The interaction of the four most commonly used preservatives in contact lens solutions (chlorbutol, thiomersal, chlorhexidine gluconate and benzalkonium chloride) with polyhydroxyethylmethacrylate (polyHEMA), has been examined. Benzalkonium chloride and chlorhexidine gluconate show typical high affinity type isotherms. The interaction of benzalkonium chloride with polyHEMA from aqueous solution was reversible whereas that of chlorhexidine was only reversible in the presence of electrolyte or surfactant. Chlorbutol showed a typical reversible linear isotherm. Thiomersal does not interact with polyHEMA above pH 5.0. The extent of chlorhexidine--polyHEMA interactions in increased by the presence of formulatory adjuvants such as electrolyte and hydrophilic polymers. PolyHEMA lenses that apparently have been equilibrated with chlorhexidine gluconate will, on the addition of fresh preservative solution, bind further quantities of chlorhexidine above that which would be predicted from the sorption isotherm.

Benedetto, D.A., D.O. Shah, and H.E. Kaufman

Ann Ophthalmol, 1978. 10(4): p. 437-42.

Using an in vitro technique, a number of commercial as well as pure polymer solutions were evaluated for their ability to form thick aqueous layers on contact lens materials. It was demonstrated that the thickness of adhered pure polymer films was strictly viscosity dependent and did not depend upon the solution's wetting properties (ie, contact angle and surface tension) nor the surface upon which the solution was deposited (eg, glass, a hydrophilic surface versus Plexiglass, a relatively hydrophobic surface). The clinical implications of this study are that the desired solution properties of tear substitutes may be quite different from those of wetting and "cushioning" solutions.

Stodtmeister, R. and I. Wilmanns

Albrecht Von Graefes Arch Klin Exp Ophthalmol, 1978. 206(4): p. 261-8.

In electroretinography, coating agents are usually applied to improve the contact between the contact-lens electrode and the eye. These agents influence electroretinographic responses. In this experimental study we show that the characteristic properties of the electrode circuit are not influenced by the coating agent. Thus we conclude that these coating agents influence the eye itself. The mechanism of this interaction may be physical, or may be an unknown pharmacologic drug side effect.

Kempster, A.J. and J.R. Larke

Br J Ophthalmol, 1978. 62(1): p. 66-8.

The use of hydrophilic gel contact lenses as a carrier of a non- isotonic saline solution provokes an irreversible increase in corneal thickness in the in-vivo rabbit eye. Studies on humans confirm the nature of the animal response, and it is therefore suggested that particular care should be taken when patients prepare saline solutions.

Kagawa, H. and H. Asai

J Biochem (Tokyo), 1978. 84(4): p. 957-63.

The diffusion phenomena of myosin (myosin A, H-meromyosin or subfragment-1) in F-actin plus ATP solutions were investigated. The upper part of the diffusion cell was filled with F-actin plus ATP, and the lower part was filled with F-actin, ATP, and myosin, then both parts were brought into contact so that a boundary of the two solutions was formed and the diffusion of myosin in F-actin plus ATP solutions started. The diffusion pattern was observed with a schlieren lens system. When almost all the ATP in the lower part of the cell had been consumed by actomyosin, a hyper-sharp schlieren pattern appeared near the boundary. On analyzing this pattern, it was found that a local fast migration of proteins was occurring. Simple Brownian motion of myosin molecules could not explain the hyper-sharp phenomenon. This phenomenon occurred in ther pesence of Mg2+ or Ca2+, but very little in the presence of EDTA. Although it is well known that the superprecipitation of myosin B suspension occurs only at physiological ionic strength, this phenomenon occurred over a relatively wide range of ionic strengths. The molecular mechanism of this phenomenon is discussed in relation to the basic mechanism of the interaction between myosin and F- actin.

Josephson, J.E.

J Am Optom Assoc, 1978. 49(3): p. 280-1.

The multi-purge procedure has been used to remove or dilute preservatives in chemical rinsing, storage or disinfecting solutions for soft lenses. It is used for patients who use preserved solutions and who develop eye reactions to these solutions.

Loran, D.F.

Am J Optom Physiol Opt, 1977. 54(12): p. 837-44.

The red spot phenomenon was investigated by examining sagittal sections of corroded ferrous particles embedded in the matrix of hydrogel contact lenses and also by analyzing the incidence of this contamination. The incidence of the red spot phenomenon was found to be 4.4% and was unrelated to the method of manufacture or whether the lens was new or used. The ferrous particles are of probable exogenous origin, introduced by environmental or aqueous debris, and the subsequent corrosion is accelerated by heat disinfection.

Richardson, N.E., et al.

J Pharm Pharmacol, 1977. 29(12): p. 717-22.

The preservative content of 34 commercially available contact lens solutions has been determined. Over half of the solutions contained less than 90% of the stated preservative content. Storage tests conducted at 40 degrees, using both simulated and commercially available contact lens solutions in plastics containers of the type used to present these products showed that thiomersal and chlorbutol appeared to be sorbed by these containers in contrast to benzalkonium chloride and chlorhexidine gluconate which interacted mainly by a surface adsorption process. The extent of any interactions was dependent upon the type of plastics material used to fabricate the container.

Hill, R.M.

J Am Optom Assoc, 1977. 48(3): p. 387-9.

The rigid contact lens continues to offer many prescription features which are difficult to match in the flexible lens realm, e.g.,: readily measured parameters, predictable optics, low production cost and minimum patient care requirements for reasonable hygienic safety. But poor tear pump efficiency remains a challenge in many conventional (i.e., PMMA) cases, even today. Oxygen permeable rigid materials represent the obvious solution to this problem, but how adequately do they perform? Two such materials are examined in this report in relation to the oxygen needs of the cornea.

Gasset, A.R.

Am J Ophthalmol, 1977. 84(2): p. 169-71.

A 36-year-old woman fitted with a soft contact lens after an uneventful extracapsular cataract extraction was wearing her aphakic lens successfully until she switched her lens-soaking solution to an isotonic solution of boric acid, potassium chloride, and sodium carbonate preserved with benzalkonium chloride and edetic acid. After three days her eye became inflamed and vision decreased. No endothelial damage was apparent and the anterior chamber showed 2+ cell and flare reaction. Three weeks after removal of the lens and fitting with an aphakic lens visual acuity was 6/9 (20/30). Study of the preservative by a semiquantitative dilution method together with the clinical evidence in this case proved the cytotoxic effect of benzolkonium chloride when used to sterilize soft contact lenses.

Declercq, S.S.

Am J Ophthalmol, 1977. 83(2): p. 267-71.

Two animal groups were subjected to electroretinographic studies under identical circumstances with the exception of the coating agent on the surface of the corneal electrode, which consisted in one group of an ophthalmic artificial tear solution containing 1.6% hydroxyethylcellulose, and in the other group, an ophthalmic artificial tear solution containing 0.2% hydroxyethylcellose. A similar comparative recording was performed on five human subjects. Electrophysiological responses recorded with 0.2% ophthalmic artificial tear solution increased up to 81%, as compared to the values obtained with the 1.6% solution. The difference in electrical conductivity of these two solutions, which is also time dependent, correlated with differences in electroretinographic amplitudes. I cannot explain these observations at the present time.

Carney, L.G. and R.M. Hill

Am J Optom Physiol Opt, 1976. 53(9 Pt 1): p. 456-8.

Although hydrophilic contact lenses are specifically designed for compatibility with the eye environment, i.e., the tears, they will, with the exception of continuous wear types, spend a significant fraction of their daily cycle in other solutions. This investigation explores the pH characteristics of certain of those alternative media.

Miller, D., S.M. Brooks, and E. Mobilia

Ann Ophthalmol, 1976. 8(1): p. 65-7.

A clinical case of adrenochrome staining of a soft contact lens is described. A laboratory model for such staining is then described in which a soft lens is boiled in a basic, saturated solution of L-DOPA. Repetition of this process in fresh solutions of L-DOPA can achieve any level of black staining desired. The lens can then be made transparent by immersing it in a 3% solution of hydrogen.

Mester, U., C. Krasemann, and H.J. Stein

Klin Monatsbl Augenheilkd, 1976. 169(4): p. 492-5.

Investigations were performed with two groups of anaesthetised rabbits to test the possibility of increasing the penetration of topically administered. Gentamicin into the eye through the use of hydrophilic contact lenses. After application of Gentamicin drops the drug concentration in the aqueous humour was biologically quantitated. In the first group one eye of the animal was fitted with a hydrophilic contact lens and the other eye was submitted to a comparative measurement. In the second group both eyes were fitted with contact lenses which had been soaked in Gentamicin solutions of two different con-entrations. The result showed an increased intraocular Gentamicin level in the eyes fitted with hydrophilic contact lenses. However, in the latter group we found low intraocular drug levels where only contact lenses soaked in Gentamicin solution were used.

Sundmacher, R., C. Junker, and P. Fanti

Klin Monatsbl Augenheilkd, 1976. 169(4): p. 422-30.

74 therapeutic problem-cases of various corneal diseases were treated with the highly hydrophilic Weicon 72 (W 72) which proved to be a valuable therapeutic tool. Additional applications of hypertonic saline and of industrial preparations of steroids, antivirals and antibiotics were tolerated without observable side effects. Additional therapy is often inevitable to achieve an optimal therapeutic effect. Nearly all treated cases of chronic herpetic keratitis - mainly metaherpetic corneal diseases - responded well or excellently to W 72 therapy. If, however, the indication for soft lens therapy is somehow inadequate, if additional therapy is wrong or not applied at all and if the patient does not keep strictly to the therapeutic regime undesired side effects are likely to develop.

Gerhard, J.P.

Klin Monatsbl Augenheilkd, 1976. 168(1): p. 44-9.

Four possibilities are offered to provide a good correction for aphakic individuals: no correction at all; spectacles; more than 60% adopt this solution, the contact lens which has optical, functional and aesthetic advantages. The intra-ocular lens (the best solution, but it is, not without complications). Since 1956 we have followed up 588 unilateral aphakians. Tolerance of contact lenses after one year is excellent: 61% wear the contact lenses 10-12 hrs. per day, 18% wear them 6-8 hrs. per day and 21% lost courage. There is a parallel between binocular vision and tolerance, which decreased over the years. Three factors are determinant here: state of binocular vision: many factors influence the quality of fusion: nature of the cataract, the moment of adaptation of the lens, loss of accommodation and anisoconie. Surrounding conditions e.g. dusty atmosphere also influence the tolerance; local state of the tissues. 15 years later, the situation has changed. 71.5% gave up the contact lenses completely and only 15% wear them 10-12 hrs. per day. The reasons of this abandonment are: diplopie, inflammation and local complications.

Penner, J.L., D.M. Jackson, and W.S. Dixon

Can J Ophthalmol, 1976. 11(4): p. 323-6.

Ten Pseudomonas aeruginosa and six Pseudomonas cepacia strains recently isolated from infected patients were tested for susceptibility to the antimicrobial activity of two commercially-available soft contact lens soaking solutions. No strain showed evidence of viability after two hours but survivors were found in both solutions after one-half hour and in one solution after one hour. The solution most effective in inhibiting the Pseudomonas strains contained chlorhexidine and disodium edetate but each solution was effective in reducing heavy inocula of both species within the times recommended by the manufacturers.

Aquavella, J.V.

Adv Ophthalmol, 1976. 32: p. 2-34.

The introduction of the hydrophilic contact lens has been a significant advance in ophthalmology for the correction of ametropia, as well as for the therapy of corneal disease. The number of potential contact lens candidates has been greatly expanded by the introduction of both spin-cast and lathe-cut lenses composed of a variety of individual hydrophilic polymers. Myopia, hyperopia, presbyopia, aphakia and moderate astigmatism can be corrected with a reasonable degree of success with the present lenses. Even in keratoconus hydrophilic lenses offer a nonsurgical alternative, especially when combined with spectacle overcorrection. The introduction of hydrophilic bandages in the treatment of corneal disease has been an important addition to the therapeutic armamentarium of the ophthalmologist. When properly applied, these lenses can provide subjective relief of pain while serving to protect the damaged cornea from the traumatic action of the lids and desiccating effects of the atmosphere. The hydrophilic material is permeable to many topically instilled medications and tends to prolong the contact time of the drugs with the corneal surface. Proper fitting of the bandage lenses can eliminate superficial corneal irregularities and, thus, improve the visual acuity while treatment progresses. Medical indications for the use of this therapy include bullous keratopathy, dry eye syndromes, chemical burns, exposure keratitis, and neurotropic keratitis. A number of recurrent erosions and ulcerations have also responded to this form of therapy. Surgical indications include lacerations, postoperative lamellar and penetrating keratoplasty, and keratectomies. One of the most promising applications concerns their use in the postoperative management of alkaline burns. Best results have been obtained by constant wear of the bandage lens, with topical administration of steroids, antibiotics, and saline solution (hypotonic or hypertonic) as indicated. The possible deleterious effects of standard ocular medication containing preservatives has been overstated. Patients receiving medications without preservatives must be placed on prophylactic antibiotics to avoid secondary infection. In many cases, the therapeutic efficacy is closely related to the diameter and curvature of the bandage lens as well as the inherent physical properties of the polymers. With meticulous fitting and close observation complications have been minimal. In many instances the results have been dramatic, but even if unsuccessful the method provides a safe and relatively simple nonsurgical alternative in the treatment of severe corneal disease. Just as with older modalities, the ultimate success or failure depends upon the intrinsic nature of the disease process as well as reasonable therapeutic application based on a knowledge of the mechanics involved.

Ruben, M. and R. Watkins

Br J Ophthalmol, 1975. 59(8): p. 455-8.

The use of hydrophilic soft contact lenses for dispensation of pilocarpine is described. The release rate of pilocarpine from three materials of different water content was estimated and from this the surface concentrations were calculated. It is estimated that PolyHEMA can after 15 hours provide a 1 per cent surface concentration of pilocarpine, whereas higher water content materials (70 and 85 per cent) halve this, although they provide a much higher concentration in the first few hours of use. These results are based upon pre-soaking in 4 per cent pilocarpine solution. Because contact lenses present a management problem, this method of dispensation will be used only for selected cases. Some clinical examples treated successfully over a 20 month period are discussed.

Hillman, J.S., J.B. Marsters, and A. Broad

Trans Ophthalmol Soc U K, 1975. 95(1): p. 79-84.

Patients with acute closed-angle glaucoma were treated with a hydrophilic contact lens saturated in 1, 4, or 8 per cent. pilocarpine or bt intensive 4 per cent. pilocarpine drops. The greatest hypotensive response was produced by the 1 per cent. presoaked lens and increased strength of soaking solution gave reduced response. Intensive drops gave the least response. In vitro studies show that the lens is effectively saturated after 2 hrs' soaking holds c. 700 mug. pilocarpine and yields almost all of the contained pilocarpine after 2 hrs' elution. The method of lens preparation is described and pharmaceutical studies confirm a shelf life of 4 months in a domestic refrigerator.

Miller, B.

Klin Monatsbl Augenheilkd, 1975. 167(1): p. 34-45.

In contrast to the hard lenses the soft lens has enough permeability for oxygen and water-soluble substances, whereas high molecular substances, bacteria and virus cannot penetrate the soft lenses, so long as their surfaces are intact. The two principal production methods, the spin cast method and the lathe-turned method are compared. The duration of wearing of the soft lens depends on the deposits of proteins from the tears on the surface of the lens and the desinfection method. The daily boiling of the lenses shortens their useful life, while chemical desinfection causes besides bacteriolysis, damage of the corneal cell protein. The new cleaners on the base of proteolytic plant enzymes promise good results. For the optical correction of astigmatism with more than 1 cyl, soft lenses with conic outer surface are used or combinations of a soft and a hard lens (Duosystem). The therapeutic use of soft lenses has as aim: protection of the cornea against mechanical irritation, release of pain, protracted administration output of medicaments. Further indications for use: aseptic corneal inflammation and corneal defects.

Ehrich, W. and R. Konsgen

Albrecht Von Graefes Arch Klin Exp Ophthalmol, 1975. 194(2): p. 133-42.

Six different soft lens solution have been tested to investigate their effect on the healing process of a corneal erosion, experimentally scratched in rabbit-cornea. Healing delays have been observed in every cases; also by three medicaments which are used for "dry" eyes. The latter ones should never have a conjunctival application. Theexplanation of those healing delays is given by the concentration properties of HEMA-lenses for disinfectants. The admixtures of soft lens solutions like buffers and liquid polymerscause and additive effect on retardment of coeneal regeneration.

Fichman, S.H.

Can J Ophthalmol, 1975. 10(1): p. 51-5.

Hardberger, R.E., C. Hanna, and R. Goodart

Am J Ophthalmol, 1975. 80(1): p. 133-8.

Varying concentrations of tetracycline hydrochloride were topically applied to the rabbit eye in several ophthalmic vehicles. The antibiotic levels in the corneal epithelium, aqueous humor, and lens were markedly elevated by increasing the drug concentration and the drug contact time with the eye. The ocular levels of tetracycline were increased by the vehicle in this ascending order: isotonic saline, 1.4% polyvinyl alcohol, 1% alpha-methylcellulose, and a 6:4 mixture of white petrolatum-mineral oil ointment. Tetracycline hydrochloride as a 2.0% suspension in ointment produced anterior chamber and corneal concentrations for several hours in the range of bacteriostasis for many gram-negative bacteria that occasionally invade the eye.

Harris, M.G. and L.G. Mock

Am J Optom Physiol Opt, 1974. 51(7): p. 457-64.

Conrads, H. and D. Winterhoff

Klin Monatsbl Augenheilkd, 1974. 165(1): p. 192-5.

Arner, R.S. and R.H. Rengstorff

Am J Optom Arch Am Acad Optom, 1973. 50(10): p. 812-3.

Lamy, P.P. and R.F. Shangraw

Am J Optom Arch Am Acad Optom, 1971. 48(1): p. 37-51.

Lewis, E.L.

Eye Ear Nose Throat Mon, 1971. 50(4): p. 141-3.

Krezanoski, J.Z.

J Am Pharm Assoc, 1970. 10(1): p. 13-8.

Wilson, M.S.

Trans Ophthalmol Soc U K, 1970. 90: p. 31-45.

Krezanoski, J.Z. and J.C. Petricciani

Eye Ear Nose Throat Mon, 1969. 48(8): p. 459-64.

Burns, C.A. and R.A. Rarey

Am J Ophthalmol, 1968. 65(2): p. 251.

Bixler, D.P.

Am J Ophthalmol, 1968. 65(1): p. 122-3.

Krishna, N.

Am J Ophthalmol, 1966. 61(6): p. 1538.

Dabezies, O.H., T. Naugle, and L. Reich

Eye Ear Nose Throat Mon, 1966. 45(10): p. 78 passim.