Effect of lens care systems on the clinical performance of a contact lens.

PURPOSE: To evaluate subjective responses, rates of solution-induced corneal staining (SICS), and corneal infiltrative events (CIEs) associated with a silicone hydrogel when worn under a daily disposable (DD) or daily wear (DW) modality. METHODS: Data were obtained from seven prospective clinical trials, involving 283 subjects wearing Senofilcon A contact lenses (Johnson and Johnson Vision Care, Jacksonville, FL). Four groups wore the contact lens on a DW basis using multipurpose solutions (DW-MPS, n = 160), two groups using hydrogen peroxide (DW-H2O2, n = 83), and one group as a DD (n = 40). Participants were followed for 3 months using the same protocol. Subjective ratings were compared between DD and DW groups using a linear mixed model. Rates of SICS and CIE were calculated as the percent frequency of first events within the 3-month study. Association of SICS and CIE with subjective responses was analyzed using a linear mixed model. RESULTS: End-of-day comfort and dryness ratings were significantly better for DD (8.5 ± 1.7 and 8.6 ± 1.7, respectively) compared with DW-H2O2 (7.7 ± 1.8, p = 0.01; 7.6 ± 1.9, p = 0.006, respectively) and DW-MPS (7.7 ± 1.7, p = 0.004; 7.6 ± 2.0, p = 0.003, respectively). Compared with DD, a higher incidence of CIE and SICS was found for DW-MPS (0.0 vs. 3.9%, p = 0.021; 0.9 vs. 8.6%, p = 0.002, respectively). Comfort at insertion and end of day and end-of-day dryness scores were significantly lower for participants who experienced SICS (8.2 ± 1.6, 7.0 ± 1.9, and 7.0 ± 2.2) than those who did not (8.8 ± 1.2, p = 0.004; 7.9 ± 1.7, p = 0.002; and 7.9 ± 1.8, p = 0.003, respectively). Comfort at insertion scores were significantly lower for participants who experienced CIEs than those who did not (8.2 ± 1.5 vs. 8.8 ± 1.4, p = 0.032). CONCLUSIONS: Senofilcon A clinical response is modulated by the lens care products. All lens care products tested reduced subjective responses relative to DD modality, whereas MPS increased the incidence of CIEs and SICS. Senofilcon A performs best when used on a DD basis.

Solutions for care of silicone hydrogel lenses.

PURPOSE: During wear of contact lenses on a daily wear basis, it is necessary to disinfect the lens overnight before reinserting the lens the next day. The ability of the solutions used for this to disinfect lenses and lens cases is important for safe lens wear. METHODS: The literature on the disinfecting ability of multipurpose disinfecting solutions (MPDS) commonly used with silicone hydrogel lenses reported during the period 2000 to 2012 is reviewed, as this is the period of time during which these lenses have been commercially available. Particular emphasis is placed on the ability of disinfecting solutions to control colonization of lens cases by microbes and changes in composition and use of the solutions. In addition, the literature is reviewed on ways of minimizing lens case microbial contamination. RESULTS: Maintaining the hygiene of contact lenses and lens cases is important in minimizing various forms of corneal infiltrative events that occur during lens wear. Although lens case contamination is not associated with different lenses, it is determined by use of different MPDS. MPDS that allow more frequent or heavy contamination of cases by Gram-negative bacteria are associated with a higher incidence of corneal infiltrative events. MPDS are now available that contain dual disinfectants. Wiping lens cases with tissues or using lens cases that incorporate silver are associated with reductions in contamination in clinical trials. Similarly, using MPDS to rub and rinse lenses before disinfection may reduce levels of microbes on lenses. The MPDS also contain surfactants that help reduce deposition and denaturation of proteins on lenses. CONCLUSIONS: Improvements in MPDS formulations and hygiene practices may help to reduce the incidence of adverse events that are seen during use with silicone hydrogel lenses.

The future of silicone hydrogels.

Significant advances during the past decade in silicone hydrogel lenses have made them the primary mode for new contact lens wear. Their dominance in the market place is driven largely by the elimination of structural and physiological changes induced by contact lens-induced hypoxia, as exemplified especially by the reduction in limbal redness. However, end-of-day dryness and discomfort still drives many to discontinue lens wear. Evidence also indicates that the rate of serious adverse events, such as microbial keratitis, have not been impacted with the use of silicone hydrogel lenses. Moreover, there are additional challenges relating to 'corneal staining' and corneal infiltrates associated with the incompatibility of lens care product with contact lens polymers. On the other hand, technological advances enabled by the high oxygen platform present opportunities for expanding the use of contact lenses in areas that have exhibited limited uptake in the past such as astigmatism, presbyopia, and importantly myopia control. The challenges and opportunities facing the field will be discussed.

Contact lens complications in an urgent-care population: the University of California, Los Angeles, contact lens study.

OBJECTIVES: This is a prospective study in an urgent-care ophthalmic setting to investigate contact lens (CL) complications and their association with extended wear (EW). METHODS: Data on CL designs, care system(s), and ocular complications were collected over a 6-month period. RESULTS: One thousand three hundred and sixty-nine patients presented to the Jules Stein Eye Institute urgent care with symptoms of eye problems. Of these, 56 were identified with diagnoses etiologically associated with CL wear, and 49 were studied. The five most common ocular diagnoses found in our study were in the following order: epithelial staining or abrasion/epithelial defect, conjunctival injection, papillae, corneal neovascularization, and presumed microbial keratitis (PMK). Fifteen of 49 patients were diagnosed with PMK. The mean number of complications was 3.43 per eye. Most of the patients (65%) reported some form of EW. Analysis of the patients with PMK showed an association with EW. There seemed to be no statistical difference in the number of complications per symptomatic eye with hydrogel and silicone hydrogel lenses although 13 of the 15 patients with PMK were silicone hydrogel wearers. CONCLUSIONS: We studied various aspects of care and compliance in an urgent-care population and found that most of our urgent-care patients slept with CLs on their eyes. Symptomatic CL wear-related complications, and specifically MK, strongly correlate with EW with less relation to lens design, material, and wear modality. We therefore conclude that CL EW is a risk factor leading to urgent-care visits.

Impact of lens case hygiene guidelines on contact lens case contamination.

PURPOSE: Lens case contamination is a risk factor for microbial keratitis. The effectiveness of manufacturers' lens case cleaning guidelines in limiting microbial contamination has not been evaluated in vivo. This study compared the effectiveness of manufacturers' guidelines and an alternative cleaning regimen. METHODS: A randomized cross-over clinical trial with two phases (n = 40) was performed. Participants used the lens types of their choice in conjunction with the provided multipurpose solution (containing polyhexamethylene biguanide) for daily wear. In the manufacturers' guideline phase, cases were rinsed with multipurpose solution and air dried. In the alternative regimen phase, cases were rubbed, rinsed with solution, tissue wiped, and air-dried face down. The duration of each phase was 1 month. Lens cases were collected at the end of each phase for microbiological investigation. The levels of microbial contamination were compared, and compliance to both regimens was assessed. RESULTS: The case contamination rate was 82% (32/39) in the manufacturers' guideline group, compared with 72% (28/39) in the alternative regimen group. There were significantly fewer (p = 0.004) colony forming units (CFU) of bacteria from cases used by following the alternative regimen (CFU range of 0 to 10, and median of 12 CFU per well) compared with that of the manufacturer's guidelines (CFU range of 0 to 10, and median of 28 CFU per well). The compliance level between both guidelines was not significantly different (p > 0.05). CONCLUSIONS: The alternative guidelines are more effective in eliminating microbial contamination from lens cases than that of the current manufacturer's guideline. Simply incorporating rubbing and tissue-wiping steps in daily case hygiene reduces viable organism contamination.

Acanthamoeba keratitis--a diagnostic challenge.

This is a case study of a 23 year old male diagnosed with Acanthamoeba keratitis. Initial misdiagnosis and inappropriate treatment lead to increased severity of the infection requiring surgical intervention. This case illustrates the complexity of Acanthamoeba keratitis infection, highlighting the diagnostic challenges which often begin with misdiagnosis and treatment, the role of the laboratory in providing confirmatory testing, and the relevance of patient knowledge related to contact lens wear and care.

Care regimen and lens material influence on silicone hydrogel contact lens deposition.

PURPOSE: To quantitatively detect proteins and cholesterol extracted from worn silicone hydrogel contact lenses and determine the effect of various lens care solutions on deposit accumulation. METHODS: Contact lenses, made from different polymers and worn on a daily wear schedule with different lens care solutions, were collected. Lipid and protein deposits were extracted by methanol:chloroform (1:1, v/v) and protein extraction solution (containing urea and surfactant), respectively. Lipid extracts were separated and cholesterol quantified using thin layer chromatography. Protein extracts were quantified using standard techniques. RESULTS: Among all lenses tested, Balafilcon A lenses exhibited greatest extracted cholesterol (4.1 to 8.2 microg/lens) and total protein (5.4 to 23.2 microg/lens). AQuify was the most effective solution in reducing extracted deposits, especially extracted protein, from Balafilcon A lenses. AQuify and Opti-Free RepleniSH solutions were most effective in reducing extracted cholesterol from Senofilcon A and Galyfilcon A lenses, respectively. Use of Opti-Free Express solution resulted in more extracted protein from Lotrafilcon B lenses than use of other solutions. Generally, Lotrafilcon B, Senofilcon A, and Galyfilcon A lenses accumulated relatively low amount of proteins. Lotrafilcon B lenses accumulated the least amount of cholesterol deposit among all lenses tested regardless of solution used. CONCLUSIONS: Lens polymer (possibly associated with surface characteristics) is a prominent factor affecting lipid and protein accumulation. Within a lens polymer type, lens care solutions exhibit varying effectiveness in reducing protein and lipid accumulation.

Soft contact lens cleaning: rub or no-rub?

PURPOSE: To compare effectiveness of cleaning with and without rubbing of soft contact lenses. METHODS: Three-hundred new biweekly disposable hydrogel lenses (Ocufilcon D, FDA Group IV; 55% water content) were artificially deposited with serum albumin, hand cream (semi-transparent deposits) and mascara (black deposits). The treated lenses were randomly divided into three groups, each group cleaned by one of three methods of cleaning--Rubbing (R), No-Rub following the manufacturer's instruction on duration of rinsing (NR1) and No-Rub with a shorter duration of rinsing (NR2). Four commercially-available multipurpose solutions (MPS) and a saline were used. The cleaning effectiveness was determined by the amount of deposits remaining on the contact lenses after cleaning, assessed with the aid of a slit-lamp. The level of deposits remaining (in terms of coverage of lens surface) were determined using a five-point scale [0 (no observable deposits)--4 (>80% deposits remained)] for semi-transparent deposits (protein and hand cream) and black deposits (mascara). The investigators were masked as to the solutions used (except for one MPS which has a different rinsing time than the other MPS), and the investigator who assessed the deposits left on the lenses did not know which solution or cleaning method was used to clean each lens. RESULTS: Lenses cleaned by the R method were significantly cleaner than those cleaned by methods NR1 and NR2. No significant difference was found between lenses cleaned by NR1 and NR2 methods. The median grade of deposits for lenses cleaned by R method was 0.5 for both semi-transparent and black deposits. For lenses cleaned by NR1 and NR2 methods, the median grade of deposits left on lens surfaces was 4.0 for both types of deposits. Different solutions used did not affect the level of deposits left on lens surfaces for all three cleaning methods. CONCLUSIONS: Not rubbing the soft lens when cleaning is ineffective in removing loosely-bound deposits. A longer rinse, as recommended by the manufacturers, does not remove significantly more deposits than a shorter rinse with the MPS. This work supports the view that contact lens wearers should be encouraged to rub their lenses when cleaning.

Multipurpose solutions and rates of biocidal efficacy.

OBJECTIVE: To investigate the hypothesis that reasonable levels of disinfection are achievable over relatively short exposure durations of microorganisms to multipurpose solutions, this study examined the stand-alone disinfection efficacy at 10, 20, and 30 min of five different multipurpose solutions products, each against five different pathogens eye care practitioners may encounter in their contact lens practice. METHODS: ReNu MultiPlus, ReNu Multi-Purpose, AQuify, OptiFree Express, and OptiFree RepleniSH were evaluated for their microbiocidal efficacy using the stand-alone method at 10, 20, and 30 min of exposure to either Fusarium solani, Candida albicans, Staphylococcus aureus, Serratia marcescens, or Pseudomonas aeruginosa. RESULTS: Solutions which showed significantly higher rates of disinfection at 30 min were ReNu MultiPlus against Fusarium solani and Candida albicans, and both ReNu MultiPlus and AQuify against Staphylococcus aureus and Serratia marcescens. There were no statistically significant differences at 30 min amongst solutions against Pseudomonas aeruginosa. CONCLUSIONS: The product attribute of rapid rate of disinfection may give a greater level of assurance to practitioners when patients are noncompliant and do not follow the recommended time period for lens disinfection. The results of this study, however, should not be interpreted as a recommendation to use any of the solutions tested for a disinfection period less than the recommended soak time. Patient compliance with recommended lens care regimens is essential in minimizing the risk of contamination of contact lenses and lens care accessories.

Hydrogel Contact Lens Water Content is Dependent on Tearfilm pH.

Introduction: Based on clinical inferences, investigators theorized in situ soft lens hydration was linked to the precorneal tearfilm pH. Methods: Forty-one myopic subjects at Fort Rucker, AL, USA were fitted with one of two types of extended-wear soft contact lenses, and were followed quarterly for a period of 33 mo. The anterior soft contact lens surface pH was measured in situ, while the in vitro lens water content was measured immediately after lens removal, using a hand-held refractometer on one lens, and a gravimetric means of hydration measurement on the other lens. Results: The in situ pH increased logarithmically across extended wearing time, reaching an asymptote at approximately 5 d' wearing time at a pH of 7.45 ± 0.03. Lens water content was shown to similarly decrease at an inversely logarithmic rate, leveling off at 4-5 d' extended wearing time. Both means of hydration assessment correlated well with each other across days' extended wearing time (R = 0.98; p < 0.0001). Discussion: A log-log dual conversion yielded significantly different linear slopes (p < 0.001), based on a multifactorial analysis of both lens types, by the pH, and by their water content. The differing ionic status of each material accentuated their varied polar attraction characteristics. Two soft lenses, identical in all patient-based parameters, could provide differing oxygen availability, as well as differing physical fits in patients of identical physical characteristics, as a result of their unique tearfilm pH differences. Conclusion: The in situ hydrogel lens water content is directly dependent on the precorneal tearfilm pH.

Evaluation of safety and efficacy of a new multipurpose disinfecting solution on silicone hydrogel contact lenses.

PURPOSE: To evaluate the safety and efficacy of a new multipurpose disinfecting solution (MPDS) with a formulation that includes aloe vera on its composition. METHODS: This is a prospective, randomized, double-masked clinical trial with a crossover design that included seven examinations. Two different MPDSs, Avizor Alvera® (study solution) and All Clean Soft® (control solution), each were used for 1 month. Comfilcon A silicone hydrogel contact lenses were used during the trial. The main outcome variables were corneal staining and deposits on the surfaces of the contact lenses. Other parameters including ocular surface response, contact lens wettability, user satisfaction, and adverse events, were analyzed according to the International Organization for Standardization (ISO) 11980:2010 guidance for clinical investigation. RESULTS: Twenty subjects (10 women, 10 men) (mean age, 27.7±5.6 years; range, 20-41) were included. No differences between both MPDSs were found in the percentage of subjects with corneal staining >0 at day 30 (study: 35%, control: 50%; p=0.46); neither in the percentage of subjects with deposits on the surface of the contact lens >0 at day 30 (study: 26.32%, control: 52.63%; p=0.18). The study MPDS received higher rates in comfort (study: 8.14±1.09, control: 7.94±0.92; p=0.56) and satisfaction at day 30 (study: 8.63±0.91, control: 8.29±0.80; p=0.19), however the scores were not significantly different with the control MPDS. CONCLUSIONS: The clinical trial showed that the study MPDS is safe, efficient, and has acceptable physiologic tolerance, according to the ISO 11980:2010 guidance for clinical investigation.

Review of standard for evaluating the effectiveness of contact lens disinfectants.

A new standard has been developed by the International Organization for Standardization (ISO) for evaluating contact lens disinfectants. This paper reviews the ISO 14729 standard and applies it to marketed products. The historical significance, justifications, scope, interpretations, application, and worthiness are discussed. The standard provides a more consistent procedure and a higher standard for contact lens disinfectants. As a result, more effective contact lens disinfectants have been marketed.