Multifocal contact lens success predictability.

PURPOSE: The current multi-study analysis combined data from three studies to quantify the relationship between the initial reaction to soft multifocal contact lens (MFCL) design types at dispensing and evaluate the predictability of overall vision satisfaction (OVS) and intention to purchase (ITP) after 1 week of wear. METHOD: Three prospective studies tested MFCLs over 1-week of wear following the same protocol, using a range of potentially predictive ratings at dispensing, and both OVS and ITP at 1-week as an indicator acceptance level. In each study, two of MyDay® multifocal, clariti® 1 day multifocal, Biofinity® multifocal (worn as a daily disposable lens) or 1 DAY ACUVUE® MOIST MULTIFOCAL were dispensed for 1-week of daily wear. OVS was recorded on a 100-point VAS and ITP on a 5-point LIKERT scale. Fourteen possible predictors were entered in the statistical model, and predictability was assessed using Chi-square Automatic Interaction Detector (CHAID) statistical test. RESULTS: A total of 210 participants (152 female & 58 male; 53.9 ± 6.5 years, range 41-71 years), representing 420 MFCL fits, equally distributed between emergent n = 65, established n = 70 and advanced n = 75 presbyopes, completed the studies. OVS on dispensing was the predictor of both OVS (p < 0.001) and ITP (p < 0.001) at 1-week. For OVS predictability, 70.8 % with OVS at dispensing > 91 points reported good OVS at 1-week and 73.4 % with OVS on dispensing ≤ 80 points reported poor OVS at 1-week. For ITP predictability, 74.6 % with OVS at dispensing > 94 points reported a positive ITP at 1-week and 65.9 % with OVS on dispensing ≤ 63 points reported negative ITP at 1-week. CONCLUSION: Overall vision satisfaction at the time of dispensing MFCLs is a powerful indicator of both OVS and ITP after 1-week of wear. Initial patient subjective assessments provide a clinically useful indicator of the likeliness of success.

Axial length targets for myopia control.

PURPOSE: Both emmetropic and myopic eyes elongate throughout childhood. The goals of this study were to compare axial elongation among untreated progressing myopes, progressing myopes treated with a myopia control contact lens and emmetropes, in order to place axial elongation in the context of normal eye growth in emmetropic children, and to consider whether normal physiological eye growth places limits on what might be achieved with myopia control. METHODS: Axial elongation data were taken from the 3-year randomised clinical trial of a myopia control dual-focus (MiSight® 1 day) contact lens. These were compared with data for myopic and emmetropic children in two large cohort studies: the Orinda Longitudinal Study of Myopia (OLSM) and the Singapore Cohort Study of the Risk Factors for Myopia (SCORM). Each study's published equations were used to calculate annual axial elongation. Four virtual cohorts-myopic and emmetropic for each model-were created, each with the same age distribution as the MiSight clinical trial subjects and the predicted cumulative elongation calculated at years 1, 2 and 3 for myopes and emmetropes using both the OLSM and SCORM models. RESULTS: The untreated control myopes in the MiSight clinical trial showed mean axial elongation over 3 years (0.62 mm) similar to the virtual cohorts based on the OLSM (0.70 mm) and SCORM (0.65 mm) models. The predicted 3-year axial elongation for the virtual cohorts of emmetropes was 0.24 mm for both the OLSM and SCORM models-similar to the mean 3-year elongation in MiSight-treated myopes (0.30 mm). CONCLUSIONS: The 3-year elongation in MiSight-treated myopes approached that of virtual cohorts of emmetropes with the same age distribution. It is hypothesised that myopic axial elongation is superimposed on an underlying physiological axial elongation observed in emmetropic eyes, which reflects increases in body stature. We speculate that optically based myopia control treatments may minimise the myopic axial elongation but retain the underlying physiological elongation observed in emmetropic eyes.

Changes in the tarsal conjunctiva viewed by in vivo confocal microscopy are associated with ocular symptoms and contact lens wear.

PURPOSE: To investigate the effect of soft contact lens (CL) wear on the morphology of the epithelial-lamina propria junction as well as the possible association with symptoms of discomfort. METHODS: Ninety-two subjects were recruited, including 60 soft CL wearers, 16 previous wearers, and 16 non-wearers. Additionally, subjects were classified as symptomatic or asymptomatic using the Contact Lens Dry Eye Questionnaire 8 for the CL wearers (a score ≥ 12 was considered symptomatic) and the Dry Eye Questionnaire 5 for the previous wearers and non-wearers (a score ≥ 5 was considered symptomatic). In vivo confocal microscopy of the tarsal conjunctiva was performed on a single occasion. Papillae density, shortest diameter, longest diameter, area, circularity, lumen/wall brightness ratio, irregularity, reflectivity, inhomogeneous appearance of wall and inhomogeneous appearance of rete ridges were evaluated. Effects of CL wear, symptoms and their interaction were analysed using two-way analysis of variance. Correlations were investigated using Spearman's coefficient. Data are presented as mean (standard deviation) or median [interquartile range]. RESULTS: Contact lens wearers, compared to previous wearers and non-wearers, showed higher circularity [0.65 (0.08) vs 0.59 (0.10) vs 0.57 (0.11), p = 0.003]. Subjects with symptoms, compared to asymptomatic participants, showed higher circularity [0.64 (0.08) vs 0.61 (0.10), p < 0.001] and lower irregularity (1.0 [0.7-2.0] vs 1.3 [1.0-2.3], p = 0.009). For previous wearers, those with symptoms showed greater density (135.4 [107.3-183.3] vs 87.5 [85.4-116.7], p = 0.013) and circularity [0.64 (0.07) vs 0.54 (0.10), p = 0.016]. For non-wearers, those with symptoms showed higher circularity [0.65 (0.08) vs 0.50 (0.08), p < 0.001]. DEQ-5 correlated with circularity (ρ = 0.55, p = 0.001). CONCLUSIONS: Soft CL wear modifies papillae of the epithelial-lamina propria junction into a more rounded shape; however, CL cessation appears to resolve this alteration. Additionally, a more rounded papillae shape is associated with ocular symptoms in subjects not actively wearing CLs.

Comparative Analysis of Adverse Events From a Series of Proof-of-Principle Extended Wear Studies.

AIM: A series of proof-of-principle extended wear (EW) contact lens studies were conducted to assess what effect different interventions had on adverse events (AEs). Comparative analysis of AEs across studies was conducted to determine whether some interventions were more effective at reducing inflammatory AEs. METHOD: Multiple logistic regression analysis of AEs from 30-day EW studies each with a different intervention including (1) nightly replacement (NR) of lenses, (2) morning replacement (MR) of lenses, (3) instillation of prophylactic antibiotic drops (AB) each morning/evening, (4) daily lens cleaning (LC) each morning. All studies conducted at the same site using same lens type (lotrafilcon A) and EW schedule. RESULTS: Comparison of the different interventions to the individual control groups showed no difference in significant corneal infiltrative event (CIE) or mechanical events. Replacing lenses nightly, during an EW schedule, had the highest incidence of significant CIEs (4.9% [NR] vs. 2.5% [MR] vs. 1.8% [AB] vs. 0% [LC]); however, adjusted logistic regression analysis of the combined control data compared with the individual interventions showed no difference in significant CIEs (P=0.086) or mechanical AEs (P=0.140). CONCLUSIONS: Replacing lenses each night seemed to be inferior compared with the other interventions of replacing lenses each morning, daily lens cleaning, and daily antibiotic drop instillation during EW. The results of the collective studies and additional analysis suggest that overnight wear of contact lenses seems to create an adverse environment that remains, despite the various interventions intended to improve this adverse environment.

Measuring Daily Disposable Contact Lenses against Nonwearer Benchmarks.

SIGNIFICANCE: Since becoming a popular form of refractive error correction, contact lenses have aspired to replicate the nonwearer experience. This study assessed how well currently available daily disposable soft lenses have achieved that goal, using a graphical representation to show individual lens behavior relative to benchmarks. PURPOSE: The purpose of this study was to assess comfort, vision, and adverse events during daily disposable contact lens wear, relative to emmetropes and spectacle wearers. METHOD: Three-month clinical studies, where participants either wore one of five daily disposable contact lenses (n = 201), were full-time spectacle wearers with no history of contact lens wear (n = 34), or emmetropic non-contact lens wearers (n = 40). Vision quality and comfort were assessed at the beginning and end of the day (1 to 10). Corneal infiltrative events were recorded. Between-group comparisons were made using a linear mixed model and literature estimates of clinical significance. RESULTS: Initial comfort among emmetropes (mean ± 95% confidence interval, 8.0 ± 0.5) was not significantly different from any of the lens types (range, 7.2 ± 0.4 to 8.0 ± 0.4, all P > .06) or spectacle wearers (7.3 ± 0.5, P = .45). Comfort deteriorated during the day in all groups (P < .05). End-of-day comfort for emmetropes (7.3 ± 0.6) was significantly better, only than lenses B (5.7 ± 0.6, P < .001) and D (6.2 ± 0.5, P = .01). Vision quality for emmetropes (8.6 ± 0.5) was better than spectacle wearers (7.8 ± 0.5, P = .04) and lenses A (7.6 ± 0.4, P = .003) and B (7.5 ± 0.4, P < .001). Corneal infiltrative events occurred in 0% of emmetropes and 2.9% of spectacle wearers and ranged from 2.4 to 7.5% in lens wearers. CONCLUSIONS: Under the conditions of this study, comfort and vision with some contemporary daily disposable contact lenses were indistinguishable from nonwearing emmetropes. Although the contact lens-wearing groups had rates of corneal infiltrative events that were not statistically different from the nonwearers, the study had insufficient power to permit robust conclusions in this respect.

Discrimination of subjective responses between contact lenses with a novel questionnaire.

PURPOSE: To describe a ranked symptoms scale (RSS) discriminating subjective responses in contact lens (CL) wear in various situations. METHOD: Forty experienced clinical trial participants were interviewed for their perceptions of ocular comfort scales, resulting in a numerical RSS. For further evaluation, 20 CL wearers enrolled into a prospective, randomised, crossover trial. Two silicone-hydrogel CLs and a lens care solution (LCS) [Combinations A & B] were selected based on prior performance identifying best/worst combinations for end-of-day comfort. The RSS and a numerical rating scale (NRS) were administered at two time-points (insertion/removal) on alternating days for 6 days. RESULTS: Both NRS and RSS showed acceptable internal consistency for comfort, vision and handling (Cronbach alpha=0.71 for both scales) and similar repeatability for comfort and handling (coefficients-of-repeatability within 0.1 and 0.2 units, respectively, for each scale). The NRS and RSS discriminated differences between combinations for comfort (p≤0.031) and vision (p≤0.026) at both time-points. Additionally, the RSS showed lens/edge awareness influenced discomfort the most, ranking higher at insertion (p=0.038) and higher for Combination-B at both time-points (p≤0.002). Symptoms of dryness and tired eyes increased for both combinations at removal (p<0.02). The RSS also showed haziness and blurred distance vision influenced vision dissatisfaction with Combination-B at lens removal (p≤0.038) while eye strain/headache increased for both combinations by time of removal (p≤0.013). CONCLUSIONS: The RSS is able to discriminate subjective responses between combinations and time-of-day. The RSS's ability to rank symptoms may be a useful tool in understanding perceptions of discomfort or dissatisfaction with CL wear.

Demographic Factors Affect Ocular Comfort Ratings During Contact Lens Wear.

PURPOSE: To determine if rating of ocular comfort during soft contact lens wear is affected by demographic factors. METHODS: Retrospective analysis of ocular comfort ratings during soft contact lens wear extracted from 44 nonrandomized similar clinical trials (n = 986). Subjects wore one of seven daily wear silicone hydrogels (SiHy) in combination with one of nine lens care products (LCP), and two daily disposables lenses. The effects on comfort rating of demographic factors were examined after adjusting for lens and LCP effects using general linear model. RESULTS: Males reported lower comfort on insertion than females (7.9 ± 1.6 vs. 8.1 ± 1.6, p = 0.001). Over 45 years old had higher comfort ratings than those between 26 and 45 or <26 years old at insertion (8.7 ± 1.3 vs. 8.1 ± 1.6 vs. 7.8 ± 1.6, p < 0.001), during the day (8.6 ± 1.2 vs. 8.0 ± 1.6 vs. 8.2 ± 1.2, p < 0.001), and end of day (7.7 ± 1.6 vs. 6.8 ± 2.0 vs. 7.0 ± 1.6, p < 0.001). Neophytes reported lower comfort on insertion (7.3 ± 1.6 vs. 8.2 ± 1.5, p < 0.001) and during day (8.0 ± 1.3 vs. 8.3 ± 1.3, p = 0.020) than experienced wearers. Participants with Rx ≥-3.50D had higher comfort ratings than those with ≤-3.50D on insertion (8.3 ± 1.4 vs. 7.8 ± 1.6, p < 0.001), during the day (8.4 ± 1.3 vs. 8.1 ± 1.3, p = 0.010), and end of day (7.2 ± 1.7 vs. 6.9 ± 1.8, p = 0.046). Comfort during the day was different between participants of different ethnic origin (p = 0.024) with Asians reporting the lowest (8.1 ± 1.3). CONCLUSIONS: Demographic factors such as age, gender, lens wear experience, ethnicity, and refractive status can influence the rating of ocular comfort in clinical studies. The confounding effects of such demographic factors can be controlled by implementing randomization and appropriate multivariable statistical analysis.

Intersubject and Interday Variability in Human Tear and Meibum Lipidomes: A Pilot Study.

PURPOSE: Our aim was to quantitate day-to-day changes in the tear and meibum lipid profile of individual subjects in a pilot study of healthy humans. METHODS: Matched tear and meibum samples were obtained from four subjects on three consecutive days. Quantitative lipid profiles of human basal tears and meibum were compared using multivariate analysis by principal components. RESULTS: Substantial differences in the lipid profile between subjects were observed, while lipid profiles were steady across the three consecutive days of sampling. Multivariate principal component analysis demonstrated that lysophosphatidylcholine was the largest variant lipid class between subjects in tears, while wax esters comprised the most variation between subjects in meibum secretions. CONCLUSION: Interday variability is shown to be much smaller than interpatient variability, suggesting that tears and meibum subjects both have unique profiles in humans.

Influence of Meibomian Gland Expression Methods on Human Lipid Analysis Results.

PURPOSE: To compare the lipid composition of human meibum across three different meibum expression techniques. METHODS: Meibum was collected from five healthy non-contact lens wearers (aged 20-35 years) after cleaning the eyelid margin using three meibum expression methods: cotton buds (CB), meibomian gland evaluator (MGE) and meibomian gland forceps (MGF). Meibum was also collected using cotton buds without cleaning the eyelid margin (CBn). Lipids were analyzed by chip-based, nano-electrospray mass spectrometry (ESI-MS). Comparisons were made using linear mixed models. RESULTS: Tandem MS enabled identification and quantification of over 200 lipid species across ten lipid classes. There were significant differences between collection techniques in the relative quantities of polar lipids obtained (P<.05). The MGE method returned smaller polar lipid quantities than the CB approaches. No significant differences were found between techniques for nonpolar lipids. No significant differences were found between cleaned and non-cleaned eyelids for polar or nonpolar lipids. CONCLUSION: Meibum expression technique influences the relative amount of phospholipids in the resulting sample. The highest amounts of phospholipids were detected with the CB approaches and the lowest with the MGE technique. Cleaning the eyelid margin prior to expression was not found to affect the lipid composition of the sample. This may be a consequence of the more forceful expression resulting in cell membrane contamination or higher risk of tear lipid contamination as a result of reflex tearing.

Cytokine changes in tears and relationship to contact lens discomfort.

PURPOSE: To determine the reproducibility of a multiplex bead assay for measuring cytokines in tears and correlations between ocular discomfort with or without contact lens wear and the concentration of cytokines in tears. METHODS: Ninety participants (divided into two groups) were enrolled in this prospective study. They were asked to rate their ocular comfort and collect their tears in the morning and just before sleep for 10 days with or without contact lenses. The participants collected their tears using a glass microcapillary tube for both stages. Galyfilcon A lenses were worn on a daily disposable basis during the contact lens stage, and comfort scores and tears were collected before lens insertion and prior to lens removal at the end of the day. Tears were analyzed for cytokine concentrations using a 27-plex multibead assay. Correlations were sought between cytokine concentrations and comfort. RESULTS: There was a significant (p<0.022) decrease in ocular comfort over the day with or without lens wear. The magnitude of ocular discomfort was significantly greater (p<0.009) with lens wear. The concentrations of 12 cytokines differed significantly between the groups; thus, these cytokines were not analyzed further. For the remaining 15 cytokines, interleukin-8 (IL-8) was the only cytokine that changed in both groups during the day without (reduced by >-0.5 Log pg/ml, p<0.001) or with lens wear (reduced by >-0.2 Log pg/ml, p<0.001). The change in the vascular endothelial growth factor (VEGF) concentration only in tears was correlated to ocular comfort, but this was not changed by contact lens wear. CONCLUSIONS: Ocular comfort during the day is magnified by contact lens wear. However, the increase in the change in comfort during lens wear was not associated with changes in 15 cytokines in the tear film.

The effect of compliance on contact lens case contamination.

PURPOSE: To determine the efficacy of written instructions on contact lens case hygiene and to quantify the effect of noncompliance on contact lens case contamination. METHODS: Data were retrospectively analyzed from 16 prospective, 3-month daily-wear studies during which six commercially available silicone hydrogel contact lenses and seven lens care solutions (LCS) were tested following a similar protocol. Verbal instructions regarding case hygiene (rinse case with LCS, not tap water) were given in nine studies, while the same instructions were given verbally and in written format in seven studies. A survey on contact lens, LCS, and lens case hygiene was completed at 1- and 3-month visits and compliance with case hygiene instructions was determined. Regular contact lens cases were used for 1 month and collected for microbial analysis at the 1- and 3-month visits. The rate of case contamination and the types of microbes contaminating cases were evaluated. RESULTS: Participants given verbal and written instructions were more likely to be compliant with case hygiene instructions than those just given verbal instructions (odds ratio [OR]: 2.19, p < 0.001, 95% confidence interval [CI]: 1.40-3.44). The overall case contamination rate was 79%. Use of tap water to rinse contact lens cases was associated with significantly more cases contaminated with Gram-negative bacteria (GNB) (30% vs. 10%, p < 0.001), a greater risk of GNB case contamination (OR: 2.91, p < 0.001. 95% CI: 1.72-4.92), and a higher quantity of GNB in cases (mean colony-forming unit/case ± SD: 28,286 ± 131,935 vs. 6477 ± 60,447, p < 0.001). CONCLUSIONS: Lens case hygiene can be improved by effective communication of instructions. Contact lens wearers should be actively discouraged from rinsing contact lens cases with tap water because of the increased risk of GNB contamination.

Short-term clinical comparison of two dual-disinfection multipurpose disinfecting solutions.

OBJECTIVE: To compare the short-term clinical performance of two dual-disinfectant multipurpose disinfecting solutions (MPDS) when used in conjunction with two silicone hydrogel contact lenses. METHODS: Participants wore galyfilcon A and balafilcon A lenses, randomly allocated one type to each eye. Multipurpose disinfecting solutions were double-masked and allocated using a randomized crossover design. Lenses were presoaked overnight in the allocated MPDS, containing either polyquaternium-1/alexidine dihydrochloride (PQ-alexidine) or polyquaternium-1/myristamidopropyl dimethylamine (PQ-MAPDA). Lenses were worn daily for 4 days and disinfected with the same MPDS in which they had been soaked. Clinical assessments occurred immediately after insertion, 2 hours after insertion, and after 2 hours of wear on day 4. Subjective ratings were collected at each assessment and after 6 hours of wear on days 1 to 3. Linear mixed models were used for statistical analysis. RESULTS: Solution-induced corneal staining (SICS) incidence was significantly different between MPDS lens combinations (P=0.01) with PQ-MAPDA-balafilcon A showing the highest incidence (27.8%). The incidence of SICS was significantly higher when balafilcon A lenses were worn compared with galyfilcon A (19.4% vs. 2.8%; P=0.04). There was no significant difference in SICS incidence between MPDS (PQ-alexidine=5.6%, PQ-MAPDA=16.7%; P=0.08). Polyquaternium-1/alexidine dihydrochloride was associated with significantly fewer symptoms of burning/stinging (9.7±0.6 vs. 9.1±2.2; P=0.03) and self-assessed redness (9.8±0.5 vs. 9.2±1.9; P=0.03) on initial lens insertion. There were no significant differences between MPDS for comfort ratings (P>0.05). CONCLUSION: These short-term clinical results provide an initial indication that PQ-alexidine is associated with fewer symptoms on insertion but no significant difference in ocular comfort compared with PQ-MAPDA. Longer studies are required to provide further evidence.

A comparison of patient matched meibum and tear lipidomes.

PURPOSE: To quantify the molecular lipid composition of patient-matched tear and meibum samples and compare tear and meibum lipid molecular profiles. METHODS: Lipids were extracted from tears and meibum by bi-phasic methods using 10:3 tert-butyl methyl ether:methanol, washed with aqueous ammonium acetate, and analyzed by chip-based nanoelectrospray ionization tandem mass spectrometry. Targeted precursor ion and neutral loss scans identified individual molecular lipids and quantification was obtained by comparison to internal standards in each lipid class. RESULTS: Two hundred and thirty-six lipid species were identified and quantified from nine lipid classes comprised of cholesterol esters, wax esters, (O-acyl)-ω-hydroxy fatty acids, triacylglycerols, phosphatidylcholine, lysophosphatidylcholine, phosphatidylethanolamine, sphingomyelin, and phosphatidylserine. With the exception of phospholipids, lipid molecular profiles were strikingly similar between tears and meibum. CONCLUSIONS: Comparisons between tears and meibum indicate that meibum is likely to supply the majority of lipids in the tear film lipid layer. However, the observed higher mole ratio of phospholipid in tears shows that analysis of meibum alone does not provide a complete understanding of the tear film lipid composition.

Adverse events during 2 years of daily wear of silicone hydrogels in children.

PURPOSE: Type and incidence of adverse events and rate of discontinuations for 2 years of daily wear with silicone hydrogel contact lenses in Chinese children with myopia. METHODS: Two hundred forty children aged 7 to 14 years were enrolled in a prospective randomized clinical trial from November 2008 to April 2009. Children with myopia of up to -3.50 diopters (D) spherical equivalent with astigmatism less than or equal to -0.75 D were randomized to one commercial and three experimental lens designs of Lotrafilcon B silicone hydrogel lenses (four groups) used bilaterally on a daily wear, monthly replacement schedule. The main outcome measures were incidence per 100 patient-years (incidence, in percentage) of adverse events and rate of discontinuations. RESULTS: There were no events of microbial keratitis. Fifty-five adverse events (incidence, 14.2%) were seen. There were also 12 recurrent events. The type and incidence percentage were contact lens papillary conjunctivitis (16 events, 4.1%), superior epithelial arcuate lesions (SEALs, six events, 1.5%), corneal erosions (eight events, 2.1%), infiltrative keratitis (five events, 1.3%), asymptomatic infiltrative keratitis (seven events, 1.8%), and asymptomatic infiltrates (13 events, 3.42%). There were differences in the incidence of SEALs between groups (p = 0.023), with the incidence of SEALs being greater with one of the experimental designs. No event resulted in any vision loss. Seventy participants (29.2%) discontinued, with one-third (26 participants, 10.8%) occurring in the first month of lens wear. Discomfort and non-lens-related reasons such as safety concern and disinterest were frequently cited reasons for discontinuations. CONCLUSIONS: Adverse events with daily wear of silicone hydrogels in children were mainly mechanical in nature, and significant infiltrative events were few. The large number of dropouts in the early days of lens wear and their reasons for discontinuation suggest that adaptation and patient motivation are critical for survival in lens wear.

Combined effect of comfort and adverse events on contact lens performance.

PURPOSE: To report the performance of various contact lenses and lens care solution combinations based on the combined response of subjective comfort and adverse events (AEs). METHODS: A retrospective analysis of 28 lens/solution combinations each tested on approximately 40 participants who wore their assigned combination on a daily wear basis and were followed for a 3-month period, with visits at baseline, 2 weeks, and 1 and 3 months. Lenses included frequent replacement and daily disposables. Solutions included hydrogen peroxide and multipurpose types. Subjective comfort (scale of 1 to 10) and AEs were collected and reported as a group mean and percentage, respectively. The data were converted into a ratio between 0 and 1 to represent the relative performance within the combination series, with a higher ratio indicating better performance in both AE rates and comfort. RESULTS: The overall AE rate was 3.6 events per 100 participant-months (95% confidence interval [95% CI], 2.7 to 4.7%). The rate was found to be lower in daily disposables compared with that in daily wear lenses (3.1 vs. 10.9%, p < 0.001). The overall comfort on insertion rating was 8.3 (95% CI, 8.1 to 8.4), and comfort at end of day was 7.2 (95% CI, 7.0 to 7.4). Based on the 28 lens/solution combinations, there was no significant correlation between overall AE rates and comfort on insertion or at end of day (Pearson correlation, -0.34, p = 0.08; and Pearson correlation, -0.23, p = 0.25, respectively). Less than 18% of the combinations tested combined good comfort with low AE rates. CONCLUSIONS: Both subjective comfort responses and AE rates varied according to the combination of lens type and care system in use. The combinations with the best comfort ratings did not necessarily have a favorable AE rate. Practitioners can maximize behavior with respect to both these factors by choosing an appropriate care system for the lenses they prescribe.

In vivo corneal oxygen uptake during soft-contact-lens wear.

PURPOSE: We develop a new method to compute in situ corneal oxygen uptake during soft-contact-lens (SCL) wear using a micro-polarographic Clark electrode. METHODS: After steady SCL wear and subsequent removal, a membrane-covered polarographic microelectrode is immediately placed onto the cornea. The resulting polarographic signal is related to the steady-state corneal oxygen uptake rate during soft-contact-lens wear. We devise a new analysis to quantify oxygen uptake into the cornea during lens wear. The proposed procedure is applied to new polarographic data for 10 human subjects with 12 different commercial lenses during open eye. We compare our results with recent theory. RESULTS: Average corneal oxygen uptake rates at open eye during SCL wear for 10 subjects wearing 12 different commercial lenses vary from 2 to 10 µL(STP)/cm(2)/h. High oxygen permeability lenses have uptake rates of -10 µL(STP)/cm(2)/h, in close agreement with our previously obtained no-lens human uptake rates of 9 to 13 µL(STP)/cm(2)/h at open eye.(40) Application of the classical data-interpretation procedure to our experimental data gives corneal-uptake results that are approximately three to five times smaller than those obtained with our new interpretation scheme. CONCLUSIONS: We provide a simple and reliable tool to quantify corneal-oxygen-uptake rates during in vivo soft-contact-lens wear. Comparison of our newly measured in vivo oxygen uptakes to model prediction for SCLs of varying oxygen transmissibility is in good agreement with available theory.

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.

Effect of lens and solution choice on the comfort of contact lens wearers.

PURPOSE: To determine if the ocular comfort of symptomatic contact lens (CL) wearers can be substantially influenced by choosing a better or worse performing CL-lens care product (LCP) combination. METHODS: Twenty-four symptomatic and 13 nonsymptomatic CL wearers were enrolled into a prospective, crossover, randomized clinical trial. Two CL-LCP combinations were chosen from studies previously conducted at the Brien Holden Vision Institute that were found to provide the best (galyfilcon A/polyhexanide, combination 1) and worst performance (balafilcon A/polyquaternium-1 and myristamidopropyl dimethylamine + TearGlyde, combination 2) in terms of end-of-day comfort. Subjects were not informed whether they were categorized as symptomatic or nonsymptomatic nor were they aware of the rankings of each CL-LCP combination. Subjects were randomly allocated to one of the CL-LCP combinations for 8 days on a daily wear basis. Contact lens fitting was assessed after insertion from the packaging solution. Take-home questionnaires assessing ocular comfort and dryness (1 to 10 numeric rating scale) were completed on insertion and after 2 and 8 hours of wear on days 2, 4, and 6. Ocular symptoms were assessed on days 2, 4, and 6 after 8 hours of wear. A 48-hour washout period during which CLs were not worn was applied, with the procedure repeated using the second combination. RESULTS: In symptomatic subjects, combination 1 was rated significantly better than combination 2 after 8 hours of wear for ocular comfort (7.7 ± 1.3 vs. 7.1 ± 1.5, p = 0.01) and ocular dryness (7.5 ± 1.6 vs. 7.0 ± 1.6, p = 0.045), with less frequent symptoms of ocular dryness (p < 0.01) and lens awareness (p < 0.01) reported. No significant differences were found in nonsymptomatic subjects. CONCLUSIONS: Ocular comfort and symptoms in symptomatic CL wearers can be perceptibly improved by switching to an alternative CL-LCP combination. This finding provides justification for the efforts of both eye care practitioners and researchers to improve the comfort of CL wearers.

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.