Risk Factors for Nonulcerative Contact Lens Complications in an Ophthalmic Accident and Emergency Department

Risk Factors for Bacterial Keratitis and Severe Disease in Hydrogel Contact Lens Users: A Multicenter Case-Control Study and Case-Only Analysis

PURPOSE

To assess risk factors for contact lens (CL)-related bacterial keratitis, cases and high-risk controls were enrolled. Using high-risk controls can help elucidate whether certain CL types or modalities are attributable to disease burden if risky wear patterns are similar between the cases and controls. This analysis identified whether such CL factors were associated with the occurrence of bacterial keratitis. In addition, a case-only analysis determined CL factors associated with severe disease.

METHODS

From 2018 to 2021, 158 controls were enrolled at University Hospitals of Cleveland Eye Institute, and 153 bacterial keratitis cases were enrolled across 14 sites in the United States. Cases were soft CL wearers with either culture-proven bacterial keratitis or a corneal infiltrate with an overlying epithelial defect within the central 4 mm of the cornea, uveitis, or significant pain. Fungal, protozoan, or nonsoft CL wear-related microbial keratitis cases were excluded. Controls were recruited from high-risk CL wearers with no history of disease. All participants completed a questionnaire related to demographics, type of CL used, wearing schedule, lens handling practices, and storage case handling. Cases with ulcer/infiltrate size ≥2 mm in size, presence of hypopyon, or had fortified antibiotics prescribed were classified as severe keratitis. Univariate and multivariable logistic regression was used to assess association of CL variables with the occurrence of bacterial keratitis as well as occurrence of severe disease among the cases only.

RESULTS

Compared with the control cohort, cases were older (mean age 45.6 vs. 38.9 years), had more males (42.5% vs. 23.6%), and had more current or former smokers (41.7% vs. 12.9%). There were no significant associations between CL material (silicone hydrogel vs. not) or CL type (daily disposable vs. reusable) and occurrence of bacterial keratitis. More than two-thirds (67.3%) of cases were classified as severe. Among cases only, univariate analyses found current smokers to have increased risk of severe disease (OR=2.87; 95% CI 1.13-7.26, P =0.03). Adjusting for age, sex, and smoking among the cases only, daily disposable lenses were protective against severe disease (OR=0.32; 95% CI 0.11-0.89, P =0.03). Reusable lenses increased risk of severe microbial keratitis between 3.0- and 4.4-fold compared with compliant daily disposability.

DISCUSSION/CONCLUSION

Compared with a high-risk control cohort, no specific lens factors were associated with occurrence of CL-associated bacterial keratitis. Among cases only, current smokers and patients wearing reusable lenses are at increased risk of severe keratitis. Daily disposable lenses were protective even when noncompliance to daily disposability was considered.

Silicone hydrogel versus hydrogel soft contact lenses for differences in patient-reported eye comfort and safety: A Cochrane systematic review summary

SIGNIFICANCE

This work is significant because it is the first Cochrane systemic review that compares the comfort and safety of hydrogel and silicone hydrogel soft contact lenses (SCL).

PURPOSE

This study aimed to conduct a systemic review of randomized trials comparing the comfort and safety of silicone hydrogel and hydrogel SCLs.

METHODS

CENTRAL, MEDLINE Ovid, EMBASE.com, PubMed, LILACS, ClinicalTrials.gov, and World Health Organization International Clinical Trials Registry Platform were searched on or before June 24, 2022, to identify randomized clinical trials that compared silicone hydrogel and hydrogel SCLs.

RESULTS

Seven trials were identified and evaluated. One trial reported Ocular Surface Disease Index results, with the evidence being very uncertain about the effects of SCL material on Ocular Surface Disease Index scores (mean difference, -1.20; 95% confidence interval, -10.49 to 8.09). Three trials reported visual analog scale comfort score results, with no clear difference in comfort between materials, although results were of low certainty; trial results could not be combined because the three trials reported results at different time points. None of the included trials reported Contact Lens Dry Eye Questionnaire 8 or Standard Patient Evaluation of Eye Dryness scores. There was no evidence of a clinically meaningful difference (>0.5 unit) between daily disposable silicone hydrogel and hydrogel SCLs in corneal staining, conjunctival staining, or conjunctival redness (very low certainty evidence).

CONCLUSIONS

The overall evidence for a difference between all included silicone hydrogel and hydrogel SCL trials was of very low certainty, with most trials judged as having a high overall risk of bias. There was insufficient evidence to support recommending one SCL material over the other. Future well-designed trials are needed to generate high certainty evidence to further clarify differences in SCL material comfort and safety.

Examining daily disposable soft contact lens wearers' attitudes and beliefs using the Health Belief Model

PURPOSE

To use the Health Belief Model (HBM) to understand daily disposable (DD) soft contact lens (SCL) wearers' attitudes and beliefs.

METHODS

A convenience sample of DD SCL wearers (18-33 years) was enrolled at two sites. Participants were queried about demographics, SCL wear and HBM constructs. Rasch analysis was used to assess the psychometric properties of the survey instrument and generate scores for each HBM subscale. ANOVA was used to determine relationships among HBM constructs, subject demographics and DD SCL-related health behaviours.

RESULTS

One hundred people participated (mean ± SD), age = 24.2 ± 3.9 years, 76% female. Thirty-seven percent reported sleeping in DD SCLs and 25% reported reusing DD SCLs. Self-report of reusing DD SCLs was associated with scores on the benefits: reuse (p = 0.02) and barriers (p = 0.007) subscales, and sleeping in lenses was associated with scores on the susceptibility (p = 0.05), benefits: wear behaviours (p = 0.006) and barriers (p = 0.01) subscales. Rasch analysis showed some subscales demonstrated multidimensionality.

CONCLUSIONS

Selected health belief constructs were associated with DD SCL-related behaviours including reusing and overnight wear. Increased understanding of SCL attitudes and beliefs could inform patient education and interventions to decrease risks associated with improper SCL wear.

Contact Lens Safety for the Correction of Refractive Error in Healthy Eyes

ABSTRACT

Contact lenses are a safe and effective method for correction of refractive error and worn by an estimated 45 million Americans. Because of the widespread availability and commercial popularity of contact lenses, it is not well appreciated by the public that contact lenses are U.S. Food and Drug Administration (FDA)-regulated medical devices. Contact lenses are marketed in numerous hard and soft materials that have been improved over decades, worn in daily or extended wear, and replaced in range of schedules from daily to yearly or longer. Lens materials and wear and care regimens have impact on the risks of contact lens-related corneal inflammatory events and microbial keratitis. This article reviews contact lens safety, with specific focus on the correction of refractive error in healthy eyes.

Addressing common myths and misconceptions in soft contact lens practice

Advances in contact lens technology over the past 50 years since the commercialisation of the first soft lenses in 1971 have been incredible, with significant changes in contact lens materials, frequency of replacement, care systems and lens designs occurring. However, despite the widespread availability of contact lenses, penetration rates for those who need vision correction remain in the low single digits and many practitioners seem to hold on to concepts around the potential value of contact lenses that appear based in the dim and distant past and are certainly no longer valid today. This review addresses 10 common 'myths and misconceptions' around soft contact lenses using an evidence-based approach that can hopefully dispel some of these incorrect assumptions.

Review of 20 years of soft contact lens wearer ocular physiology data

BACKGROUND

Since the introduction of Silicone hydrogel (SiHy) contact lenses 20 years ago, industry has continued to modify lens materials, designs, lens care products and manufacturing processes, striving to improve contact lens physiological performance, comfort, and convenience for wearers. The purpose of this study was to investigate whether the ocular health of habitual soft contact lens wearers today is better than it was in previous decades.

METHODS

Baseline ocular physiology data for 3624 participants from a The Brien Holden Vision Institute clinical trials database were retrospectively reviewed. Records were grouped into 3 time periods; A: >2 decades ago (1997-1999), B: one decade ago (2009-2014) and C: recent years (since 2015). Physiology data for both neophytes and habitual contact lens wearers included; bulbar, limbal and upper palpebral conjunctival redness, corneal and conjunctival staining and conjunctival indentation from contact lenses.

RESULTS

Corneal staining levels are similar between neophytes and contact lens wearers at time points A and C but worse for contact lens wearers at time point B. Limbal redness was greater in contact lens wearers than in neophytes at time point A but at time points B and C they are not different to the non-contact lens wearing population. In recent years, most ocular physiological variables in habitual contact lens wearers are similar to neophytes.

CONCLUSIONS

While there have been changes over the past two decades in ocular physiological responses to contact lens wear, it appears that ocular health with current day contact lens wear is similar to no lens wear in most respects.

Effect of Water Exposure on Contact Lens Storage Case Contamination in Soft Lens Wearers

SIGNIFICANCE

Water exposure during contact lens wear can transfer pathogenic microorganisms to the eye, causing ocular complications. This study determined that water exposure is prevalent among lens wearers and is independently associated with higher case contamination. Contact lens compliance education to minimize water exposure should be reenforced by contact lens organizations and practitioners.

PURPOSE

Given the increasing association between water exposure and contact lens disease, this study aimed to explore the effect of water exposure and storage case contamination in soft contact lens users.

METHODS

A total of 165 daily soft lens wearers completed a self-administered questionnaire on contact lens hygiene. Lens cases were collected, and microbial analysis was conducted using an adenosine triphosphate assay (for overall microbial bioburden) and limulus amebocyte lysate assay (for endotoxin levels). The lens hygiene (excellent, >35; moderate, 28 to 35; poor, <28) and water contact (≤1, good; >1, poor) scores measured the compliance and water exposure during lens wear, respectively. Multiple regression determined the association between water behaviors and case contamination.

RESULTS

The average (standard deviation) age of participants was 28 (13.5) years (18 to 78 years), and 65% were female. The average overall microbial bioburden of storage cases was 3.10 (0.98) log colony-forming unit/mL (1.09 to 5.94 log colony-forming unit/mL). Forty-five percent of participants reported showering, 49.7% reported swimming while wearing lenses (65.4% of whom swam without goggles), 27.8% used wet hands to handle lenses, and 17.5% used tap water to rinse storage cases. Showering with lenses significantly increased the risk of higher storage case bioburden (P = .001), whereas using wet hands (P = .01) doubled the risk of higher case endotoxin levels (odds ratio, 2.41; confidence interval 1.19 to 4.86).

CONCLUSIONS

Water contact behavior while wearing lenses is prevalent among soft lens wearers and is associated with higher case contamination. Practitioners may improve contact lens education to reduce water exposure and case contamination to reduce the risk of lens-related adverse events.

Effect of material and care system combination on subclinical inflammation of the ocular surface in soft contact lens wear

PURPOSE

To investigate the ocular subclinical inflammatory response in two soft contact lens materials when used in combination with two different care systems ('solutions').

METHODS

Fifteen established soft contact lens wearers wore each of two lenses: Acuvue® 2 (CH) and Acuvue® Oasys® (SiH) or no lenses in random sequence for one week. Two care systems were used: a peroxide system: Oxysept 1 Step® (P) for the right lens and Opti-Free® Replenish® (MPS) for the left lens. After one week of lens/no lens wear, in vivo confocal microscopy (IVCM) of corneal and conjunctival regions was carried out. Density of presumed dendritic cells (DC) and 'white spots' (WS) were quantified. Impression cytology of the bulbar and upper eyelid margin conjunctivae was carried out and samples were analysed for CD45+, CD3+ and CD11c+ cells.

RESULTS

The SiH + MPS combination showed a greater inflammatory response compared to SiH + P in seven out of 12 parameters investigated (p < 0.05). The remaining five were not statistically different between the two solutions. The converse was found for the CH lens, with four of the 12 parameters showing a greater response with the P solution compared to the MPS (p < 0.05).

CONCLUSION

This study suggests that the SiH lens investigated demonstrated an upregulated response when used with a MPS compared to a P solution whereas the converse is true for the CH lens which showed a reduced response when used with a MPS compared to a P solution. This finding aids in the understanding of the biological underpinnings of manifest corneal inflammatory events during contact lens wear.

Regular soft contact lens wearers' comprehension of graphical symbols labelled on multipurpose solutions

CLINICAL RELEVANCE

Symbols are commonly used to represent information of health care products included multipurpose solutions (MPSs) for contact lens (CL) care.

BACKGROUND

Little knowledge is available about recognition and comprehension by regular soft CL wearers of commonly used symbols in the instructions of CL MPSs marketed worldwide.

METHODS

CL wearers from the UK and Spain were invited to answer an anonymous on-line questionnaire (distributed though Facebook and Twitter) concerning the recognition and comprehension of seven common symbols (ISO 15223:2017 and EN 980:2008) included in MPS package instructions.

RESULTS

Answers of one hundred-ten soft CL wearers who use MPS (27 in the UK and 83 in Spain) were analysed showing low recognition and comprehension of the surveyed symbols even in wearers with > 5 years of CL wear (71.8%). The CE marked was the most recognised (96% in the UK and 88% in Spain, P = 0.29) and understood (78% in the UK and 85% in Spain, P = 0.25) symbol, but other important symbols, such as 'Caution' and 'Do not reuse', were under recognised (22% in the UK and 19% in Spain, P = 0.78 and 11% in the UK and 6% in Spain, P = 0.40 respectively) and understood (close to 30% in both countries P > 0.15). Participants with > 5 years of experience, showed slightly higher comprehension (P < 0.05) in some symbols ('Sterilised'; 'Do not reuse'; 'Use by date' and 'CE marked').

CONCLUSION

These results suggest an insufficient comprehension of seven common symbols included in MPS instructions among regular CL wearers in the UK and Spain without high impact of CL wear experience. Improving the education and symbol comprehension of regular CL wearers could help to get better patients' behaviour and safe use of MPS in soft CLs care.

Evaluation of Corneal Densitometry and Endothelial Layer in Soft Contact Lens Users

SIGNIFICANCE

Soft contact lens wear may lead to physiological changes in the cornea. Corneal densitometry is a new software tool that may detect these physiological changes by monitoring their effects on corneal transparency.

PURPOSE

This study aimed to assess corneal densitometry values and corneal endothelium in patients using soft contact lenses.

METHODS

The study included 36 eyes of 36 subjects with soft contact lens use (group 1) and 36 eyes of 36 healthy control subjects (group 2). Anterior segment parameters and corneal densitometry of all subjects were evaluated using Scheimpflug corneal topography (Pentacam; Oculus Inc., Wetzlar, Germany). A total corneal area of 12 mm was divided into four annular zones (0 to 2, 2 to 6, 6 to 10, and 10 to 12 mm) and into three regions as anterior, central, and posterior for densitometry examination. Cell density, cell distribution, and cell morphology (quadrangular, pentagonal, hexagonal, and other cell percentages) of the endothelial layer were examined in both groups using specular microscopy (Nidek CEM 530; Nidek Co., Gamagori, Aichi, Japan).

RESULTS

In group 1, the mean duration of contact lens wear was 4.45 ± 2.15 years. The anterior segment parameters were not significantly different between the two groups (P > .05). The anterior 0- to 2- and 2- to 6-mm corneal densitometry values were significantly higher in group 1 compared with group 2 (23.2 ± 4.7 for group 1 and 17.3 ± 5.6 for group 2 [P = .03]; 22.4 ± 6.4 for group 1 and 17.8 ± 1.4 for group 2 [P = .03], respectively). There were no significant differences between the groups for corneal densitometry values between 6 and 12 mm, or for cell density, cell distribution, and cell morphology (P > .05).

CONCLUSIONS

Although the cornea remains transparent in soft contact lens wearers, corneal densitometry may increase in the 0- to 6-mm annular zone of the anterior region.

Factors Affecting Microbial Contamination on the Back Surface of Worn Soft Contact Lenses

SIGNIFICANCE

The results of this study demonstrate that Smart Touch Technology packaging, which is designed to reduce and simplify contact lens handling before insertion, is effective in reducing the frequency of bacterial contamination of the back surface of contact lenses after short-term wear.

PURPOSE

The purpose of this study was to investigate the effect of lens packaging type, chelating agent, and finger contamination on microbial contamination on the back surface of worn soft contact lenses.

METHODS

Twenty-five subjects completed each contralateral lens wear comparison in this randomized study: Smart Touch Technology versus conventional blister packaging for (1) silicone hydrogel lenses with ethylenediaminetetraacetic acid (EDTA) and (2) hydrogel lenses without EDTA in the packaging, and (3) silicone hydrogel lenses without EDTA versus hydrogel lenses with EDTA both in Smart Touch Technology packaging. Participants washed hands, underwent finger swabs, and inserted the lenses. After 45 minutes, lenses were removed aseptically and the posterior lens surfaces cultured.

RESULTS

Thirty-eight subjects (average age, 30.9 ± 12.5 years) participated in this study. Overall, the level of back surface contamination was low for both lens materials, ranging from 0 to 43 colony-forming unit (CFU)/lens for the silicone hydrogel and 0 to 17 CFU/lens for the hydrogel lenses. The proportion of lenses with zero back surface contamination ranged from 16 to 64% for silicone hydrogel lenses and 28 to 64% for hydrogel lenses. Contact lenses from conventional packaging containing EDTA had 3.38 times increased risk (95% confidence interval [CI], 1.02 to 11.11; P = .05) of contamination being present compared with lenses from Smart Touch packaging with EDTA. Contact lenses from conventional packaging without EDTA had 3.4 times increased risk (95% CI, 1.02 to 11.36; P = .05) of contamination being present compared with Smart Touch packaging without EDTA, and silicone hydrogel lenses had a 6.28 times increased risk (95% CI, 1.65 to 23.81; P = .007) of contamination being present compared with hydrogels. The median (interquartile range) number of bacteria isolated from fingers used to perform lens insertion after handwashing but before lens insertion was not significantly different between the silicone hydrogel and hydrogel lenses (63.7 [204.2] vs. 59 [84.5], P = .09). Finger contamination was not significantly associated with lens contamination in the presence or absence of EDTA.

CONCLUSIONS

Smart Touch Technology packaging was effective in reducing the proportion of contaminated lenses. Although silicone hydrogel lenses were more likely to be contaminated, the presence of EDTA ameliorated this effect. Finger contamination was not associated with lens contamination.

In vitro analysis of the interaction of tear film inflammatory markers with contemporary contact lens materials

PURPOSE

Several clinical studies have suggested that reusable silicone hydrogel contact lens materials exhibit a two-times increased rate of corneal infiltrative events compared to reusable hydrogels. One potential factor contributing to this complication relates to the differential uptake of tear film-based pro-inflammatory cytokines. The purpose of this study was to use an in vitro assay to investigate whether four pro-inflammatory cytokines differed in their uptake onto six contemporary contact lens materials.

METHODS

Conventional hydrogel (etafilcon A, omafilcon A) and silicone hydrogel (balafilcon A, comfilcon A, senofilcon A, somofilcon A) contact lens materials were soaked in solutions containing pro-inflammatory cytokines IL-1β, IL-6, IL-8 and TNF-α. Samples of the soaking solutions were collected over various time points and analyzed using the Meso Scale Discovery system, which served as a measurement of cytokine uptake onto the contact lens materials.

RESULTS

Both conventional hydrogels (etafilcon A, omafilcon A) and two of the four silicone hydrogels tested (balafilcon A, comfilcon A), exhibited some uptake of IL-1β, IL-8 or TNF-α (p < 0.05). Senofilcon A and somofilcon A did not exhibit uptake of any of these cytokines (p > 0.05). There was no uptake of IL-6 onto any of the contact lens materials investigated (p > 0.05).

CONCLUSION

The contact lens materials tested did not exhibit any uptake of IL-6 and furthermore, did not exhibit more than 10 ± 3 % to 25 ± 12 % uptake of IL-1β, IL-8 or TNF-α. Numerous factors could contribute to the reported increase in corneal infiltrative events with reusable silicone hydrogel materials, however, based on these results, it appears that uptake of these four cytokines are unlikely to contribute to this finding.

CLEAR - Evidence-based contact lens practice

Evidence-based contact lens -->practice involves finding, appraising and applying research findings as the basis for patient management decisions. These decisions should be informed by the strength of the research study designs that address the question, as well as by the experience of the practitioner and the preferences and environment of the patient. This reports reviews and summarises the published research evidence that is available to inform soft and rigid contact lens history and symptoms taking, anterior eye health examination (including the optimised use of ophthalmic dyes, grading scales, imaging techniques and lid eversion), considerations for contact lens selection (including the ocular surface measurements required to select the most appropriate lens parameter, lens modality and material selection), evaluation of lens fit, prescribing (teaching self-application and removal, adaptation, care regimen and cleaning instructions, as well as -->minimising risks of lens wear through encouraging compliance) and an aftercare routine.

Contact Lenses and Infectious Keratitis: From a Case-Control Study to a Computation of the Risk for Wearers

PURPOSE

Contact lens (CL)-related microbial keratitis (MK) has major public health implications, with about 300 million wearers worldwide, and certain potentially modifiable risk factors. This study aimed to identify the risk factors of CL-related MK.

METHODS

A multicenter case-control study was conducted between 2014 and 2017. Cases presenting with CL-related MK were submitted to an anonymous 52-item questionnaire, which was also completed by healthy controls. Univariate followed by multivariate logistic regression analysis was performed. Risk factors for CL-related MK were given as odds ratio (OR) with 95% confidence interval and P-value.

RESULTS

The study included a total of 2267 patients (1198 cases and 1069 controls). The MK risk factors for the daily disposable lenses group were exceeding the lens renewal period (OR = 9.16, P = 0.008) and occasionally wearing CL when sleeping (OR = 15.83, P = 0.035). The most important risk factors in the nondaily disposable lenses group were lens cleaning solution distributed by eye care brands (OR = 3.50, P < 0.001) and failure to renew lens cases (OR = 3.39, P = 0.001). Statistically and clinically significant variables were used to establish the MK risk equation for CL wearers, allowing an individual calculation of the risk of MK under lenses.

CONCLUSIONS

The MK risk equation is a valuable tool for educating patients about the risks associated with wearing CL. It allows the patient to be informed about their overall risk of infection while detailing the precipitating elements of the infectious risk with the aim of modifying risk behavior.

Development of a contact Lens risk survey

PURPOSE

To describe the development and report psychometric properties of the Contact Lens Risk Survey (CLRS) to identify patients at risk for soft contact lens-related complications.

METHODS

Psychometric properties of the CLRS, a web-based survey with branching logic, were determined using data from 5 multi-site fieldings (n = 1059), including re-fielding to sub groups. Responses from participants with and without an active red eye were used to identify risk factors of a red eye event and calculate an overall risk score. A 6th fielding of the CLRS (n = 171) was used to assess discriminate validity.

RESULTS

Participants needed 11-12 min to complete the survey with a negligible difference by age. Internal consistency was excellent (Cronbach's α ≥ 0.70) for 3 of the 5 constructs identified by factor analysis. Twelve of the 17 survey items exhibited excellent within-subject repeatability (Kappa ≥ 0.61). Between-subject agreement, assessed in 18-25 year olds, was high for the majority of items, suggesting good generalizability across different populations of SCL wearers. The ability of the model using individual items of the CLRS to discriminate Controls and participants with a red eye was good with an area under the curve of 0.779.

CONCLUSION

The CLRS tool is a repeatable and valid instrument to standardize documentation of demographic, behavior, and exposure factors which appear to drive the greatest risk of a contact lens related red eye event.

Safety and Efficacy of Scleral Lenses for Keratoconus

SIGNIFICANCE

This study affirms the long-term safety and efficacy of scleral contact lens use in patients with keratoconus.

PURPOSE

This study aimed to evaluate the safety and efficacy of contemporary scleral contact lenses in the visual rehabilitation of the keratoconic population.

METHODS

A retrospective study of keratoconic subjects examined between 2013 and 2018 was conducted. Subjects were included regardless of age, sex, pre-existing morbidity, or scleral lens design. Only eyes fit successfully with scleral contact lenses for ≥1 year were included. Exclusion criteria were prior corneal surgery, dystrophy, degeneration, and trauma.

RESULTS

A total of 157 eyes of 86 subjects met the study criteria. The mean Keratoconus Severity Score at initial fitting was 3.6 ± 1.0. Lenses were gas-permeable and nonfenestrated, with a mean overall diameter of 15.8 ± 0.6 mm and 70.1% toric scleral periphery. Physiological adverse events occurred in 9.6% of eyes, including microbial keratitis (0.6%), phlyctenulosis (0.6%), corneal abrasion (1.3%), contact lens–induced acute red eye (1.3%), corneal infiltrative events (1.3%), pingueculitis (1.3%), and hydrops (3.2%). Lens-related adverse events were documented in 55.4% of eyes. Adverse events related to surface issues included poor wetting in 1.9%, handling in 3.8%, reservoir fogging in 7.0%, lens intolerance in 7.6%, deposit in 8.9%, and broken lenses in 26.1% of eyes. The most common management strategies involved refits (54.0% of interventions), patient reeducation (29.5%), medical treatment (5.5%), surgical referral (6.8%), adjustment to wear time (2.5%), surface treatment (1.2%), and lens replacement (0.6%). Best-corrected distance logMAR visual acuity improved significantly from a mean of 0.50 in spectacles to a mean of 0.08 in scleral lenses (P < .0001). During the study period, 14.6% of eyes lost best-corrected scleral lens visual acuity, all from keratoconus progression.

CONCLUSIONS

Consistent with other groups, our study demonstrates excellent safety and efficacy of scleral contact lenses in subjects with keratoconus.

The morphology of corneal endothelial cells in long term soft contact lens wearers in Kuala Lumpur

PURPOSE

To analyse and compare the alterations in corneal endothelium morphology induced by different materials and durations of wearing soft contact lenses (CL) among young adults living in Kuala Lumpur.

METHODS

Healthy soft CL wearers were invited to participate in this study. Visual acuity (VA) was measured using the Snellen chart, and subjective refraction was performed using cross-cylinder technique. Standard ocular assessments were conducted using a slit lamp biomicroscope and morphology of corneal endothelial cells (endothelial cell density, ECD, coefficient variation, COV, hexagonality, HEX and central corneal thickness, CCT) were evaluated using a non-contact specular microscope. Statistical analysis was conducted using ANOVA and data from the right eye only is included.

RESULTS

A total of 72 subjects (32 SiHy and 40 HCL wearers) and 24 non-CL wearers (control) participated in this study. The gender distribution for study subjects was 13 males and 59 females, with a mean age 22.15 ± 1.84 years old. The mean refraction was -1.86 ± 1.25DS. The duration of wearing CL ranged from 1 to 9 years. Subjects were later divided into 2 groups following duration of CL wear: Group 1 (<5 years) and Group 2 (≥5 years) for analysis purposes. Statistical analysis showed significant alterations in ECD, COV and HEX of CL wearers (p < 0.05), with more changes found in HCL and Group 2 wearers. No significant change was found in CCT.

CONCLUSION

This study concludes that soft CL wear induced alterations in the morphology of corneal endothelial cells. Contact lens material and duration of CL wear (in years) are factors that affect the alterations. Optometrists are recommended to regularly evaluate the morphology of corneal endothelial cells in CL wearers and provide necessary intervention when required.

Compliance behaviour change in contact lens wearers: a randomised controlled trial

BACKGROUND

Water exposure during contact lens wear has been associated with contact lens disease including microbial keratitis and sterile corneal infiltrates. Despite the documented risks, water exposure is common amongst lens wearers. This study aimed to determine the effect of water education in the form of "no-water" lens case stickers on water-contact behaviours and storage case contamination.

METHODS

In a prospective, masked, randomised controlled trial, 200 daily lens wearers were randomised to either receive a storage case with a "no-water" sticker (test) or without a "no-water" sticker (control). Both groups received written compliance information. Participants completed a self-administered lens hygiene questionnaire at baseline and after 6 weeks. Microbial analysis of used storage cases, collected at both study visits, was conducted using ATP and limulus amebocyte lysate (LAL) assays for overall microbial contamination and endotoxin levels, respectively. A one-way ANCOVA and multiple logistic regression determined the change in water-contact behaviours and storage case contamination over time.

RESULTS

A total of 188 lens wearers completed both study visits; 128 females and 60 males; average age 29 ± 13 (range 18-78 years); 95 test and 93 control participants. After 6 weeks, the overall water exposure score and endotoxin levels reduced significantly in the test group compared with the control group (p < 0.05). There were no significant changes in individual water-contact behaviours or overall storage case contamination.

CONCLUSION

A no-water infographic on the contact lens case improved overall water-contact behaviours and reduced storage case endotoxin. Refining the messaging may be beneficial in future to improve other aspects of compliance.

The COVID-19 pandemic: Important considerations for contact lens practitioners

A novel coronavirus (CoV), the Severe Acute Respiratory Syndrome Coronavirus - 2 (SARS-CoV-2), results in the coronavirus disease 2019 (COVID-19). As information concerning the COVID-19 disease continues to evolve, patients look to their eye care practitioners for accurate eye health guidance. There is currently no evidence to suggest an increased risk of contracting COVID-19 through contact lens (CL) wear compared to spectacle lens wear and no scientific evidence that wearing standard prescription spectacles provides protection against COVID-19 or other viral transmissions. During the pandemic there will potentially be significant changes in access to local eyecare. Thus, it is imperative CL wearers are reminded of the steps they should follow to minimise their risk of complications, to reduce their need to leave isolation and seek care. Management of adverse events should be retained within optometric systems if possible, to minimise the impact on the wider healthcare service, which will be stretched. Optimal CL care behaviours should be the same as those under normal circumstances, which include appropriate hand washing (thoroughly with soap and water) and drying (with paper towels) before both CL application and removal. Daily CL cleaning and correct case care for reusable CL should be followed according to appropriate guidelines, and CL exposure to water must be avoided. Where the availability of local clinical care is restricted, practitioners could consider advising patients to reduce or eliminate sleeping in their CL (where patients have the appropriate knowledge about correct daily care and access to suitable lens-care products) or consider the option of moving patients to daily disposable lenses (where patients have appropriate lens supplies available). Patients should also avoid touching their face, including their eyes, nose and mouth, with unwashed hands and avoid CL wear altogether if unwell (particularly with any cold or flu-like symptoms).

Safety of soft contact lenses in children: retrospective review of six randomized controlled trials of myopia control

PURPOSE

To examine the rate and types of ocular adverse events among children wearing soft contact lenses.

METHODS

This study is a retrospective review of ocular adverse event data from six randomized controlled trials among a total of 581 myopic children (aged 7-15 years at baseline) administered daily disposable hydrogel contact lenses (etafilcon A).

RESULTS

During 816 patient years of contact lens wear, no significant or serious ocular adverse events were reported. A total of 86 non-significant ocular adverse events occurred in 53 children. The crude rate of ocular adverse events was 10.6 per 100 patient years with the estimated pooled incidence being 8.9 per 100 patient years (95% CI: 4.5-17.4). Two asymptomatic corneal infiltrative events were reported (both non-significant), which is an incidence of 0.3 (95% CI: 0.1-0.9) per 100 patient years. The most common ocular adverse events (n) were slit-lamp findings of Grade 2 or less requiring treatment (26), unspecified conjunctivitis (14), and allergic conjunctivitis (13). No cases of microbial keratitis were observed. Of the 86 adverse events, 37 were classified as highly likely or possibly lens-related, giving a crude incidence of 4.5 per 100 patient years for contact lens-related events. The crude incidence of ocular adverse events among spectacle wearers was 1.8 per 100 patient years.

CONCLUSION

These data suggest that daily disposable soft contact lenses can be safely worn by children. Additional studies will be needed to precisely quantify the adverse event rate of soft contact lenses in normal clinical practice.

Thirty years of 'quiet eye' with etafilcon A contact lenses

Frequent replacement contact lenses made from the etafilcon A hydrogel lens material were introduced onto the market over 30 years ago, and etafilcon A remains the most widely used hydrogel lens material today. Although the prescribing of silicone hydrogel lenses is increasing, millions of lens wearers globally have been wearing hydrogel lenses for many years and exhibit a physiologically-stable 'quiet eye', with a low profile of adverse events. Hydrogel lenses are demonstrated to maintain a low inflammatory response and infection risk profile during daily wear, which in the case of etafilcon A, may be related to its low modulus, and the naturally-protective, anti-microbial, non-denatured lysozyme absorbed into the lens from the tear fluid. Although improved corneal physiology from decreased hypoxia with silicone hydrogel lenses is well accepted, equivalent levels of corneal oxygenation are maintained during daily wear of low to medium powered hydrogel lenses, which do not impede the daily corneal de-swelling process, and do not induce clinically significant changes in ocular health. Therefore, hydrogel lenses remain an important alternative for daily wear in modern contact lens practice.

Ocular conditions and dry eye due to traditional and new forms of smoking: A review

Addiction to cigarette smoking has high prevalence rates recorded worldwide. Smoking has been linked to several life-threatening systemic conditions such as cancer, heart attack and stroke, in addition to a range of ocular pathologies. In recent years, electronic cigarettes (EC) have emerged as alternatives to smoking. ECs are nicotine delivery devices which produce an aerosol by heating, rather than combusting, a liquid which contains nicotine, flavours and preservatives. This review focuses on the association of traditional and new forms of smoking with dry eye disease, contact lens wear and four other common ocular diseases: cataract, age-related macular degeneration, glaucoma and Graves' ophthalmopathy. It is concluded that smoking and vaping appear as a risk factor for the aforementioned ocular conditions. An evidence-based, clear link between cigarette smoking, or EC vaping and ocular problems is yet to be discovered.

Silicone hydrogel daily disposable benefits: The evidence

Daily disposable (DD) contact lenses first came to the market approximately 25 years ago and eye care professionals (ECPs) started prescribing silicone hydrogel (SiH) contact lenses, primarily for extended or continuous wear, approximately 20 years ago. It has now been over ten years since SiH DD contact lenses have been available, and while SiH materials are routinely prescribed by ECPs for reusable daily wear, hydrogel materials are still frequently selected for the DD modality of contact lens wear. This article reviews the evidence to support the benefits of both a DD modality and SiH materials and how patients' needs may be met with SiH DD contact lenses, with respect to clinical performance, health outcomes, satisfaction, compliance and convenience. Factors which may enable or constrain ECPs from prescribing SiH DD contact lenses, as opposed to hydrogel DD and reusable contact lenses, for more of their patients are discussed with the objective of providing ECPs with a greater understanding of the advantages that can be afforded by prescribing SiH DD contact lenses to both their new and existing contact lens wearers.

The Development of an Antimicrobial Contact Lens - From the Laboratory to the Clinic

Contact lens wear is generally safe and provides excellent vision. However, contact lens wear is often associated with the risk of developing ocular surface infection and inflammation, and in severe cases, the infection can result in loss of vision. Antimicrobial peptide-coated contact lenses have been made to help reduce the incidence of infection and inflammation. This paper reviews the research progress from conception, through the laboratory and preclinical tests to the latest information on clinical testing of an antimicrobial contact lens. We provide insights into the pathways followed and pitfalls that have been encountered. The journey has not always been linear or smooth, but has resulted in some of the first published clinical testing of antimicrobial peptide-coated contact lenses in humans. We hope this may help lead to the development and commercialisation of antimicrobial contact lenses in the future.

The short-term physiological impact of switching reusable silicone hydrogel wearers into a hydrogel daily disposable multifocal

Purpose: To evaluate ocular physiological responses to etafilcon A multifocal (etMF) daily disposable (DD) lenses after 4 weeks of wear, when switching from habitual silicone hydrogel (SiHy) daily wear.

Method: A single-arm, open-label, bilateral dispensing study was conducted in 39 habitual spherical SiHy wearers (14 hyperopes; 25 myopes). Clinical visits occurred with habitual SiHy (control) at baseline and after 4 weeks of etMF DD open-eye lens wear at exit. Objective limbal/bulbar hyperemia using the Oculus K5M (0–4) and subjective grading of lid wiper epitheliopathy (LWE) (0–4) were tested for non-inferiority (NI), using a margin of 1 grade. Corneal thickness along a 10 mm cord was measured using the Visante OCT and tested for NI using a 30 μm margin. Corneal staining area was graded (0–100%).

Results: The least-square mean differences (LSMD) and 95% confidence interval (95% CI) between etMF DD and habitual SiHy in central and peripheral corneal thickness (μm) were 3.64 (−2.0, 9.29) and 3.0 (−7.72, 13.72) in hyperopic, and 3.56 (−0.66, 7.78) and 6.40 (−1.62, 14.42) in myopic subjects. The LSMD (95% CI) for bulbar and limbal hyperemia were −0.08 (−0.19, 0.02) and −0.01 (−0.12, 0.09) in hyperopes, and 0.04 (−0.03, 0.12) and 0.04 (−0.04, 0.11) in myopes. The LSMD (95% CI) for LWE were 0.11 (−0.39, 0.60) and 0.30 (−0.07, 0.67) for hyperopes and myopes, respectively.

Conclusions: No clinically significant differences in a variety of physiological responses were found when habitual reusable SiHy daily wear subjects were refitted into hydrogel etMF, when the subjects were followed for 4 weeks.

Water Exposure and the Risk of Contact Lens-Related Disease

PURPOSE

To describe the association of water exposure with contact lens (CL)-related disease and explore the guidelines regarding water exposure to CL wearers, provided by CL manufacturing industry, global public health, and CL-related professional associations.

METHODS

A review of the literature was conducted by searching PubMed, MEDLINE, and Web of Science databases up to September 2017 for articles published or translated in English using keywords: contact lens* AND tap water OR swimming OR showering OR water exposure AND microbial keratitis OR Acanthamoeba keratitis OR corneal infiltrate* OR ocular adverse event*. References in all relevant publications were also reviewed.

RESULTS

Water exposure during CL wear is associated with complications ranging from sterile corneal infiltrative events to sight-threatening infections. Despite the documented risks due to water exposure, water-related habits are common among CL wearers. This suggests a lack of awareness and understanding regarding the risks among CL wearers and potentially CL practitioners. Discrepancies exist in guidelines for CL hygiene and compliance provided by the CL manufacturing industry, global public health, and CL-related professional associations. There is also widespread use of water imagery within CL marketing and packaging materials. These factors may give rise to confusion among wearers and may contribute toward risk-taking behaviors.

CONCLUSIONS

Consensus among stakeholders about water and CL care is needed. Guidelines should unequivocally advocate for the avoidance of any water exposure including handling CLs with wet hands, rinsing CLs or storage cases in tap water, showering while wearing CLs and swimming with CLs without wearing goggles.

Review of Contact Lens-Related Complications

The purpose of this article is to provide a review of existing literature describing complications with contemporary contact lenses and their management. It is envisioned that this will serve as a useful summary of noninfectious and infectious complications associated with contact lens wear.

Hand hygiene is linked to microbial keratitis and corneal inflammatory events

Lack of or inadequate hand washing is a risk factor in the development of contact lens related microbial keratitis and corneal inflammatory events. In the public health domain there is compelling evidence that proper hand washing with soap can save lives. The purpose of this review is to draw attention to some of the public health literature in support of hand washing and how education can influence patients' hand hygiene behavior. Contact lens wearers are also guilty of poor hand washing behavior but there is scant evidence that education of hand washing procedures of lens wearers alters patient non-compliance. It is well known that pathogenic microbial contamination of contact lenses, lens cases, care solutions and anterior ocular components have been found with contact lens wear. However while the originating source may be hands or water, it is most likely both of these. Besides proper hand washing this paper will include mitigating strategies for avoiding microbial contamination.

Prevalence, habits and outcomes of using contact lenses among medical students

Objectives:

To determine the prevalence, reasons of use, reported hygienic practices, and complications related to CLs’ usage, and to assess awareness of medical students about CLs’ hygienic behaviours, King Abdulaziz University (KAU), Jeddah, Saudi Arabia.

Methods:

A cross-sectional design was done. A multi-stage stratified random sampling was utilized to select 536 medical students. A validated, self-administered, anonymous questionnaire was used. Both descriptive and inferential statistics were applied.

Results:

The prevalence of current users of CLs was 40.5%. Females reported significantly much higher prevalence of usage compared to males (OR=8.38; 95% CI:5.2-13.3). Second-year students, and those living in university dormitory had the highest prevalence of CLs usage compared to others. The commonest reason for wearing CLs was cosmetic purpose. Improper CLs-hygienic practices were reported; as exceeding the period required for renewal (45.6%), sharing lenses (16.6%), and sleeping (29.9%), swimming (24.6%) or showering (29.0%) with CLs. Only 16.6% of the participants cleaned their lenses daily. At least one CLs’ related complications was reported by 30.4% of the users. Acute red eye (19.8%), conjunctivitis (18.9%), and corneal abrasion (8.3%) were the commonest CLs’ complications.

Conclusion:

A relatively high prevalence of CLs’ usage was found. Participants were aware about CLs-hygienic practices. However, unhygienic CLs-related practices and complications were also reported. Provision of educational messages and training on sound CLs’ hygienic practices are needed.

Acanthamoeba keratitis: confirmation of the UK outbreak and a prospective case-control study identifying contributing risk factors

BACKGROUND/AIMS

Acanthamoeba keratitis (AK) is a chronic debilitating corneal infection principally affecting contact lens (CL) users. Studies were designed to test claims that the UK incidence may have increased in 2012-2014 and to evaluate potential causes.

METHODS

Annualised incidence data were collected from January 1984 to December 2016. Case-control study subjects were recruited between 14 April 2011 and 05 June 2017. Reusable CL users with AK were recruited retrospectively and prospectively. Controls were reusable CL users, recruited prospectively, with any disorder other than AK. Multivariable analysis of questionnaire data measured independent risk factors for AK.

RESULTS

The current outbreak of AK started in 2010-2011 with an incidence threefold higher than in 2004-2009. Risk factors for AK were: Oxipol disinfection, CLs made of group IV CL materials, poor CL hygiene, deficient hand hygiene, use of CLs while swimming or bathing, being white British, and for those in social classes 4-9.

CONCLUSION

AK is a largely preventable disease. The current outbreak is unlikely to be due to any one of the identified risk factors in isolation. Improving CL and hand hygiene, avoiding CLs contamination with water and use of effective CL disinfection solutions, or daily disposable CLs, will reduce the incidence of AK. In the longer-term, water avoidance publicity for CL users can be expected to reduce the incidence further. Ongoing surveillance of AK numbers will identify changes in incidence earlier. Evaluation of Acanthamoeba contamination in end-user drinking water would contribute to our understanding of regional variations in the risk of exposure.

Factors Affecting Microvascular Responses in the Bulbar Conjunctiva in Habitual Contact Lens Wearers

Purpose

To investigate the factors affecting microvascular responses in the bulbar conjunctiva of habitual contact lens (HCL) wearers.

Methods

A functional slit-lamp biomicroscope (FSLB) was used to image the temporal bulbar conjunctiva of habitual contact lens (HCL) wearers and non-contact lens (NCL) wearers. The vessel diameters and blood flow velocities (BFVs) were measured. Fractal analysis using Dbox as vessel density and D0 as vessel complexity were used to quantitatively analyze the microvascular network. One eye each of 91 NCL wearers and 75 HCL wearers was imaged.

Results

The BFV of NCL wearers was 0.50 ± 0.14 mm/s, which was negatively correlated with age (r = -0.22, P < 0.05). The BFV, vessel diameter, Dbox, and D0 of HCL wearers was significantly higher than NCL wearers (P < 0.05). In these HCL wearers, BFVs were positively correlated with contact lens (CL) hours of wear per day and CL days of wear per week. BFV, Dbox, and D0 were not related to CL years of wear, CL power, CL base curve, and CL diameter (P > 0.05).

Conclusions

Vascular responses on the bulbar conjunctiva occurred in HCL wearers and appeared to be unrelated to sex or age, CL years of wear, and lens parameters, indicating that wearing a CL itself may be the predominant factor inducing these responses.

Multicenter Testing of a Risk Assessment Survey for Soft Contact Lens Wearers With Adverse Events: A Contact Lens Assessment in Youth Study

PURPOSE

To test the ability of responses to the Contact Lens Assessment in Youth (CLAY) Contact Lens Risk Survey (CLRS) to differentiate behaviors among participants with serious and significant (S&S) contact lens-related corneal inflammatory events, those with other events (non-S&S), and healthy controls matched for age, gender, and soft contact lens (SCL) wear frequency.

METHODS

The CLRS was self-administered electronically to SCL wearers presenting for acute clinical care at 11 clinical sites. Each participant completed the CLRS before their examination. The clinician, masked to CLRS responses, submitted a diagnosis for each participant that was used to classify the event as S&S or non-S&S. Multivariate logistic regression analyses were used to compare responses.

RESULTS

Comparison of responses from 96 participants with S&S, 68 with non-S&S, and 207 controls showed that patients with S&S were more likely (always or fairly often) to report overnight wear versus patients with non-S&S (adjusted odds ratio [aOR], 5.2; 95% confidence interval [CI], 1.4-18.7) and versus controls (aOR, 5.8; CI, 2.2-15.2). Patients with S&S were more likely to purchase SCLs on the internet versus non-S&S (aOR, 4.9; CI, 1.6-15.1) and versus controls (aOR, 2.8; CI, 1.4-5.9). The use of two-week replacement lenses compared with daily disposables was significantly higher among patients with S&S than those with non-S&S (aOR, 4.3; CI, 1.5-12.0). Patients with S&S were less likely to regularly discard leftover solution compared with controls (aOR, 2.5; CI, 1.1-5.6).

CONCLUSIONS

The CLRS is a clinical survey tool that can be used to identify risky behaviors and exposures directly associated with an increased risk of S&S events.

Consequences of Preservative Uptake and Release by Contact Lenses

OBJECTIVES

To assess contact lens preservative uptake and release from multipurpose solutions (MPS) and subsequent acquisition of lens antibacterial activity.

METHODS

Kinetics of uptake and release of poly (hexamethylene biguanide hydrochloride) (PHMB) or polyquaternium-1 (PQ-1) from various contact lenses were studied initially with the pure compounds and then after soaking in MPS containing these compounds. Lenses soaked in MPS were tested for antibacterial activity.

RESULTS

Only lenses with a negatively charged component absorbed these preservatives. For lenses containing methacrylic acid (MA), uptake of PHMB from preservative-only solution was fast, yet little was released, in contrast to its rapid release from lenses containing other anionic groups. This trend persisted with PHMB-containing MPS. PQ-1 from preservative-only solution was only absorbed by lenses containing MA and was released from MA-containing hydrogels, but not significantly from an MA-containing silicone hydrogel. Lens uptake of PQ-1 was much lower from MPS and release was essentially undetectable from all lenses evaluated. Antibacterial lens activity was acquired by lenses containing MA after an overnight soak in MPS containing PQ-1, and for balafilcon A and omafilcon A after 5 exchanges in PHMB-containing MPS. Acquired activity was maintained during cycling between artificial tear protein solution and MPS.

CONCLUSIONS

Lens preservative uptake and its subsequent release are dependent on lens chemistry, preservative nature, and other MPS components. A few lens/solution combinations acquired antibacterial activity after one or more overnight soaks in MPS, depending on the nature of the anionic lens component and the preservative. Uncharged lenses did not acquire antibacterial activity.

Epidemiology of contact lens-induced infiltrates: an updated review

Corneal infiltrative events (CIEs) are well established as a risk associated with soft contact lens wear. The incidence of symptomatic CIEs during extended soft lens wear ranges from 2.5 to six per cent; when asymptomatic CIEs are included, the incidence can be as high as 20-25 per cent. In daily soft lens wear, the annual incidence of symptomatic CIEs is about three per cent. There are various accepted methods of categorising CIEs, and a scoring system based on clinical signs and symptoms is a good approach to grade severity. Lens-related risk factors include extended wear, silicone hydrogel material, the use of multipurpose solutions, bacterial bioburden and reusable lenses. Recent studies report that daily disposable lenses reduce the risk of CIEs.

Risk factors and causative organisms in microbial keratitis in daily disposable contact lens wear

Purpose

This study investigated independent risk factors and causative organisms in microbial keratitis in daily disposable contact lens (CL)-wearers.

Methods

A multisite prospective case-control study was undertaken. Cases were daily disposable CL-wearers attending Moorfields Eye Hospital with microbial keratitis and those reported through a one-year surveillance study in Australia and in New Zealand. A population-based telephone survey identified daily disposable CL-wearing controls. Subjects completed a questionnaire describing CL-wear history, hygiene and demographics. The sample used for risk factor analysis was weighted in proportion to the CL-wearing population at each location. Corneal scrape results were accessed. Independent risk factors were determined using multiple binary logistic regression. Causative organisms in different CL-wear modalities were compared using a chi-squared test.

Results

963 daily disposable CL-wearers were identified, from which 67 cases and 374 controls were sampled. Independent risk factors were; wearing CLs every day compared with less frequent use (OR 10.4x; 95% CI 2.9–56.4), any overnight wear (OR 1.8x; 95% CI 1.6–2.1), less frequent hand washing (OR 1.8x; 95% CI 1.6–2.0), and smoking (OR 1.3x; 95% CI 1.1–1.6). Certain daily disposable CLs (OR 0.2x; 95% CI 0.1–0.2) had protective effects. Environmental organisms were less frequently recovered with daily disposable CLs (20%), compared with other modalities (36%; p<0.02).

Conclusion

Overnight wear, increased exposure in daily wear, smoking and poor hand hygiene are significant risk factors for microbial keratitis with daily disposable CLs. Risk varied with daily disposable CL type. The profile of causative organisms is consistent with less severe disease.

Mucin Balls Influence Corneal Infiltrative Events

PURPOSE

To determine whether mucin ball (MB) formation is protective against corneal infiltrative events (CIEs) as previously reported.

METHODS

Two hundred eighty-two eligible participants were enrolled at three sites in the USA. Participants began a 1-month continuous wear run-in period with high modulus lotrafilcon A lenses to assess their ability to form MBs (phase 1). Subsequently, they were stratified by this characteristic and randomized to balafilcon A or comfilcon A lenses for 7-day extended wear and followed for 1 year (phase 2). MB formation in each phase was defined as repeated presence of any MBs on a person level. Multivariable Cox proportional hazards regression was used to model the probability of a CIE as a function of MB formation in each phase and other covariates.

RESULTS

Of the 282 participants who entered phase 1, 218 of them entered the phase 2 randomized trial during which 33 CIEs occurred. Overall, 74%, 61%, and 79% of participants repeatedly produced MBs in lotrafilcon A, balafilcon A, and comfilcon A lenses, respectively. Early repeated MB presence in phase 1 with lotrafilcon A lenses significantly increased the rate of CIEs in phase 2 (12-month follow-up) by 466% (HR 4.66, 95% confidence interval 1.10-19.79, P = .0372). Repeated, longer-term MB presence during wear of balafilcon A or comfilcon A in phase 2 did not significantly reduce the incidence of CIEs; however, it significantly decreased the rate of CIEs by 62% (hazard ratio (HR) 0.380, 95% confidence interval 0.145-0.998, P = .0494).

CONCLUSIONS

The overarching hypothesis that MB formation is protective against CIEs throughout extended wear was not supported. Although a protective effect of longer-term MB presence on rate of CIEs was detected, early-onset MB formation substantially increased the hazard for CIE in subsequent wear with different lens types.

Biocidal efficacy of multipurpose solutions against Gram-negative organisms associated with corneal infiltrative events

Background

Because corneal infiltrative events (CIEs) may result from bacterial components on contact lenses, which can come from contaminated lens cases, we evaluated the biocidal efficacy of five multipurpose solutions against Gram‐negative commonly isolated and CIE‐associated organisms.

Methods

Of the multipurpose solutions tested, one contained polyhexamethylene biguanide (PHMB)/polyquaternium‐1 (PQ‐1; Bausch & Lomb Incorporated: Biotrue), one contained alexidine dihydrochloride (alexidine)/PQ‐1 (AMO: RevitaLens OcuTec) and three contained PQ‐1/myristamidopropyl dimethylamine (MAPD; Alcon: Opti‐Free PureMoist, PQ‐1/MAPD‐1; Opti‐Free RepleniSH, PQ‐1/MAPD‐2; Opti‐Free Express, PQ‐1/MAPD‐3). Challenge organisms were CIE‐associated Achromobacter xylosoxidans, Delftia acidovorans and Stenotrophomonas maltophilia at manufacturer‐recommended durations (stand‐alone), in lens cases without lenses (up to seven days) and in lens cases with etafilcon A lenses (up to 30 days).

Results

In stand‐alone testing against CIE‐associated organisms, PHMB/PQ‐1 and alexidine/PQ‐1 were significantly superior versus MAPD‐based multipurpose solutions against A. xylosoxidans (all p ≤ 0.01), D. acidovorans (all p ≤ 0.001) and S. maltophilia (all p ≤ 0.05). In lens cases, PHMB/PQ‐1 and alexidine/PQ‐1 achieved greater than 3‐log reductions against all challenge organisms at all times evaluated. PQ‐1/MAPD‐1 achieved a greater than 3‐log reduction against D. acidovorans at 24 hours; PQ‐1/MAPD‐1 and PQ‐1/MAPD‐3 achieved greater than 3‐log reductions at seven days against all organisms. In lens cases with lenses, PHMB/PQ‐1 and alexidine/PQ‐1 achieved greater than 3‐log reductions against all organisms at all times. PQ‐1/MAPD‐1 and PQ‐1/MAPD‐3 achieved greater than 3‐log reductions at seven or more days against all organisms. PQ‐1/MAPD‐2 did not achieve a greater than 3‐log reduction at any time; some regrowth was observed.

Conclusions

PHMB‐ and alexidine‐based multipurpose solutions demonstrated significantly greater biocidal activity compared with PQ‐1/MAPD‐based agents against Gram‐negative organisms commonly isolated and CIE‐associated pathogens.

Risk factors for contact lens-related microbial keratitis in Singapore

PURPOSE

To investigate independent risk factors for contact lens-related microbial keratitis in Singapore and estimate their impact on disease load.

METHODS

Cases were contact lens wearers presenting to Singapore National Eye Centre with microbial keratitis between 2008 and 2010. Community contact lens wearers were recruited as controls. All wearers completed a previously validated questionnaire describing contact lens wear history, hygiene and compliance habits, and demographics. Risk factors significant in univariate analysis (P<0.2) were evaluated in a multivariate model.

RESULTS

In all, 58 cases of microbial keratitis and 152 contemporaneous controls were identified. When controlling for other variables, Chinese had a 7 × lower risk compared with other races (95% CI: 2.3-21.3, P=0.001). Those aged between 25 and 44 years were at 3 × increased risk compared with younger wearers (95% CI: 1.1-9.6, P=0.04). Occasional overnight contact lens wear (less often than one night per week) was associated with a 4 × higher risk (95% CI: 1.2-15.4, P=0.03) compared with daily use. Not washing hands before handling was associated with a 13 × increased risk (95% CI: 1.9-84.8, P=0.008). Use of multipurpose solution A carried a 16 × higher risk compared with hydrogen peroxide (95% CI: 1.5-174.0, P=0.02). The combined PAR% for modifiable risk factors (occasional overnight wear, not washing of hands, and MPS A) was 82%.

CONCLUSIONS

Consistent with previous findings, independent risk factors for contact lens-related microbial keratitis include poor hand hygiene, occasional overnight wear, and type of lens care solution. Prolonged overnight or extended contact lens use was infrequent in this population.

Biological and Clinical Implications of Lysozyme Deposition on Soft Contact Lenses

Within a few minutes of wear, contact lenses become rapidly coated with a variety of tear film components, including proteins, lipids, and mucins. Tears have a rich and complex composition, allowing a wide range of interactions and competitive processes, with the first event observed at the interface between a contact lens and tear fluid being protein adsorption. Protein adsorption on hydrogel contact lenses is a complex process involving a variety of factors relating to both the protein in question and the lens material. Among tear proteins, lysozyme is a major protein that has both antibacterial and anti-inflammatory functions. Contact lens materials that have high ionicity and high water content have an increased affinity to accumulate lysozyme during wear, when compared with other soft lens materials, notably silicone hydrogel lenses. This review provides an overview of tear film proteins, with a specific focus on lysozyme, and examines various factors that influence protein deposition on contact lenses. In addition, the impact of lysozyme deposition on various ocular physiological responses and bacterial adhesion to lenses and the interaction of lysozyme with other tear proteins are reviewed. This comprehensive review suggests that deposition of lysozyme on contact lens materials may provide a number of beneficial effects during contact lens wear.