Risk factors for corneal infiltrative events with 30-night continuous wear of silicone hydrogel lenses

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.

Wearing Pattern and Awareness About Contact Lens Wear in Secondary School Students in Kuala Lumpur

PURPOSE

To investigate the wearing pattern and awareness about contact lens care among secondary school students in Kuala Lumpur.

PATIENTS AND METHODS

This is a cross-sectional study using self-administered validated questionnaires. A total of 2500 questionnaires were distributed to secondary school students (aged 13 to 18 years) from 5 selected schools in Kuala Lumpur. Descriptive statistics were used to analyze the results.

RESULTS

A total of 987 completed questionnaires were returned and analyzed. The response rate was 39.5%. Mean age of respondents was 15.5±2.5 years with 54.6% females. Around 9.9% of the respondents were contact lens wearers with female majority (78.6%) and the main reasons for wearing contact lenses were cosmesis (42.8%) and comfort (32.7%). Majority (92.2%) were soft contact lens wearers and daily wear (monthly disposable) is the preferred modality. Nevertheless, 42.4% purchased their lenses from unlicensed vendors and 18.4% rinsed their lenses using tap water. Regarding contact lens care, more than 50% of the respondents were not aware about the correct way of handling contact lenses.

CONCLUSION

Soft contact lens wear is popular among the secondary school students in Kuala Lumpur but the level of practice and knowledge about CL care are unsatisfactory. Thus, health communication strategies and aggressive public ocular health education that can influence behavior changes in teenagers are needed to overcome these issues.

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.

Patterns of Use and Knowledge about Contact Lens Wear amongst Teenagers in Rural Areas in Malaysia

BACKGROUND

Contact lenses (CLs) are more popular than spectacles for vision correction amongst the youth. Knowledge about the risks of wearing CLs is critical especially for those with poor access to public health education. This study investigates the patterns of use and level of knowledge about CL wear amongst teenagers living in rural areas in Selangor, Malaysia using a set of validated questionnaires.

METHODS

A total of 8500 self-administered questionnaires were distributed in eight selected secondary schools. The results were analysed using descriptive statistics.

RESULTS

A total of 2474 (29%) completed questionnaires were collected. The mean age of the respondents was 14.8 ± 1.5 years, and approximately 7.2% were CL wearers. The majority of the wearers were females (76.0%) and wore soft CLs (92.2%). Cosmetic purposes (58.1%) and comfort (24.6%) were the main reasons for wearing CLs. Many of the respondents purchased their lenses from optical shops (50.1%) and beauty accessory shops (15.6%), and approximately 10% did not disinfect their lenses properly. Regarding knowledge about CL care, approximately 56% of the respondents responded correctly.

CONCLUSION

Half of the respondents do not have sufficient knowledge about the risks of wearing CLs. Thus, aggressive public health education aimed at teenagers is needed to prevent improper CL usage.

Inter-visit measurement variability of conjunctival vasculature and circulation in habitual contact lens wearers and non-lens wearers

Background

The inter-visit variation of measuring bulbar conjunctival microvasculature and microcirculation needs to be considered when the results from multiple visits are interpreted. This study examined the inter-visit variability of measuring conjunctival microvasculature and microcirculation in habitual contact lens (HCL) wearers and non-contact lens (NCL) wearers.

Methods

Twenty-eight subjects were recruited including 13 HCL wearers (10 females and 3 males; mean age ± standard deviation, 25.8 ± 4.6 years) who had worn contact lenses on a daily basis for at least 3 years and 15 NCL wearers (10 females and 5 males, age 25.5 ± 4.0 years) were recruited. The temporal bulbar conjunctiva was imaged using a functional slit-lamp bio-microscope (FSLB) imaging system. FSLB imaging was performed in the morning when the HCL wearers did not wear their lenses. The measurements included conjunctival vessel diameter, vessel density, blood flow velocity and flow volume. In addition, conjunctival microvasculature was analyzed using monofractal (Dbox, representing vessel density) and multifractal (D0 representing vessel complexity) analyses. The repeated measurement was conducted at least one week after the first visit and both eyes of each participant were imaged. The coefficient of variation (CV) was calculated as the standard deviation of the differences between test and re-test then divided by the mean of the measurements. The intra-class correlation coefficient (ICC) was also calculated.

Results

No significant differences of all vascular measurements in both the right and left eyes were found between two groups (P > 0.05). Between two measurements on two different visits, the CV was from 2.4% (vessel density D0) to 63.5% (blood flow volume Q) in HCL wearers and from 3.4% (D0) to 40.6% (blood flow volume) in NCL wearers. The ICC was from 0.60 (vessel diameter) to 0.81 (axial blood flow velocity VA) in HCL wearers and from 0.44 (Q) to 0.68 (cross-sectional blood flow velocity VS) in NCL wearers.

Conclusions

The measurement variability of the vessel density of the bulbar conjunctiva appeared to have the smallest inter-visit variation. The measurement variability of the vasculature and circulation in HCL wearers were similar to that in NCL wearers.

Evaluated Conjunctival Blood Flow Velocity in Daily Contact Lens Wearers

OBJECTIVE

This study examined conjunctival microvasculature development in long-term habitual contact lens (HCL) wearers after a night of sleep.

METHODS

Twenty HCL wearers (15 women and 5 men, aged 28.6±6.9 years, mean age±standard deviation) who had worn contact lenses on a daily basis for at least 3 years and 40 noncontact lens (NCL) wearers (23 women and 17 men, aged 36.5±6.6 years, mean age±standard deviation) participated in the study. A functional slitlamp biomicroscopy imaging system was used to image the temporal bulbar conjunctiva. Imaging was performed in the morning while the contact lens wearers were not wearing their lenses after a night of sleep. The conjunctival vessel diameters, blood flow velocities, and flow rates were measured. In addition, fractal analyses were performed to obtain the vessel network density (Dbox) and complexity (D0).

RESULTS

The average blood flow velocity in HCL wearers after a night of sleep was 0.59±0.19 mm/s, which was significantly higher than that in NCL wearers (0.48±0.17 mm/s, P<0.05). The microvessel network density and complexity levels (Dbox=1.64±0.05 and D0=1.71±0.05, respectively) in the HCL wearers were significantly higher than those in NCL wearers (Dbox=1.61±0.05 and D0=1.69±0.04, both P<0.05). The blood flow velocity was positively correlated with the duration of contact lens wear (r=0.46, P<0.05) and with the daily number of lens-wearing hours (r=0.49, P<0.05) in HCL wearers.

CONCLUSIONS

This study identified microvascular alterations in the conjunctiva in response to daily contact lens wear after a night of sleep in long-term daily contact lens wearers. The unrecovered changes may indicate that para-inflammation occurs on ocular surfaces because of contact lens wear and that overnight sleeping with no lenses may not sufficiently restore the ocular surface to an intact state.

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.

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.

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.

Non-invasive objective and contemporary methods for measuring ocular surface inflammation in soft contact lens wearers - A review

Contact lens wear is one of the primary risk factors for the development of ocular surface inflammatory events. The purpose of this review is to examine and summarize existing knowledge on the mechanisms of contact lens related ocular surface inflammation and the evidence for the effectiveness of current objective methods to measure ocular surface inflammation. Contact lens wear is postulated to trigger an inflammatory response on the ocular surface due to mechanical, chemical, hypoxic stress, or by the introduction of microbes and their toxins. Apart from the traditional signs of inflammation, such as swelling, oedema, redness and heat, on the ocular surface, other methods to measure ocular surface inflammation in sub-clinical levels include tear inflammatory mediator concentrations, conjunctival cell morphology, and corneal epithelial dendritic cell density and morphology. Tear inflammatory mediator concentrations are up- or down-regulated during contact lens wear, with or without the presence of associated inflammatory events. There is higher conjunctival cell metaplasia observed with contact lens wear, but changes in goblet cell density are inconclusive. Dendritic cell density is seen to increase soon after initiating soft contact lens wear. The long term effects of contact lens wear on dendritic cell migration in the cornea and conjunctiva, including the lid wiper area, require further investigation. Currently patient factors, such as age, smoking, systemic diseases and genetic profile are being studied. A better understanding of these mechanisms may facilitate the development of new management options and strategies to minimize ocular surface inflammation related to contact lens wear.

Age, behavior, environment, and health factors in the soft contact lens risk survey

PURPOSE

Previous studies have reported that the risk of corneal infectious and inflammatory events (CIEs) with soft contact lens (SCL) wear is highest in late adolescence and early adulthood. This study assesses the associations between patient age and other factors that may contribute to CIEs in young SCL wearers.

METHODS

After ethics approvals and informed consent, a nonclinical population of young SCL wearers was surveyed in five US cities. Data from 542 SCL wearers aged 12-33 years were collected electronically. Responses were analyzed by age bins (12-14, 15-17, 18-21, 22-25, 26-29, and 30-33 years) using chi-square test.

RESULTS

The cohort was 34% male and balanced across age bins. There were several significant associations between survey response and age (in bins). Wearers aged 18-21 years reported more recent nights with less than 6 hours of sleep (p < 0.001), more colds/flu (p = 0.049), and higher stress levels (p < 0.001). Wearers 18-21 and those 22-25 years were more likely to wear SCLs when showering (p < 0.001) and also reported more frequent naps with SCLs (p < 0.001). They reported sleeping in SCLs after alcohol use (p = 0.031), when traveling (p = 0.001), and when away from home (p = 0.024). Lower rates of regular hand washing before lens application (p = 0.054) was also associated with these groups. In addition, the relationship between reactive replacement and recommended replacement was dependent on age (p < 0.0001).

CONCLUSIONS

Patient age influences lens wearing behaviors, environmental exposures, and other determinants of health that may contribute to increased CIEs in younger wearers. Targeted, age-specific education should be considered for both new and established SCL wearers.

Effect of antibiotic drops on adverse events during extended lens wear

PURPOSE

Overnight lens wear is associated with increased lens contamination and risk of developing a corneal infiltrate or infectious event. Antibacterial lenses have been proposed as a potential strategy for reducing lens contamination. A proof-of-principle study was conducted to investigate what effect control of potential pathogens, through the use of antibiotic eye drops, would have on the incidence of corneal infiltrative events (CIEs) and on the ocular microbiota and lens contamination.

METHODS

This is a prospective, open-label, controlled, parallel-group, 1-month clinical study in which 241 subjects were dispensed with lotrafilcon A silicone hydrogel lenses for 30 days of continuous wear. Subjects were randomized into either test (moxifloxacin 0.5%) or control (rewetting solution) group. One drop was instilled into each eye on waking and before sleeping, while lenses were on-eye. Follow-ups were conducted after one night and 1 month. Lid margin swabs were taken at baseline and at 1 month and worn lenses were aseptically collected at 1 month.

RESULTS

The incidence of CIEs was not significantly different between the test (2.6%) and control (3.9%) groups (p = 0.72). Microorganism levels from the test group swabs were significantly lower than those from the control group (p = 0.001). Gram-positive bacteria were less frequently recovered from lower lid swabs from the test group (39.6% vs. 66.0% [p < 0.001], test vs. control, respectively) or from contact lens samples (1.9% vs. 10.5% [p = 0.015], test vs. control, respectively), but there was no difference in gram-negative bacteria (GNB). Corneal infiltrative events were associated with higher levels of lens contamination (p = 0.014) and contamination of lenses with GNB (CIE: 7.3% vs. 0.6% [p = 0.029], GNB contamination vs. no GNB contamination, respectively).

DISCUSSION

Twice-daily antibiotic instillation during continuous wear of lenses did not significantly influence the rate of inflammatory events. Corneal infiltrative events were associated with higher levels of lens contamination in general and with contamination by GNB specifically.

The effect of daily lens replacement during overnight wear on ocular adverse events

PURPOSE

Compared with daily disposable wear schedule, continuous wear (CW) or extended wear of contact lenses has been associated with an increased risk of developing an ocular infection. Proof-of-principle studies were conducted to investigate the impact of daily replacement of lenses on the rate of contact lens-related ocular adverse events (AEs) during 30-night CW.

METHODS

A total of 215 subjects were dispensed with silicone hydrogel lenses on a 30-night CW schedule but replaced lenses daily either each night before sleeping (n = 178 eyes) or each morning after waking (n = 252 eyes). Scheduled clinic visits were conducted at 1 week and 1 month. Neophytes were required to complete 1 week of daily wear before commencing CW. A historical control (n = 191 eyes) using the same site, subject demographics, and visit schedule but monthly lens replacement was used for AE rates.

RESULTS

Logistic regression analysis showed a significant reduction in mechanical AEs (0.8 vs 5.2%, p = 0.01) and overall AEs (inflammatory and mechanical events) (4.0 vs 8.9%, p = 0.04) when lenses were replaced each morning compared with being replaced monthly. Estimation of handling-related lens contamination of unworn lenses in a subgroup of subjects showed isolation of Staphylococcus aureus from the lenses of 35% of subjects, and 65% of subjects had more than 1000 colony-forming units per lens of gram-positive bacterial contamination.

CONCLUSIONS

Morning lens replacement during CW reduced mechanical and overall ocular AEs. Replacing lenses at night had no beneficial effects perhaps because the benefit of a fresh lens at night might be partially negated by contamination of the contact lens caused by lens handling before overnight eye closure. Contact lens wearers on an extended wear or CW schedule should be advised to minimize lens handling before sleep to reduce the risk of complications.

Risk factors for corneal inflammatory and mechanical events with extended wear silicone hydrogel contact lenses

PURPOSE

To identify risk factors for contact lens-related corneal inflammatory events and mechanical events in wearers of silicone hydrogel lenses on a 30-night extended wear (EW) schedule in India.

METHODS

An interventional study with 188 subjects wearing silicone hydrogel lenses bilaterally on a 30-night EW schedule. Subjects were dispensed with lenses and reviewed at scheduled visits up to 6 months of EW. Multivariate logistic regression, after adjusting for within subject correlation, was used to develop the statistical model.

RESULTS

Occupations in non-ideal environments were found to predispose a lens wearer to inflammatory events (p = 0.003). Wearers in the non-ideal group, who had varying degrees of exposure to ocular irritants in their work environment had highest incidence of inflammatory events (19.2%). Wearers in a controlled, ideal environment had lowest levels of events (3.3%). Students occupied a position between the two groups (9.3%). Inflammatory rate was higher among wearers with increased microbial contamination of lenses (p = 0.002). Wearers with an inflammatory event had mean colony forming unit of 1.97 log compared with mean colony forming unit of 1.45 log in group with no inflammatory event. Corneal vascularization was associated with the development of inflammatory events (p = 0.001) with 50% of wearers with vascularization experiencing events compared with 7.6% of subjects with no vascularization. Reduced lens movement was associated with inflammatory events with subjects more likely to develop inflammatory events compared with those wearers with optimal lens movement (p = 0.027).

CONCLUSIONS

A multitude of factors, including environmental influences, lens contamination, ocular characteristics, and lens fit, contributes to the development of inflammatory events, information that is of clinical relevance to practitioners worldwide. Occupational environment was also a contributory factor, confirming that a duty of clinicians is to ascertain the nature of the work environment of lens wearers (and potential wearers) and to balance the needs of the wearer with the potential risks.

Risk factors for corneal infiltrative events during continuous wear of silicone hydrogel contact lenses

PURPOSE

This study determined which microbiologic, clinical, demographic, and behavioral factors are associated with corneal infiltrative events (CIEs) during continuous wear of silicone hydrogel (SH) contact lenses.

METHODS

Subjects (n = 205) were fitted with lotrafilcon A lenses for continuous wear and observed for 1 year. The main exposures of interest were corneal staining and bacterial lens contamination. Kaplan-Meier (KM) plots were used to estimate the cumulative unadjusted probability of remaining CIE free, and Cox proportional hazards regression was used to model the hazard of having a CIE, as a function of key predictor variables.

RESULTS

The KM-unadjusted cumulative probability of remaining CIE free was 73.3%. Approximately 53% of subjects had repeated episodes of corneal staining (mild or greater), and 11.3% had repeated episodes of moderate or greater corneal staining. Corneal staining was not associated with the development of a CIE. The frequency of substantial bacterial bioburden on worn lenses at the time of a CIE was 64.7%, compared with only 12.2% during uncomplicated wear. The presence of substantial lens bacterial bioburden was associated with the development of a CIE (adjusted hazards ratio [HR], 8.66; 95% confidence interval [CI], 2.88-26.01). Smoking was also associated with a CIE (adjusted HR, 4.13; 95% CI, 1.27-13.45).

CONCLUSIONS

Corneal staining is common during continuous wear of SH lenses, but it is not associated with the development of a CIE. Smoking and substantial lens bacterial bioburden pose prominent risks of a CIE. In this study, more than 70% of the total risk of CIE in those with substantial lens bioburden is attributable to this exposure. (ClinicalTrials.gov number, NCT00727402).

Are inflammatory events a marker for an increased risk of microbial keratitis?

PURPOSE

To consider whether inflammatory events, such as contact lens-induced peripheral ulcers, contact lens-induced acute red eye, and infiltrative keratitis are a marker for an increased risk for the occurrence of microbial keratitis.

METHODS

A review of relevant studies was undertaken with the view to answering two questions: 1) Do inflammatory events associated with contact lens wear progress to infection or microbial keratitis; and 2) Do episodes of inflammatory events predispose a patient to having an event of microbial keratitis?

RESULTS

The large body of laboratory work, along with the epidemiologic data on incidence rates and clinical data with regard to differences between the nature of inflammatory events and infection, supports the supposition that inflammatory events are not a marker for increased risk of microbial keratitis.

CONCLUSIONS

Inflammatory events are not a marker for increased risk of microbial keratitis, nor will they progress to infection because they are separate disease entities.

Prescription and management of contact lenses in patients with monocular visual impairment

PURPOSE

Contact lens correction for refractive error in patients with monocular visual impairment may be desirable. However, the potential for damage to the sound eye must always be considered in such patients. This report outlines the prescription and management of contact lens wear in a monocular patient. The case report is followed by a discussion of the risks of vision loss associated with contact lens wear.

CASE REPORT

The author conducted a clinical interview, refraction, ocular examination, and contact lens evaluation of a 38-year-old female patient who had undergone a lensectomy in her right eye and the enucleation of her left eye. The patient presented wearing a conventional aphakic hydrogel contact lens in her right eye. She routinely wore her contact lens for up to 16 hours daily and occasionally slept while wearing it. Best-corrected spectacle acuity was 20/40-2 with +13.75 diopter sphere in her right eye. Clinical examination showed 3 to 4 mm of well-perfused neovascularization with associated pannus in the superior quadrant of her cornea and 1 to 2 mm of peripheral neovascularization in the remainder of the cornea. She was refit with a 2-week replacement hydrogel contact lens that partially corrected her refractive error, and she was encouraged to wear polycarbonate spectacles full time for the remainder of her refractive correction and for protection of the right eye.

CONCLUSIONS

Monocularly impaired patients who choose to wear contact lenses for the correction of refractive error should be aware of the risk of potentially sight-threatening contact lens complications. The importance of meticulous hygiene and appropriate contact lens wearing schedules should be emphasized with monocular patients. They should also be encouraged to wear the appropriate spectacle correction to reduce the risk of injury to their sound eyes.

Severe acanthamoeba keratitis after overnight orthokeratology

PURPOSE

To document a clinical case of Acanthamoeba keratitis associated with orthokeratology overnight lens wear that resulted in severe, permanent vision loss.

METHODS

Case report.

RESULTS

At the age of 11 years, a boy received a spectacle correction for the following refractive error: -3.25 -0.50 x090 in the right eye and -3.50 -0.25 x 040 in the left eye. Alternative wear of daily-wear, disposable, soft contact lenses and rigid gas-permeable lenses was used for athletic activities to the age of 16 years. Between the ages of 16 and 19 years, the patient wore Boston Equalens 2c27 (type Percision Corneal Molding - 51) lenses with a base curve of 9.25, power of +2.50 diopters (D), and diameter of 10.6 mm in the right eye and a base curve of 9.15, power of +3.00 D, and diameter of 10.6 mm in the left eye for overnight orthokeratology wear. A corneal ulcer in the left eye was noted on November 13, 2004 (age of 19 years) and confirmed as Acanthamoeba infection by confocal microscopy on February 15, 2005, when triple topical therapy (Brolene, polyhexamethylbiguanide, and chlorhexidene) was initiated. Vision deteriorated to light perception with accurate projection by cessation of therapy on March 28, 2006. Additional complications included secondary angle-closure glaucoma, treated with an Ahmed tube shunt on April 12, 2005, and a mature cataract.

CONCLUSIONS

The important message conveyed by this case was the finding that for several years, unknown to his eye care physicians, the patient cleaned his lenses with the Boston Cleaning System, as instructed, but followed this step with a routine rinse with tap water and storage in tap water in his lens case, which was not replaced or cleaned. The tragic loss of vision in this case probably could have been prevented by focused attention to lens hygiene by the patient, parents, and practitioner. Such heightened scrutiny is critically important in orthokeratology rigid lens wear, especially in children, independent of the lens polymer or fitting algorithm used.

Risk factors for corneal infiltrates with continuous wear of contact lenses

PURPOSE

To describe the factors associated with symptomatic corneal infiltrates in a postmarket surveillance study of continuous wear contact lenses.

METHODS

Patients intending to wear lotrafilcon A lenses continuously for 30 days and nights were registered in a 1-year study at 131 clinical sites. A self-administered questionnaire was used to gather demographic and other data at baseline. The severity of the incidence of corneal infiltrative events during the year-long study was graded by an independent adjudication committee.

RESULTS

Of 6245 lens wearers, 163 were reported to have symptomatic corneal infiltrative events (2.6%). In 159 wearers, the infiltrates were judged to be lens-related (2.5%). Age < or =25 years and >50 years was significantly associated with the development of corneal infiltrates (< or =25 years OR = 1.75, 95% CI = 1.24-2.48 and >50 years OR = 2.04, 95% CI = 1.40-2.98). Ametropia of > or =5.00 D was significantly associated with corneal infiltrates (OR = 1.60, 95% CI = 1.08-2.37). Study participants who typically wore lenses for >21 consecutive days and nights were significantly less likely to have infiltrates than those who wore lenses for fewer consecutive days and nights (OR = 0.43, 95% CI = 0.24-0.75). Smoking concurrent with contact lens wear was weakly associated with corneal infiltrates (OR = 1.47, CI = 0.99-2.18).

CONCLUSIONS

Patient age, degree of refractive error, and failure to achieve the intended wearing schedule were associated with development of symptomatic corneal infiltrative events.

Characteristics of and risk factors for contact lens-related microbial keratitis in a tertiary referral hospital

AIM

A retrospective case-control study was conducted at a tertiary referral hospital to determine the characteristics of and risk factors for contact lens (CL) related presumed microbial keratitis.

METHODS

Two hundred and ninety-one cases of presumed microbial keratitis were retrospectively identified over a 2-year period. Records were reviewed for a history of CL wear and, where identified, CL, demographic, and clinical data were collected. Lens wearing controls (n=186) were identified by a community telephone survey. Multiple logistic regression estimated risk factors for infection and vision loss.

RESULTS

Ninety-nine (34%) new cases of presumed microbial keratitis were associated with CL wear. Overnight soft CL use was associated with an increased risk of infection compared to daily disposable CL wear (odds ratio (OR): 8.03, 95% confidence interval (CI): 1.82-35.46). Compared with older CL wearers, 15-24 year olds had a 3.5 times greater risk of infection (OR, 95% CI: 1.7-7.4). Of the 84 cases with available data, 24 (29%) lost two or more lines of best-corrected visual acuity. Delaying treatment by 49-72 h had a 4.5 times (OR, 95% CI: 1.4-14.9) greater risk of visual loss compared to seeking treatment early. Of the 99 cases of infection, 88 were scraped and 78% (69/88) of these returned a positive culture. Gram-positive bacteria were the predominant causative organisms.

CONCLUSION

Overnight use of CL and youth carry a greater risk of infection. Practitioners should reinforce the importance of proper CL care at all times, and early presentation following the onset of symptoms.

Inflammatory and Mechanical Complications Associated With 3 Years of up to 30 Nights of Continuous Wear of Lotrafilcon A Silicone Hydrogel Lenses

PURPOSE

To report the ocular complications occurring during a 3-year clinical trial of subjects wearing lotrafilcon A silicone hydrogel lenses for up to 30 nights of continuous wear.

METHODS

Nineteen sites enrolled 317 subjects (286 current wearers and 31 new wearers), who were dispensed lotrafilcon A lenses with 3 years of follow-up.

RESULTS

By the 1-month visit, continuous wear of up to 30 nights was recommended for 87% of subjects. The 27 lens-related adverse events included 15 (2.4%) eyes in year 1, seven (1.3%) eyes in year 2, and five (0.8%) eyes in year 3. Lens-related inflammatory events involved 12 (1.9%) eyes in year 1 and five (0.8%) eyes each in years 2 and 3. One third of the inflammatory events occurred in the first 3 months. Mechanical events included two superior epithelial arcuate lesions and one case of bilateral contact lens papillary conjunctivitis in years 1 and 2. No subjects experienced microbial keratitis during the 3-year trial. Two subjects with events discontinued from the trial.

CONCLUSIONS

These results show that the rate of contact lens adverse events occurring with lotrafilcon A is low in this cohort, with the highest likelihood occurring during the first 3 months of the study. There was a decrease in the rate of events during the later years of the study. Although clinicians should understand the likelihood of adverse inflammatory and mechanical events and their possible recurrence, the rate of these events may be lower in practice than previously reported.

Risk of corneal inflammatory events with silicone hydrogel and low dk hydrogel extended contact lens wear: a meta-analysis

PURPOSE

High Dk silicone hydrogel (SH) lenses have been shown to significantly decrease the risk of hypoxic complications compared to traditional low Dk hydrogels. However, the risks of inflammatory complications with SH compared to low Dk lenses are not as clear. A meta-analysis was performed to combine the relevant literature to evaluate the risks of corneal inflammatory events in users of SH and low Dk hydrogel extended wear lenses.

METHODS

A systematic search was conducted using online databases, unpublished meeting abstracts, and retrieval of other cited references presented or published between 1990 and February 2006. Each study was evaluated for quality in terms of the research question, and these quality assessments were used to determine which studies should be used in subgroup analyses. A generalized linear mixed model framework with an underlying Poisson distribution for the occurrence of events was employed to combine information from the included studies.

RESULTS

Twenty-three studies published or presented on either or both arms by February 2006 were selected for analysis. A total of 9,336 subjects and 18,537 eyes comprised the entire sample. Seven studies were published in the 1990s. Eighteen studies (78%) were prospective, and 11 (48%) used randomization. The follow-up ranged from 4 to 36 months, with a median of 12 months. The rates of infiltrates for low Dk hydrogels and SH lenses were 7.7 (2.2, 26.7) and 14.4 (4.3, 48.2) per 100 eye-years, respectively. In the subset of five best quality studies, the unadjusted risk ratio for corneal inflammatory events for SH lenses compared to low Dk lenses was 2.18 (p < 0.005). Across studies, adjusted risk ratios ranged from 2.18 to 2.23 (p < 0.05), with strong confounding between material and length of wear.

CONCLUSIONS

Based on published or presented studies between 1991 and 2006, there is approximately a twofold higher risk for corneal inflammatory events in users of SH lenses when typically worn for up to 30 days extended wear when compared with low Dk extended wear lenses when typically worn for 7 days extended wear. The increased risk cannot be definitively linked to SH lens materials because the effect of material on outcome is confounded by length of wear.

The epidemiology of contact lens related infiltrates

With estimated numbers of contact lens wearers worldwide exceeding 140 million, even complications with a low incidence will affect a significant number of individuals. Although contact lenses clearly have many advantages for wearers, certain risks have been associated with their use. Differences in risk for different types of contact lenses and wearing patterns have been demonstrated for both rare and common lens related complications. This review particularly focuses on the incidence and etiology of contact lens related corneal infection and inflammation. An understanding of the risks and contributory factors to these conditions is important for practitioners and will enable an informed choice of safer lens wear modalities, wear schedules, and hygiene regimes to be made.

Long-term Clinical Results: 3 Years of Up to 30-Night Continuous Wear of Lotrafilcon A Silicone Hydrogel and Daily Wear of Low-Dk/t Hydrogel Lenses

PURPOSE

To summarize results of a 3-year clinical trial assessing subjective and objective experience with lotrafilcon A silicone hydrogel (SH) lenses for up to 30 nights of continuous wear or low-Dk/t daily-wear (LDW) hydrogel lenses.

METHODS

Nineteen sites dispensed SH lenses to 317 subjects (286 current wearers and 31 new wearers) and 2-week replacement LDW lenses to 81 new wearers in a 3-year study.

RESULTS

For the SH cohort, limbal redness, conjunctival redness, and corneal neovascularization improved among 23%, 21%, and 13% of eyes, respectively (P<0.001), with no signs increasing significantly. For the LDW cohort, limbal redness, papillary conjunctivitis, and corneal staining increased among 11%, 21%, and 13% of eyes, respectively (P<0.02), with no signs improving significantly. The change in average spherical equivalent power was -0.03 diopters for the age-matched SH cohort and -0.40 diopters for the LDW cohort (P=0.007). During the 3 years, the SH group reported significantly less frequent dryness during and at the end of the day, redness, photophobia, lens awareness, and blurred vision. Significantly more LDW lens wearers reported frequent during-the-day and end-of-day dryness and blurred vision.

CONCLUSIONS

During the 3 years, lotrafilcon A lens wearers who wore their lenses continuously for up to 30 nights showed stable, long-term improvements in many signs of corneal health and symptoms along with less myopic progression versus daily wearers of low-Dk/t hydrogel lenses. Many biomicroscopy signs and symptoms worsened among neophytes wearing daily-wear low-Dk/t hydrogel lenses. The use of lotrafilcon A lenses may minimize many ocular changes from soft contact lens wear.

Rethinking contact lens associated keratitis

This review presents a critical analysis of the literature relating to the use of binomial and polynomial classification schemes for categorising corneal infiltrative events (CIEs) associated with contact lens wear and the epidemiology of such events. The results of the Manchester Keratitis Study-a 12-month, prospective, hospital-based epidemiological study of contact lens wearer suffering from CIEs-are used as a tool to challenge and test traditional thinking in relation to contact lens associated keratitis. An innovative aspect of this study is the use of a novel clinical severity matrix to systematically score the severity of CIEs based on 10 key signs and symptoms. The ambiguities inherent in using binomial classification schemes (such as, microbial versus sterile, ulcerative versus non-ulcerative etcetera) are highlighted. The failure of a polynomial scheme-due to extensive classification overlap between proposed sub-types of CIEs-is demonstrated using a Venn diagram. A cartographic analysis reveals that infiltrates tend to occur in the superior cornea of patients wearing extended wear silicone hydrogel lenses, in the central cornea of patients wearing daily wear hydrogel daily disposable lenses and in the peripheral cornea of patients wearing daily wear hydrogel (excluding daily disposable) lenses. Infiltrates that occur more towards the limbus are less severe. The incidence of CIEs is higher when contact lenses are worn overnight. Logistic analysis reveals that the risk of developing a severe CIE is five times greater with conventional hydrogel extended wear versus silicone hydrogel extended wear. The male gender, smoking, a healthy eye and body, and the late Winter months are associated with an increased risk of developing CIEs. The rate of significant visual loss as a result of developing a CIE is low. Two key conclusions are drawn from this work, which represent a radical rethinking of this potentially sight-threatening condition. CIEs should be considered as a continuous spectrum of ocular disease. If a contact lens wearer presents with a sore eye that is becoming progressively worse and a CIE is observed in that eye, lens wear should be suspended and anti-microbial therapy initiated immediately.

Prolonging contact lens wear and making contact lens wear safer

PURPOSE

To summarize the present status of safety and efficacy of contact lens wear.

DESIGN

Literature review.

METHODS

Ovid Medline searches were performed on records from 1966 through 2005 using keywords: keratitis, contact lens complications, extended-wear contact lenses, and silicone-hydrogel contact lenses.

RESULTS

Patients desire comfort, clarity of vision, and prolonged contact lens wear when contact lenses are used to correct refractive error. Practitioners desire patient satisfaction but also require maintenance of the integrity of the eye and no complications that jeopardize vision or health of the eye. Improvements in the oxygen permeability of the contact lens materials, design of the contact lens and its surface, and solutions for the maintenance of the lens have reduced but not eliminated the risks of infection, inflammation, and conjunctival papillary reaction associated with contact lens wear. The lessons of past and recent history suggest that patient education and practitioner participation in the management of contact lens wear continue to be critical factors for patient satisfaction and safety in the extended wear of contact lenses.

CONCLUSIONS

The availability of highly oxygen permeable contact lenses has increased the tolerance and safety of extended contact lens wear, but patient instruction and education in proper use and care of lenses is required and caution is advised.

Investigation of the performance of the Menifocal Z gas-permeable bifocal contact lens during continuous wear

PURPOSE

The Menifocal Z is an alternating vision, concentric, bifocal gas-permeable (GP) contact lens; center distance is connected to near periphery by a smooth transition zone. The lens is produced using tisilfocon A (Menicon Z material), which is approved for up to 30 days of continuous wear (CW). The aim of this study was to evaluate the clinical performance of the Menifocal Z when worn for up to 30 days of CW for 6 months.

METHODS

Thirty-five existing GP lens wearers were enrolled in the study. Subjects were fitted with Menifocal Z lenses and follow-up visits were conducted after 2 weeks of daily wear and 1 day, 1 week, 6 weeks, 3 and 6 months of CW. A range of objective and subjective clinical performance measures were assessed, including distance and near visual acuity, the physiological response to CW, and subjective evaluation of vision and comfort.

RESULTS

Twenty-seven subjects (77%) completed the study and eight (23%) discontinued: five (14%) as a result of lens-related problems (four vision, one comfort) and three (9%) as a result of non-lens related reasons. Average CW time achieved by the subjects was 22 +/- 2 days. Mean binocular logarithm of the minimum angle of resolution (logMAR) acuities at 6 months were: high contrast distance 0.03 (20/20-), low contrast distance 0.63 (20/80-), and high contrast near 0.26 (20/25, N4). Adverse responses and lens binding were minimal, and there were no significant increases in corneal staining, corneal vascularization, or superior palpebral conjunctival papillae over time (p > 0.05). Problems with night vision (distance and near) with the lenses were the most common difficulties reported by the subjects.

CONCLUSIONS

The Menifocal Z appears to be a promising option for presbyopic vision correction, providing successful correction of distance and near vision in a group of experienced GP lens wearers. The hyper Dk tisilfocon A (Menicon Z) material allowed for safe wear of the lenses on a CW basis.

Three-Year Follow-up of Biomicroscopy Signs and Refractive Status in Patients Wearing Lotrafilcon A Lenses

PURPOSE

To report the wearer experience, biomicroscopy signs, and stability of refractive error after 3 years' use of lotrafilcon A lenses.

METHODS

Seventy-four subjects from a multicenter clinical trial with lotrafilcon A lenses were queried on aspects of lens wear. Biomicroscopy signs and refractive error were compared to baseline measurements.

RESULTS

A total of 66% of subjects reported continuing to wear lotrafilcon A lenses, usually for more than 21 nights, with high satisfaction. Signs of limbal, palpebral, and bulbar redness improved significantly. Average refractive error remained stable.

CONCLUSIONS

Long-term use of lotrafilcon A lenses resulted in high wearer satisfaction, reduction of ocular redness, and stable refractive error.

Impact of Previous Extended and Daily Wear Schedules on Signs and Symptoms With High Dk Lotrafilcon A Lenses

PURPOSE

This study measured the impact of previous contact lens wearing schedule on the resolution of signs and contact lens-related symptoms among wearers of lotrafilcon A lenses.

METHODS

One hundred forty adapted low Dk daily wear (DW) and 140 adapted low Dk extended wear (EW) subjects were enrolled and examined for 1 year (overall study length is 3 years). All subjects wore lotrafilcon A lenses on a wearing schedule of up to 30 nights continuous wear with monthly replacement of lenses. Examinations were conducted at 1 week, 1, 6, and 12 months.

RESULTS

The former EW wearers presented at baseline with significantly higher conjunctival staining and epithelial microcysts (p < 0.05) and lower ocular surface symptoms of end of day dryness than the former DW wearers. There were no significant differences in other ocular signs at baseline for the former DW and EW wearers. After use of lotrafilcon A, clinical signs of limbal, conjunctival redness, and neovascularization were significantly better by the 1-week visit for both groups of wearers. Regardless of former wearing schedule, symptoms of dryness (during and at the end of the day) and photophobia were significantly better after 1 week of lotrafilcon A use. The frequency and severity of symptoms of dryness during the day improved significantly among former low Dk DW and EW wearers within 1 week as did severity of dryness during the day for the former DW wearers, in part as a result of their higher prevalence at baseline in the DW group. Subjects reported redness improved significantly by the 1-month visit.

CONCLUSIONS

Continuous wear of high Dk silicone hydrogel lenses resulted in an improvement in ocular redness and neovascularization and dryness symptoms among subjects in this trial, regardless of their previous low Dk lens-wearing schedule. All improvements in signs and symptoms were sustained through 12 months.

Adverse Events and Discontinuations With Rigid and Soft Hyper Dk Contact Lenses Used for Continuous Wear

PURPOSE

The purpose of this study was to assess the relative clinical success of hypertransmissible rigid and soft contact lenses in terms of the rates of adverse events and clinical discontinuations.

METHODS

One hundred subjects (50 experienced wearers and 50 neophytes) were fitted with either the Z-alpha lens (Menicon) or the Focus Night & Day lens (CIBA Vision), which were worn on a 30-day continuous wear basis. The rates of adverse events and clinical discontinuations were monitored over 12 months.

RESULTS

There were 20 adverse events that were categorized as being serious or significant--four with rigid lenses and 16 with soft lenses (p = 0.003). There was no significant difference between the experienced (10) and the neophyte (10) groups (p = 1.00). There were 23 clinical discontinuations--13 with rigid lenses and 10 with soft lenses (p = 0.46). Fewer experienced wearers (five) discontinued than neophytes (18) (p = 0.002).

CONCLUSIONS

Practitioners should anticipate fewer adverse events with rigid versus soft lenses prescribed for continuous wear. Experienced wearers are less likely to discontinue compared with neophytes.

A 6-month follow-up of successful refits from daily disposable soft contact lenses to continuous wear of high-Dk silicone-hydrogel lenses

PURPOSE

To compare, in routine optometric practice, the outcome of keeping successful soft contact lens (SCL) wearers in their lenses to re-fitting them with continuous wear of silicone hydrogel (SiH) lenses.

METHODS

Forty-nine successful daily disposable lens wearers were recruited; 19 continued to wear daily SCLs and 30 were refitted with high-Dk SiH lenses on a 30-day/night schedule. Patients were assessed at baseline, 3 and 6 months by slit lamp examination along with the Efron grading scales, and central corneal thickness (CCT) and the corneal endothelium were assessed by non-contact specular microscopy.

RESULTS

No substantial changes in subjective vision, refraction, visual acuity or overall lens comfort occurred for those completing the study, although five SiH lens wearers did discontinue due to reduced comfort, eyelid problems or seasonal allergy. Contact lens induced peripheral ulcers (CLPU) were observed in three patients in the first 3 months in the SiH lens group and these were also discontinued. Over the 6 month period, a complete set of records was obtained for 16 in each group. For those completing the study, lens dryness scores were variable, but there was a slight improvement in favour of SiH lenses. Small, but statistically significant, reductions in corneal staining, bulbar hyperaemia, and limbal neovascularisation in favour of the SiH lenses were also evident but mainly because of further increases in the daily lens wearers. Contact lens induced papillary conjunctivitis (CLPC) and corneal endothelial polymegethism were mild to moderate and showed slight increases in the daily lens wearers at 6 months.

CONCLUSIONS

The present studies confirm that the continuous wear of SiH lenses for up to 30 days can be considered as an alternative to daily disposable soft lens wear, but is not suitable for everyone.