Doris Richter

A patient questionnaire approach to estimating the prevalence of dry eye symptoms in patients presenting to optometric practices across Canada

Objective. To collect questionnaire data from patients in a large clinical population that would allow for an estimate of the prevalence of self-reported symptoms of dry eyes. Methods. A 13-point questionnaire (The Canada Dry Eye Epidemiology Study, CANDEES) was mailed to all optometric practices in Canada in October 1994, with the request that it be completed by 30 successive nonselected patients. Results. Four hundred fifty sets of questionnaires (total, 13,517) were analyzed (a 15.7% return rate) from patients aged from <10 years to >80 years; 55% were in the 21- to 50-year age group; 60.7% were female; and 24.3% were contact lens wearers. A total of 28.7% reported dry eye symptoms, of whom 24.2% reported concurrent dry mouth, 24.5% had worse symptoms in the morning, 30.3% reported concurrent lid problems, and 35.7% reported a history of allergies. Of the 3716 patients reporting symptoms, 62 (1.6%) were in the “severe” category and 290 (7.8%) were in the “constant but moderate” category. Contact lens wear, concurrent allergies, dry mouth, lid problems, or use of medications increased the chance of a patient reporting dry eye symptoms. Conclusions. The prevalence of patients reporting any level of symptoms of dry eyes was approximately 1 in 4; severe symptoms were reported by 1 in 225 patients.

Vascular response to extended wear of hydrogel lenses with high and low oxygen permeability

Purpose. The purpose of this study was to determine the impact of extended wear of high and low oxygen permeability (Dk) lenses on the development or resolution of limbal hyperemia and corneal neovascularization in a randomized prospective clinical trial. Methods. Adapted daily-wear contact lens wearers were randomly assigned to one of two groups. The low-Dk group (N = 23) wore etafilcon A lenses (Dk/t = 40) for up to 7 days and 6 nights, and the high-Dk group (N = 39) wore lotrafilcon A lenses (Dk/t = 175) for up to 30 days and nights. Limbal hyperemia and neovascularization were assessed and graded during 9 months of extended wear. A stratified analysis to determine how change in ocular redness depended on initial presentation was also conducted. Results. On a 0 to 100 scale, extended wear of low-Dk lenses resulted in a 16-point increase in limbal hyperemia (p < 0.0001); no significant change occurred with the high-Dk lenses. The difference was greatest for low-Dk participants who initially presented with lower levels of hyperemia (N = 18). There was a slight resolution of redness in participants who initially presented with higher levels of hyperemia (N = 10) after wearing the high-Dk lenses. Neovascularization increased by an average of 0.5 on a scale of 0 to 4 in low-Dk lens wearers (p < 0.0001) but remained unchanged in the high-Dk lens wearers. The increase was most marked for the low-Dk group with lower levels of neovascularization at baseline. Conclusions. Subjects who wore lenses with higher oxygen permeability for 9 months of extended wear exhibited a lower vascular response of the ocular surface compared with subjects who wore lenses of lower oxygen permeability for the same period. This result was found both for the surface limbal vessels and in the deeper neovascular stromal vessels. Moderate neovascularization also developed after 3 months of extended wear of low-Dk hydrogels, whereas high-Dk lenses caused no neovascularization.

The ocular response to extended wear of a high Dk silicone hydrogel contact lens

Purpose: A four‐month extended wear clinical trial was conducted to compare die ocular effects of a high Dk Balafilcon A silicone hydrogel lens and a low Dk HEMA 38.6 per cent H2O soft lens.

Compliance with contact lens replacement in Canada and the United States.

Purpose. To assess eye care practitioners (ECPs) recommendations for replacement frequency (RF) of silicone hydrogel (SH) and daily disposable (DD) lenses in Canada and the U.S. and to compare noncompliance (NC) with manufacturer recommended RF by the ECP and patient, and the reasons given for NC. Methods. Invitations to participate were sent by e-mail to ECPs in Canada and the U.S. Twenty patient surveys were sent to 420 ECPs, and 2232 eligible surveys were received from 216 ECPs (26% Canada, 74% U.S.). Questions related to patient demographics, lens type, wearing patterns, ECP instructions for RF, and actual patient RF. ECPs provided lens information and their recommendation for RF after the surveys were completed and sealed in envelopes. Responses were anonymous. Results. DD accounted for 18% (Canada) vs. 16% (U.S.) of wearers (p > 0.05); 35% (Canada) vs. 45% (U.S.) wore 2-week replacement SH (2WR; p = 0.011); and 47% (Canada) vs. 39% (U.S.) wore 1-month replacement SH (1MR) lenses (p = 0.025). Thirty-four percent (Canada) vs. 18% (U.S.) of ECPs recommended longer RFs than the manufacturer recommended RF for 2WR lens wearers (p < 0.001); 6% (Canada) vs. 4% (U.S.) for DD wearers; and 2% (Canada) vs. 1% (U.S.) for 1MR lens wearers. NC rates for actual RFs reported by patients were not different between countries (p > 0.05) and were lowest for DD (13% Canada, 12% U.S.), followed by 1MR (33% Canada, 28% U.S.). The highest NC rates were with 2WR (50% Canada, 52% U.S.). The most frequent reason for NC with 2WR and 1MR was “forgetting which day to replace lenses” (54% Canada, 53% U.S.) and in DD wearers “to save money” (56% Canada, 29% U.S., p < 0.001). Conclusions. 1MR lenses are more frequently prescribed in Canada. ECPs in Canada were NC with 2WR lenses more frequently than U.S. ECPs, but patient NC rates were the same in both countries for all lens types. ECP and patient NC rates were highest for 2WR lens wearers.

Distribution of overnight corneal swelling across subjects with 4 different silicone hydrogel lenses.

Purpose: To determine distribution of central corneal swelling (CCS) across subjects after 8 hr of sleep in eyes wearing silicone hydrogel lenses with various oxygen transmissibility (Dk/t) values and in eyes without lenses. Methods: Twenty-nine neophytes wore lotrafilcon A (Dk, 140), balafilcon A (Dk, 91), galyfilcon A (Dk, 60), and senofilcon A (Dk, 103) lenses in powers −3.00, −10.00, and +6.00 diopters on separate nights, in random order, and on 1 eye only. The contralateral eye (no lens) served as the control. Central corneal thickness was measured using a digital optical pachometer before lens insertion and immediately after lens removal on waking. Results: The average difference between the mean (7%) and the median (6.8%) CCS of all lenses was only 0.2%, suggesting a normal distribution. There was no correlation between the mean and the range of the CCS (r=0.058, P=0.766). Normal CCS distributions were also found with each lens-wearing eye and the control eye (P>0.20 for all). There was a significant correlation between lens-wearing eye and control eye (r=0.895, P<0.001) and between lotrafilcon A and each of the other 3 lenses for mean CCS across the study participants (P<0.001 for all). Conclusions: Distribution of corneal swelling in both lens-wearing eye and control eye followed a normal curve. An individuals corneal swelling response seems to be independent of lens type.

Repeatability and comparability of automated keratometry: the Nikon NRK-8000, the Nidek KM-800 and the Bausch and Lomb keratometer

This study assessed the repeatability of the Nikon NRK‐8000, the Nidek KM‐800 and the Bausch and Lomb keratometer. In addition, the comparability of the Nikon NRK‐8000 and the Nidek KM‐800 are evaluated relative to the Bausch and Lomb keratometer. Measurements were taken with all three techniques on two separate occasions with a test–retest separation of at least 24 hr. The right eyes of 30 normal subjects were used. Repeatability and comparability statistics and plots were generated using matrix representations of dioptric power. The Nidek KM‐800 coefficient of repeatability values were found to be 0.345, 0.187, and 0.321 in the vertical, torsional, and horizontal meridians while the Nikon NRK‐8000 values were 0.346, 0.232, and 0.276 respectively.

Comfort Response of Three Silicone Hydrogel Daily Disposable Contact Lenses

Purpose To evaluate subjective ocular comfort across the day with three silicone hydrogel daily disposables (SHDDs) in a group of adapted lens wearers. Methods Masked subjects (asymptomatic or symptomatic of end-of-day (EOD) dryness with habitual lenses) wore three SHDDs: DAILIES TOTAL1 (DT1), Clariti 1day (C1D), or 1-DAY ACUVUE TRUEYE (AVTE), each for 3 days. On day 2, wearing time (WT) and comfort ratings after insertion, at 4, 8, and 12 hours, and at EOD were recorded. Because not all subjects wore lenses for 12 hours, comfort was analyzed across the day (up to 8 hours, 8 to 12 hours), and a new variable (“cumulative comfort” [CC]) was calculated for EOD. Results One hundred four subjects completed the study (51 asymptomatic, 53 symptomatic). The two groups had different WTs (mean WT, 14.0 and 12.7 hours, respectively; p < 0.001). Ocular comfort was rated higher in the asymptomatic group throughout the day (p < 0.001). One hundred four subjects wore all three SHDDs for at least 8 hours, whereas 74 (45 asymptomatic, 29 symptomatic) subjects wore them for 12 hours or longer. Comfort ratings were higher with DT1 (least square means [LSM] = 91.0) than with C1D (LSM = 86.5; p < 0.001) and AVTE (LSM = 87.7; p = 0.011) for the first 8 hours and lower with C1D compared with DT1 (p = 0.012) from 8 to 12 hours. Mean EOD (± SD) comfort with the C1D lens was 72 ± 21, lower than both DT1 (mean, 79 ± 17; p = 0.001) and AVTE (mean, 78 ± 21; p = 0.010). Mean CC was higher in the asymptomatic group (mean, 1261 ± 59) compared with that in the symptomatic group (mean, 1009 ± 58; p < 0.001) and higher for DT1 (mean, 1184 ± 258) than C1D (mean, 1094 ± 318; p = 0.002) and AVTE (mean, 1122 ± 297; p = 0.046). Conclusions All three SHDDs had average WTs of 12 hours or longer for 1 day. Comfort during the first 12 hours was highest with DT1 (similar to AVTE between 8 and 12 hours) and lowest with C1D. End-of-day comfort was lowest with C1D, and CC was highest for DT1. Cumulative comfort may be a valuable new metric to assess ocular comfort during the day.

Compliance with lens replacement and the interval between eye examinations.

Purpose Eye care practitioners (ECPs) acknowledge that their patients do not always follow recommendations for lens replacement, but many may not realize the possible implications for their offices. The study was conducted to investigate whether there is a relationship between contact lens compliance and the interval between full eye examinations (IEE). Methods The study was conducted in ECP offices in the United States. Eye care practitioners and patients independently completed linked questionnaires, evaluating their contact lens wear and care. Patients were required to be current wearers of daily disposable (DD) lenses or reusable silicone hydrogel lenses with a manufacturer-recommended replacement frequency (MRRF) of 2 weeks (2WR) or 1 month (1MR). Results A total of 2147 questionnaires from 141 offices were eligible. Fifty-four percent of patients were wearing 2WR, 37% 1MR, and 9% DD lenses. Wearers of 2WR lenses were significantly less compliant with replacement than wearers of both DD and 1MR lenses (34% vs. 74% and 67%, both p < 0.001); patients purchasing an annual supply were more compliant (55% vs. 45%, p < 0.001). The mean IEE was 16 months and was longer for wearers who were noncompliant with the MRRF (17.4 months vs. 14.5 months, p < 0.001). Other factors affecting IEE were household income (p = 0.030), insurance (p < 0.001), purchase source (p < 0.001), and sex (p = 0.007). Conclusions Patients who were not compliant with the MRRF had longer IEEs and were less likely to purchase an annual supply of lenses. Patients who purchased lenses from their ECP, had a higher household income, had eye examination insurance, and were female had shorter IEEs. Patients failing to replace their lenses when scheduled were also found to be less compliant with lens care procedures. Eye care practitioners should reinforce the importance of all aspects of lens wear and care with their patients, with the overall aim of reducing possible complications and retaining successful contact lens wearers in their offices.