Acanthamoeba keratitis associated with disposable contact lenses

Two patients developed Acanthamoeba keratitis associated with the use of disposable extended-wear hydrogel contact lenses. Both patients removed, irrigated, and reinserted the contact lenses without disinfecting them. One patient wore the lenses on a daily basis, rinsed the lenses in tap water, stored them overnight, and discarded them weekly. Both infections were treated successfully. In a third patient, Acanthamoeba species was cultured from two pairs of disposable lenses that had been stored in cases rinsed with well water. Potential benefits from disposable contact lens wear are negated when patients do not comply with a continuous wearing schedule.     

Colonization of hydrogel lenses with Streptococcus pneumoniae: risk of development of corneal infiltrates.

PURPOSE: To report the association between colonization of contact lenses with Streptococcus pneumoniae and the observation of corneal infiltrative events in a group of patients wearing disposable hydrogel lenses on an extended-wear schedule. METHODS: In a prospective clinical trial, 330 patients wore disposable hydrogels on a 6-night extended-wear and replacement schedule. The contact lens, lid, and conjunctival microbiota of these subjects was analyzed at frequent intervals and at the time of an adverse event. RESULTS: Streptococcus pneumoniae was an uncommon isolate and was recovered from only one of the 3,763 conjunctival samples, five (0.1%) of the 3,764 lid samples, and 33 (0.8%) of the 4,315 contact lens samples. Of the 33 lens samples, 10 (30%) were associated with corneal infiltrative events. Many of the events were mild inflammatory responses and resolved rapidly on discontinuation of lens wear. The presence of S. pneumoniae on the contact lens was associated with a significant risk of development of corneal infiltrates (odds ratio, 3.0; p = 0.0227, logistic-regression analysis). CONCLUSIONS: Presence of S. pneumoniae on hydrogel lenses is a significant risk factor for the development of corneal infiltrates.     

Acanthamoeba keratitis. A growing problem in soft and hard contact lens wearers

Eleven contact lens-wearing patients presented with Acanthamoeba keratitis. Eight cases were culture- and/or stain-positive for Acanthamoeba and three were presumed to have Acanthamoeba keratitis based on history and clinical findings. Six wore daily wear soft contact lenses, two wore extended-wear soft contact lenses, one wore a polymethylmethacrylate hard contact lens, one wore a gas-permeable hard contact lens, and one wore a Saturn lens (combined hard and soft lens). Four patients used distilled water and salt tablet saline, three used tap water and salt tablet saline, two used tap water rinse, two used well water rinse or storage, and one used intravenous (IV) saline. It is apparent that all contact lens wearers are at some risk for Acanthamoeba keratitis developing if proper contact lens care is not maintained. Of great concern is the inability of most current chemical sterilization methods to kill the organism if the lens becomes contaminated. Heat disinfection will kill Acanthamoeba trophozoites and cysts but the lens must not be placed into contaminated solutions afterward. Prevention is very important because medical and surgical treatment failures are frequent. Eye care practitioners who fit contact lenses are advised to use heat disinfection for low-water content stock soft contact lenses, and to use hydrogen peroxide without a catalyst for a minimum of 6 hours for all other stock lens fitting sets, to specifically inquire about contact lens care habits used by their patients, and to discourage the use of homemade saline solutions.     

Ulcerative keratitis associated with contact lens wear

From October 1982 through June 1986, 658 patients developed ulcerative keratitis. In 196 of these patients it was contact lens-related. Fifty-nine patients wore extended-wear contact lenses for cosmetic purposes. On culture, Pseudomonas species was the organism most frequently isolated from the ulcers associated with contact lens wear. No cases of fungal keratitis were found in the contact lens group as compared to 40 cases (17%) in the noncontact lens group. Compared to results of a similar study covering January 1977 through September 1982, current results showed a larger number of patients using extended-wear lenses for cosmetic reasons (59 vs one) and overall younger age.     

Association of acinetobacter species with contact lens-induced adverse responses.

PURPOSE: To determine the levels of Acinetobacter species associated with normal soft contact lens wear and to determine whether Acinetobacter species are involved in adverse reactions that occur during contact lens wear. METHODS: Patients wore soft contact lenses on an extended-wear basis. The bacteria on lenses and ocular swabs during asymptomatic and symptomatic lens wear were identified using standard microbiologic methods. RESULTS: Acinetobacter species were isolated and identified from 16 (13%) of 126 patient samples. Greater numbers of Acinetobacter species were isolated from lenses of patients experiencing adverse responses than from asymptomatic patients.Acinetobacter species were isolated from patients experiencing symptomatic adverse responses in 4 (13%) of 32 cases. CONCLUSION: It appeared that Acinetobacter species colonized the eye of extended contact lens wearers at a time when the normal functioning of the eye was compromised by contact lens wear. When Acinetobacter species were in high numbers on a contact lens, an adverse response occurred. This may implicate Acinetobacter species as a contributing factor to adverse responses associated with contact lens wear.     

Corneal endothelial polymegathism after the extended wear of rigid gas-permeable contact lenses

To determine if there are any corneal endothelial cell size and shape changes in subjects wearing rigid gas-permeable contact lenses for cosmetic extended wear, six unadapted lens wearers were fitted using four different lens materials. Each subject wore one lens extended-wear and the other daily-wear for 3 months. Before lens wear and after 3 months, noncontact endothelial photographs were taken. Cell tracings were analyzed by a digitizing computer. This study showed significant endothelial polymegathism, an increase in maximum cell area to minimum cell area, and a significant decrease in percent frequency of hexagonal cells in the extended-wear eyes. There existed in these subjects a significant correlation between changes in cell size (polymegathism) and cell shape (pleomorphism).     

Corneal epithelial alterations induced by disposable contact lens wear.

PURPOSE: To study the effect of disposable extended-wear soft contact lenses on the corneal epithelium. METHODS: Thirteen healthy patients (1 male, 12 females; average age, 26.3 +/- 7.6 years) with or without histories of previous contact lens use were recruited for this study. Specular microscopic pictures of the corneal epithelium and endothelium were taken with the help of a specular contact lens, before and after 3 months of contact lens use. The pictures were analyzed by means of a computer-assisted morphometric analysis system. RESULTS: The mean cell area and coefficient of variation (CV) of the mean cell area of the corneal epithelium before contact lens use were 639.4 +/- 84.0 microns 2 and 29.1 +/- 13.2, respectively. After lens wear, the mean cell area increased to 819.7 +/- 99.2 microns 2 (P less than 0.01), whereas the CV decreased to 20.0 +/- 6.1 (P less than 0.05). The corresponding values for the endothelium were 300.8 +/- 22.5 microns 2 and 36.4 +/- 7.3 before contact lens use, and remained at 322.3 +/- 27.8 microns 2 and 32.8 +/- 3.7 after contact lens use, respectively (P greater than 0.05). CONCLUSIONS: Based on the 3-month results, disposable extended-wear soft contact lenses caused similar enlargement of the mean cell area of the superficial corneal epithelium, as has been reported previously. It would appear that disposable lenses may cause the same metabolic and physiologic changes in the corneal epithelium as do conventional extended-wear soft contact lenses.     

Corneal ulcers associated with daily-wear and extended-wear contact lenses

Over a 21-month period, we treated corneal ulcers in 11 patients using daily-wear contact lenses and 29 patients using extended-wear contact lenses. Since more patients use daily-wear than extended-wear lenses, this suggests that patients using extended-wear lenses are at greater risk for the development of corneal ulcers. Positive bacterial cultures were obtained from the corneal scrapings of nine of 11 patients using daily-wear lenses and 20 of 29 patients using extended-wear lenses. In the daily-wear group, all 11 patients failed to exercise satisfactory care in using and disinfecting their contact lenses: three did not wash their hands before manipulating the contact lenses, eight wore them overnight, two did not use any disinfecting system, and four had contaminated contact lens cases, solutions, or drops. In the extended-wear group, 17 patients failed to exercise satisfactory care in using and disinfecting their contact lenses: 12 had contaminated contact lens care systems, two did not use any disinfection system, five reported not washing their hands before contact lens manipulation, and two disinfected their contact lenses at intervals of more than a month. We were unable to identify any defect in the way 12 patients took care of their extended-wear lenses, suggesting that there may be a problem with these contact lenses even when care is satisfactory.     

Complications of disposable extended-wear contact lenses. Apropos of 6 cases]

We report six cases of corneal complications observed in disposable extended-wear contact lens users: two corneal ulcers, one superficial infiltrate, two punctate keratitis with subepithelial infiltrates and one superficial punctate keratitis. In four cases a bacterial etiology was confirmed. Disposable contact lenses are not complication-free. In our series, complications were favoured or provoked by incorrect use in most cases. Other possible risk factors include poor hygiene during lens manipulation, damage to the corneal epithelium during lens exchange or lens wear, use of contaminated lubricant eyedrops, relative corneal hypoxia during overnight wear or in the case of improper fitting. Correct and adequate patient information is therefore essential to ensure that these lenses constitute a safe choice.     

The prevalence and pattern of contact lens use in a Singapore community.

PURPOSE: We conducted a cross-sectional survey to determine the prevalence, socio-demographic patterns, and characteristics of contact lens use in an electoral community in Singapore. METHODS: One thousand eight hundred fifteen persons aged between 12-55 years from 768 households were surveyed using a standardized pre-tested questionnaire. RESULTS: The percentage of contact lens wearers in the survey populations was 9.0%. Forty-two percent of surveyed individuals were myopes, 21.8% of whom wore contact lenses. Contact lens wearers tended to be young Chinese females with higher level education and incomes. Most wore monthly disposable or daily wear soft contact lenses. Convenience and cosmesis were the main reasons cited for contact lens wear. Optometrists, who prescribed the bulk of contact lenses, were also the most influential in determining consumers' choice of lenses. CONCLUSION: Information gathered in this population-based survey may be used to facilitate national eye-care planning and provide a baseline for comparison with rates of lens wear found in other countries and in future surveys.