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People who regularly wear contact lenses while sleeping are at least
eight times more likely to develop corneal damage than those who don't,
according to a new study.
The study, from scientists at The Johns Hopkins Wilmer Eye Institute, the Oregon Health Sciences University's Casey Eye Institute, and Michigan State University, concludes that eliminating overnight use of disposable and conventional extended-wear lenses would reduce the rate of lens-associated ulcerative keratitis by as much as 74 percent.
Ulcerative keratitis is a destructive inflammation of the cornea, the clear cover of the eye, caused by infection with bacteria or other germs. The study appears in the February issue of the Archives of Ophthalmology.
"The main point is that most of the risk is due to overnight wear, not lens type," says Oliver Schein, M.D., M.P.H., of Wilmer's Cornea Service and Dana Center for Preventive Ophthalmology, and senior author of the paper. "Even 41 lens care hygiene, although recommended, does not protect the wearer against the excess risk of overnight wear."
The report expands a previous finding by the same team Archives of Ophthalmology, November 1992) that disposable contact lens use puts people at higher risk for ulcerative keratitis. Most of this excess risk associated with disposable contact lenses now can be explained by overnight wear of these lenses.
Overnight use of lenses approved only for daily wear also contributes to the problem, he adds. Eliminating overnight use of these lenses would reduce the rate of ulcerative keratitis among daily lens wearers by about 50 percent.
Other authors of the study include Joanne Katz, Sc.D. (Johns Hopkins); Patricia 0. Buehler, M.D., M.P.H. (Oregon Health Sciences Center, Portland); and John F. Stamler, M.D., Ph.D., and David D. Verdier, M.D. (Michigan State University). The study was supported by grants from the Merck Company Foundation and the National Institutes of Health.