The long and short of contact lenses.The long and short of contact lenses The largest study yet of contact lens contact lens, thin plastic lens worn between the eye and eyelid that may be used instead of eyeglasses. Actors, models, and others wear them for appearance, and athletes use them for safety and convenience. use in the United States indicates extended-wear lenses--those worn overnight--carry a 2 to 4 times greater risk of serious complications than daily-wear lenses. The study of 22,500 lens wearers reveals greater risk of sight-threatening complications, such as serious corneal abrasion Corneal Abrasion Definition A corneal abrasion is a worn or scraped-off area of the outer, clear layer of the eye (cornea). Description The cornea is the clear, dome-shaped outer area of the eye. , growth of blood vessels Blood vessels Tubular channels for blood transport, of which there are three principal types: arteries, capillaries, and veins. Only the larger arteries and veins in the body bear distinct names. onto the cornea cornea: see eye. , corneal ulcers and severe corneal corneal pertaining to the cornea. See also keratitis, keratopathy. corneal anomaly includes microcornea, coloboma, megalocornea, dermoid, congenital opacity. corneal black body see corneal sequestrum (below). scarring. Scott MacRae of the Oregon Health Sciences University in Portland found that daily lens users sufer corneal ulcers -- sores that can lead to infection and loss of sight -- at a rate of about 1 in 2,000 yearly and that 1 in 300 daily lens wears suffers other serious complications. Among extended-wear users, which includes both costmetic wear and use by patients after cataract surgery, MacRae found rtes of 1 in 500 for corneal ulcers and 1 in 100 for others serious reactions. The study, based on case histories gathered by lens manufacturers for the Food and Drug Administration from 1980 to 1988, includes patients who were followed from three to 24 months. |
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