The newest extended-wear contact lenses have a similar risk of eye\ninfections as older soft lenses worn for fewer nights.\n\nThat news is reported in Ophthalmology. It comes from postmarketing\nstudies funded by CIBA Vision, which makes the silicone hydrogel\nlenses, marketed as Night & Day.\n\nThe researchers included Oliver Schein, MD, MPH, of Johns Hopkins\nUniversity's medical school.\n\nLenses' History\n\nThe FDA approved the silicone hydrogel lenses in 2001 for continuous\nwear for up to 30 nights.\n\nOlder generations of extended-wear contacts had been associated with\nrare cases of vision loss and eye infections. That prompted the FDA's\n1989 decision to cut extended wear to seven days.\n\nYears later, silicone hydrogel lenses were developed. Compared with\nolder lenses, they allow four times as much oxygen to reach the eye.\nBetter oxygen flow was seen as a way to possibly lower infection risk\nin the eye's cornea.\n\nThe FDA ordered postmarketing studies of silicone hydrogel lenses to\ncheck corneal infection rates.\n\nYear-Long Study\n\nThe study included 6,245 people who had been given prescriptions for\nthe silicone hydrogel lenses. Most (80%) wore their lenses nonstop for\nat least three weeks.\n\nDuring the year-long study, few participants had corneal infections.\nTwo had corneal infections that led to vision loss. Eight others had\ncorneal infections that didn't cause vision loss.\n\nOverall, the yearly rate of corneal infections was 18 per 10,000\npeople, the study shows.\n\nThat's similar to rates previously reported for conventional,\nextended-wear soft lenses worn for fewer consecutive nights, according\nto the researchers.\n\nResearchers' Pecking Order\n\nSchein's team calls contact lenses "very safe" in general, though\nthey note that contact lenses are associated with some extra risks,\ncompared with eyeglasses.\n\nThey rank the risk of vision loss from eye infection for different\ntypes of contact lenses:\n\n\nLowest risk: Rigid, gas-permeable contact lenses for daily wear\n\n\nNext-to-lowest risk: Soft contact lenses for daily wear\n\n\nHighest risk: Silicone hydrogel contact lenses for extended wear of\nthree-to-four weeks\n\nHowever, they're not calling silicone hydrogel lenses dangerous. The\nodds appear "reasonable," write the researchers, for people who\nunderstand the risks and want to wear their contacts around the clock.\n\nThe study notes that one researcher is a CIBA Vision consultant and one\nis a CIBA Vision employee.\n\nSOURCES: Schein, O. Ophthalmology, Dec. 2005; vol 112: pp 2172-2179.\nNews release, Johns Hopkins University.\n\n\nBy Miranda Hitti\nReviewed by Louise Chang, MD \n© 2005, WebMD Inc. All rights reserved.