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Overnight contact-lens use leads to damaging infection

July 26, 1999
Web posted at: 6:04 PM EDT (2204 GMT)

In this story:

More wearers means more infections

All contact-lens wearers at some risk, but overnight wearers at highest risk

Improvements in materials and hygiene have not reduced the risk


By Daniel Hayes, M.D.

(WebMD) -- Overnight wearers of soft contact lenses have an almost 20 times greater risk of developing an eye infection than people who take their contact lenses out before going to bed, researchers have found.

The study, published in a recent issue of the medical journal Lancet, brings support to ophthamologists' belief that wearing contact lenses overnight makes people more susceptible to an infection in the cornea, a transparent layer in the front of the eyeball.

More wearers mean more infections

The number of users of contact lenses -- 28 million in the country -- has grown steadily in the past decade, wrote lead author Dr. Kam Cheng of the Rotterdam Eye Hospital in Rotterdam, the Netherlands. And with that, the number of corneal infections has risen as well.

A corneal infection is the most serious complication that contact-lens wearers face: The infection can lead to permanent loss of vision. The infection and resulting inflammation is usually caused by bacteria, fungi or parasites that proliferate in the eyes of overnight contact-lens wearers.

All contact-lens wearers at some risk, but overnight wearers at highest risk

The researchers pooled information on 92 new cases of corneal infections during a three-month period in 1996. People who wore soft contact lenses for 24 hours at a time or less were more than three times as likely to develop corneal infections than people who took their contact lenses out at night. People who wore their lenses for more than 24 hours at a time were more than 18 times as likely to develop infections.

Therefore, the researchers wrote, overnight use of contact lenses increases the risk of corneal infection. Wearing contact lenses overnight should be discouraged.

Improvements in materials and hygiene have not reduced the risk

People shouldn't rely on advances in contact-lens technology to protect them from developing infections, said Dr. Eugene C. Pogio, an ophthalmologist and executive director of Abt Associates, an eye research institute in Cambridge, Massachusetts. Better contact-lens materials and better solutions to care for the lenses have not decreased the number of infections.

Extended-wear lenses reduce the cornea's ability to protect itself from bacteria and other agents that can cause infections, he said. So preventing infection means wearing contact lenses less frequently and for shorter periods of time.

Doctors treat minor corneal infections with antibiotic eye drops. For more severe cases, doctors prescribe more intensive antibiotic or antifungal treatments to eliminate the infection, according to the National Eye Institute. Some patients may require steroid eye drops, which help to reduce inflammation caused by the infection. Depending on the severity of the case, the infection can take months to treat.

Copyright 1999 by WebMD, Inc. All rights reserved.

Contact Lenses and Other Risk Factors in Microbial Keratitis

American Academy of Ophthalmology
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