Disposable lenses can cause infection
ORLANDO, Florida (UPI): Disposable contact lenses, developed to reduce the risk of serious eye infections, fail to keep the eye free of potentially damaging bacteria, a researcher said earlier this week.
After a person has worn lenses for only six hours, researchers can find bacteria associated with uncommon but serious corneal ulcerations, said Dr. H. Dwight Cavanagh, professor and vice- chairman of the department of ophthalmology at the University of Texas Southwestern Medical Center in Dallas.
Cavanagh said the idea of using disposable lenses to overcome infection risks was "simple, easy and wrong."
People who wear lenses overnight increase their risk of eye infections tenfold, Cavanagh told a conference sponsored by the New York-based, non-profit organization Research to Prevent Blindness.
About 27,000 Americans each year develop infections that can leave pits and holes in the eye's clear outer covering, a condition called ulcerative keratitis, that can dim eyesight. Doctors find the problem in four out of 10,000 people who wear lenses overnight.
If diagnosed early, most cases can be treated successfully, but "they can certainly ruin your week," because of pain and frequent medication, Cavanagh said.
Manager of the research clinic for contact lens maker Bausch & Lomb, Tim Comstock, said, "Disposable lenses have helped some, but I would agree with Dr. Cavanagh that we have not eliminated the problem."
Manufacturers created disposable lenses after studies of infection lent credibility and urgency to the search for a safer and more convenient alternative to reusable lenses. The U.S. Food and Drug Administration approved disposable for periods of steady wear up to six nights.
Throwing away a lens a week means less buildup of filth. Comstock said that when companies first introduced the disposable lens, they thought hygiene would be the main factor in reducing infections.
Cavanagh said, "Unfortunately, two recent well-documented studies report that extended wear of disposable lenses does not offer a safer alternative when compared with daily wear."
He said the current generation of hard or rigid lenses is far less likely than soft contacts to cause ulcerative keratitis.
Studies have shown that safety depends in large part on how much oxygen passes through the lens. The new rigid lenses provide almost as much oxygen as wearing no lenses at all, studies show.
Unfortunately, said Cavanagh, users of contact lenses overwhelmingly prefer the soft contacts.
"Bausch & Lomb is very aware of the need for more oxygen, and we're addressing it in research," said company spokeswoman Holly Echols in the Rochester, New York, headquarters.