Disposable contact lenses are causing thousands of serious eye infections each year despite manufacturers' claims that they are safer than reusable lenses, researchers said Monday.
Overnight use of contact lenses has been known to be associated with an increased risk of infections, the worst of which can lead to blindness.
Disposable lenses were introduced with the idea that they would reduce the opportunities for bacterial contamination because they wouldn't be handled as much and wouldn't be stored in solutions that could harbor germs.
"That idea was simple, easy and wrong," said Dr. H. Dwight Cavanagh, a professor of ophthalmology at the University of Texas Southwestern Medical Center at Dallas.
Speaking at a seminar sponsored by Research to Prevent Blindness, a voluntary organization that supports research, Cavanagh said: "The implication now in mass marketing of disposable lenses is that these things are safe--game over, time out, totally safe. That's not true."
Nearly all American contact-lens wearers wear soft contact lenses, and about 4 million to 5 million Americans wear disposable lenses, Cavanagh said. Those who wear their lenses overnight have a risk of eye infection 10 to 15 times that of users who insert and remove their lenses daily, he said.
Tim Comstock of Bausch & Lomb, one of the nation's largest manufacturers of contact lenses, said the company had not made any special claims for the safety of disposable lenses other than to say they are cleaner and fresher than reusable lenses.
Cavanagh's research has shown that the increased risk of infection occurs because extended-wear soft lenses, disposable or not, do not allow enough oxygen to reach the surface of the cornea. That damages the corneal surface, giving bacteria an opportunity to invade, he said.