Can eyedrops prevent or treat cataracts?

A. Cataracts are a clouding of the lens in the eye, which interferes with normal vision by blurring the light passing through the lens to the retina at the back of the eye. They usually emerge with age and are very common; by age 80, more than half of Americans can expect to have a cataract or have been treated for one.

Sherleen Chen, director of the cataract and comprehensive ophthalmology service at Massachusetts Eye and Ear Infirmary, says that the only effective known cure for cataracts is surgery. It usually involves making a small incision in the eye and using a tiny probe to deliver ultrasound waves that break up the lens, which is then removed. In some cases, a larger incision is made to remove the lens manually. In most cases, the surgeon replaces the lens with an artificial one.

There has long been interest in finding less invasive ways to prevent or treat cataracts, through drops or an oral drug or supplement. The Internet is full of links to products that claim to prevent or treat cataracts. But, says Chen, “There have been no drops that have been proven to prevent . . . or even treat cataracts.’’

Part of the problem is that it’s still unknown exactly why lenses become cloudy. Research suggests that a process called oxidative stress may be to blame, and several studies have investigated antioxidant eyedrops as well as oral antioxidant supplements for cataract prevention. One of the more popular agents is N-acetylcarnosine, which was shown in preliminary research to have anti-cataract potential, but its safety and effectiveness have not been proven in larger studies.