Scientists use light-activated drug in fight against elderly blindness

Published: Saturday, February 06, 1999


Age-related macular degeneration, AMD, is the leading cause of blindness in people over 50.esznosonuld

Now scientists are trying an experimental light-activated drug to help preserve patients' eyesight. Visudyne is not a cure, cautioned Dr. Neil Bressler of Johns Hopkins University. Nothing can restore already-lost vision.

But for early-stage patients, "we may be able to slow down vision loss, or reduce the chance of (AMD) costing them any more vision," said Bressler, who heads a nationwide Visudyne study.

And the National Eye Institute, worried that the graying of America means millions more people are at risk, is pouring $25 million into research to curb the disease. Among the work:

An ongoing trial of 4,800 people is comparing whether vitamins C, E or beta carotene or the mineral zinc can stop the progression of AMD-caused vision loss.

A government-funded study is about to enroll 350 people to see if a new type of surgery to remove a tuft of disease-caused blood vessels could stop the blindness.

In March, the government starts a third study to see if removing drusen - yellow deposits on the retina that are a precursor of AMD - from people's eyes can actually prevent the disease from ever striking.

AMD is a budding epidemic, warns institute director Carl Kupfer: Some 1.7 million sufferers are legally blind already, and the aging population means some 6 million more could go blind in 20 years.

The macula is the light-sensitive layer of tissue in the center of the retina. Two types of AMD destroy it.

"Dry" AMD, which accounts for 90 percent of cases, slowly breaks down the macula's light-sensitive cells. There is no treatment. But the damage occurs very slowly so victims only gradually notice a blind spot in their central vision and don't completely lose sight.

"Wet" AMD is rarer but much worse. New blood vessels form behind the retina, leaking onto the macula and rapidly destroying it. First, straight lines appear wavy. Then sufferers suddenly develop a central blind spot that often progresses to blindness within two years.

The research focuses on wet AMD.


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