Antioxidant vitamins and zinc may reduce the impact of age-related macular degeneration, according to a study by researchers at the Wilmer Eye Institute and 10 other institutions throughout the United States.
Among people at high risk for late-stage AMD (those with intermediate AMD or advanced AMD in one eye) and central vision blindness in both eyes, a dietary supplement of vitamins C, E and beta carotene along with zinc lowered the risk of progressing to advanced disease by about 25 percent. The daily supplements also reduced the risk of vision loss by about 19 percent. By contrast, the supplements had no preventive effects against development of cataracts or for people without AMD or early AMD only.
Results of the Age-Related Eye Disease Study, supported by the National Eye Institute, are published in the October issue of Archives of Ophthalmology.
The study looked at 4,757 adults ages 55 to 80 with varying levels of AMD. More than 470 participated in AREDS trials at Hopkins.
Susan B. Bressler, professor of ophthalmology, served as the Wilmer Eye Institute's principal investigator. She was surprised by the findings, she says, since preliminary studies did not suggest a consistent relationship between supplements and AMD.
"Until now, there has been no proven treatment to slow the progression of disease and possible vision loss in people with the non-neovascular or dry form of AMD," she says. "The benefit of dietary supplements seen in our study was modest. However, given that they were relatively nontoxic and the fact that there are no other proven options for early intervention, these findings provide an exciting preventive measure we can offer our patients."
Bressler cautions that dietary supplements are not a blanket cure for all cases of AMD, and that patients should consult their eye care provider to learn if these findings are relevant to them. "These supplements were shown effective only in patients with specific manifestations of the dry form of AMD. All patients should check with their eye care provider to determine if they may specifically benefit from these supplements."
The supplements contained 500 milligrams of vitamin C, 400 milligrams of vitamin E, 15 milligrams of beta carotene, 80 milligrams of zinc as zinc oxide and two milligrams of copper as cupric oxide.
AMD is the leading cause of blindness among older adults in developed countries.