March 14, 2007 -- A team of investigators at Washington University School of Medicine in St. Louis and other centers around the United States is evaluating dietary supplements to determine if they can prevent some of the damage from age-related macular degeneration (AMD), a leading cause of blindness in Americans over the age of 65.

Called AREDS2 (Age-Related Eye Disease Study 2), the National Eye Institute-funded trial follows a previous study that concluded dietary supplements containing antioxidants and zinc reduced risk of progressing from moderate to advanced disease by about 25 percent over five years.

"The original study, and some smaller studies, also noticed potential protective effects from other dietary supplements," says Rajendra S. Apte, M.D., Ph.D., assistant professor of ophthalmology and visual sciences and principal investigator for AREDS2 at the Washington University site. "The numbers of patients involved have been too small to determine whether these supplements really help, but the results are promising enough to investigate."

Apte and other vision researchers around the country are recruiting 4,000 patients with age-related macular degeneration between the ages of 50 and 85. To qualify for the study, patients must have either moderate disease in both eyes or advanced disease in one eye. Those are patients at the highest risk of losing significant vision and experiencing progression of their disease over the next five years. Investigators will follow study patients for at least that long.

All subjects recruited into the trial will be eligible to receive the antioxidants and zinc supplements that were shown to reduce risk in the first study. Some patients also will receive certain omega-3 fatty acids that are contained in fish oils, and others will take supplements containing either lutein and zeaxanthin that normally are made in the retina.

"The retina and the macula are rich with compounds such as lutein and zeaxanthin, and there is some preliminary, albeit non-randomized, evidence suggesting these substances may be protective against certain eye diseases," Apte says. "Omega-3 fatty acids from fish oils also might help, but we don't yet have a clear answer because none of these supplements have been studied within the context of a randomized trial."

There are two major forms of age-related macular degeneration, the more common "dry" form of the disease and the less common "wet" form. The wet form, which is the more damaging of the two, involves the growth and leakage of abnormal blood vessels beneath the retina. Although the wet form of the disease accounts for only about 10 percent of cases, it is responsible for up to 90 percent of the vision loss associated with the disease. Apte says the goal of the trial and most of his other research is to keep patients with the dry form from progressing to the wet form of the disease.

For more information about AREDS2 and Apte's other ongoing studies, call the Barnes Retina Institute at (314) 367-1181.