Want to keep your eyesight sharp as you age? Eating lots of fish packed with healthy omega-3 fatty acids could help, new research suggests.

Among 1,837 people who had early signs of age-related macular degeneration (AMD), those with the highest consumption of omega-3 fatty acids were 30 percent less likely to progress to the advanced form of the disease over a 12-year period than those with the lowest omega-3 intake, researchers found.

Dr. John Paul SanGiovanni of the National Eye Institute at the National Institutes of Health in Bethesda, Maryland, and his colleagues report their findings in the December issue of the American Journal of Clinical Nutrition.

AMD is a deterioration of the retina that is the leading cause of vision loss among older US adults.

About 1.75 million Americans and 3.35 million Europeans have AMD severe enough to impair their vision, according to the researchers.

While there are some drug treatments for the disease, they add, these medications have limited effectiveness, are expensive, and can lead to serious complications. Because inflammation is likely to be involved in AMD progression, and omega-3 fatty acids have anti-inflammatory effects, they add, these nutrients have the potential to help slow the progress of disease.

To investigate, SanGiovanni and his colleagues analyzed data from the Age-Related Eye Disease Study, a clinical trial run by the National Institutes of Health to investigate nutrition-based approaches to preventing and treating AMD. All of the study participants were free of advanced AMD in at least one eye, but did have some degree of earlier stage disease.

Over the course of 12 years, about 20 percent of people in the current study developed dry AMD, in which the tissue at the center of the retina disappears. Another 32 percent developed wet AMD, or neovascular AMD, in which abnormal blood vessels grow in the macula.

People who consumed the largest amounts of the two main dietary types of omega-3 fatty acids -- docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) -- were about 30 percent less likely to develop either wet or dry AMD than people with the lowest intake, the researchers found.

Those who consumed the most DHA and EPA got about 11 percent of their calories from omega-3s, compared to about 1 percent for people with the lowest intake.

Our results, if confirmed by other studies and extended by clinical trials, may guide the development of low-cost, easily implemented, and widely accepted interventions to prevent the progression to advanced AMD, SanGiovanni and his team conclude.

SOURCE: American Journal of Clinical Nutrition, December 2009.

Medicine