More than nine million Americans have age-related macular degeneration (AMD), the leading cause of vision loss for people over 60. But new research is helping to turn the tide on this disease.
Age-related macular degeneration (AMD) destroys sharp central vision, which is necessary for seeing objects clearly and for common daily tasks such as reading and driving.
Nearly two million people have the advanced form of the disease, called wet AMD, which can cause rapid vision loss in both eyes. An early symptom of wet AMD is that straight lines may appear wavy and distorted, and images on TV may appear blurry. It is caused when abnormal blood vessels grow beneath the retina and leak blood and fluid under the macula, the small area near the center of the retina responsible for central vision.
Initial Study Encouraging
In 1992, the National Eye Institute (NEI) launched the Age-Related Eye Disease Study (AREDS), a nationwide clinical trial. Results from the study were published in 2001 and showed that an experimental combination of three anti-oxidant vitamins (C, E, and beta carotene) and the minerals zinc and copper reduced the risk of progressing to advanced AMD by 25 percent and the risk of moderate vision loss by 19 percent.
“The results were of public health significance,” says AREDS lead investigator Emily Chew, M.D., deputy director of NEI’s Division of Epidemiology and Clinical Research. “About seven million people are at risk of developing AMD in the next five years, so you could reduce the risk of developing advanced AMD and its accompanying vision loss by 300,000 people if all seven million took the AREDS supplement. That’s pretty big savings in health care and productivity.”
Foods Lower AMD Risk
Several years ago, as a follow-up to AREDS, NEI and its partner clinical centers conducted AREDS2, a study to determine how high doses of anti-oxidant and fish oil supplements affect the risk of advanced AMD, the need for cataract surgery, and moderate vision loss. Four thousand participants between the ages of 50 and 85 who have AMD were enrolled for the study. The trial was “double-masked,” meaning neither investigators nor participants know who is getting which combinations of the supplements or a placebo.
From earlier studies, NEI researchers knew that adults eating kale, mustard greens, collard greens, and raw or cooked spinach (vegetables high in lutein and zeaxanthin, two anti-oxidants from the same family as beta carotene), were at considerably less risk of developing advanced AMD than those who didn’t. And adults consuming more sources of the omega-3 fatty acids DHA and EPA (found in fish, especially salmon) also appeared to be at less risk.
Over the next several years, researchers will be testing the effects of the two kinds of nutrients—the vegetable-derived vitamins lutein/zeaxanthin (vitamins in the carotenoid family), and the fatty acids DHA and EPA—in four participant groups. One group is to receive lutein and zeaxanthin supplements; one will get DHA and EPA; one will get both the vitamins and the fatty acids; and a fourth (control) group will get a placebo. All participants will be given the choice of also taking the initial AREDS combination of vitamins (C, E, and beta carotene) and minerals (zinc and copper).
For more information about participating in vision-related clinical trials, visit www.nei.nih.gov/eyeclinic.