Q. I was recently diagnosed with macular degeneration and am concerned about it progressing and losing my eyesight. What is macular degeneration, and what can I do to preserve my sight? Are supplements helpful?

A. Age related macular degeneration (AMD) is the leading cause of blindness and visual impairment in Americans over 60. A progressive disease, AMD is particularly debilitating because it affects the central part of the retina, known as the macula, which is essential for seeing fine detail.

The incidence of AMD increases with age and is associated with the deposition of drusen, which is composed of lipids and proteins, within the retinal layers in the macula. Though a few small drusen may not cause much visual distortion, as AMD progresses drusen become larger and more numerous. This causes the center of the vision to become distorted and blurry, making tasks involving fine visual acuity, such as reading, difficult.

There are two forms of AMD -- wet and dry. The most common, dry macular degeneration, is associated with the slow accumulation of drusen and a slow decline in visual acuity. In wet AMD, fluid leaks from tiny blood vessels under the macula, often causing sudden loss of vision. Note that wet and dry AMD may coexist, and dry AMD may progress to wet at any time.

Major advances in treatments for wet AMD in the past decade include development of injectable medications that inhibit growth of the leaky blood vessels. Although there are no similar medical treatments for dry AMD, in randomized clinical trials the National Eye Institute found vitamins can help slow disease progression.

The original Age-Related Eye Disease Study (AREDS), published in 2001, examined the effects of vitamins and minerals on AMD. After more than 5 years, participants receiving both 500 mg Vitamin C, 400 IU Vitamin E, 15 mg beta carotene and 80 mg zinc showed a statistically significant decrease in progression to advanced AMD.

A follow-on study, AREDS2, published earlier this year, investigated altering the AREDS formula by adding lutein and zeaxanthin, the primary carotenoids in the eye, and omega-3 fatty acids. Other changes included reducing the amount of zinc to 25 mg, and removing beta carotene, since studies suggest it may increase cancer risk in smokers.

Results from AREDS2 showed that reduced amounts of zinc were equally effective, and adding lutein and zeaxanthin benefited two subgroups: 1) those taking AREDS1 formula without beta carotene and 2) those with low levels of lutein and zeaxanthin in their diet. Adding omega-3 fatty acids did not further reduce the progression to advanced AMD.

Since AMD is a chronic and progressive condition, it's important to have frequent discussions with your eye care specialist, who can advise you regarding what treatments or supplements would be most appropriate.

Sources:

1. Daily Camera:
   Macular Degeneration.