Age-Related Macular Degeneration Prevention
Some studies indicate that people can take steps to prevent severe or late-stage AMD or slow its progression. The most convincing evidence supports taking dietary supplements. The effect of dietary supplements on the risk and progression of AMD was investigated in the Age-Related Eye Disease Study (AREDS), which included more than 3,500 people age 55 to 80.
For an average of six years, participants took dietary supplements containing high doses of antioxidants, zinc, antioxidants plus zinc, or a placebo. None of the dietary supplements reduced the risk of developing AMD in the first place. But they did affect the risk that the disease would get worse: Among those with intermediate AMD (drusen deposits of a particular size and area) in one or two eyes or advanced AMD in one eye only, the supplement containing antioxidants plus zinc reduced the risk of progressing to more advanced AMD by about 25 percent.
Taking these vitamin and mineral supplements will not prevent AMD in healthy people or protect against the progression of AMD in people with early AMD. But people with unilateral or bilateral intermediate or unilateral advanced AMD may benefit from the supplements studied in the AREDS trials and should ask their doctor about them.
The antioxidant plus zinc supplement used in the study contained
- 500 mg of vitamin C
- 400 IU of vitamin E
- 15 mg of beta-carotene
- 80 mg of zinc oxide
- 2 mg of cupric oxide
Sold under the brand names Ocuvite PreserVision and ICaps AREDS Formula, both are available without a prescription. If you smoke or have recently quit, do not use this supplement without first talking with your physician because beta-carotene in supplement form has been found to increase the risk of lung cancer in smokers.
The National Eye Institute, part of the National Institutes of Health, is now sponsoring a clinical trial (called AREDS2) to evaluate whether lutein/zeaxanthin (carotenoids) or fish oils will reduce the progression of AMD. Other studies have suggested that eating fewer simple carbohydrates, like sugar and white bread, and more fruits and vegetables high in carotenoids, especially those high in beta-carotene (carrots, spinach, and cantaloupes, for example), as well as foods such as fatty fish that are high in omega-3 fatty acids actually might help prevent AMD.
These studies were used to justify the new AREDS2 trial, which is testing the effects of additional carotenoids and fish oil in supplement form. The AREDS2 study has recruited more than 4,000 participants who will be followed for five years.
In addition, some studies have tested whether there is an association between sun exposure and AMD. In the Beaver Dam Eye Study, people who in their teens and 20s spent at least five hours a day outside during the summer had twice the rate of some features of AMD as those who were outside less than two hours a day. Those who wore hats and sunglasses, on the other hand, tended to have a lower rate of those same features.
These associations do not prove that reducing exposure to sunlight lowers the risk of developing AMD. Nonetheless, protecting your eyes from ultraviolet (UV) rays by wearing sunglasses and a wide-brimmed hat when outdoors is probably worthwhile, because this may protect against cataracts.
A five-year trial completed in late 2006 established that low-powered laser treatment is of no benefit in preventing the progression of AMD. A large study still under way is investigating whether injections of the drug anecortave acetate can prevent new blood vessel growth.
Other suspected risk factors for AMD include high cholesterol levels, obesity, and coronary heart disease. Research also suggests that smokers with early AMD are more likely than their nonsmoking counterparts to progress to advanced AMD. Although the degree of impact these risk factors have is unclear and appears to be modest, taking steps to lower your risk of these conditions and to stop smoking if you're a smoker is wise because of their impact on your overall health.