How to Prevent Age-Related Macular Degeneration
Age-related macular degeneration (AMD) is a condition that affects the macula—the central, most critical part of the retina for providing sharp vision. In the United States, it is the leading cause of severe and irreversible loss of central vision in people over age 50. More than 7 million Americans have some evidence of AMD; more than 2 million have late, or advanced, AMD.
The prevalence of severe vision loss from AMD increases with age, and most people with impaired vision from AMD are 60 or older. Fortunately, most cases of AMD do not result in severe vision loss, which is commonly defined as a decline in visual acuity to 20/200 or less. Visual acuity of 20/200 corresponds to being able to see only the big “E” on a traditional eye chart. People who can see no better than 20/200 despite corrective aids, such as glasses or contact lenses, are considered legally blind.
Some studies indicate that people can take steps to prevent severe or late-stage age-related macular degeneration (AMD). 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 ages 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. The likelihood of disease worsening was reduced: 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 over a 10-year period; the supplement also reduced the risk of related vision loss by about 19 percent. The findings were published in 2001 in the Archives of Ophthalmology (now JAMA Ophthalmology.)
Taking those vitamin and mineral supplements may 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 international units (IU) of vitamin E, 15 mg of beta-carotene, 80 mg of zinc oxide and 2 mg of cupric oxide. Sold under the brand names PreserVision and ICaps AREDS Formula, both are available without a prescription. If you smoke or have recently quit, do not use this supplement because beta-carotene in supplement form has been found to increase the risk of lung cancer in smokers.
Some 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 might help prevent AMD. These studies prompted the National Eye Institute, part of the National Institutes of Health, to sponsor the AREDS2 trial, a clinical trial that evaluated whether lutein/zeaxanthin (carotenoids) or fish oil in supplement form would reduce the progression of AMD.
More than 4,000 participants at risk for progression to advanced AMD were followed for five years in AREDS2. Results published in 2013 in the Journal of the American Medical Association showed that adding omega-3 fatty acids did not improve the AREDS formula. The plant-derived antioxidants lutein and zeaxanthin also had no overall effect on AMD when added to the combination; however, the researchers suggested they were potentially safer than the related antioxidant beta-carotene.
Today, use of the AREDS or AREDS2 supplements is recommended care for all patients with intermediate or advanced AMD. However, smokers and former smokers should take only the AREDS2 supplements, available commercially as PreserVision AREDS 2 Formula.
Certain dietary supplements are marketed as being helpful specifically for vision health, but a recent study revealed that many of the best-selling eye supplements don’t even contain precisely the same ingredients in the same dosages as have been shown to help slow AMD.
In a 2015 study published in Ophthalmology, researchers found that only four products were identical to either the AREDS or AREDS2 formula: Bausch and Lomb’s PreserVision Eye Vitamin AREDS Formula tablets, PreserVision Eye Vitamin AREDS Formula soft gels, and PreserVision AREDS 2 Formula; and Alcon Laboratories’ ICaps Eye Vitamin AREDS Formula. 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 tended to have a lower rate of those same features.
Those associations do not prove that reducing exposure to sunlight lowers the risk of developing AMD. Nonetheless, protecting your eyes from ultraviolet rays by wearing sunglasses and a wide-brimmed hat when outdoors is worthwhile, because doing so protects against cataracts.
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 those conditions (and to stop smoking if you’re a smoker) is wise because of their impact on your overall health.