More than 19 million Americans have visual impairment—meaning impairment that cannot be corrected by eyeglasses or contact lenses—and about 700,000 are blind. Age-related macular degeneration, cataract, diabetic retinopathy, and glaucoma are the main causes of visual impairment and blindness in older Americans.
What the Science Says
- Age-Related Macular Degeneration (AMD). AMD is a common eye condition among people age 50 and older. It is a leading cause of vision loss in older adults. It gradually destroys the macula, the part of the eye that provides sharp, central vision needed for seeing objects clearly. Treatment is only partially effective. The National Institutes of Health sponsored a major study called the Age-Related Eye Disease Study (AREDS), which looked at whether a dietary supplement could reduce the risk of developing AMD, and a second study, called Age-Related Eye Disease Study 2 (AREDS2), which tested changes to this dietary supplement.
- AREDS showed that a dietary supplement containing high doses of vitamins C and E, beta carotene, and zinc may delay the development of advanced AMD in people who are at high risk because they either have (1) intermediate-stage AMD in one or both eyes or (2) advanced AMD in one eye but not the other.
- AREDS2 investigated several modifications of the original AREDS supplement formula in people with AMD who were at risk for progressing to the advanced stage of the disease. The results of this study showed that
- Adding omega-3 fatty acids (fish oil) did not improve the effectiveness of the supplement combination.
- Reducing the amount of zinc or omitting beta-carotene from the supplements did not decrease their effectiveness.
- Adding lutein and zeaxanthin (two carotenoids found in the eye) to the supplements improved their effectiveness in people who were not taking beta-carotene and those who consumed only small amounts of lutein and zeaxanthin in foods. The results also suggested that the supplements might be improved by substituting lutein and zeaxanthin for beta-carotene.
- Cataracts. A cataract occurs when the lens of the eye becomes clouded, causing blurring or discoloration of vision. If vision loss from a cataract becomes severe enough to interfere with normal activities, surgery to remove the lens and replace it with an artificial one may be needed. Studies on supplements of antioxidants (vitamins C and E and beta-carotene) indicate that these supplements do not prevent cataracts or slow their progression.
- Diabetic Retinopathy. In diabetic retinopathy, an eye disease that occurs as a complication of diabetes, the blood vessels of the retina become damaged. This can cause blurring of vision and vision loss. No dietary supplements have been shown to be helpful for diabetic retinopathy.
- Glaucoma. Glaucoma can damage the optic nerve, resulting in a loss of vision, starting with peripheral (side) vision. Early detection and treatment of glaucoma are important. Researchers have studied several dietary supplements for glaucoma, including Ginkgo biloba, coenzyme Q10, melatonin, resveratrol, and antioxidants. However, the amount of evidence is limited, and none of these supplements has been proven to be helpful.
Side Effects and Risks
- It’s important to follow your eye care professional’s instructions for treating eye conditions. Don’t use unproven approaches to replace conventional medical treatments.
- Antioxidant and zinc supplements are recommended only for some people who have AMD, not all. For example, if you have early-stage AMD, they are not recommended for you. If you have AMD, ask your eye care professional whether taking supplements is advisable.
- Keep in mind that dietary supplements can cause health problems if not used correctly or if used in large amounts, and some may interact with medications you take.
For more information on eye health, visit the National Eye Institute (NEI) Web site.