Age-related macular degeneration (AMD) is an acquired eye disorder and a leading cause of legal blindness in people over age 60.1 AMD affects the macula (the central part of the retina), which is responsible for providing the clear, sharp vision needed for reading, writing, driving and other visually demanding activities.
The severity of this condition varies depends on the individual patient. Many people with AMD lose some central vision in one or both eyes.
Approximately 90 percent of patients with AMD have a non-exudative (or dry) form of the disease. In this form of the disease, dry, atrophic scars develop in the macular area. Typically, non-exudative AMD patients lose vision gradually.
Only 10 percent of patients develop an exudative (or wet) form of the disease. In the wet form of the disease, fluid beneath the retina leaks. Compared with non-exudative patients, exudative patients lose central vision more rapidly.
Patients with exudative AMD who are identified early in the disease process2 can be treated with laser photocoagulation. Other treatments include photodynamic therapy and surgical transplantation of the macula.
Research suggests that AMD development is linked to depleted macular pigment. This retinal layer efficiently filters out harmful blue wavelengths of light. It also reduces the amount of free radicals in the macular area, which can cause oxidation of cell membranes.3
Researchers theorize that certain antioxidant compounds reduce the effect of these free radicals on the macular pigment and, consequently, may affect the development of AMD.4,5,6 These antioxidants, known as carotenoids, build and maintain the thickness of the retinal pigment layer.
Carotenoids, such as beta-carotene, lutein and zeaxanthin, are a family of colored compounds found in fruits and vegetables. We consume and use 14 different carotenoids in our diet. Lutein and zeaxanthin-found in dark, leafy green vegetables such as spinach, collard greens and kale-are particularly effective in the retinal pigment layer. Studies show that a diet high in these materials have some effect on delaying the advancement of AMD.7,8,9,10
Taking synthetic supplements that contain these carotenoids, along with the vitamins C and E and zinc, has been proven to limit the disease in patients with advanced signs and symptoms of AMD.11 Also, because the method of food preparation can impact your body's ability to fully benefit from these natural sources of carotenoids, taking supplements can help assure people are getting the proper levels.
Antioxidants cannot reverse the damage already caused by AMD, but they may prevent or slow the progression of AMD in certain patients. Dietary supplementation of antioxidants, taken with vitamins C and E and zinc, may be most appropriate for people who:
- Show early evidence of AMD.
- Are over age 50.
- Have a family history of AMD.
- Don't have enough vitamins and minerals in their diet.
Additional studies and data are needed to further define what nutritional and antioxidant therapies and dosages can prevent AMD.
Other risk factors for AMD, although not thoroughly understood, may include smoking, alcohol intake, excessive sunlight and high total cholesterol levels. The American Optometric Association recommends patients reduce their risk of AMD by wearing appropriate sun protection to limit ultraviolet exposure, stop smoking, moderate alcohol consumption, maintain a nutritionally balanced diet, increase consumption of foods or supplements that contain antioxidants, and seek periodic optometric retinal examinations.
- Prevent Blindness America. Vision problems in the U.S. Schaumburg, IL: Prevent Blindness America 1994.
- Cavallerano AA, Cummings JP, Freeman, PB, et al. Optometric Clinical Practice Guideline on Care of the Patient With Age-Related Macular Degeneration. St. Louis: American Optometric Association, 1994.
- Van Der Hagen AM, Yolton DR, Karninski MS, Yolton RL. Free Radicals and Antioxidant Supplementation: A Review of Their Roles in Age-Related Macular Degeneration. J Am Optom Assoc 1993; 64:871-878.
- Hayes KC. Retinal Degeneration in Monkeys Induced by Deficiencies of Vitamin E or A. Invest Ophthalmol 1974; 13:499-510.
- Ham WT, Mueller Ha, Ruffolo JJ et al. Basic Mechanisms Underlying the Production of Photochemical Lesions in the Mammalial Retina. Curr Eye Res. 1984; 3:165-174.
- Organisciak DT, Wang HM, Li Z, Tso MO. The Protective Effect of Ascorbate in Retinal Light Damage of Rats. Invest Ophthalmol 1985; 26:1580-1588.
- Seddon JM, Ajani UA, Sperduto RD, et al. Dietary Carotenoids, Vitamins A, C, and E and Advanced Age-Related Macular Degeneration. JAMA 1994; 272:1413-1420.
- Age-Related Macular Degeneration Study Group. Multicenter Ophthalmic and Nutritional Age-Related Macular Degeneration Study-part 1; design, subjects and procedures. J aM Optom Assoc 1996; 67:12-29.
- Age-Related Macular Degeneration Study Group. Multicenter Ophthalmic and Nutritional Age-Related Macular Degeneration Study-part 2; antioxidant intervention and conclusions. J aM Optom Assoc 1996; 67:30-49.
- The Eye Disease Case-Control Study Group, Antioxidant Status and Neovascular Age-Related Macular Degeneration. Arch Ophthalmol 1993; 111:104-109.
- A Randomized, Placebo-Controlled, Clinical Trial of High-Dose Supplementation With Vitamins C and E, Beta Carotene, and Zinc for Age-Related Macular Degeneration and Vision Loss. Arch Ophthalmol 2001; 119:1417-1436.