Macular degeneration is a disease that damages the eyes and causes vision loss. It is one of the leading causes of visual impairment and blindness in Americans over age 65, and is often referred to as age-related or adult macular degeneration (AMD). There is no cure for AMD, and treatment is somewhat limited.
The macula is the central part of the retina of the eye that makes it possible to see the fine detail needed for reading, driving, and recognizing faces. AMD causes the macula to malfunction or deteriorate. The result is loss of sight in the center of the visual field; fortunately, peripheral vision is rarely affected.
Most cases of AMD are due to a combination of genetic and environmental factors. In addition to age, research points to several traits and habits associated with an increased risk of AMD, including:
- Family history
- Fair skin or light-colored eyes
- Exposure to sunlight
- Cataract surgery
Any factor that increases the presence of free radicals also increases risk for macular degeneration. Free radicals are naturally produced when your body processes food for energy. They can also result from other stresses on the body, such as exposure to ultraviolet rays of the sun, smoking, and environmental pollution. Free radicals are unstable molecules that may cause damage to DNA and other molecules. Over time, this damage may lead to AMD or many other diseases, such as cancer.
In addition, any factor that undermines the circulatory system increases risk for macular degeneration. The macula needs a rich blood supply. Therefore, any interference with it, such as smoking or a sedentary lifestyle, can increase risk of AMD. Nutritional Supplements Nutritional supplements and antioxidants in particular, have been the focus of much research on the prevention of AMD. Antioxidants are thought to protect cellsin the eye and elsewherefrom free radical damage. High levels of antioxidants are found naturally in fruits and vegetables, as well as in other foods including egg yolks; nuts and grains; and some meats, poultry, and fish. They can also be concentrated in supplements. Though the benefits of supplementation are often extolled in the media, recent clinical studies have had inconsistent results. While some studies reveal a link between higher levels of antioxidants and lower risk of AMD, many do not. Antioxidants that have been shown to protect the macula in research studies include vitamin C, vitamin E, zinc, beta-carotene, and flavonoids. Mixture of Zinc and Antioxidants For example, a major clinical study sponsored by the National Institutes of Health was designed to determine whether high levels of antioxidants and zinc could reduce the risk of developing advanced macular degeneration. For six years, researchers followed 3,600 people with varying stages of AMD. The results showed that high doses of vitamin E, vitamin C, beta carotene, and zinc lowered their risk of developing advanced AMD by 25%. The supplements did not seem to have any effect on people with no evidence of the disease or very early stages of the disease.
Carotenoids Two lesser known carotenoidslutein and zeaxanthinare present in a concentrated area in the macula itself. Theoretically, in addition to preventing AMD by reducing the damaging effects of free radicals, these antioxidants are thought to prevent AMD by protecting the eye against the damaging effects of ultraviolet and blue light. Lutein and zeaxanthin are found mostly in green leafy vegetables and corn. Flavonoids Flavanoids, found in high levels in tea and red wine, may be particularly helpful because they act as powerful antioxidants and also thin the blood, improving circulation. Living a Healthful Lifestyle The following recommendations for a healthful lifestyle apply to those with AMD and those who are at risk of developing the disease: Eat Right Although scientific evidence is inconclusive, a diet rich in nutrients may lower your risk of AMD. Try to ingest a high level of antioxidants by eating at least five servings a day of varied fruits and vegetables. Green leafy vegetables such as spinach, kale, and collard greens are particularly recommended. Engage in Regular Physical Exercise Cardiovascular exercise improves the bodys overall health and helps maintain a healthy circulatory system.
Reduce Sun Exposure Always wear a hat or cap when outdoors, and wear sunglasses or protective lenses all year. See Your Doctor To treat hypertension, high cholesterol, or other heart-related conditions.For regular eye examsonce every other year before age 50, and every year after that.Before taking any type of antioxidant supplement. RESOURCES: American Macular Degeneration Foundation http://www.macular.org Foundation Fighting Blindness http://www.blindness.org Lighthouse International http://www.lighthouse.org Macular Degeneration Partnership http://www.amd.org Prevent Blindness America http://www.preventblindness.org CANADIAN RESOURCES: Canadian Family Physician http://www.cfpc.ca/cfp/ Canadian Ophthalmological Society http://www.eyesite.ca/ References: Adult macular degeneration. Macular Degeneration Partnership website. Available at: http://www.amd.org. Accessed October 9, 2005. Antioxidant vitamins and zinc reduce risk of vision loss from age-related macular degeneration. National Eye Institute, Press Release (October 12, 2001). Available at: http://www.nei.nih.gov/amd. Accessed October 9, 2005.
The AREDS formulation and age-related macular degeneration: are these high levels of antioxidants and zinc right for you? National Eye Institute, Press Release (October 12, 2001). Available at: http://www.nei.nih.gov. Accessed October 9, 2005. Basic anatomy of a normal human eye. The American Macular Degeneration Foundation website. Available at: http://www.macular.org. Accessed October 9, 2005. Beers, MH, Fletcher AJ, Jones TV, et al. The Merck Manual of Medical Information. Second Home Edition. Merck Research Laboratories: Whitehouse Station, NJ; 2003. Dry macular degeneration. The American Macular Degeneration Foundation website. Available at: http://www.macular.org. Accessed October 9, 2005. Frequently asked questions. Adult macular degeneration. MD Foundation, Inc. Available at: http://www.eyesight.org. Accessed October 9, 2005. Macular degeneration. American Academy of Ophthalmology. Available at: http://www.aao.org. Accessed October 9, 2005. Macular degeneration. Dynamed website. Available at: http://dynamedical.com/dynamed.nsf?opendatabase. Accessed October 9, 2005.
Macular degeneration. The Mayo Clinic website. Available at: http://www.mayoclinic.com/invoke.cfm?id=DS00284. Accessed October 9, 2005. Macular degeneration. University of Maryland Medical Center website. Available at: http://www.umm.edu/altmed/consconditions/maculardegenerationcc.html. Accessed October 31, 2005. Wet macular degeneration. The American Macular Degeneration Foundation website. Available at: http://www.macular.org. Accessed October 9, 2005. Last reviewed January 2008 by Alexander J. Anetakis, MD Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.