It may be possible for patients to reduce the risk of progression of age-related macular degeneration by following a plan that emphasizes a diet containing foods high in omega-3 fatty acids, lutein, and zeaxanthin, following a healthy lifestyle, and protecting the eyes from damaging effects of blue light.
Dr. Gelb, who practices in Woodbridge, NJ, advocates a 10-point plan aimed at decreasing the overall risk of AMD as well as the risk of progression.
"I recommend my plan or part of my plan to anyone who has AMD and one or a combination of the following risk factors: family history, smoking, obesity, low macular pigment, advanced age, elevated C-reactive protein, elevated homocysteine, cardiovascular disease, few small drusen, and chronic sunlight exposure," he said.
"AMD is also a nutrition-responsive disease, but the sad fact is that 92% of us are deficient in at least one or more central vitamins or minerals, and only 2% of us eat our green vegetables on a daily basis," he said. "Eight million of us are at risk of getting advanced macular degeneration, and that's where we (optometrists) could play a role in helping prevent it or at least slow it down. The number one risk factor for AMD is age, and as the population ages we need techniques to prevent and detect this terrible disease."
Evidence of the influence of nutrition on eye health has been accumulating for decades, and researchers continue to probe the complex interactions in this relationship. For Dr. Gelb, the particularly important dietary factors are what he called the "dynamic trio:" lutein, zeaxanthin, and omega-3 fatty acids.
"Lutein, zeaxanthin, and omega 3s have a far superior effect in decreasing overall risk of AMD than vitamin C, vitamin E, and beta-carotene, considered to be the antioxidant component in the original [Age-Related Eye Disease Study (AREDS)]," he said.
"Most experts agree," Dr. Gelb continued, "that zinc is the most integral part of the original AREDS formula because of its important role in controlling inflammation by enhancing the body's natural antioxidant function. Zinc decreases AMD progression almost as much as antioxidants and zinc together. Zinc alone reduced the risk 21% versus 25% for a combination of antioxidants and zinc in the AREDS study."
Studies of lutein, zeaxanthin, and omega-3 studies fall into three categories: dietary, plasma/dietary, and supplements. Most have shown a reduced risk of advanced AMD and cataracts. The Lutein Antioxidant Supplement Trial (LAST) study, along with other studies, showed that lutein alone or lutein combined with zeaxanthin and additional antioxidants improved visual acuity, contrast sensitivity, blue-yellow threshold, scotomas, and metamorphosia.
It is important to note that lutein and zeaxanthin affect visual function in slightly different ways because of their different locations of concentration within the macula.
Several studies have indicated that the omega-3 fatty acids EPA and DHA have protective or preventive benefits for visual health as well as overall health. A meta-analysis of nine studies provided data on a total sample of 88,974 people, including 3,203 AMD cases. A high dietary intake of omega-3 fatty acids was associated with a 38% reduction in the risk of late AMD. Fish intake at least twice a week was associated with a reduced risk of both early and late AMD.