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Nutritional supplementation helpful in preventing, slowing ocular disease
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In recent years, increased emphasis has been placed on the role of nutrition in ocular health. Through vitamin supplementation and improved dietary habits, patients can combat and prevent a variety of ocular anomalies.
Researchers are constantly discovering more about vitamin supplements for the eyes, for diseases of both the anterior and posterior segments. Likewise, practitioners are continuing to explore the role of nutritional supplements for ocular health and investigating the latest products.
Antioxidants and zinc
A great deal of data has become available regarding nutrition and macular degeneration, most notably from the Age-Related Eye Disease Study (AREDS).
“Although the AREDS study may be old news, the results demonstrated the efficacy of antioxidants plus zinc in patients with advanced age-related macular degeneration” said Leo P. Semes, OD, FAAO, an associate professor of optometry at the University of Alabama at Birmingham. “This seems to slow the progression of macular degeneration by about 25%.”
Dr. Semes explained that because the macula is exposed to high levels of light and has a high metabolism, there is a great potential for oxidation. “Anything that would counteract or slow that process would be beneficial,” Dr. Semes said. “So, that is how the antioxidants as a class — and vitamins, A, C and E in particular — are useful.”
These nutrients are available in vitamin form, Dr. Semes said, and cited Bausch & Lomb’s Ocuvite vitamins, as well as Medical Ophthalmic’s Maxivision product.
Lutein studies
Dr. Semes also discussed the role of lutein, which has grown in prominence during the past several years. “One of the criticisms of the AREDS study is that it did not include lutein,” he said. “There have been a few studies since then of shorter duration and smaller numbers of patients, but they have demonstrated the efficacy of lutein in treating macular degeneration.”
According to Stuart Richer, OD, PhD, FAAO, chief of the optometry section at DVA Medical Center in Chicago, the importance of lutein is quickly gaining recognition. “Support for the role of this nutrient in eye health is growing, with objective improvement of retinal function (focal ERGs) after short-term supplementation,” he said.
Dr. Richer conducted the Lutein Antioxidant Supplementation Trial (LAST) for atrophic AMD. The study was a prospective, 12-month, placebo-controlled, double-masked, repeated measures and crossover study of lutein vs. lutein/antioxidants. It included 90 subjects, mostly male veterans with atrophic AMD. The subjects were measured for macular pigment optical density (MPOD), lens opacification rating, contrast sensitivity, low-luminance, low-contrast visual acuity and activities of daily living related to AMD.
The subjects were divided into three treatment groups: one receiving 10 mg of lutein, one receiving 10 mg of lutein/antioxidants and a placebo group.
At 12 months, the average MPOD had increased on average by 50% in both the lutein and lutein/antioxidant treatment groups. In addition, there was improvement in some measures of visual function including glare recovery, contrast sensitivity and distance/near visual acuity in both groups.
“The Veterans’ LAST Study was not designed to look at prevention of vision loss and/or prevention of advanced AMD or the progression of AMD,” Dr. Richer said. “That was the purpose of AREDS. Our research evaluates visual intervention for atrophic AMD patients, for whom visual improvement options are limited to low vision rehabilitation.”
Omega-3 and omega-6 fatty acids
The dietary and supplemental intake of omega-3 and omega-6 fatty acids has been shown to be effective in preventing and managing dry eye, blepharitis and meibomianitis.
Benjamin C. Lane, OD, MS, MPH, FAAO, discussed the role of these food oils in terms of ocular health. The omega-3 chain has alpha-linolenic fatty acid (ALA — as in walnut oil, flaxseed oil) as its dietary precursor, which, with proper nutrition, the body can convert to eicosapentaenoic (EPA) fatty acid and the retina-important DHA.
The omega-6 chain has gamma-linolenic fatty acid (GLA — as in borage oil) as its dietary precursor, which, with proper nutrition, can be converted eventually to arachidonic fatty acid (AA).
“There is controversy as to which is more important for dry eye relief, omega-3 or omega-6 supplementation,” Dr. Lane noted. “Statistically, on the average U.S. diet, more patients appear to benefit from omega-3 supplementation. The fact that a minority benefit more from omega-6 oils appears to be due to individual differences in lifestyle amd balance between omega-3 and omega-6 in human tissues.”
Adequacy and balance appear to be keys, Dr. Lane said. He pointed out that underweight seniors are at increased risk of being low in essential fatty acids and at risk for dry skin as well as dry eyes.
“As to the balance between omega-3 and omega-6, one of the ratios we look at is their conversion products EPA:AA. A high ratio increases risk for hemorrhaging; a low ratio increases the risk for thrombosis,” he said. “But many factors are involved in maintaining an ideally normal tear film. In Hart, Lane and Josephson, et al (1987), we found that a high ratio of dietary sucrose to low food-folic acid intake resulted in poor tear film break-up time (TBUT).”
Low food potassium intake also was significantly associated with TBUT less than 10 seconds, Dr. Lane said.
“Many years earlier, I agreed with Ned Paige, OD, of Toronto, that vitamin B6 adequacy is required for a normal tear film, but that also adequate ascorbic acid, vitamin A, calcium and magnesium are essential nourishment via the tear film to maintain corneal integrity.”
Dr. Lane said omega-6 fatty acids tend to be ingested in greater quantity by the average person than omega-3s. “Most Americans who put dressing on their salads usually do a pretty good job of getting omega-6 fatty acids,” he said. “It can also be found in supplements such as evening primrose oil.”
Walnut oil is a good source of omega-3 fatty acids, Dr. Lane said, as is flaxseed oil. “Supplementation is valuable for much more rapid recovery from deficit states and insurance to protect against dry eye recurrences. A good dietary habit would be to try to obtain as much as we can, simply by eating really fresh, raw vegetables and nuts that contain these oils in the presence of the vegetables’ own protective antioxidant enzymes — consumed before they can become oxidized.”
Omega-3 study
A team of scientists headed by Debra A. Schaumberg, OD, from the Schepens Eye Research Institute, the Division of Preventative Medicine, Brigham and Women’s Hospital, and the Harvard Medical School, has examined Women’s Health Study data on 32,470 female health care professionals between the ages of 45 and 84.
The researchers looked at dietary intake of essential fatty acids, using a validated food frequency questionnaire, and incidence of clinically diagnosed dry eye. The results of the study, to be presented at ARVO and funded in part by a grant from Advanced Vision Research, suggested that women with a higher dietary intake of omega-3 fatty acids are at a decreased risk of developing dry eye, reported Jeffrey P. Gilbard, MD, founder and CEO of Advanced Vision Research, makers of TheraTears Nutrition (omega-3 supplement with EPA and DHA-enriched flaxseed oil, fortified with vitamin E.)
For Your Information:
- Leo P. Semes, OD, FAAO, is a Primary Care Optometry News Editorial Board member and an associate professor of optometry at the University of Alabama at Birmingham. He can be reached at 1716 University Blvd., Birmingham, AL 35294-0010; (205) 934-6773; fax: (205) 934-6758.
- Stuart Richer, OD, PhD, FAAO, is chief of the Optometry Section of DVA Medical Center, and associate professor of family and preventive medicine at FUHS/Chicago Medical School. He can be reached at 3001 Green Bay Road, N. Chicago, IL 60064; (847) 688-1900; fax: (847) 578-6914.
- Benjamin C. Lane, OD, MS, MPH, FAAO, is director of Nutritional Optometry Institute. He can be reached at 16 North Beverwyck Road, Lake Hiawatha, NJ 07034-0131; (973) 335-0111; fax: (973) 541-1649. Neither Dr. Semes, Dr. Richer nor Dr. Lane has any direct financial interest in the products mentioned in this article, nor are they paid consultants for the companies mentioned.
- Jeffrey Gilbard, MD, is president and CEO of Advanced Vision Research. He can be reached at 12 Alfred St., Suite 200, Woburn, MA 01801; (781) 932-8327; fax: (781) 935-5075.