The lens of the eye focuses an image of the world on a portion of the retina called the macula, the area of finest visual perception. Gradual deterioration of the macula is called macular degeneration. After cataracts, damage to the macula is the second most common cause of visual impairment in those over 65. Smoking, high blood pressure, and atherosclerosis are associated with progressive damage to the macula. Ultraviolet light may also play a role by creating harmful free radicals in the eye.
In the most common form of macular degeneration (dry macular degeneration), a substance known as lipofuscin accumulates in the lining of the retina. A much less common form of macular degeneration involves the abnormal growth of blood vessels (wet macular degeneration). This can be treated very successfully, if attended to soon enough, but may lead to irreversible blindness if left untreated. For this reason, medical consultation in all cases of macular degeneration (or any other type of vision loss) is essential.
Note: The treatments described in this section are intended as support to standard ophthalmalogical care, not as a substitute for it. In addition, all studies refer primarily to the more common type of macular degeneration, dry macular degeneration.
A single solid study suggests that zinc, or a mixture of zinc and antioxidants can prevent or slow the progression of early macular degeneration. However it is not clear whether the antioxidant portion of this mixture added any additional benefit.
This double-blind, placebo-controlled trial evaluated the effects of zinc with or without antioxidants on macular degeneration in 3,640 individuals in the early stage of the disease.1 Participants were randomly assigned to receive one of the following treatments: antioxidants ( vitamin C at 500 mg, vitamin E at 400 IU, and beta-carotene at 15 mg), zinc (80 mg) and copper (2 mg), antioxidants plus zinc, or placebo. The results indicate that zinc alone or zinc plus antioxidants, significantly slowed the progression of the disease.
Note: Zinc at doses of 80 mg and higher daily can be harmful. One of the problems is that high-dose zinc supplementation impairs copper absorption. That's why extra copper was provided in the study described above. However, there may be other risks as well. Physician supervision is advised. For other dosage and safety issues, see the full Zinc article.
Smaller studies of zinc for macular degeneration have found mixed results.3,4
Note that it’s not clear how much the antioxidants in the mixture contributed to the benefits. In fact, there is no convincing evidence that antioxidants alone are effective for preventing or delaying the onset of macular degeneration. A 4-year, double-blind, placebo-controlled trial of 1,193 people with macular degeneration failed to find vitamin E alone helpful for preventing or treating macular degeneration.16 An even larger and longer study, following over 20,000 people for over 10 years, failed to find that beta-carotene alone reduced the incidence of macular degeneration.23 A mixture of beta-carotene, vitamin E, and vitamin C has also failed to prove beneficial.15 And, a review of 3 randomized controlled trials involving a total of 23,099 subjects found no evidence of benefit for vitamin E and beta-carotene.24
Carotenoids are a group of substances that are found in many fruits and vegetables, especially yellow-orange and dark green ones. ( Beta-carotene is the most famous carotenoid). Observational studies suggest that higher intake of dietary carotenoids is associated with a lower incidence of macular degeneration.5,6 However, observational studies prove little about cause and effect. To determine whether carotenoids can actually prevent or treat macular degeneration, double-blind, placebo-controlled studies are necessary. (For information on why this is the case, see Why Does This Database Rely on Double-blind Studies?)
As noted above, in one very large study, beta-carotene failed to prove effective for preventing macular degeneration. However, the less well-known carotenoids lutein and zeaxanthin might be more promising.7,8 These carotenoids, principally found in corn and dark green leafy vegetables, are found in high concentrations in the eye. It has been suggested that they may protect the macula from light-induced damage by dyeing it yellow, thereby acting as a kind of natural sunglasses. They also act in the usual antioxidant fashion by neutralizing free radicals.9
These hopes received support from a double-blind, placebo-controlled trial.18 This study enrolled 90 people with dry macular degeneration and followed them for 12 months. The participants received either lutein (10 mg), lutein plus antioxidants and a multivitamin/mineral supplement, or placebo. At the end of the study period, participants who had taken lutein alone or lutein plus the other nutrients showed improvements in vision, while no change in vision was seen in the placebo group. A subsequent study failed to find benefit with lutein, but it used a lower dose (6 mg daily) and involved fewer people.21 Ultimately, further study will be needed to establish whether lutein is actually helpful for macular degeneration. For more information, see the full Lutein article.
Like carotenoids, flavonoids are found in many plants and may offer a variety of beneficial effects. Weak but interesting evidence suggests that bilberry and oligomeric proanthocyanidins (OPCs), both rich in flavonoids, may prevent or treat macular degeneration.11-13
The herb Ginkgo biloba also contains many flavonoids and is additionally thought to increase circulation. In a 6-month, double-blind, placebo-controlled study of 20 people with macular degeneration, use of ginkgo at a dose of 160 mg daily resulted in improved visual acuity.12 Furthermore, positive results were seen in a 24-week, double-blind study of 99 people with macular degeneration that compared ginkgo extract at a dose of 240 mg per day against ginkgo at a dose of 60 mg per day.17 Vision improved in both groups, but to a greater extent with the higher dose. This study would have been more meaningful if it had included a placebo group, but nonetheless, “dose-related” effects of this type hint that a treatment may really work. It has been suggested that ginkgo aids vision by increasing blood flow to the optic nerve. However, one study designed to evaluate this possible mechanism of action failed to document such an effect.22
In observational studies, people who happen to consume a diet rich in omega-3 fatty acids (fish oil) seem to lower their risk of macular degeneration.25 Similarly, a review of 2 randomized trials with 2,343 patients found that omega-3 fatty acid supplements (taken for periods of up to 5 years) were not effective in preventing or delaying the progression of macular degeneration.26 One controlled study appeared to find benefit with a combination of acetyl-L-carnitine, fish oil and coenzyme Q10 but the trial unfortunately failed to use a placebo group which decreases.20
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14. Watson V. Wine consumption decreases risk of age-related blindness. Medical Tribune. 1997 June 5.
15. Age-Related Eye Disease Study Research Group. A randomized, placebo-controlled clinical trial of high-dose supplementation with vitamins C and E and beta carotene for age-related cataract and vision loss: AREDS report no. 9. Arch Ophthalmol. 2001;119:1439-1452.
16. Taylor HR, Tikellis G, Robman LD, et al. Vitamin E supplementation and macular degeneration: randomised controlled trial. BMJ. 2002;325:11.
17. Fies P, Dienel A. Ginkgo extract in impaired vision—treatment with special extract EGb 761 of impaired vision due to dry senile macular degeneration. Wien Med Wochenschr. 2002;152:423-426.
18. Richer S, Stiles W, Statkute L, et al. Double-masked, placebo-controlled, randomized trial of lutein and antioxidant supplementation in the intervention of atrophic age-related macular degeneration: the Veterans LAST study (Lutein Antioxidant Supplementation Trial). Optometry. 2004;75:216-230.
19. Chiu CJ, Hubbard LD, Armstrong J et al. Dietary glycemic index and carbohydrate in relation to early age-related macular degeneration. Am J Clin Nutr. 2006;83:880-886.
20. Feher J, Kovacs B, Kovacs I, et al. Improvement of Visual Functions and Fundus Alterations in Early Age-Related Macular Degeneration Treated with a Combination of Acetyl-L-Carnitine, n-3 Fatty Acids, and Coenzyme Q10. Ophthalmologica. 2005;219:154-166.
21. Bartlett HE, Eperjesi F. Effect of lutein and antioxidant dietary supplementation on contrast sensitivity in age-related macular disease: a randomized controlled trial. Eur J Clin Nutr. 2007 Jan 31. [Epub ahead of print]
22. Wimpissinger B, Berisha F, Garhoefer G, et al. Influence of ginkgo biloba on ocular blood flow. Acta Ophthalmol Scand. 2007 Feb 26. [Epub ahead of print]
23. Christen WG, Manson JE, Glynn RJ, et al. Beta-carotene supplementation and age-related maculopathy in a randomized trial of US physicians. Arch Ophthalmol. 2007;125:333-339.
24. Evans J, Henshaw K. Antioxidant vitamin and mineral supplements for preventing age-related macular degeneration. Cochrane Database Syst Rev. 2008;1:CD000253
25. Chong EW, Kreis AJ, Wong TY, et al. Dietary omega-3 fatty acid and fish intake in the primary prevention of age-related macular degeneration: a systematic review and meta-analysis. Arch Ophthalmol. 2008;126:826-833.
26. Lawrenson JG, Evans JR. Omega 3 fatty acids for preventing or slowing the progression of age-related macular degeneration. Cochrane Database Syst Rev. 2015;4:CD010015.
Last reviewed December 2015 by EBSCO CAM Review Board Last Updated: 12/15/2015