Dietary supplements of omega-3-polyunsaturated fatty acids (PUFA), the healthy fatty acid found in certain fish or fish oils, nuts, seeds, vegetable oils and other foods, reduces the disease progress in the eye.

The essential omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic (EPA), given as diet supplements, may help prevent retinal disease (retinopathy) and also has beneficial effects on the heart, Dr. Lois E. H. Smith, from Harvard Medical School and Children's Hospital in Boston, told Reuters Health. "It is a win/win situation to prescribe this low-cost over-the-counter supplement."

The retina is composed of nerve tissue that converts light images into impulses transmitted through the optic nerve to the brain. Retinal angiogenesis is the growth of destructive blood vessels in areas they do not belong, in this case in the retina where is eventually causes blindness.

In the current study, published in the advance online edition of the journal Nature Medicine, the investigators conducted a series of experiments in mice with retinal angiogenesis to evaluate the effects of omega-3-PUFA and omega-6-PUFA (which has the opposite effect of omega-3-PUFA.)

Raising tissue levels of omega-3-PUFA with dietary supplementation, or through genetic manipulation, led to more than a 50 percent decrease in the ratio of omega-6- to omega-3-PUFA, the researchers report, and this was associated with a protective of the eye from the pathological process.

Increasing omega-3-PUFA levels also decreased blood vessel growth around the retina. Treatment with bioactive products derived from DHA and EPA conferred significant protection from the angiogenic effects, indicating that the protective effect of omega-3-PUFA against retinal damage is mediated in part through DHA and EPA.

Additional experiments suggested that a subset of retinal white blood cells (immune cells that fight off invaders and infection) were involved in retinal disease process, setting off a sequence of activities that similarly increased omega-3-PUFA levels.

"Omega-3 fatty acids are also deficient in most Western diets," Smith said. Therefore, eating more foods that are rich in omega-3 oils may help prevent eye disease in adults.

A study sponsored by the National Institutes of Science will examine the impact of omega-3 supplements on the development of age-related macular degeneration, "the most common cause of blindness in the elderly," Smith said. "We also hope to extend these studies to examine the effect of supplementation on patients with diabetes at risk for diabetic retinopathy."

"Some supplements contain omega-6 fatty acids which have the opposite effect," Smith added. "It is important to make this clear to patients."