By David Liu and editing by Aimee Keenan-Greene

Tuesday Feb 21, 2012 (foodconsumer.org) -- Eating a diet high in long chain omega-3 fatty acids may help prevent loss of vision acuity in patients who suffer retinitis pigmentosa, according to a study published online Feb 13 in the Archives of Ophthalmology.

Eliot L. Berson, MD and colleagues at Massachusetts Eye and Ear Infirmary conducted the study and found patients who had high intake of omega-3 fatty acid in their diet had slower rates of decline of acuity.

For the study, the researchers calculated dietary intake of omega-3 fatty acids for 357 patients who were enrolled in three randomized trials and received 15,000 IU/d of vitamin A for 4 to 6 weeks. They compared those who had 0.20 grams per day with those who had less than 0.2 grams per day.

The researchers reported "Mean rates of decline of acuity were slower among those with high -3 intake: Early Treatment Diabetic Retinopathy Study distance acuity: high intake = 0.59 letter per year, low intake = 1.00 letter per year, P = .001; Snellen retinal acuity: high intake = 1.5% per year, low intake = 2.8% per year, P = .03."

They concluded "mean annual rates of decline in distance and retinal visual acuities in adults with retinitis pigmentosa receiving vitamin A, 15 000 IU/d, are slower over 4 to 6 years among those consuming a diet rich in -3 fatty acids."

Retinitis pigmentosa is an eye disease in which the retina is damaged.  It's believed that genetics play a major role in this disease.  One in 4,000 people in the United States are believed to live with this disease.

People with retinitis pigmentosa will eventually lose peripheral and central vision.  They often develop cataracts at an early age or macular edema.

Another study published in January in the Acta Ophthalmologica suggests omega-3 fatty acids may help prevent or stop deterioration of age-related macular degeneration or AMD.

The study was a review led by H.P. Sin and colleagues from The Chinese University of Hong Kong. The authors found that high dietary intake of omega-3 fatty acids, and macular xanthophylls lutein and zeaxanthin have been associated with a lower risk of prevalence and incidence of age-related macular degeneration.

In addition, they also found that a formula with vitamins C, E, beta-carotene and zinc with copper can prevent progression of AMD while it is not conclusive whether Vitamin B and extracts from wolfberry, Gingko biloba and berry anthocyanins help reduce the risk of AMD or slow its progression.

Long chain omega-3 fatty acids are found in cold water fish such as salmon.