CHICAGO–Combining omega-3 essential fatty acids (EFAs) with vitamin A boosted eye health for people who suffer from retinitis pigmentosa, a retinal disease that causes decreased night vision, loss of peripheral vision and, in advanced cases, loss of central vision (Arch Ophthalmol.DOI:10.1001/archophthalmol.2011.2580). Researchers found mean annual rates of decline in distance and retinal visual acuities in adults with retinitis pigmentosa receiving 15,000 IU/d of vitamin A are slower over four to six years among those consuming a diet rich in omega-3s.
Eliot L. Berson, M.D., of Harvard Medical School and the Massachusetts Eye and Ear Infirmary, Boston, and colleagues noted this is the first report that nutritional intake can modify the rate of decline of visual acuity in retinitis pigmentosa.
In the study, they calculated dietary intake from questionnaires completed annually by 357 adult patients from three randomized trials who were all receiving 15,000 IU/d of palmitate vitamin A for four to six years. The time frame for the studies were from 1984 to 1991, 1996 to 2001 and 2003 to 2008. Rates of visual acuity decline were compared between those with high (more than 0.20 g/d) versus low (less than 0.20 g/d) intake of omega-3s.
Results showed mean rates of decline of acuity were slower among those with high omega-3 intake. Their results indicate that patients with a diet high in long-chain omega-3 fatty acids had a 40-percent slower average annual rate of decline in distance visual acuity than those with a diet low in those fatty acids.
The authors also commented about the rate of decline in letters per year on Early Treatment Diabetic Retinopathy Study (ETDRS) distance acuity testing. They explained the mean rate of decline in letters per year was 0.59 letter for patients receiving vitamin A with high omega-3 intake versus 1.00 letter for patients receiving vitamin A with low omega-3 intake over a four to six year period.
“A representative patient who starts receiving vitamin A by age 35 years and eats an omega-3-rich diet (i.e., one to two three-ounce servings of oily fish per week) with an ETDRS acuity of 50 letters (equivalent to 20/30 on the Snellen chart) would, on average, be expected to decline to an ETDRS acuity of 24 letters (equivalent to 20/100 on the Snellen chart) at age 79 years, whereas this patient receiving vitamin A with a low dietary omega-3 intake (e.g. less than one three-ounce serving of oily fish per week) would decline to this level at age 61 years," they concluded.
The researchers noted they previously reported an effect of dietary omega-3 intake on retaining central visual field sensitivity. Patients receiving vitamin A palmitate, 15,000 IU/d, with omega-3 intake of at least 0.20 g/d had almost a 50-percent slower rate of decline in central visual field sensitivity than those receiving this dose of vitamin A with a lower omega-3 intake.
About one in 4,000 people, or about 2 million worldwide, have retinitis pigmentosa. The condition typically results in night blindness in adolescence before the loss of side vision in young adulthood, followed by tunnel vision as it worsens and virtual blindness by the time a patient turns 60, researchers write in the study background.
Previous research has shown omega-3s are good for eye health in numerous ways, including reducing dry eye syndrome and dry eye inflammation.
