Omega-3 intake and Visual Acuity in Patients With Retinitis Pigmentosa Receiving Vitamin A

January 1, 2012 Human Health and Nutrition Data 0 Comments

Omega-3 intake and Visual Acuity in Patients With Retinitis Pigmentosa Receiving Vitamin A

Year: 2012
Authors: Berson, E.L. Rosner, B. Sandberg, M.A. Weigel-DiFranco, C. Willett, W.C.
Publication Name: Arch Ophthalmol.
Publication Details: doi:10.1001/archophthalmol.2011.2580

Abstract:

Objective: To evaluate whether a diet high in long chain omega 3 fatty acids can slow the rate of visual acuity loss among patients with retinitis pigmentosa receiving vitamin A palmitate. Methods: We calculated dietary intake from questionnaires completed annually by 357 adult patients from 3 randomized trials who were all receiving vitamin A, 15000 IU/d, for 4 to 6 years. Rates of visual acuity decline were compared between those with high (≥ 0.20 g/d) vs low (<0.20g/d) omega 3 intake. Analyses took age into account. Results: Mean rates of decline of acuity were slower among those with high omega 3 intake: Early Treatment Diabetic Retinopathy Study distance acuity: high intake of 0.59 letter per year, low intake of 1.00 letter per year, P=.001; Snellen retinal acuity high intake of 1.5% per year, low intake of 2.8% per year, P=.03. Conclusions: We conclude that mean annual rates of decline in distance and retinal visual acuities in adults with retinitis pigmentosa receiving vitamin A, 15000 IU/d, are slower over 4 to 6 years among those consuming a diet rich in omega 3 fatty acids. To our knowledge, this is the first report that nutritional intake can modify the rate of decline of visual acuity in retinitis pigmentosa. (Authors abstract)
Retinitis pigmentosa has a prevalence of about 1 in 4000; about 2 million people are affected worldwide. Patients typically report night blindness in adolescence and loss of side vision in young adulthood. As the condition advances, they develop tunnel vision and some become virtually blind by age 60 years. Three clinical trials conducted by us in adults with typical retinitis pigmentosa provided evidence that oral vitamin A as retinyl palmitate (15000 IU/d) alone or in combination with an omega 3 rich diet (≥0.20g/d), on average, slowed the rate of decline of retinal function in this condition without toxic adverse effects. In these trials of 4 to 6 year duration, treatment effects were observed on the rate of decline of the ERG 16 or visual field but no significant effects on decline in distance or retinal acuity were reported. This study combined data from all 3 clinical trials to have sufficient statistical power to clarify whether any effect of omega 3 intake on acuity occurred over a 4 to 6 year period. In this cohort of 357 patients with typical retinitis pigmentosa receiving 15000 IU/d of vitamin A as retinyl palmitate for 4 to 6 years, those with a diet high in long-chain omega 3 fatty acids (≥0.20g/d) had a 40% slower mean annual rate of decline in distance visual acuity than those with a diet low in these fatty acids. Since vitamin A plus an omega 3 rich diet slowed the rate of decline of distance and retinal acuity by about the same extent, the benefit of this combination was believed to be due to an effect on preserving central retinal function. Although annual rates of decline in distance and retinal acuities were significantly different when comparing patients with high vs low omega 3 intake (P=.001 and P=.03, respectively), a significant difference in annual rates of decline for full-field cone ERGs were not detected. The authors estimate that a representative patient who starts receiving vitamin A by age 35 years and eats an omega 3 rich diet (one to two 3-oz 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 (less than one 3-oz serving of oily fish per week) would decline to this level at age 61 years. Therefore, the treatment regimen of vitamin A combined with an omega 3 rich diet should make it possible for many patients with typical retinitis pigmentosa to retain both visual acuity and central visual field for most of their lives. (Editors comments)



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