Effect of DHA Supplements on Macular Function in Patients With Stargardt Macular Dystrophy and Stargardt-like Macular Dystrophy

We propose to undertake a double-masked, randomized, placebo-controlled, crossover study on the effect of docosahexaenoic acid (DHA) dietary supplementation in subjects with macular dystrophy to determine whether DHA can improve macular function. Subjects will receive either oral DHA supplementation (5x200 mg BID, 2,000 mg/day) or placebo. Subjects will 'crossover' to the opposite treatment twice during this study. Primary outcomes will measure the change in macular function during periods with and without DHA supplementation. Zhang and colleagues found a mutation in the gene, ELOVL4 (elongation of the very long chain fatty acid-4), in individuals with Stargardt-like macular dystrophy. The gene is presumed to function in the pathway of synthesis of very long chain polyunsaturated fatty acids, including DHA. DHA is the major very long chain polyunsaturated fatty acid of the retina. As our North American diet is poor in DHA, we hypothesize that a DHA dietary supplement might improve macular function in individuals with the ELOVL4 mutation. Since the effect of DHA supplementation may be non-specific, we propose to study a second cohort with Stargardt macular dystrophy, which has a different genotype involving a different metabolic pathway in the eye, but presents with a similar phenotype. Two cohorts of up to 10 subjects for analysis will be recruited from patients with either Stargardt-like macular dystrophy or Stargardt macular dystrophy.