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PURPOSE: Preclinical studies support a protective role for omega-3 fatty acids (FAs) on diabetic retinopathy (DR), but these observations have not been confirmed in randomized trials. We present randomized evidence for the effects of omega-3 FAs on DR outcomes. DESIGN AND PARTICIPANTS: A sub-study of the ASCEND (A Study of Cardiovascular Events iN Diabetes) double-blind, randomized, placebo-controlled trial of 1g omega-3 fatty acids (containing 460mg eicosapentaenoic acid and 380mg docosahexaenoic acid) daily for the primary prevention of serious cardiovascular events, in 15,480 UK adults at least 40 years of age, with diabetes. METHODS: Linkage to electronic NHS Diabetic Eye Screening Programme records in England and Wales, and confirmation of participant-reported eye events via medical record review. Logrank and stratified logrank methods were used for intention-to-treat analyses of time until the main outcomes of interest. MAIN OUTCOME MEASURES: The primary efficacy endpoint was time to the first post-randomization recording of referable disease, a composite of referable retinopathy (R2 or R3a/s) or referable maculopathy (M1) based on the grading criteria defined by the UK National Screening Committee. Secondary and tertiary outcomes included the referable disease outcome stratified by the severity of DR at baseline, any progression in retinopathy grade, and incident diabetic maculopathy. RESULTS: Linkage data were obtained for 7360 participants (48% of those who were randomized in ASCEND). During their mean follow-up of 6.5 years, 548 [14.8%] had a referable disease event in the omega-3 FAs group, compared to 513 [13.9%] in the placebo group (rate ratio 1.07; 95% confidence interval: 0.95-1.20; P = 0.29). There were no statistically significant between-group differences in the proportion of events for either of the secondary or tertiary outcomes. DISCUSSION: Representing the first large-scale, prospective test of its kind, these data exclude any clinically meaningful benefits of 1g daily omega-3 FAs on DR.

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Omega-3 fatty acids, diabetic retinopathy, randomized controlled trial