To determine whether a therapeutic dose of docosahexaenoic acid (DHA),an ω-3 fatty acid, will slow the course of retinal degeneration in adultpatients with retinitis pigmentosa who are also receiving vitamin A.
Randomized, controlled, double-masked trial of 221 patients, aged 18to 55 years, evaluated over a 4-year interval. Patients were given either1200 mg/d of docosahexaenoic acid or control capsules. All were given 15 000IU/d of vitamin A (given as retinyl palmitate). Randomization considered genetictype and baseline dietary ω-3 fatty acid intake.
Main Outcome Measures
The primary outcome measure was the total point score for the 30-2 programof the Humphrey field analyzer; secondary outcome measures were the totalpoint score for the 30-2 and 30/60-1 programs combined, 30-Hz electroretinogramamplitude, and Early Treatment Diabetic Rentinopathy Study visual acuity.
No significant differences in decline in ocular function were foundbetween the docosahexaenoic acid plus vitamin A (DHA + A) group and controlplus vitamin A (control + A) group over a 4-year interval among all 221 randomizedpatients or among the 208 patients who completed all 4 follow-up visits. Themean annual rate of loss of sensitivity for the Humphrey Field Analyzer 30-2program was 37 dB for the DHA + A group and 38 dB for the control + A group(P = .88). For the Humphrey Field Analyzer 30-2 and30/60-1 programs combined, the mean annual rates of loss of field sensitivitywere 57 dB for the DHA + A group and 60 dB (P = .73)for control + A group. No toxic adverse effects were observed. No significantdifferences by treatment group assignment were observed within genetic typesor within the category of baseline ω-3 fatty acid intake.
In patients assigned to receive 15 000 IU/d of vitamin A, thisrandomized trial showed that 1200 mg/d of docosahexaenoic acid supplementationover a 4-year interval did not, on average, slow the course of disease inpatients with retinitis pigmentosa.