Objective: To determine whether a therapeutic dose of docosahexaenoic acid (DH A), an ω-3 fatty acid, will slow the course of retinal degeneration in adult p atients with retinitis pigmentosa who are also receiving vitamin A. Design: Rand omized, controlled, double-masked trial of 221 patients, aged 18 to 55 years, e valuated over a 4-year interval. Patients were given either 1200 mg/d of docosa hexaenoic acid or control capsules. All were given 15000 IU/d of vitamin A (give n as retinyl palmitate). Randomization considered genetic type and baseline diet ary ω-3 fatty acid intake. Main Outcome Measures: The primary outcome measure was the total point score for the 30-2 program of the Humphrey field analyzer; secondary outcome measures were the total point score for the 30-2 and 30/60-1 programs combined, 30-Hz electroretinogram amplitude, and Early Treatment Diab etic Rentinopathy Study visual acuity. Results: No significant differences in de cline in ocular function were found between the docosahexaenoic acid plus vitami n A (DHA +A) group and control plus vitamin A (control +A)-group over a 4-ye ar interval among all 221 randomized patients or among the 208 patients who comp leted all 4 follow-up visits. The mean annual rate of loss of sensitivity for the Humphrey Field Analyzer 30-2 programwas 37 dB for the DHA +A group and 38 dB for the control +A group (P=0.88). For the Humphrey Field Analyzer 30-2 and 30/60-1 programs combined, the mean annual rates of loss of field sensitivity were 57 dB for the DHA +A group and 60 dB (P=0.73) for contro l +A group. No toxic adverse effects were observed. No significant differences by treatment group assignment were observed within genetic types or within the c ategory of baseline ω-3 fatty acid intake. Conclusion: In patients assigned to receive 15000 IU/d of vitamin A, this randomized trial showed that 1200 mg/d of docosahexaenoic acid supplementation over a 4-year interval did not, on averag e, slow the course of disease in patients with retinitis pigmentosa.
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