Treatment With 9-cis β-Carotene-Rich Powder in Patients With Retinitis Pigmentosa A Randomized Crossover Trial

IMPORTANCE Retinitis pigmentosa (RP) is the leading cause of incurable inherited blindness in the developed world, with an estimated prevalence of 1 in 3500 individuals. Therefore, it is important to develop new treatments for this disease. OBJECTIVE To determine the effect of oral treatment with 9-cis beta-carotene on visual function of patients with RP. DESIGN Randomized, double-masked, placebo-controlled, crossover clinical trial. SETTING University tertiary medical facility. PARTICIPANTS Thirty-four patients with RP who were at least 18 years of age. Twenty-nine patients completed the study and were included in the analysis. INTERVENTIONS Patients were treated daily for 90 days with capsules containing 300 mg of 9-cis beta-carotene-rich alga Dunaliella bardawil (beta-carotene, approximately 20 mg) or placebo (starch). Following a 90-day washout period, they were treated for 90 days with the other capsules. MAIN OUTCOMES AND MEASURES The primary outcome was the change for both eyes from baseline to the end of each treatment in dark-adapted maximal electroretinographic b-wave amplitude. The secondary outcomes were the changes in light-adapted maximal b-wave amplitude, dark- and light-adapted visual field, and best-corrected visual acuity. RESULTS The mean change in dark-adapted maximal b-wave amplitude relative to initial baseline was +8.4 mu V for 9-cis beta-carotene vs -5.9 mu V for placebo (P = .001). Ten participants (34.5%) had an increase of more than 10 mu V for both eyes (range, 11-42 mu V) after 9-cis beta-carotene treatment compared with no participants after placebo treatment. The percentage change in light-adapted b-wave response was +17.8% for 9-cis beta-carotene vs -3.0% for placebo (P = .01). No significant differences were found between the groups for visual field and best-corrected visual acuity. No adverse effects were observed. CONCLUSIONS AND RELEVANCE Treatment with 9-cis beta-carotene significantly increased retinal function in patients with RP under the tested conditions. The optimal therapeutic regimen will be determined in future, larger clinical trials. 9-cis beta-Carotene may represent a new therapeutic approach for some patients with RP.