Abstract
Purpose: :
High oral doses of 9-cis beta carotene were shown to improve retinal functions as measured by electroretinography (ERG) and perimetry in patients with congenital stationary night blindness and in rodent models of retinitis pigmentosa (RP). The purpose of this study was to determine whether this therapy is efficacious for RP
Methods: :
In a double-masked, placebo-control, cross-over trial, patients with RP (not genetically diagnosed) were given daily 4 commercially available 15mg capsules containing powder containing 7.5 mg 9-cis beta carotene for 90 days. This was followed by a washout and a cross-over period, each of 90 days. Before and after each period, the patients were tested for best corrected visual acuity and underwent ERG using the ISCEV compliant protocol and Goldmann perimetry. Maximal scotopic b-wave ERG responses were used as the primary end point. Z-test was used to evaluate the average differences between treatment and from baseline.
Results: :
Twenty nine patients completed the study, the visual functions of 34.5% of them showed marked improvement. The dark adapted b-wave improved significantly by an average of 56% in average (p=0.002) and the light adapted b-wave by 21% (p=0.01).The visual field showed significant improvement after treatment as compare to baseline (p=0.01) but not to placebo treatment which caused some improvement, probably due to the subjective nature of perimetry.
Conclusions: :
The ERG response and visual field of over a third of the RP patients improved significantly by the 9-cis beta carotene treatment compare to placebo. This treatment is probably beneficial only to patients with relevant to pathogenetic mechanisms. The results presented here have to be evaluated in patients with genetically selected forms of retinitis pigmentosa and the optimal dose has yet to be determined.
Clinical Trial: :
http://www.clinicaltrials.gov NCT00569023
Keywords: clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • retinal degenerations: hereditary • carotenoids/carotenoid binding proteins