A therapeutic trial of vitamin A in patients with pigmentary retinal degenerations: a negative study

A prospective therapeutic trial was designed to test the hypothesis that measurable improvement of retinal functions might occur in some patients with pigmentary retinal degeneration when placed on high doses of solubilized vitamin A (Aquasol A, 50,000 I.U. per day by mouth for 28 days). After a standard ophthalmic history and examination pre-trial examinations consisting of visual acuity, visual fields, color vision tests, dark adaptations and cone thresholds were obtained on two separate occasions. Electroretinography was usually performed only once. Forty-seven patients were entered into the study of which 27 had typical retinitis pigmentosa. The patients showed no significant change in visual function from pre-trial results when tested after taking the vitamin A for 28 days. Post-trial electroretinography performed on 10 patients with recordable pre-trial electroretinograms showed no change. The 10 patients retested at six and 12 months after the trial showed no significant change in visual function.