Treatment with taurine, diltiazem, and vitamin E retards the progressive visual field reduction in retinitis pigmentosa: a 3-year follow-up study.

The purpose of this study to assess the effect of the formula taurine/diltiazem/vitamin E on the progression of visual field loss in retinitis pigmentosa. A double blind, placebo controlled study in 62 patients: visual field threshold values were obtained in a Humphrey Field Analyzer from center (30 degrees) and periphery (30-60 degrees), every 4 months during 3-year follow-up. Data were analyzed by univariate regression, with slopes obtained from the best fit lines. Based on slope values, three groups of patients were identified as those showing negative, positive, or zero slope: > or = 1 to < or = +1. In controls (32 patients), at central area, the distribution in negative, zero, or positive slope was, respectively, 16 (50%), 11 (35%), and 5 (15%). In the treated group (30 patients) this distribution was 6 (20%) negative, 17 (53%) zero, and 7 (23%) positive slope. In periphery, 16 control patients were distributed as 11 (69%) negative, 4 (25%) zero, and 1 (6%) positive slope. In the treated group (17 patients), the distribution was opposite: 1 (6%) negative, 7 (41%) zero, and 9 (53%) positive slope. Nineteen patients receiving treatment up to 6 years showed similar distribution by slope values. Eight out of 9 patients switched from placebo (2 years) to treatment (2-3 years), showed improving changes in their slope values. A beneficial effect of the treatment decreasing the rate of visual field loss was observed, likely through a protective action from free radical reactions in affected photoreceptors.