IMPACT OF ANNUAL DOSING WITH IVERMECTIN ON PROGRESSION OF ONCHOCERCALVISUAL-FIELD LOSS

Reported are the results of a randomized, double-masked, placebo-contr olled trial of annual ivermectin dosing in 34 rural communities, Kadun a State, northern Nigeria, where guinea savanna onchocerciasis is meso endemic. A fetal of 939 individuals underwent Friedmann field analysis at the first examination and saw at least 19 spots in at least one ey e. Of these, 636 (68%) completed a subsequent Friedmann field analysis 2-3 years later The adjusted incidence rate ratio for the ivermectin group versus the placebo group was 0.64 (95% confidence interval (CI): 0.42-0.98). There was some evidence that the impact of ivermectin was greatest among those who had received one dose of ivermectin. The maj ority of the deteriorations occurred in eyes that gave evidence of opt ic atrophy at the first examination. An analysis restricted to individ uals with optic atrophy at baseline indicated a reduction of 45% in th e incidence of visual field deterioration in the ivermectin group (95% CI: 8-67%). Previous findings have shown that ivermectin has an impac t on the incidence of optic atrophy. Our results indicate, for the fir st time, that ivermectin has a substantial impact on the progression o f visual field loss among those with pre-existing optic atrophy.