[Prevention of ocular toxicity of ethambutol: study of zincaemia and chromatic analysis (author's transl)].

In order to define the means of prevention of the ocular toxicity of ethambutol (EMB), 72 patients under treatment with EMB-INH-Rifampicin combination were subjected to systematic analysis of plasma, blood and urinary zinc levels together with a full ophthalmic examination. Comparison of the results from 12 patients sustaining ocular damage at the time of treatment with the results of 60 others: 1) demonstrates the existence of a correlation between plasma zinc levels before treatment and the probability of ocular damage from EMB (high risk for zinc is less than 0.70 mg/l - almost no risk for zinc greater than 1 mg/l); 2) confirms that dyschromatopsia is one of the first signs of ocular damage through EMB and thus constitutes an alarm signal; 3) suggests that the ocular toxicity of EMB might appear in the retina before the optic nerve.