The incidence of optic neuropathy in 84 patients treated with ethambutol.

The authors examined 84 patients with pulmonary TBC treated with ethambutol (25 mg/Kg/die). The patients were divided into two groups on the basis of zinc plasma levels: 53 patients with zinc plasma level greater than 1 mg/l and 31 with zinc plasma levels less than 0.7 mg/l. The two groups underwent periodical follow-up of visual acuity, fundus, color vision (Fransworth 100 HUE) and visual field. The checks were monthly on the first group and fortnightly in the second. Eight patients presented signs of optic neuropathy. Patients with lower zinc plasma levels showed a higher percentage of optic neuropathy.