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N.M. Rodriguez, M. Kupersmith; The Long–term Effects of Ethambutol on the Optic Nerve . Invest. Ophthalmol. Vis. Sci. 2005;46(13):664.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To study the visual outcome of patients with presumed ethambutol toxicity. Methods:A retrospective review of patients in one neuro–ophthalmology service that were diagnosed with ethambutal ocular toxicity. The parameters investigated included monocular Snellen visual acuity, abbreviated color vision using the Ishihara color plates and the mean deviations using Humphrey perimetry. Results:Fourteen patient charts were reviewed. There were an equal number of men and women, and the average age was 57 years old (range of 12 to 85 years of age.) The average period of follow–up was 18 months (range of 5 to 58 months.) The average duration of use of ethambutol prior to discontinuation in nine patients was 9 months (range of 3 to 18 months.) Twelve out of fourteen patients had optic nerve pallor in both eyes on clinical examination, and the remaining two had optic nerve head swelling. On presentation, the visual acuity was 20/200 or worse in both eyes in 7 patients, and in one eye in 3 patients. The color plates seen were less than five in both eyes in 9 patients, and in one eye in 2 patients. Of the twelve patients having visual fields, the mean deviations were worse than –4.0db in both eyes in 11 patients and in one eye in 1 patient. After discontinuation of ethambutol, the visual acuity was 20/40 or greater in both eyes in 6 patients and in one eye in 2 patients. Of the thirteen patients that had final color vision testing, the color plates seen were more than 7 in both eyes in 6 patients and in one eye in 1 patient. Of the 9 patients having final visual fields, the mean deviations were better than –4.0db in both eyes in 3 patients and in one eye in 1 patient. There were three patients that had worse than 20/80 final vision in both eyes, one of whom had a clinical exam compatible with nonorganic visual loss and another that is undergoing testing for Leber’s optic neuropathy. A separate patient that had only partial visual recovery in one eye has macular degeneration. Conclusions:In contrast to prior reports from countries outside of the United States, patients in the US with ethambutol related toxic optic neuropathy improve visual acuity, color testing and visual field with cessation of the drug.
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