Color vision defect in patients with tuberculosis receiving Ethambutol treatment

Abstract

Purpose: To evaluate the incidence of color vision defect in patients with tuberculosis receiving ethambutol (EMB) treatment and to evaluate the sensitivity of the two methods of color vision tests in detecting the color vision defect.

Materials and methods: The authors prospectively evaluated patients newly diagnosed to have tuberculosis from infectious clinic at Thammasat Hospital. The patients were enrolled from October 2018 to December 2019. The patients underwent complete eye examinations included optical coherence tomography (OCT) optic nerve analysis and visual field at their first visit. Color vision measured using the Ishihara Pseudo-isochromatic 17-plates and Farnsworth-Munsell D-15 test at initial visit and monthly were recorded. The patients were followed-up for at least 6 months or until they stopped EMB treatment.

Results: Twenty-seven patients (54 eyes) were included in the study. Thirteen were female and fourteen were male. They had a mean age of 49.8 ±17.6 years (range 22 to 77 years). The mean daily dose of ethambutol is 17.38 ±2.39 mg/ kg (range 13.6-21.8 mg/kg). Baseline color vision and monthly color vision was remained normal in all patients. After following up the patients for about 6 months after anti-tuberculous drugs were stopped, color vision remained normal in all patients using both color vision tests.

Conclusion: Although the present study did not find the incidence of color vision defect in our patients like as predicted. But the authors still emphasizing the importance of color vision test screening in patients receiving EMB treatment because color vision defect may indicate early toxic optic neuropathy.

Keywords: Color vision, Tuberculosis, Ethambutol, Toxic optic neuropathy