Ocular side effects in tuberculosis patients receiving direct observed therapy containing ethambutol

Abstract

Background: India is among the largest countries to implement the revised national tuberculosis (TB) control program (RNTCP). Ocular toxicity of ethambutol has been known since 1962. It can be halted with early detection and cessation of the contributing drug. Aims and Objectives: This study aims to detect early ocular toxicity of ethambutol in TB patients under directly observed treatment strategy (DOTS). Materials and Methods: This was a prospective cross-sectional study of 30 patients getting AKT including ethambutol along with isoniazid, rifampicin, and pyrazinamide under RNTCP‑DOTS center at a tertiary care hospital. The detailed history, best-corrected visual acuity (BCVA), color vision, fundus examination, visual field, retinal nerve fiber layer (RNFL) thickness, and central subfield macular thickness were carried out in all patients pretreatment and then at the 2nd month of treatment. Results: The mean age of patient was 44.87 years. Reduced visual acuity from the baseline was noted at the second in 23.33% of the right eyes (P = 0.01) and 30% of the left eyes (P < 0.01). Mean temporal RNFL thickness was significantly reduced from baseline after 2 months of treatment (P = 0.046). No significant difference was observed with color vision and visual fields pre- and post-treatment. Conclusion: The assessment of BCVA, color vision, visual field, RNFL, and macular thickness is essential at baseline and thereafter at frequent intervals to detect early ethambutol toxicity and probable reversible visual loss.