Clinical profile and incidence of toxic optic neuropathy (TON) in patients receiving anti tuberculous therapy: A prospective study

Abstract

Introduction: Ethambutol is a first line drug against tuberculosis. It can cause side effects like optic neuropathy, hyperuricemia and allergic reactions. Optic neuritis due to ethambutol is said to be dose dependent and with varying reversibility on discontinuation of the treatment in different studies. Several studies showed incidence of TON close to 1%. Aim: To study the incidence and clinical profile of patients developing toxic optic neuropathy after receiving standard Anti tuberculous treatment (ATT). Methods: We evaluated the enrolled patients who met the inclusion criteria between December 2021 and December 2023 by assessing their BMI, comorbidities and conducted an ophthalmic evaluation at the start of treatment and periodically thereafter at 3 monthly interval and 4 weeks after stoppage of treatment. After the development of defective vision, visual evoked response was done, ethambutol was stopped and patients were reassessed periodically. The data was processed with SPSS software version 20.0.Descriptive data were explained in frequency. Pearson’s Chi - square test was used to compare the categorical variables and Fischer exact test when expected values were less than 5 with a p value