A prospective study of ocular toxicity in patients receiving ethambutol as a part of directly observed treatment strategy therapy

Abstract

Background and Objectives:India is among the largest countries to implement the revised National Tuberculosis Control Program (RNTCP). This program provides intermittent regimens to the patients, where the doses of isoniazid and ethambutol are more as compared to the daily regimen, which is a cause of concern, particularly with regard to the ocular toxicity of ethambutol. The present study was undertaken to explore the ocular toxicity in the patients registered under the program.Materials and Methods:This was a prospective single center cohort study of 64 patients of categories I and II, coming to the RNTCP-Directly Observed Treatment Strategy (DOTS) center at a tertiary care referral hospital. The detailed history, best corrected visual acuity, fundus examination, and color vision test were carried out in all patients at the start of treatment and then at the first and second month of treatment.Results:Loss in visual acuity from the baseline was noted at the second month follow up in 12 (9.4%) eyes (P = 0.001), visual field defects were seen in eight (6.3%) eyes (P = 0.0412), and optic disc abnormalities were observed in six (4.7%) (P = 0.013) eyes. Color vision abnormalities were noted in 16 (12.6%) eyes (P = 0.003), four eyes showed impairment in red–green color perception, and the others showed impairment in blue–yellow color perception as well. Patients with ocular symptoms were advised to stop ethambutol and they showed improvement in visual acuity after follow up of one to two months. The overall outcome of treatment was not affected by discontinuation of ethambutol in these patients.Conclusion:Ethambutol when taken according to program could cause ocular toxicity. The early recognition of ocular symptoms is important to prevent unnecessary delay in diagnosis and probable irreversible visual loss.

Role of Contrast Sensitivity and Optical Coherence Tomography (Oct) in Early Detection of Ethambutol Induced Toxic Optic Neuropathy a Hospital Based Prospective Study

“…Garg P et al (2015). 8 in their prospective study of ocular toxicity of ethambutol evaluated 64 patients. Their baseline visual acuity ranged from 6/6-6/60.…”

Ocular toxicity with ethambutol therapy: Timely recaution

“…[ 1 2 ] However, in this issue of Lung India, Garg et al . [ 3 ] caution against the continued threat of ocular side effects of the drug among patients on the commonly employed directly observed short course (DOTS) regimen for treatment of tuberculosis, which argues for an active surveillance for detection and management of ocular toxicity during EMB therapy. The incidence of EMB ocular toxicity has been reported in various ways.…”

“…[ 4 ] The incidence of toxicity among various previously reported Indian studies ranged from 0.6 to 3% among those receiving antitubercular medication,[ 5 6 7 ] whereas, Garg et al ., from a carefully planned evaluation, reported loss of visual acuity in 9.4% ( n = 12) eyes, visual field defects in 6.3% ( n = 8), optic disc abnormalities in 4.7% ( n = 6), and color vision abnormalities in 12.3% ( n = 16) eyes. [ 3 ]…”

“…[ 16 ] Formal visual field evaluation, whether it is static (Humphrey) or kinetic (Goldmann), and color vision testing are thus important to unravel the underlying visual defects. Even as commonly used Ishihara charts and Farsworth-Mussel D-15 test, used by Garg et al .,[ 3 ] elicit the usual color perception defect; the subtle blue-yellow defect can only be detected with the use of the generally unavailable desaturated panel of Lanthony. [ 14 ] Optical coherence tomography (OCT), which is commonly used to measure nerve fiber layer thickness in patients with glaucoma, can also be used to quantify such changes caused by EMB, in patients with optic neuropathy.…”

“…This was also acknowledged by Garg et al . [ 3 ]. However, their concern was offset by the recovery of visual impairment upon stoppage of isoniazid.…”