Programmatic Assessment of Ethambutol-Related Optic Neuropathy in Patients with Mycobacterial Infections: A Prospective Observational Cohort Study.

Introduction: Comprehensive data on ethambutol (EMB)-related optic neuropathy (EON) are lacking, creating a knowledge gap. Accordingly, this prospective programmatic study established a collaborative multidisciplinary team to explore EON.

Methods: This study enrolled patients who received EMB as part of their treatment regimen for mycobacterial infections. Programmatic assessments of visual abnormalities were performed for each patient by the team. EON was diagnosed by ophthalmologists. Patients diagnosed as having EON completed short-term (6-month) and long-term (5-year) follow-up.

Results: Of 476 patients, 31 (6.5%) were diagnosed as having EON. Older age (≥ 65 years, odds ratio [OR] = 2.5, P = 0.043) and diabetes mellitus (OR = 2.2, P = 0.045) were independent predictors of EON, and coexisting subjective and objective ocular abnormalities (OR = 4.8, P = 0.009) and concomitant visual acuity and color discrimination impairment (OR = 5.9, P = 0.009) were independently associated with EON in patients with ocular abnormalities at EMB discontinuation. Among patients with EON, 56.7% and 50.0% had favorable 6-month visual acuity and color discrimination outcomes, respectively. Among patients with unfavorable 6-month visual acuity outcomes, 45.5% had favorable outcomes at the 5-year follow-up. Moreover, 88.2% and 100% of patients with favorable and unfavorable 6-month visual acuity outcomes, respectively, already had these outcomes at the third month of follow-up. Additionally, 50.0% and 100% of patients with favorable and unfavorable 6-month color discrimination outcomes, respectively, already had these outcomes at the fourth month of follow-up.

Conclusions: The incidence of EON exceeded 6%. This study provides a feasible model for the comprehensive management of EON in clinical practice.