Optic neuropathy induced by ethambutol: A rare case from Nepal

Area of Science:

• Ophthalmology
• Neurology
• Pharmacology

Background:

• Ethambutol is a first-line antitubercular drug.
• Optic neuropathy is a known, albeit rare, side effect of ethambutol.
• The typical onset is 4-12 months, with a prevalence of 1%.

Observation:

• A 42-year-old male presented with ethambutol-induced optic neuropathy.
• The condition developed unusually early, after only six weeks of ethambutol treatment.
• Other potential causes of optic neuropathy were systematically excluded.

Findings:

• This case demonstrates ethambutol toxicity occurring much earlier than typically reported.
• The patient's presentation was characterized by progressive, bilateral vision loss.
• Differential diagnoses including nutritional, ischemic, compressive, demyelinating, and genetic optic neuropathies were ruled out.

Implications:

• Highlights the potential for rapid onset of ethambutol-induced optic neuropathy.
• Suggests vigilance for optic toxicity even with short-term ethambutol use in tuberculosis treatment.
• Emphasizes the importance of considering drug-induced toxicity in new-onset pulmonary tuberculosis patients with visual disturbances.