[Severe and reversible optic neuropathy by ethambutol and isoniazid]

Ethambutol and isoniazid are antimicrobial agents used to treat multi-drug-resistant tuberculosis. The most commonly recognized toxic effect of these drugs is optic neuropathy, usually manifesting as a decrease in visual acuity, deficits in colour vision and cecocentral scotomas. This study presents the case of a 59-year-old Nigerian woman diagnosed of multi-drug-resistant tuberculosis who developed a severe bilateral optic neuropathy induced by ethambutol and isoniazid. Ophthalmologic examination revealed normal intraocular pressure, normal funduscopic examination and normal biomicroscopy. Automated visual field revealed 360º peripheral constriction and central scotoma. Magnetic resonance images of the brain and orbits were normal. Ten months after suspending treatment, the patient recovered complete visual function. Visual loss is a rare complication that can be related to ethambutol and isoniazid toxicity. Both eyes are usually symmetrically affected with deficits in colour vision and cecocentral scotoma. For successful treatment of visual loss, it is important to make a differential diagnosis between infection and adverse effects of anti-TB drugs. Ophthalmological examination is thus important before and after treatment.