Ethambutol is associated with which ocular toxicity?

• A. Retinal detachment
• B. Optic neuropathy and color vision deficits
• C. Cataracts
• D. Glaucoma

Answer: (B)

Ethambutol can cause optic neuropathy with color vision deficits. The toxicity targets the optic nerve, leading to decreased central vision and impaired color discrimination, particularly red–green vision. Visual field testing often reveals central or cecocentral scotomas, and color vision testing (for example with Ishihara plates) is frequently abnormal. This effect is dose-related and more likely with higher daily doses or renal impairment, and it may be reversible if the drug is stopped early enough. Therefore, baseline and periodic monitoring of visual acuity, color vision, and visual fields are recommended during therapy. The other conditions listed—retinal detachment, cataracts, and glaucoma—do not describe the typical ocular toxicity pattern of ethambutol.