Which tuberculosis medication is known to occasionally cause bilateral retrobulbar optic neuritis?

Which tuberculosis medication is known to occasionally cause bilateral retrobulbar optic neuritis?

• A. Rifampin
• B. Isoniazid
• C. Ethambutol
• D. Pyrazinamide

Answer: (C)

Ethambutol stands out because it can cause optic neuritis, often affecting both eyes (bilateral retrobulbar optic neuritis). This toxicity tends to be dose-related and is more likely in higher doses or with renal impairment. The warning signs are a gradual decrease in visual acuity and trouble with color vision, especially red-green discrimination. Because the problem can become permanent if the drug isn’t stopped early, clinicians monitor vision before and during therapy and stop Ethambutol at the first sign of visual change. After stopping, vision often improves, though recovery isn’t guaranteed. The other TB drugs have different side effects and aren’t typically linked to optic neuritis.

Ethambutol stands out because it can cause optic neuritis, often affecting both eyes (bilateral retrobulbar optic neuritis). This toxicity tends to be dose-related and is more likely in higher doses or with renal impairment. The warning signs are a gradual decrease in visual acuity and trouble with color vision, especially red-green discrimination. Because the problem can become permanent if the drug isn’t stopped early, clinicians monitor vision before and during therapy and stop Ethambutol at the first sign of visual change. After stopping, vision often improves, though recovery isn’t guaranteed. The other TB drugs have different side effects and aren’t typically linked to optic neuritis.