Which monitoring is essential for ethambutol therapy?

• A. Regular liver function tests
• B. Regular visual acuity and color vision testing
• C. Regular ECG monitoring
• D. Regular urinalysis

Answer: (B)

Ethambutol can cause optic neuritis, leading to decreased visual acuity and impaired color vision, especially red-green discrimination. Because this toxicity can develop gradually and may become permanent if not caught early, monitoring vision is essential during therapy. A baseline eye exam followed by regular checks of visual acuity and color vision allows prompt detection of any changes, and stopping ethambutol early can prevent lasting damage. The other tests—liver function, ECG, and urinalysis—aren’t specific to ethambutol’s toxicity and are more related to monitoring other TB drugs or general health, so they’re not the primary monitoring focus for this medication.