A patient taking Ethambutol may develop which optic-related symptom indicating an adverse effect?

• A. Nausea
• B. Blurred vision
• C. Hearing loss
• D. Rash

Answer: (B)

Ethambutol can cause optic neuropathy, which damages the optic nerve and leads to problems with vision and color discrimination. Blurred vision directly reflects this optic toxicity, so it’s the best match for an optic-related adverse effect. Other options involve non-visual systems (nausea is GI, hearing loss is ototoxic, rash is skin-related) and don’t indicate optic nerve damage. In practice, if blurred vision occurs, the clinician should evaluate vision promptly, consider stopping or adjusting the drug, and monitor baseline and periodic visual function (including color vision), with attention to renal function since Ethambutol dosing is impacted by clearance.