A 46-year-old man who was a prisoner comes to the clinic because of 2-month history of productive cough, malaise. During this time, he also has had shortness of breath and a 6-kg (13-Ib) weight loss. Chest x-ray reveals a right upper lobe infiltrate. Acid-fast bacilli are present on sputum smear. The patient is started on combination therapy with isoniazid, ethambutol, rifampin, pyrazinamide, and pyridoxine. One month later, he returns to the office reporting blurring of vision. Examination shows bilateral central scotomas. Which of the following is most likely responsible for this patient's visual symptoms?

Question

A 46-year-old man who was a prisoner comes to the clinic because of 2-month history of productive cough, malaise. During this time, he also has had shortness of breath and a 6-kg (13-Ib) weight loss. Chest x-ray reveals a right upper lobe infiltrate.  Acid-fast bacilli are present on sputum smear.  The patient is started on combination therapy with isoniazid, ethambutol, rifampin, pyrazinamide, and pyridoxine.  One month later, he returns to the office reporting blurring of vision.  Examination shows bilateral central scotomas.  Which of the following is most likely responsible for this patient's visual symptoms?

Quizplus · Accepted Answer

Eductional Objective: Ethambutol can cause optic neuropathy that results in color blindness, central scotoma, and decreased visual acuity.  This adverse side effect may be reversed with discontinuation of the drug.

A 46-Year-Old Man Who Was a Prisoner Comes to the Clinic