A patient reports seeing yellowish-green halos around lights and experiences vision changes. Which medication is likely causing this toxicity?

• A. Lisinopril
• B. Losartan
• C. Lasix
• D. Digoxin

Answer: (D)

Visual symptoms like yellowish-green halos around lights are a classic sign of digoxin toxicity. Digoxin is a cardiac glycoside with a very narrow therapeutic window used in heart failure and certain arrhythmias. When digoxin levels become too high or when electrolytes are imbalanced (for example, low potassium or renal impairment), toxicity can occur. The ocular changes—yellow halos, blurred vision, and color vision changes—are hallmark manifestations, often along with GI symptoms and confusion.

The reason this is the best answer is that these visual disturbances are specifically associated with digoxin toxicity due to its effect of inhibiting the Na+/K+ ATPase pump, which increases intracellular calcium and enhances contractility but also raises the risk of dangerous arrhythmias when levels are excessive. Management involves holding the drug, checking the serum digoxin level and electrolytes, and treating severe toxicity with digoxin-specific antibody fragments if needed, along with supportive care and addressing any contributing factors like renal function.

The other medications listed do not typically cause these yellow halos or this specific vision change.