Which mydriatic is used with tropicamide for adult dilation, with caution against 10% in hypertensive crisis?

• A. Phenylephrine 2.5%, 10%
• B. Tropicamide 1%
• C. Cyclopentolate 1%
• D. Atropine 1%

Answer: (A)

Phenylephrine is the agent used with tropicamide to achieve adult dilation because it stimulates the iris dilator muscle via alpha-1 receptors, giving a fuller, more reliable mydriasis when combined with the muscarinic-blocking effects of tropicamide. Tropicamide alone dilates little and wears off relatively quickly, but pairing it with phenylephrine enhances dilation without prolonging cycloplegia. The standard combo is tropicamide 1% with phenylephrine 2.5%, which provides effective dilation for examinations.

However, the 10% concentration of phenylephrine carries a much higher risk of systemic effects like severe hypertension and related cardiac strain. In a patient with hypertensive crisis or significant cardiovascular risk, this higher concentration should be avoided; the lower 2.5% dose is preferred with careful monitoring.