Which medication would least likely cause dry eye?

Which medication would least likely cause dry eye?

• A. Tropicamide
• B. Pilocarpine
• C. Atropine
• D. Homatropine

Answer: (B)

Tear production is driven by parasympathetic input to the lacrimal gland via muscarinic receptors. Drugs that block these receptors reduce lacrimal secretion, increasing the likelihood of dry eye. In contrast, pilocarpine is a muscarinic receptor agonist that stimulates lacrimal secretion, potentially increasing tearing. Therefore, pilocarpine would be least likely to cause dry eye, while the other medications—tropicamide, atropine, and homatropine—decrease tear production through muscarinic blockade.

Tear production is driven by parasympathetic input to the lacrimal gland via muscarinic receptors. Drugs that block these receptors reduce lacrimal secretion, increasing the likelihood of dry eye. In contrast, pilocarpine is a muscarinic receptor agonist that stimulates lacrimal secretion, potentially increasing tearing. Therefore, pilocarpine would be least likely to cause dry eye, while the other medications—tropicamide, atropine, and homatropine—decrease tear production through muscarinic blockade.