In Adie's pupil, which very dilute pilocarpine solution will cause constriction due to supersensitivity?

• A. Constriction
• B. Dilation
• C. No change
• D. Progressive mydriasis

Answer: (A)

In Adie’s pupil the parasympathetic input to the iris sphincter is damaged, so the sphincter becomes hypersensitive to muscarinic stimulation. When you apply a very dilute pilocarpine solution (the classic test uses a dilute concentration), the supersensitive sphincter contracts, causing the pupil to constrict. This constriction is seen in the affected pupil but not in a normal one, which explains why constriction is the correct outcome. Pilocarpine is a cholinergic agent, so it drives constriction rather than dilation, and the other options don’t fit the mechanism or expected response in Adie’s.