In Adie tonic pupil, which test helps diagnose the condition?

• A. 0.125% Pilocarpine to constrict the pupil
• B. 2% Pilocarpine to dilate the pupil
• C. Apraclonidine testing
• D. Hydroxyamphetamine testing

Answer: (A)

Adie tonic pupil arises from denervation of the iris sphincter, leaving the pupil poorly reactive to light but with slow, sustained constriction to accommodation. The iris sphincter becomes supersensitive to acetylcholine after this nerve injury. Using a very dilute pilocarpine solution (0.125%) takes advantage of that supersensitivity: the affected eye constricts in response to this low concentration, while a normal eye does not. That selective constriction confirms the diagnosis of Adie, because the response relies on the cholinergic supersensitivity of the denervated sphincter. The other tests target the sympathetic system and Horner syndrome, not parasympathetic denervation, so they don’t diagnose Adie.