A 55-year-old man with a history of untreated syphilis presents with pupils that constrict when focusing on a near object but do not react to direct light. This finding is characteristic of which condition?

• A Horner syndrome
• B Marcus Gunn pupil
• C Adie tonic pupil
• D Argyll Robertson pupil ✓

Explanation

Argyll Robertson pupil shows light-near dissociation: the pupil accommodates to near but does not react to light. This is pathognomonic for neurosyphilis. Adie tonic pupil reacts slowly to both light and near stimulation. Marcus Gunn pupil is a relative afferent pupillary defect detected by the swinging flashlight test. Horner syndrome presents with ptosis, miosis, and anhidrosis due to sympathetic disruption.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.