Light Near Dissociation in a Tonic Pupil

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: This is a 65-year-old woman who noticed difficulty reading and heightened sensitivity to lights OS for the last 6 months. On examination, there was mydriasis OS of about 6 mm (3 mm OD). The left (mydriatic) pupil constricted minimally to light, but constricted much better to a near stimulus. When looking back to a distant target, the pupil was slow to dilate (i.e., a ‘tonic' dilation). During slit lamp examination, there was sectoral constriction of the left pupil, with the inferior iris constricting much more than the superior segment. Upon review of old photos, there was relative mydriasis OS for at least 12 months. Examination of motility and eyelid function was unremarkable with normal alignment and no ptosis. Deep tendon reflexes were normal (i.e., this was not Adie's syndrome). There was constriction OS (but not OD) with dilute (0.1%) pilocarpine, and she was diagnosed with a left tonic pupil. She was given a higher power prescription for reading OS, and over years the left pupil spontaneously became less mydriatic. 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: This video depicts the common features of a tonic pupil, including poor pupil reactivity to light and better constriction to a near stimulus, as well as a tonic (slow) dilation of the affected pupil when looking from near to distance. https://collections.lib.utah.edu/ark:/87278/s61p390k