Tonic Pupil

  • Dilated pupil caused by lesion of ciliary ganglion or nerves
  • Part of limited post-viral or idiopathic dysautonomia
  • May also result from orbital surgery
  • Often misdiagnosed as partial third cranial nerve palsy
  • Dilated pupil that does not constrict to bright light, constricts slowly to target fixated at close range, and dilates slowly upon refixation on distant target
  • Slit lamp examination often shows that pupil constricts segmentally (stromal streaming)
  • Accommodation may be impaired in affected eye
  • Deep tendon reflexes may be absent
  • Iris damage from trauma, intraocular surgery, inflammation
  • Accidental or deliberate ocular instillation of anticholinergic substances
  • Do not refer patient to emergency room for unilaterally dilated pupil unless ptosis, diplopia, or eye movement abnormality present
  • Refer to ophthalmologist non-urgently to confirm diagnosis of tonic pupil
  • Life-long condition but does not cause troublesome symptoms
  • Affected pupil often becomes smaller than unaffected pupil
  • No related medical problems will emerge, but...
  • Pupil of other eye may later become similarly affected
  • Refer patient emergently to ophthalmologist or emergency room if you find upper lid ptosis and miosis, especially if acute and accompanied by new neck pain or diplopia