Episodic Mydriasis

    • Transient unilateral pupil dilation lasting <12 hours attributed to autonomic dysregulation
    • Common causes: idiopathic, migraine
    • Uncommon cause: seizure
    • Core clinical features
      • Patient reports blurred vision or difficulty focusing in the affected eye, or merely notices anisocoria by looking in the mirror
      • Both pupils may constrict normally to light, or the mydriatic pupil may constrict relatively poorly to light
    • Possible accompanying clinical features
      • Migraine attack
      • Seizure
    • Pharmacologic mydriasis
    • Physiologic anisocoria
    • Horner syndrome
    • If the anisocoria is still present at the time of your examination, and both pupils constrict normally to light, rule out Horner syndrome with apraclonidine instillation, which should not cause reversal of anisocoria
    • If the mydriatic pupil fails to constrict normally to light, rule out third nerve palsy, tonic pupil, pharmacologic mydriasis, and iridoplegic mydriasis with appropriate diagnostic maneuvers
    • If you diagnose episodic mydriasis, advise the patient that this is a benign condition that usually occurs without explanation or as part of migraine or a seizure, and may occur again
    • Plan no further evaluation
    • Recurrences usually affect the same eye

    Pupil Disorders

    Anisocoria Overview Physiologic Anisocoria Horner Syndrome Tonic (Adie) Pupil Argyll Robertson Pupil Pharmacologic Mydriasis Episodic Mydriasis Iridoplegic Mydriasis Mydriasis of Third Nerve Palsy Tectal Pupils