Anisocoria

An inequality in pupil size between the two eyes, unilateral or bilateral, resulting from disruption of autonomic pupillary control, efferent pupillary pathways, or structural abnormalities of the iris.

Causes

• Physiological causes: Normal asymmetry without underlying pathology

• Neurological causes

  • Horner syndrome

  • Adie’s tonic pupil

  • Brain hemorrhage

  • Stroke

  • Carotid artery dissection

  • Vertebral artery dissection

  • Increased intracranial pressure

  • Third cranial nerve (oculomotor nerve) dysfunction

  • Brainstem lesions

• Pharmacological causes

  • Topical ophthalmic medications affecting pupil size

  • Anticholinergic agents

  • Sympathomimetic agents

  • Miotic agents

  • Exposure to recreational or toxic substances affecting autonomic function

• Structural ocular causes

  • Uveitis

  • Glaucoma

  • Eye trauma

  • Iris sphincter damage

  • Iris surgery or other intraocular procedures

  • Congenital iris abnormalities