What Causes Anisocoria

Generally, anisocoria is caused by impaired dilation (a sympathetic response) or impaired constriction (a parasympathetic response) of pupils. An injury or lesion in either pathway may result in changes in pupil size.

What is anisocoria a symptom of?

Bleeding inside the skull caused by head injury. Brain tumor or abscess (such as, pontine lesions) Excess pressure in one eye caused by glaucoma. Increased intracranial pressure, because of brain swelling, intracranial hemorrhage, acute stroke, or intracranial tumor.

Can anisocoria be harmless?

Simple anisocoria — also called essential anisocoria or physiologic anisocoria — is the most common type of anisocoria. It’s a benign (harmless) condition that affects approximately 20% of the population.