Anisocoria is a condition characterized by an unequal size of the eyes' pupils. Affecting up to 20% of the population, anisocoria is often entirely harmless, but can be a sign of more serious medical problems.

Causes

Anisocoria is a common condition, defined by a difference of 0.4 mm or more between the sizes of the pupils of the eyes. Anisocoria has various causes:

Diagnosis

Acute onset anisocoria should be considered a medical emergency. These cases may be due to brain mass lesions which cause oculomotor nerve palsy. Anisocoria in the presence of confusion, decreased mental status, severe headache, or other neurological symptoms can forewarn a neurosurgical emergency. This is because a hemorrhage, tumor, or other intracranial mass can enlarge to a size where the third cranial nerve (oculomotor nerve) is compressed, resulting in uninhibited dilatation of the pupil on the same side as the lesion.

Popular culture

Etymology

Anisocoria is composed of prefix, root and suffix: Thus, anisocoria means the condition of unequal pupil(s).