Anisocoria

Anisocoria, or unequal pupil sizes, is a common condition. The varied causes have implications ranging from life threatening to completely benign.  The incidence and prevalence for anisocoria depend on the specific causes. The presence of physiologic anisocoria has been estimated at 20% of the normal population, so some degree of pupil difference may be expected in at least 1 in 5 clinic patients.  More devastating causes of anisocoria are related to cerebral aneurysms and Horner syndrome.