2021 May 19. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–.
Anisocoria has a wide range of causes, from those which are benign extending to those which are life-threatening. There are many complicated pathways involved in determining pupillary size and reactivity. Pupillary size may be influenced by systemic drug use or topical ophthalmics. Anisocoria also may be present in a cluster headache with lacrimation and rhinorrhea. Other rare forms of a headache also may invoke anisocoria. Additionally, some autonomic ganglion pathology may manifest as anisocoria. Also, there are reports of a variety of unusual causes involving a number of medicines as well as surgical procedures that usually occur on the face. Although anisocoria may be caused by abnormalities or injuries of the iris dilation and sphincter muscles, this discussion concentrates on specific neurologic abnormalities as the cause.