Approach to anisocoria in the emergency department

Anisocoria describes asymmetric pupillary diameter, which can result from traumatic, pharmacologic, inflammatory, or ischemic effects on the eye. In many cases, anisocoria represents a normal physiologic variant. Morbidity associated with anisocoria is directly related to the inciting cause and can vary from benign to life-threatening. A thorough understanding by emergency physicians of normal ocular neuroanatomy, and of common causes of pathologic anisocoria, including medication-induced anisocoria, can facilitate appropriate resource utilization and timely subspecialty consultation, and can help prevent irreversible ocular injury and patient morbidity. We describe a patient who presented to the emergency department with acute onset of blurry vision with anisocoria.