Walsh & Hoyt: Disorders of the Pupil

The value of observation of pupillary size and motility in the evaluation of patients with neurologic disease cannot be overemphasized. In many patients with visual loss, an abnormal pupillary response is the only objective sign of organic visual dysfunction. In patients with diplopia, an impaired pupil can signal the presence of an acute or enlarging intracranial mass. An adequate clinical examination of the pupils requires little time and can be meaningful when approached with a sound understanding of the principles of pupillary innervation and function. In most cases, one needs only a hand light with a bright, even beam, a device for measuring pupillary size (preferably in half-millimeter steps), a few pharmacologic agents, and an examination room that permits easy control of the background illumination.