Improving diagnostic acumen in pupillary evaluation: a review for the primary care physician.

Many primary care physicians perform only a superficial pupillary evaluation as part of the physical examination. The authors review several maneuvers that require no special equipment and help to improve diagnostic yield. The "swinging flashlight" test aids in detecting a relative afferent pupillary defect. When a patient has anisocoria, the initial diagnostic challenge is to determine which pupil is abnormal. Comparing the extent of pupillary inequality under both dim and bright illumination almost always identifies the dysfunctioning pupil(s) and narrows the differential diagnosis. The authors compare third-nerve palsy and Horner's syndrome as causes of anisocoria and review light-near dissociation, another important category of pupillary dysfunction. This latter phenomenon is seen in the Argyll Robertson pupil, the dorsal midbrain syndrome, and the tonic pupil syndromes. Pupillary size and activity are key diagnostic parameters in the evaluation of patients in coma. Structural and mechanical iris defects are also frequently responsible for pupillary anomalies.