A DIAGNOSTIC-APPROACH TO ANISOCORIA

The condition in which the pupils differ in size is referred to as anisocoria. This physical examination finding can be normal (dynamic contraction) or can indicate an underlying ocular or neurologic abnormality. Because anisocoria can be more pronounced in either bright light or dim light, pupillary size and symmetry should be assessed in various light conditions. Localization of the cause of anisocoria helps the clinician to formulate a diagnostic plan and a list of diagnostic differentials. The first step in approaching a case of anisocoria is to rule out primary ocular causes; after this is done, the clinician can pursue a neurologic cause. A few clinical observations can facilitate classification of a neurologic cause of anisocoria into one of the three major divisions: sympathetic efferent, pupillary afferent, or parasympathetic efferent. With the aid of an algorithm, this article presents a problem-oriented diagnostic approach to anisocoria.