Walsh & Hoyt: Efferent Abnormalities: Anisocoria

The presence of anisocoria usually indicates a structural defect of one or both irides or a neural defect of the efferent pupillomotor pathways innervating the iris muscles in one or both eyes. A careful slit-lamp examination to assess the health and integrity of the iris stroma and muscles is an important step in the evaluation of anisocoria. If the irides are intact, then an innervation problem is suspected. As most efferent disturbances causing anisocoria are unilateral, two simple maneuvers are helpful in determining whether it is the sympathetic or parasympathetic innervation to the eye that is dysfunctional: (1) checking the pupillary light reflex and (2) measuring the anisocoria in darkness and in bright light.