A pupillary abnormality characterized by a poor pupillary light reaction, reduced accommodation, iris sector palsies, an enhanced pupillary response to near effort that results in a prolonged, "tonic" constriction, and slow pupillary redilation. This condition is associated with injury to the postganglionic parasympathetic innervation to the pupil. (From Miller et al., Clinical Neuro-Ophthalmology, 4th ed, pp492-500)

Conditions which affect the structure or function of the pupil of the eye, including disorders of innervation to the pupillary constrictor or dilator muscles, and disorders of pupillary reflexes.

The aperture in the iris through which light passes.

Unequal pupil size, which may represent a benign physiologic variant or a manifestation of disease. Pathologic anisocoria reflects an abnormality in the musculature of the iris (IRIS DISEASES) or in the parasympathetic or sympathetic pathways that innervate the pupil. Physiologic anisocoria refers to an asymmetry of pupil diameter, usually less than 2mm, that is not associated with disease.