Tonic Pupil

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)