neurologic disorders
Third Cranial (Oculomotor) Nerve Disorders
Introduction
Third cranial nerve disorders can impair ocular motility, pupillary function, or both. Symptoms and signs include diplopia, ptosis, and paresis of eye adduction and of upward and downward gaze. If the pupil is affected, it is dilated, and light reflexes are impaired. If the pupil is affected and patients are increasingly unresponsive, neuroimaging is done as soon as possible to check for transtentorial herniation. (See also Overview of Neuro-ophthalmologic and Cranial Nerve Disorders .) 