This article reviews the underlying disorders causing pathologic anisocoria or abnormal pupils to help clinicians efficiently pursue appropriate investigations.
The pupils reflect the activity of several central nuclei, peripheral ganglia, and nerves that control two muscles of the iris: the radial dilator and the circular sphincter. Acquired asymmetry of pupil size and abnormal pupillary movement signal damage within the neural (parasympathetic or sympathetic) pathways to the eye or damage to the muscles that move the pupil. Studies have further defined which topical agents are useful in diagnosing pupil disorders.
Pupillary shape, size, and movement are readily observable. Knowledge of the relatively simple pupil anatomy and innervation can guide clinical examination to determine the pathophysiologic mechanism underlying a pupil abnormality.