Evaluation of the pupillary light response as an objective measure of visual function.

Examination of the pupil provides critical objective information that complements subjective visual measurements and can provide important clues for distinguishing among different etiologies of loss of visual function. Although automated technologies and pupillary perimetry provide valuable insight into the correspondence between visual and pupillary dysfunction, a firm understanding of the principles of the afferent examination of the pupil is all that is required for the clinician to quickly obtain this objective measure of function during any routine examination.