This is tested by having the patient gaze at a distance point in a darkened room, and then illuminating one eye. The reflex response is normally prompt constriction of both that pupil (direct response) and the other pupil (consensual response). The afferent limb of this reflex is the optic tract, which sends a few axons directly to the pretectal area. The efferent limb of the reflex involves parasympathetic components in CN III, and the ciliary ganglion.