Reflex changes in the size of the pupil triggered by the amount of light entering the eye. Bright light stimulates the pupil to contract; dim light stimulates the pupil to widen.
Constriction of the iris of the eye due to stimulation with light.
The reflex change in the size of the pupil according to the amount of light entering the eye. Bright light reaching the retina stimulates nerves of the ‘parasympathetic nervous system, which cause the pupil to contract. In dim light the pupil opens, due to stimulation of the sympathetic nervous system.
Constriction of the pupil upon stimulation of the retina by light. This reflex is mediated by the third cranial nerve.