The pupillary light reflex is a natural response of the pupil in the eye to changes in light intensity. When bright light enters the eye, the pupil constricts to limit the amount of light that reaches the retina. This reflex helps protect the retina from excessive light exposure and improves visual acuity in bright conditions. This reflex involves a neural pathway that includes the optic nerve, which detects light, and the oculomotor nerve, which controls the muscles that constrict the pupil. The response occurs in both eyes, even if only one eye is exposed to light, demonstrating the interconnectedness of the visual system.