What happens to pupils when a light is shone into them?

When a light is shone into the pupils, they constrict. This reaction is a natural response known as the pupillary light reflex, which occurs due to the involvement of the iris muscles. When bright light hits the retina, it triggers a reflex that results in the constriction of the pupils. This narrowing reduces the amount of light entering the eye, which helps protect the retina from excessive brightness and improves visual acuity by enhancing focus on nearby objects.

This constriction occurs bilaterally, meaning both pupils typically respond even if only one eye is directly exposed to light, demonstrating the coordinated function of the nervous system. Understanding this physiological response is crucial for emergency responders, as it provides valuable information about a patient’s neurological status and can help in assessing potential head injuries or other medical conditions.