pupilsa

Pupilsa is a term that refers to the small, dark circle in the center of the iris of the eye. Its primary function is to regulate the amount of light that enters the eye, allowing for clear vision in various lighting conditions. The pupil constricts in bright light, reducing the amount of light entering the eye, and dilates in dim light, allowing more light to enter. This adjustment is an involuntary reflex controlled by muscles within the iris. The size of the pupil can vary significantly, from about 2 to 8 millimeters in diameter. Changes in pupil size can also be influenced by factors other than light, such as emotional state, focus of attention, and certain medications or substances. In medical contexts, pupil response is often assessed as an indicator of neurological function. The reaction of the pupils to light, known as the pupillary light reflex, is a crucial diagnostic tool for evaluating the health of the optic nerve and brainstem. Abnormal pupil responses can signal a range of medical conditions, from head injuries to stroke.