Human eye - Pupil , Iris, Retina: The amount of light entering the eye is restricted by the aperture in the iris, the pupil . In a dark room, a person’s pupils are large, perhaps 8 mm (0.3 inch) or more in diameter. When the room is lighted, there is an immediate constriction of the pupils, the light reflex. This is bilateral, so that even if only one eye is exposed to the light, both pupils contract to nearly the same extent. After a time, the pupils expand even though the bright light is ... The pupil is the black, circular opening in the center of the eye that allows light to enter and reach the retina. It appears black because most of the light entering the pupil is absorbed by the tissues inside the eye. The size of the pupil changes in response to light intensity, controlled by the iris muscles that dilate or constrict it. This regulation ensures the appropriate amount of light enters the eye for optimal vision. The meaning of PUPIL is a child or young person in school or in the charge of a tutor or instructor : student. Learn the meaning of pupil as a student or an eye part, with examples of usage and pronunciation. Find out how to say pupil in different languages, such as Chinese, Spanish and Portuguese.
