The iris is a contractile structure, consisting mainly of smooth muscle, surrounding the pupil. Light enters the eye through the pupil, and the iris regulates the amount of light by controlling the …

Small pupils can happen when you’ve had a stroke or when you’ve used opiates, among other reasons. Mydriasis is the name of the opposite condition, having dilated pupils.

Dec 4, 2024 · Pupils are the dark-colored openings at the center of your eyes that let light in. Doctors can look at your pupils for clues about your health. The size of your pupils and how …

Apr 22, 2025 · The pupil is the opening located in the center of the iris of the eye. It controls the amount of light that enters the eye so that you can see clearly. The pupil size is controlled by …

Nov 25, 2025 · 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 …

Feb 26, 2019 · Typically, the pupils appear perfectly round, equal in size and black in color. The black color is because light that passes through the pupil is absorbed by the retina and is not …

Jul 6, 2023 · Learn about the dark openings at the center of your eyes called pupils, how they react to light, and what changes in pupil size and shape can indicate about your health.

Feelings such as surprise, fear, or attraction can trigger the sympathetic nervous system, causing the pupils to widen. This response is linked to the body’s general state of alertness.

PUPIL definition: the expanding and contracting opening in the iris of the eye, through which light passes to the retina. See examples of pupil used in a sentence.

Mar 4, 2025 · The pupils are the parts of the eye that constrict and dilate in response to light, controlled by the iris. Pupil-related eye conditions include anisocoria, cataracts, miosis and …