In optical terms, the anatomical pupil is the eye's aperture and the iris is the aperture stop. The image of the pupil as seen from outside the eye is the entrance pupil, which does not exactly …

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 …

Jan 6, 2026 · A pupil is the opening created by the iris, which controls the amount of light that enters the eye. Learn about medical conditions affecting the pupils.

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.

Feb 6, 2026 · 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 …

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.

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 …

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 …

May 26, 2023 · The opening at the center of the iris that allows light to enter the eye.