What is the reason for small pupils?

Pupils that are abnormally small under normal lighting conditions are called pinpoint pupils. Learn what causes them and how to recognize the signs. read more

Pupils that are abnormally small under normal lighting conditions are called pinpoint pupils. Another word for it is myosis, or miosis. The pupil is the part of your eye that controls how much light gets in. In bright light, your pupils get smaller (constrict) to limit the amount of light that enters. In the dark, your pupils get bigger (dilate). read more

The pupil is the opening in the center of the iris of the eye. A chief function of the pupil is to control the amount of light entering the eye. Two muscles, the sphincter and the dilator, control the size of the pupil in response to changes in light. The dilator muscle radiates out from the pupil like a star. read more

When the pupil becomes small it is said to be constricted. The process of pupil constriction is called miosis. As the body ages, the pupil becomes naturally smaller and does not open as wide in dim light. The average pupil diameter for a 30-year-old is 4.3 millimeters in the daylight and 7.0 millimeters at night. read more