How do pupils change in size with dim and bright light?

The pupil changes its size to control how much light enters the eye. The pupils tend to expand in dim light and contract when the light is bright. Light detected by the retina of your eye is converted to nerve impulses that travel down the optic nerve. read more

The pupils tend to expand in dim light and contract when the light is bright. Light detected by the retina of your eye is converted to nerve impulses that travel down the optic nerve. Some of these nerve impulses go from the optic nerve to the muscles that control the size of the pupil. read more

In dim light, your pupil expands to allow more light to enter your eye. In bright light, it contracts. Your pupil can range in diameter from 1/16 inch (1.5 mm) to more than 1/3 inch (8 mm). read more