What's the hole in the eye for?

The pupil in the eye is called the pupil. Its main function is to control the amount of light that enters the eye.

When the ambient light is strong, the pupil automatically shrinks to limit the amount of light that enters the eye. This prevents too much light from entering the eye and protects the retina from damage. When the ambient light is dim, the pupil automatically dilates to increase the amount of light that enters the eye to improve vision and perception.

In addition to regulating the amount of light that enters, the size of the pupil also reflects the emotional and physiological state of the human body. The pupil dilates when emotional or tense, and contracts when relaxed or quiet.