Iris

Definition:

The iris is a colored, thin, circular structure in the eye that controls the size of the pupil.

Anatomy:

The iris is situated directly behind the cornea and in front of the lens. It consists of muscular fibers, pigment cells, and blood vessels.

Function:

The primary function of the iris is to regulate the amount of light entering the eye. It does so by adjusting the size of the pupil, allowing more or less light to pass through.