What is the term for the colored part of the eye? The iris is the colored, ring-shaped part of the eye.
In humans, the iris surrounds the pupil, the dark central opening that lets light enter the eye. Muscles within the iris change the pupil’s diameter: circular muscles constrict it in bright conditions, while radial muscles enlarge it in dimmer conditions. This regulates how much light reaches the retina.
Eye color is the visible color of the iris, not the cornea or the pupil. The cornea is the transparent outer covering at the front of the eye, and the retina is the light-sensitive tissue lining the back. Iris color mainly reflects the amount and distribution of melanin, along with the structure of the iris tissue and the way it scatters light.
The word iris comes from the ancient Greek word for “rainbow” and also refers to Iris, the Greek goddess associated with the rainbow. Different colors in the two eyes, or distinct colors within one iris, are called heterochromia.