Medically reviewed by Johnstone M. Kim, MD Of the four main eye colors (brown, blue, green, and hazel), the rarest eye color ...

The fascinating variety of cat eye colors results from some fascinating genetic interactions, development, and adaptation due to evolution. To fully understand how cats develop their distinctive eye ...

This is the part of the eye that lets the light in. Lights out please! When it’s dark, muscles in the iris make the pupil ... green and blue, and all the millions of shades in between.