Medically reviewed by Michael Menna, DO Key Takeaways The iris is the colored part of the eye that helps control how much ...

Deep in human evolutionary history, before anything recognizable as a vertebrate existed, one of our oldest relatives had a ...

The colored part of the eye surrounding the pupil is called the iris. It automatically regulates the amount of light entering the eyes by regulating the size of the pupil. Light is the primary ...

Eye color is shaped by a complex interplay of genetics, microscopic iris structure, and the way light scatters within the eye. While lighting, pupil size, and clothing can make eyes appear to change ...