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

They scatter light so that more blue light reflects back out. Eye color depends on the iris, the colored part of the eye. It's a structure that contains muscle and other kinds of cells.

Sustained blue light exposure from electronic devices and digital screens is not kind on your overall health, and has been linked to eye strain, macular degeneration and poor sleep quality.

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.