The structural elements of the iris, the colored part of the eye, consist of thin fibers of muscle and connective tissue, which are essentially clear. When light passes through these transparent structures it bends and separates the light in the same way that a rainbow forms. The light that bends the most is blue light, and this gives the blue eye its color.
The dark brown pigment called melanin is the only substance in the body whose function is to change the color of a tissue or more specifically to change the amount of light reflected from a surface. Humans are genetically programmed to deposit the pigment melanin onto the fibers of the iris (and into the cells of the skin) in varying amounts. As the amount of dark brown melanin is increased, less of the blue light is transmitted because the pigment blocks the blue light and increases the amount of brown light being reflected from the surface of the iris. As the amount of brown increases, the eye’s color changes from gray to green to hazel and through all the browns. So in the end it’s really not a matter of how blue a person’s eyes are but rather how much brown they have.
If you would like to try a new look then colored contact lenses can change almost anyone’s eye color from blue to brown or brown to blue.
