Peacocks can teach us about eye color
Eye color and peacock feathers have something in common that may surprise you. Like the feathers of a peacock or the wings of a butterfly, the blue or green color of the eyes is the result of structural coloration. A peacock tail feathers are pigmented brown, but their microscopic structure reflects specific wavelengths of light such as blue, turquoise, and green light. This is why the tail changes color according to the angle of incident light. Therefore these iridescent colors are not made up of different pigments!
In the human eye, the upper layer of the iris called the stroma, generates the structural color. Blue and green eye colors are actually produced by the disturbance of the visible light that passes through the iris. They scatter light so that more blue light reflects back out. In other words, blue eyes don’t contain any blue pigment, green eyes do not have green pigment in them!
The iris, the colored part of the eye, consists of two layers: the epithelium at the back, the stroma at the front.
- The epithelium contains melanin, a black-brown pigment. Melanin is also the pigment that colors your skin and protects from the sun.
- The stroma, in contrast, is made up of collagen fibers that have no color. The stroma can also contain melanin in different proportions , or may not contain any: black and brown eyes have a lot of melanin. People with blue or green eyes have very small amount of pigment or none, in their stroma
Different eye colors
Brown eyes are the most common eye color. Their stroma has a high concentration of melanin. This pigment absorbs most of the light thus giving the eye its dark color. This principle is also valid for hazel eyes where the melanin level is in more moderate amount.
In green eyes the melanin level is low. The light that passes through the stroma is in part absorbed by the pigment, and also disturbed by the collagen fibers. This results in a light brown pigment color which couples to the structural blue, and creates a variety of green hues.
Finally, for blue eyes, melanin is almost completely absent. Thus, the stroma is transparent. As a result, the light rays that pass through it are fully dispersed and reflected. This gives a structural blue color with brightness and iridescence that may vary depending on the amount of light available. The color is entirely structural.
Protect your eyes
So you see, your eye color depends on how much melanin there is in your iris. Besides being responsible for your eye color, melanin helps protect your eyes from the harmful sun rays. Therefore light eyes are much more sensitive to the sun than darker eyes because they contain a smaller amount of protective melanin. It is important to protect your eyes from the sun, regardless of their color, but even more so if you have green or blue eyes. So remember to wear sunglasses and to add an excellent eye supplement to your diet, such as Vistasaffron.