There are no blue pigments in the iris to make eyes blue. Blue eyes have low levels of melanin or brown pigment in the stroma of the iris (front portion of the iris) and the pigment epithelium (back surface of the iris).Just like when we see a blue sky, longer wavelengths of light do not reflect and are absorbed by the back pigment layer of the iris. The shorter wavelengths of light (blue) are reflected and results in a blue iris which can change in appearance depending on lighting conditions.
Who has Blue Eyes?
Blue eyes are more common in Scandinavia, Northern Europe, and Western Asia and their descendants. In America, one out six children is born with blue eyes. Approximately two percent of the world’s people have blue eyes.
Green eyes are due to low levels of melanin pigment in the stroma with a combination of amber and/or light brown pigment in the stroma with light being scattered or reflected from the stroma of the iris. Green eyes are the least common eye color.
Who has Green Eyes?
Green eyes are most common in Northern Europe, South America, Iceland, North Africa, and Central Europe. Green eyes are more common in women than men.
Hazel eyes are due to a moderate level of melanin pigment in the stroma. Hazel eyes consist of brown and green colors. It can appear as a multicolored eye and the eye color can appear to change in different light conditions.
Amber eyes have a yellowish or golden color and are due to the deposition of a yellow pigment called lipochrome. Amber eyes are different from hazel eyes as hazel eyes have more than one color.
Grey eyes are similar to blue eyes in that there is a low level of melanin pigment in the epithelium and iris stroma. The grey color may be due to a difference in the thickness of the stroma or different levels or pattern of pigment in the stroma.
Who has Grey Eyes?
Grey eyes are more common in the Middle East, Pakistan, Northern Europe, and Eastern Europe.
Brown eyes are the dominant eye color in humans around the world. Brown eyes are due to the high levels of melanin in the stroma and pigment epithelium of the iris.
Associated Risks of Eye Color
Lighter colored eyes such as blue or green have a higher incidence of age-related macular degeneration. Melanoma of the iris and uveal layer of the eye is more common in people with blue, green, or grey.