Eye color - Wikipedia, the free encyclopedia

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** Eye color **

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Close up of a human iris
Map of the distribution of the light eyes(Blue, Green and Gray) in Europe
at the middle of the 20th century by the American anthropologist Carleton
S. Coon
Another map showing the distribution of light eyes(Blue and Green) and dark
eyes(Brown and Black) in Europe

*Eye color* is a polygenic phenotypic character determined by two distinct
factors: the pigmentation of the eye's iris^[1]^[2] and the
frequency-dependence of the scattering of light by the turbid medium in the
stroma of the iris.^[3]

In humans, the pigmentation of the iris varies from light brown to black,
depending on the concentration of melanin in the iris pigment epithelium
(located on the back of the iris), the melanin content within the iris
stroma (located at the front of the iris), and the cellular density of the
stroma.^[4] The appearance of blue, green, as well as hazel eyes results
from the Rayleigh scattering of light in the stroma, a phenomenon similar
to that which accounts for the blueness of the sky. Neither blue nor green
pigments are ever present in the human iris or ocular fluid.^[3]^[5] Eye
color is thus an instance of structural color and varies depending on the
lighting conditions, especially for lighter-colored eyes.

The brightly colored eyes of many bird species result from the presence of
other pigments, such as pteridines, purines, and carotenoids.^[6] Humans
and other animals have many phenotypic variations in eye color.^[7] The
genetics of eye color are complicated, and color is determined by multiple
genes. So far, as many as 15 genes have been associated with eye color
inheritance. Some of the eye-color genes include


Source: en.wikipedia.org/wiki/Eye_color


can eyes change color

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