Eye Color

Eye color is a polygenic trait and is determined by the amount and type of pigments in the eye's iris. Humans and animals have many phenotypic variations in eye color. In human eyes, these variations in color are attributed to varying ratios of eumelanin produced by melanocytes in the iris. The brightly colored eyes of many bird species are largely determined by other pigments, such as pteridines, purines, and carotenoids.
Three main elements within the iris contribute to its color: the melanin content of the iris pigment epithelium, the melanin content within the iris stroma, and the cellular density of the iris stroma.

Eye colors can range from the most common color, brown, to the least common, gray. Rare genetic specialties can even lead to unusual eye colors: black, red, and violet. Eye color is an inherited trait influenced by more than one gene, these genes are being sought using associations to small changes in the genes themselves and in neighboring genes.

The actual number of genes that contribute to eye color is unknown at present, but there are a few likely candidates. Iris color can provide a large amount of information about an individual and a classification of various colors may be useful in documenting pathological changes or determining how a person may respond to various ocular pharmaceuticals.

There are 3 true colors in the eyes that determine the outward appearance, brown, yellow and blue. How much of each color one has determines the appearance of our eyes color. The color of the eyes in turn depends on how much of these colors are present. For example, green eyes have yellow and some blue, making them appear green. Brown eyes appear brown because most of the eye contains the brown color.