Why are my eyes two shades?

Question

i don't know what it's called... that part of your eye thats brown, blue etc... my one eye is dark brown and the other is light brown.. why?

Answer 1

Heterochromia or two different colored eyes can happen in people because of lost or damaged melanocytes and/or genetic conditions like chimerism or mosaicism. (1)

Heterochromia (also known as a heterochromia iridis or heterochromia iridium) is an ocular condition in which one iris is a different color from the other iris (complete heterochromia), or where the part of one iris is a different color from the remainder (partial heterochromia or sectoral heterochromia). It is a result of the relative excess or lack of pigment within an iris or part of an iris, which may be inherited or acquired by disease or injury.[68] This uncommon condition usually results due to uneven melanin content. A number of causes are responsible, including genetics such as chimerism and Waardenburg syndrome. Trauma and certain medications, such as some prostaglandin analogues can also cause increased or decreased pigmentation in one eye. On occasion, the condition of having two different colored eyes is caused by blood staining the iris after sustaining injury.

British singer David Bowie is a famous person often wrongly attributed with heterochromia. His apparent condition is due to a teenage injury. (One eye appears darker because the pupil is permanently dilated.) American actress Kate Bosworth has sectoral heterochromia, resulting in a hazel section at the bottom of her right blue eye, while the left is completely blue. American Actress Elizabeth Berkley has sectoral heterochromia; her right eye is half green and half brown, and her entire left eye is green. So does actor Anthony Head - he has a patch of hazel in his left eye where both eyes are blue-green overall. The lead vocalist of American band Rise Against, Tim McIlrath, has heterochromia; his left eye is blue while his right is brown. American actress Mila Kunis also has heterochromia, resulting in one blue eye and one brown-green eye. American Actress Demi Moore also has heterochromia, by having one green eye, and the other hazel. (2)

If a person has two different eye colors this is called heterochromia. This is considered abnormal and may be pathological. If a person has always had two different colored eyes, then this is called congenital heterochromia and is cause by a difference in the early stages of development of the iris. This is rare, but nothing to have medical concern over. If the heterochromia is acquired after time then there is reason to believe that something has happened within the body to create changes in melanin synthesis or degradation. This can be caused by diseases in the eye or by certain types of medicines. (3)

Answer 2

The part of your eye with colouring in it is called the IRIS.

The colour of your eye is determined by the amount of pigmentation it has: the varying ratios of 'eumelanin' as produced by 'melanocytes' of the iris.

The dark brown eye must have more pigmentation in it than the light brown eye.

Hope this helps