Eye Color

The human eye gets its color from the iris, which is the colored part of the eye. The pigmentation of the iris varies depending on person to person and can be affected by factors such as ancestry, age, and environment. For example, someone with blue eyes may have less pigment in their iris than someone with brown eyes.

The Science of Eye Color

The color of the iris is created by two types of cells: melanocytes and xanthophores.

• Melanocytes produce a black pigment called melanin.
• Xanthophores produce a yellow pigment called pteridines.

The combination of these two pigments creates the various colors that are seen in human eyes.

How Pigmentation Affects Eye Color

The amount of pigment in the iris can also affect the eye color.

• If there is more melanin present, the eye will appear darker.
• If there is less melanin, the eye will appear lighter.

The same goes for xanthophores:

• If there are more present, the eye will appear yellow-hued.
• If there are less present, the eye will appear bluish.

Environmental Factors

Environmental factors, such as exposure to sunlight, can also affect the amount of pigment in the eye. For example, people who spend a lot of time outdoors may find that their eyes become darker over time due to the increased melanin production.

Age and Eye Color

Age can also affect eye color. As we age, the melanocytes in our eyes begin to break down and produce less pigment. This can cause the eyes to appear lighter or grayer as we get older.