When to See a Doctor. Share: Facebook Twitter. Ready for an appointment? Doctors Featured in this Article. Featured Doctors Images. Brown eyes have a lot of melanin, so they absorb light, which makes them dark. Hazel eyes have less melanin than brown eyes, but more than green eyes. Blue eyes have the least amount of melanin and reflect the most light.
Because eye color is due to reflected light, blue, green, and even hazel eyes can change a little in different lighting conditions. Babies are the exception. With contact lenses, you can accentuate, enhance, or completely change your eye color. These lenses come in a wide variety of colors and can correct vision or not. Learn about potential problems caused by colored contact lenses here.
A surgical procedure originally developed to treat eye injuries and other conditions, the iris implant has been used to permanently change eye color. In , the American Academy of Ophthalmology warned against undergoing this procedure. Read more about the iris implant and colored contacts here. Some medical conditions are known to affect eye color.
Instead, they usually affect the whites or cornea of your eye. These conditions include:. Common eye diseases occur less often in people with brown eyes than with gray, green, or blue eyes. This may be because melanin is protective. For example, a study found that type 1 diabetes was more common in people of northern European descent with blue eyes.
This may be why diabetic retinopathy is more common in people with light-colored eyes. A study found women with light-colored eyes, such as blue or green, experienced less pain when giving birth compared to women with dark eyes, such as hazel or brown. The inheritance of eye color is more complex than originally suspected because multiple genes are involved.
Several disorders that affect eye color have been described. Ocular albinism is characterized by severely reduced pigmentation of the iris, which causes very light-colored eyes and significant problems with vision. Another condition called oculocutaneous albinism affects the pigmentation of the skin and hair in addition to the eyes. Affected individuals tend to have very light-colored irises, fair skin, and white or light-colored hair. Both ocular albinism and oculocutaneous albinism result from mutations in genes involved in the production and storage of melanin.
Another condition called heterochromia is characterized by different-colored eyes in the same individual. Heterochromia can be caused by genetic changes or by a problem during eye development, or it can be acquired as a result of a disease or injury to the eye. Am J Hum Genet. Epub Jan PubMed: Sturm RA, Larsson M. Genetics of human iris colour and patterns.
Pigment Cell Melanoma Res. However, they have several interesting theories. One theory is the Vitamin D hypothesis, which is the idea that light colored skin, hair, and eyes co-evolved as humans moved into latitudes with shorter days, shorter summers, and therefore, less sunlight. However, molecular geneticist and Associate Professor Rick Sturm of the University of Queensland had a problem with this hypothesis. He said that there is no evidence that light-colored irides let in more light or help you see better in low lighting than dark colored irises.
Additionally, there is evidence that blue eyes evolved before light skin. Sturm and his team did a study looking at the genetic information extracted from a year-old tooth belonging to a hunter-gatherer dubbed La Brana 1, unearthed from the northwestern Spain. This archeological finding contradicts the theory that hair, skin, and eyes co-evolved in reaction to the limited sunlight.
Another theory is that people considered blue eyes to be more sexually attractive. Perhaps people were attracted to the novelty of blue eyes and therefore people with blue eyes were more likely to find mates.
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