If you’re a black person with blue eyes, you may feel like you have been mistreated. People often question your eye color, and you might be wondering if you have it naturally or if you can change it.
The eye color you have depends on how much your skin cells make melanin, a pigment that gives you skin and hair color. The two most important genes that determine your eye color are OCA2 and HERC2.
Causes
There are many different causes of blue eyes, ranging from rare genetic mutations to environmental factors. Some people also have eye conditions like ocular albinism and waardenburg syndrome that can affect the color of their eyes.
Although it is rare, black people can have blue eyes if they inherit a genetic trait that causes their eyes to light up. Specifically, they might have a genetic mutation that reduces the amount of melanin in their irises.
One of the most common causes of eye color is a gene called OCA2 (represented as O, o, H and h in Image 2), which controls the pigment in the front layer of the iris, known as the stroma. When this layer of the iris is light brown, it scatters the blue wavelengths that come in, making it appear as though the iris is blue.
Another cause of blue eyes is a gene called HERC2 (represented as O, o, h and h in Image 2), which controls pigment in the back layer of the iris, known as the pigment epithelium. This layer also scatters the blue wavelengths that come in, but because it contains melanin, it produces a color that resembles brown.
In this way, HERC2 and OCA2 are not directly related, but they work together in a dependent relationship. If one of these genes doesn’t work, the other will underachieve, failing to produce enough pigment to make brown eyes.
However, if one of the HERC2 genes does work, it will tell the OCA2 gene to make more melanin, which will result in brown eyes. In this way, eye color is a combination of 16 different genes that determine how much melanin to produce.
For most people, these genes are inherited from both parents. Occasionally, though, two parents with blue eyes can have a child with brown eyes because the OCA2 and HERC2 genes are not working.
While the exact cause of black people’s blue eyes is not known, they have a high risk for certain eye diseases that can lead to vision loss. In particular, African Americans are more susceptible to glaucoma than non-Hispanic whites, making it the leading cause of irreversible blindness in that group. This has led to intensive tracking of African American health outcomes, in an effort to better understand what is causing this problem.
Symptoms
People with blue eyes have a genetic mutation in a gene called OCA2 that makes the eyes appear blue. This isn’t a common genetic trait and is more rare among blacks than in other ethnic groups, but it’s not impossible to have blue eyes.
The color of your eyes depends on the amount of melanin (pigment) in your iris, which is the colored part of your eye. Almost everyone’s irises have brown pigment in the back layer of the iris (called the pigment epithelium) and no melanin in the front layer, which is called the stroma. The lack of melanin causes light to scatter when it hits your eyes, and this creates the blue appearance of your irises.
Some researchers are now wondering if having blue eyes might be a factor in the risk of developing some health conditions. One example is age-related macular degeneration, a disease that damages the macula, which is at the center of your retina, causing your central vision to become blurry or distorted over time.
Another is diabetes. Studies show that having brown eyes is associated with a lower incidence of diabetic retinopathy and macular degeneration.
If you have blue eyes, you might also be more likely to develop small growths on your iris that look like freckles from sun exposure, according to Jennifer Grover, an ophthalmologist in Chicago. These are called iris nevi, and they can increase your risk of eye cancer in the future, she says.
Children with blue or different-colored eyes should see their pediatrician to get an eye exam and check for any other symptoms. They may have a condition called heterochromia, in which they have one blue eye and one brown eye or two different-colored eyes that split into different colors.
Heterochromia isn’t serious and doesn’t usually need treatment, but if it’s caused by a medical condition, it can signal a more serious problem. It’s best to see an ophthalmologist as soon as you notice this change in your child’s eyes, so they can treat any other issues.
There are a few reasons why some people have different-colored eyes, including hyphema, a condition in which blood collects on the front of your eye, and uveitis, which is inflammation of the iris or the pupil. Hyphema can occur due to injury, but it’s most often caused by a blood clot inside the eye. Symptoms include a drooping eyelid and a small pupil.
Treatment
A rare genetic mutation can cause some African and black people to have blue eyes. The mutation is called OCA2, which affects the production of a protein in the eyes that helps produce melanin, the pigment that gives eye and hair color.
The OCA2 gene is found on chromosome 15 and is part of a group of genes that regulate the pigmentation of the eyes. It also controls the amount of eumelanin and pheomelanin, two different types of melanin that determine eye color.
Researchers believe that the OCA2 gene is responsible for some people with blue eyes. Specifically, a specific SNP in the OCA2 gene causes reduced transcription of the gene compared to normal. This reduces the production of eumelanin and increases the production of pheomelanin.
OCA2 is regulated by another gene called HERC2, which has also been linked to the genetics of blue eyes. The HERC2 gene is on chromosome 15, and it regulates the expression of OCA2 through its HECT domain and RCC1-like domain 2.
It’s not clear why some people with blue eyes have this particular SNP in their OCA2 gene, but researchers suspect that they may be carriers of a rare genetic disease called Waardenburg syndrome. WS is a very rare genetic disorder that causes a range of symptoms, including different-colored eyes and hearing loss.
Symptoms of WS include blue eyes, a white patch of hair on the forehead, and hearing loss. The condition can be treated by surgery, but it’s not common and it’s very rare for people with WS to have blue eyes.
A recent report has revealed that a new treatment could change all that. The procedure involves a laser that disrupts the layer of melanin in the iris, forcing it to naturally shed itself over time.
While the process isn’t yet available in the United States, it has been trialled in Mexico and Costa Rica. It uses a low-energy laser to disrupt the pigment in the iris without damaging the tissue underneath. The results are visible for several weeks, after which the blue eyes will appear naturally.
Prevention
It’s believed that blue eyes are the result of a genetic mutation that occurred 10,000 years ago. This change caused the OCA2 gene, which codes for production of a pigment called melanin, to alter its code and instead produce a blue pigment.
It is thought that this mutation began in Europe and spread to black people worldwide, but it is also possible that the genes were altered by climatic factors such as the cold and dark skies of European ancestors. This would explain why some people with brown eyes and black skin are found in tropical regions, while those with light colored eyes are more common in Europe and Asia.
The genetic mutation that causes people to have blue eyes is a recessive gene. This means that if both parents have this gene, there is a 25% chance that a child will have blue eyes. The gene is present in all people with a certain percentage of DNA from a white ancestor.
This gene also codes for the production of a pigment called melanin that protects the eyes from sun damage. It’s important to note, however, that many people with light-colored eyes are at greater risk of eye diseases, such as cataracts and macular degeneration.
One of the major reasons that light-eyed people are at a higher risk of eye disease is because their eyes are more sensitive to the sun’s UV rays than dark-eyed people. As a result, they are at greater risk of developing a form of eye cancer known as eye melanoma.
Because of this, it’s important to wear sunglasses and avoid direct sunlight whenever possible, particularly in the sun’s hottest hours. Those with blue eyes are even more at risk, because their eyes have less pigment than those with darker eye color, which makes them more susceptible to the effects of the sun’s rays.
In addition to being at higher risk of eye disease, blue eyes are also more prone to developing a form of cancer known as melanoma, which is the most deadly of all types of cancers. Fortunately, melanoma is rare, occurring in about six out of every million people.