Eye color is a special part of your appearance. This is included in the driver’s license and other identity documents. It is also one of the main descriptors used in the missing persons report.
The iris is the pigmented part of your eye. Its color is determined by genes. Many entry-level biology courses have used eye color to understand how certain genes are passed from parent to child. However, scientists are now realizing that eye color genetics are more complex, and several genes play a role in determining eye color.
Melanin production in the iris is what affects the color of the eyes. A higher amount of melanin produces a darker coloration, while a lower amount makes the eyes lighter. Green eyes are the rarest, but there are anecdotal reports that gray eyes are even less common.
Eye color isn’t just an extra part of your appearance. It can also say something about human health.
Rare Eye Colors
These are some of the rarest eye colors.
There’s not much information about gray eyes. However, a review of the classification of eye colors shows that, in fact, it is considered a different eye color than blue.
People in the Nordic countries tend to have lighter colored eyes. By comparison, darker eyes are common in warmer areas largely for the same reason that people have darker skin in southern countries.
In studios, gray and blue are often mixed. The American Academy of Ophthalmology (AAO) explains that about 27% of people in the U.S. do not have a medical license. They also include the category other, which may include grey eyes, which accounts for 1% of the population.
According to the AAO, green eyes are one of the rarest eye colors. Only 2% of the world’s population has green eyes.
People with heterochromia have eyes of two different colors. Some people are born with this. It can occur at birth in combination with conditions such as pedophilia and horner syndrome.
You may also develop heterochromia later in life. This can happen due to an injury, taking medication, or an illness. Humans rarely have heterochromia. In the United States, fewer than 200,000 people suffer from the disease.
The color of your eyes may change in adulthood. While lighting and the environment can affect eye color perception, diseases, medications, and injuries can also affect eye color later in life.
Brown freckles can appear on the iris over time, and although most are harmless, they can sometimes be cancerous. Some conditions, such as Fuchs heterochromatic iridocyclitis, can cause pigment loss in the iris, which makes the eyes appear lighter.
Several different genes play a role in determining the color of your eyes. Most have something to do with the transport, production and storage of melanin. Melanin is a pigment found in the skin, hair, and eyes. A higher amount of melanin in the iris will lead to brown eyes, while a lower amount may mean green, blue or gray eyes.
While scientists, and probably their biology teacher in high school, used to think that inheriting eye color was simply a matter of dominant, recessive genes, they now know it’s not.
For example, two people with brown eyes may have a baby with light eyes. Brown eyes are common, but there is not a single dominant gene for brown eye color as previously thought.
In addition to the amount of melanin produced, its amount in the anterior and posterior parts of the iris, as well as the composition of the middle layer of the stroma, determine the color of the eyes. There are many genes involved in defining these variables, and much of that is still not understood.
It is possible to change the color of the eyes with cosmetic contact lenses, but you should be careful because improper use increases the chances of infection. The AAO recommends consulting an eye care professional before wearing cosmetic contact lenses. You should also not buy contact lenses that do not require a prescription.
The AAO also warns against surgery to change the color of your eyes. This type of surgery can have serious side effects, such as blindness and vision problems.
Eye color and health
Eye color may seem like something that’s just about how you look. However, some research suggests that certain eye colors may increase a person’s risk of certain diseases.
Research conducted in 2011, for example, suggests a link between blue eyes and diabetes 1 type. Similarly, a 2015 review suggests a possible link between eye color and hearing loss. The data indicate the possibility that people with darker eyes may have a reduced risk of non-age-related hearing loss.
A 2014 study presented at the American Pain Society meeting in 2014 found that women with light eyes had a higher tolerance for pain during pregnancy than women with darker eyes. However, it should be noted that the sample size for this study was relatively small, with a total of 58 women.
A similar small study of 60 subjects showed the same when testing pressure pain thresholds and cold-related pain. However, remember that correlation is not equal to causality, and more research is needed to prove these effects.
Frequently asked questions
Gray eyes are very rare, but it is difficult to say exactly what percentage of the population has them. People with gray eyes are often considered people with blue eyes, who make up 27% of the U.S. population.
Yes, a person may have red eyes by nature, but they are rather light red or pink rather than bright red. This can happen to people with albinism, a condition in which less pigment forms in a person’s skin, eyes, and hair. If a person with albinism has a clear iris due to a lack of melanin, the blood vessels in their eyes become visible and result in a light red and pink color.
Eye discoloration can be caused by genetics, disease, medications, and injuries. For example, some medicines that treat glaucoma, a condition that causes increased eye pressure, can cause eye color to change over time.
About 18% of the American population has brown eyes. This occurs because of the light brown pigment in the iris that interacts with blue light in the eye, causing the eyes to turn green, speckled, or brown.