More than 50% of people worldwide have brown eyes, making brown the most common eye color. Some medical conditions can also affect eye color.
The colored part of your eye is called the iris. Its color comes from melanin, the same pigment that determines skin color. Different eye colors are the result of different amounts of melanin.
Today, brown is the most common eye color worldwide.
According to the American Academy of Ophthalmology (AAO), at one time, all humans had brown eyes. Then, a common ancestor experienced a gene change that led their descendants’ eyes to produce less melanin.
Melanin can protect the eyes from sun damage. That may explain why brown eyes are more common in hotter climates throughout Asia and Africa.
It’s challenging to determine the number of people with a certain eye color.
“Brown” eyes can range from a light reddish-yellow to a dark brownish-black.
Over 50% of the world’s population has brown eyes, according to the AAO. Just around 2% of people worldwide have green eyes.
In the United States
One 2014 survey asked over 2,000 people in the United States about their eye color. According to the AAO, the survey data can be used to determine eye color prevalence across the country at large.
Brown is the most common eye color in the United States, just as it is globally. Here’s the breakdown of eye color prevalence in the United States:
- 45% of people with brown eyes
- 27% with blue eyes
- 18% with hazel eyes
- 9% with green eyes
- 1% with eyes of another color
Most people of African descent have brown eyes, according to a
In South Asia and East Asia
Participants were categorized as South Asian if all of their grandparents had Bangladeshi, Indian, Pakistani, or Sri Lankan ancestry. East Asian participants had grandparents with Chinese, Japanese, Korean, or Taiwanese ancestry.
There was slightly more eye color variation among South Asian participants than East Asian participants. Few East Asian participants had green eyes, while none had blue eyes.
In Europe and Central Asia
A 2019 literature review on eye and hair colors included data on eye colors for countries across Europe and Central Asia. The review used the broad categories of “brown,” “intermediate,” and “blue.”
Here are statistics for a few of those countries:
|Country||Percentage with “brown” eyes|
(also includes hazel)
|Percentage with “intermediate” eyes|
(also includes green and yellow)
|Percentage with “blue” eyes|
(also includes gray)
* Source: Katsara M-A, et al. (2019). True colors: A literature review on the spatial distribution of eye and hair pigmentation. https://www.fsigenetics.com/article/S1872-4973(18)30338-7/fulltext
Scientists used to think your eye color was determined by two eye color genes, one from each parent. Since the gene for brown is dominant over blue, the belief was a blue-eyed person would have two genes for blue eyes, and two blue-eyed parents couldn’t have a brown-eyed child.
We now know that it’s much more complicated than that. According to an older 2010 study, your eye color is determined by
Melanin absorbs light. When an object absorbs light, it looks dark. When it doesn’t absorb light, the light is reflected, and the object is the color of the light it reflects. Light reflected from your eye comes from the blue part of the color spectrum.
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 you inherit genes from your parents, your eyes will likely be similar in color to their eye colors. It’s also possible for you to have brown eyes even if both of your parents have blue eyes.
Heterochromia, or different-colored eyes
If you have heterochromia, all or part of one iris is a different color than the other iris. Heterochromia can be the result of:
- a problem during eye development
- an eye injury
- various medical conditions, including:
- bleeding in the eye
- ocular melanosis, a type of lesion that may be benign or cancerous
- tumors of the iris
Because reflected light determines eye color, blue, green, and hazel eyes can look slightly different under different lighting conditions. However, once your eye color is set in childhood, your eyes can’t naturally change to a completely different color.
Babies are the exception. Melanocytes, which are specialized cells that secrete melanin, are most active in the first year of life. This means eye color is usually determined by age 1 year. However, changes in eye color begin to slow down once a baby reaches 6 months old.
You can artificially change your eye color, but it can be risky.
You can accentuate, enhance, or completely change your eye color with contact lenses. Decorative, or costume, lenses come in a variety of colors and can correct vision or not.
Note that it’s illegal to sell contact lenses, even decorative lenses, without a doctor’s prescription in the United States.
Some hazards of wearing lenses that a doctor hasn’t prescribed or are otherwise ill-fitting include:
- cuts and scratches on the eye
- eye infection
- an ulcer on the cornea, the dome-shaped front layer that bends light so the eye can focus
- corneal abrasion
- reduced oxygen flow to the eye
If you want to try colored contacts, see an optometrist first. They can guide you to a safe and healthy pair of colored contacts to enhance your look.
The best colored contact lenses
Check out our guide to the best colored contact lenses on the market.
The iris implant is a surgical procedure originally developed to treat eye injuries and other conditions. It has also been used to permanently change eye color.
In 2014, the AAO warned against undergoing this procedure for aesthetic reasons.
Prescription medications (due to side effects)
Some medications may permanently change the color of the eye over time, including:
- medications to treat glaucoma
- 0.03% bimatoprost ophthalmic solution (Latisse), an eyelash lengthener
Glaucoma medications and Latisse contain prostaglandins, hormone-like compounds that may darken your eyes by a shade.
Increased brown pigmentation in the iris is a possible, albeit rare, side effect of Latisse, according to the manufacturer’s website.
Over-the-counter (OTC) products
Some companies sell cosmetic products, like eye drops and balms, that promise to change your eye color.
The Food and Drug Administration (FDA) hasn’t approved these products, and they may not come with any supporting evidence. Before investing in any such products and potentially risking your eye health, consider seeing an optometrist.
Some medical conditions are known to affect your eye color. They don’t permanently change the color of your iris. Instead, they usually affect the sclera (“white”) or cornea.
These conditions include:
- Albinism: In albinism, your eyes don’t produce enough melanin. It may affect the pigment in your eyes, hair, and skin, or it can just affect your eyes. If your condition is mild, you’ll usually have light blue or violet eyes. If your condition is severe, you’ll have little to no melanin, and your eyes will appear pink or red. This is because the blood vessels in your eye will show through. Albinism causes severe vision issues, too.
- Anisocoria: Anisocoria is when one of your pupils is larger than the other. Because the iris in the eye with the bigger pupil is smaller, it looks darker than the other one. Some people are born with this condition. For those individuals, the difference in pupil size is small. The difference is larger when anisocoria is the result of stroke, brain injury, or eye trauma. If you experience sudden onset anisocoria, get evaluated right away.
- Arcus senilis: Arcus senilis occurs when cholesterol builds up and forms a hazy ring around your cornea. The ring may be blue, gray, white, or yellow. Arcus senilis is harmless and becomes more common as you age.
- Hepatitis and other liver diseases: When your liver is inflamed or damaged, it can’t remove bilirubin, so the substance builds up in your blood. Bilirubin makes the whites of your eyes and your skin yellow.
- Hyphema: A hyphema is blood inside your eye, usually due to an eye injury or following surgery.
- Uveitis: Uveitis is inflammation inside your eye. Causes may include infection, eye injury, or exposure to toxins. It makes the sclera of the affected eye look red. Uveitis requires immediate medical attention.
Your eye color may also be a risk factor for certain conditions.
A 2019 study of a rural population in Iran found that those with light-colored irises had a higher risk of developing:
- corneal opacity, or clouding of the cornea
- cataracts, or clouding of the lens
- a refractive error, or trouble focusing light
Eye color may also affect how you experience pain.
The amount of melanin in your iris determines your eye color. The less melanin you have in your eyes, the lighter they’ll be. Brown eyes have the most melanin and are the most common worldwide.
Researchers continue to learn more about eye color, including the wide range of iris hues. Certain iris colors may come with certain health risks. As experts learn more, people may be able to use this knowledge to improve their overall health.