Your eye color is as unique as your fingerprint. No one in the world has eyes the same color as yours. But you may share the same shade with hundreds, thousands, or even millions of people.
Eye color is determined by your iris — a colored ring surrounding your pupil at the center of your eye. The melanin content within the iris, and how it’s distributed, gives your eyes their unique color.
Is Eye Color Genetically Determined?
Traditionally, people believed that a single gene determined eye color. However, today, studies confirm that the eye color inheritance pattern is more complex.
Several genes are responsible for the amount of pigment in the eyes, making it possible for two blue-eyed parents to have brown-eyed children. Gene variations and interactions can cause someone to have different colored eyes than their parents or any other family member.
Why Are Eyes So Colorful?
Eye color is determined by the amount of melanin in the front layer of your iris. Melanin is a brown pigment. The more of it you have, the more likely your eyes will be brown.
Everyone, including people with blue eyes, has some brown pigment within the iris. But the front layer of this important structure — the stroma — can make your eyes appear brown, hazel, blue, or even green.
And many people have different amounts of pigment in different parts of their eyes. Your iris may look blue in some spots and brown in others, depending on how melanin is distributed.
The Basic Colors: Brown, Blue, Hazel, Amber, Gray & Green
Human eyes come in a dazzling array of colors, ranging from deep brown to bright green. Some colors are more common than others, and some are somewhat rare and unusual.
Brown Eyes
People with brown eyes have a large amount of melanin within both the back and front of the iris. The more melanin that appears here, the darker brown the eyes will be.
Between 70% and 80% of the world’s population has brown eyes, making this the most common color. Dark brown colors are most common in Africa and Asia. Light brown is more common in Europe and America.
Blue Eyes
People with blue eyes have melanin in the back of the iris. But they have less of this pigment in the front of the iris, allowing light to refract and scatter. The result is eyes that look blue.
Between 8% and 10% of the world’s population has blue eyes. Research suggests that everyone with this trait shares a common ancestor who had a genetic mutation allowing for reduced melanin in the front of the eye. This eye color is common in Europe.
Hazel Eyes
People with hazel eyes have an iris that isn’t entirely brown or green. Most people with this color have speckles of brown, green, and gold throughout the iris. And their eyes may seem to change color in different lighting.
About 5% of the world’s population has hazel eyes. They are most common in the Middle East, North Africa, and Brazil.
Amber Eyes
People with amber eyes have a light-brown iris that might look golden or copper-tinged. The color is caused by a high concentration of melanin interacting with a yellow pigment in the front of the iris.
About 5% of the world’s population has amber eyes. The color is most common in Pakistan, France, Italy, and Hungary.
Gray Eyes
People with gray eyes have little melanin in the front of the iris. Light entering the eye is refracted by the iris, interacting with collagen strands in the stroma. The result is a color that seems gray.
About 3% of the world’s population has gray eyes. It’s most common in Asia and the Middle East.
Green Eyes
People with green eyes have a light brown melanin pigment in one or both layers of the iris. It interacts with blue light entering the eye, and it can make the iris look green or speckled with brown. Some people have yellow pigment within the iris, enhancing the green color.
About 2% of the world’s population has green eyes. It’s common in Europe, particularly among those with Celtic or German ancestry.
Heterochromatic Eyes
Heterochromia means different colored eyes in the same individual. This may be a hereditary condition, so it may be present in multiple members of the same family. It may also be due to a medical condition.
Some conditions that can cause changing eye color include the following:
- Iris freckles
- Iris nevi
- Lisch nodules
- Fuchs heterochromic iridocyclitis
- Pigment dispersion syndrome
- Horner’s syndrome
If you notice a shift in eye color, see an ophthalmologist right away, recommends the American Academy of Ophthalmology. Some conditions are easier to treat when you catch them early.
What Is the Most Common Eye Color?
Brown is the most common eye color. In fact, the American Academy of Ophthalmology says everyone on Earth had brown eyes until about 10,000 years ago. Now, about half of all Americans have this eye color.
High levels of melanin in your eyes could protect you from conditions such as the following:
- Eye cancer
- Macular degeneration
- Diabetic retinopathy
Researchers believe that brown eyes offer more protection than lighter ones do. But people with brown eyes are more likely to get cataracts.
What Is the Rarest Eye Color?
Green is the rarest eye color worldwide, as only about 2% of the population has this color of iris. About 9% of Americans have this eye color.
Green eyes are closely associated with a German or Celtic heritage. If your ancestors emigrated to this country from those locations, you could have a higher chance of green eyes.
The color of green eyes results from light reflection, so it can be variable. Your eyes may look blue, green, or even brown, depending on the light source.
Can Eye Color Change Over Time?
Eye colors generally stay the same for an entire lifetime. However, certain medical conditions, medications, and health conditions can create changes in eye color.
You may have noticed that eye color can be affected by what you are wearing. For instance, blue eyes may seem to take on a darker shade if you’re wearing a dark blue shirt. Your eyes don’t actually change color, but the shirt color makes your eyes appear bluer.
Some people have a darker ring, called a limbal ring, around the outside of the eye. As people age, eyes can change color, and this ring may fade and become fainter.
Conditions That Affect Eye Color
Some medical illnesses can alter the color of your eyes. Some of these conditions are present at birth, while others could crop up later.
The following health issues could alter your eye color:
- Albinism: People with this inherited condition have little or no melanin in their skin, eyes, and hair. Most often, people with albinism have very light blue eyes. They may have red or pink-colored eyes.
- Cataracts: This condition causes the lens of the eye to become cloudy. Though often associated with aging, cataracts can be caused by other illnesses. The eyes may appear grayish or milky white.
- Arcus senilis: People with this condition have a light blue ring around the cornea. It typically affects people over 40 and can be a symptom of high cholesterol.
- Uveitis: This is a condition that causes inflammation in the eye, and it can lead to low vision. If it is not treated, it may lead to blindness.
Medications That Affect Eye Color
Medications may affect eye color. Prostaglandin, often used to treat glaucoma, may darken the color of the eyes.
Prostaglandins are also included in Latisse, an eyelash growth serum. Experts say this medication doesn’t seem to change the color of the iris, but check with your doctor just in case.
Eye Color FAQs
According to the American Academy of Ophthalmology, the rarest eye color is green.
There are infinite eye colors, as subtle variations include the amount and quality of pigment, spots, and flecks. Due to these factors, there are unlimited differences in eye color across individuals.
The five most common eye colors are brown, blue, hazel, amber, gray, and green. Of these, brown is the most common.
References
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Eye Color: Unique as a Fingerprint. (December 2017). American Academy of Ophthalmology.
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Is Eye Color Determined by Genetics? (July 2022). U.S. National Library of Medicine.
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Your Blue Eyes Aren’t Really Blue. (June 2023). American Academy of Ophthalmology.
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Why Are Brown Eyes Most Common? (April 2017). American Academy of Ophthalmology.
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The World’s Population by Eye Color. World Atlas.
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Why Are My Eyes Changing Color? (May 2023). American Academy of Ophthalmology.
Last Updated September 29, 2023
Note: This page should not serve as a substitute for professional medical advice from a doctor or specialist. Please review our about page for more information.