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Your eye color is something about you that’s truly unique. Nobody else on the planet has eyes with the exact same coloring as yours. And while people have channeled their creativity into poems, paintings and photos centered on eye colors, scientists know it can sometimes tell us much more about a person.
Your eye color refers to the color of each eye’s iris, a double-layered ring of muscle tissue around your pupil that controls how much light enters your eyes. The color of your iris depends on a few different factors between it and other parts of your eye.
The first main factor in your eye color is a pigment called melanin. The more melanin you have in your skin, the darker it is. Virtually everyone has melanin in the back layer of their iris (except for people with conditions like albinism).
When you have a lot of melanin in both layers of your irises — front and back — you have brown eyes. (Experts sometimes spell the plural of iris as “irides.”) People with hazel or green eyes have less melanin in the front layer of their irises than people with brown eyes. People with little or no melanin in the front layer of their irises have blue or gray eyes.
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Experts don’t always agree on the main eye colors that people can have. Some scales use colors that don’t appear on others, while other scales group colors from light to dark. The main colors that appear on many scales are:
But while there are just a few main colors, the ways those colors can show up are infinitely complex. No two people have eyes with the exact same colors. Even identical twins can have subtle — but still visible — eye color differences.
Factors that contribute to the infinite number of eye color variations include:
People with albinism have little or no melanin in their eyes. When they have very little melanin in their irises, they can have very pale blue or gray eyes. When there’s no melanin in either layer of their irises, the blood vessels in their retinas are a lot more visible, making their eyes look pink or red.
Your eye color can change with certain medications or medical conditions. Some of the changes are harmless, while others are a possible sign of something serious. Some examples include:
Sometimes, your eye color can also have a link to your risk for certain diseases. People with brown eyes may have a higher risk of developing cataracts. And people with blue eyes may be more resistant to the effects of mental health conditions like seasonal affective disorder.
If you notice eye color changes that happen quickly — or that happen along with an injury or changes in how well you see — you should talk to an eye care specialist. They can tell you if it needs further attention and care.
The most common eye color is brown. More than half of the world’s population has brown eyes (some experts include amber as a shade of brown, too).
A key reason is the range of shades that fall under this color. Brown eyes can range from light to dark. With the darkest shades of brown, it might be hard to tell where the iris ends and the pupil begins.
Not counting colors like red/pink from conditions like albinism, the rarest of the main eye colors is green. About 2% of people worldwide have green eyes.
No. It’s common for babies to have blue eyes at birth, but it’s not universal. In fact, one study from 2016 found only about 20% of babies have blue eyes at birth. That same study also found that about 63% of babies have brown eyes and a little under 6% have green eyes.
Not all babies’ eyes will change color, but many will. If your baby’s eyes do change color, you might notice it as early as when they’re 3 months old. Color changes should finish by the time most children reach 6 years old, but a small percentage can have ongoing eye color changes until adulthood.
Researchers from the above 2016 study came back two years later to examine the 73% of the original children who returned for follow-up. That follow-up found that by 2 years old, only about 1 in 3 children had eye color changes.
Yes, but their parents’ eye colors aren’t the only factor. Eye color genetics are extremely complicated. So far, researchers know of dozens of genes and DNA mutations that can affect eye color.
So, while parents’ eye colors are a major factor, they aren’t the only one. And sometimes, eye colors skip generations. So, if a baby’s eye color doesn’t match their parents’, there are plenty of reasons why that might happen.
Hazel eyes happen when your irises have less melanin than someone with brown eyes, but more melanin than someone with blue or green eyes. Hazel eyes are a combination of brown, gold or green. It’s not an equal mix. Some people have eyes that seem only to have two of those colors, while others may have eyes that show all three. The possible differences among people with hazel eyes are one easy way to see just how unique eye color can be.
A note from Cleveland Clinic
Your eye color is one of the things that makes you unique from everyone else on this planet. It can change throughout your lifetime and offer clues to your history and heritage. Understanding how it works can sometimes be a clue to medical conditions or concerns. No matter your reason for taking time to notice someone’s eye color (or your own), it’s often easy to see why it can be such a captivating feature all on its own.
Last reviewed by a Cleveland Clinic medical professional on 03/11/2024.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy