Eye Color Guide: Everything You Need to Know

Eye color is the color of your iris. 

The iris is that colored part of the eye, surrounding the center or pupil. The pupil is the small opening that appears black in the middle of your eye.

The color of your eyes is determined by the amount of pigment, known as melatonin, in your iris. Blue eyes have little or no pigment, while brown eyes have a large amount. 

Typically, the eyes stay the same color throughout life, but they may change color due to health conditions, medications, or injury.

How Is Eye Color Determined?

Traditionally, people believed that eye color was determined by a single gene. However, today, studies confirm that the eye color inheritance pattern is more complex.

In the past, many people thought that if both parents had blue eyes, they couldn’t have a brown-eyed baby. However, this is a myth. It is possible, so it turns out that this old model was too simplistic.

Eye color is directly connected with the amount and quality of pigment, also known as melanin. People with blue eyes have much less melanin. While people with brown eyes have a lot. 

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 in different genes can cause someone to have different colored eyes than their parents or even than any other family members.

How Do Eyes Get Their Color?

Eye color is formed by the amount of pigment in the front layer of the iris. Most people have brown pigment at the back layer of the iris, even individuals with green or blue eyes. 

Eye color is often compared to a specific personal marker, like a fingerprint, that is uniquely yours. No one else has the exact same eye color that you do. 

The Basic Colors: Brown, Blue, Hazel, Amber, Gray & Green

While eyes can be varying shades of each, the basic eye colors include brown, blue, hazel, amber, gray, and green.

Brown Eyes

Brown is the most common eye color in the world. 

People with brown eyes are less likely to develop certain eye conditions, including macular degeneration, eye cancer, or diabetes-related retinopathy. However, people with brown eyes have a higher risk of cataracts.

Blue Eyes

Blue is the eye color of people who have little or no pigment in the front part of the iris. In the United States, about 25 percent of people have blue eyes.

Due to the lack of pigment, the eye absorbs less light. The blue color is not the result of a blue pigment, but rather the way light reflects off the surroundings. People with blue eyes may be more sensitive to light.

Hazel Eyes

Hazel is a combination of the colors brown and green. People with hazel eyes may have flecks or spots of these colors as well. 

According to the American Academy of Ophthalmology, about 18 percent of people in the U.S. have hazel eyes.

Amber Eyes

Amber is often compared to the color of copper or gold. It is a light brown shade.

According to the World Atlas, about 5 percent of the world’s population has this unique color. 

Gray Eyes

Like blue, gray is the color that appears when the front layer of the iris has little or no melanin. This color is often compared to the color of the eyes of a cat. 

According to the World Atlas, 3 percent of people in the world have gray eyes. Extra collagen in the eye blocks a blue color from appearing, creating a grayish hue.

Green Eyes

Green is the least common eye color worldwide. According to the American Academy of Ophthalmology, only 9 percent of people in the U.S. have green eyes. 

Green, blue, gray, and hazel eye colors are most commonly found among people of European 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 such as glaucoma or an injury such as bleeding in the eye. 

Typically, different eye colors are the result of a harmless change in genes. However, it may result from a medical disease or injury. One condition that can lead to eyes being different colors is Horner’s syndrome. 

Heterochromia is more commonly seen in dogs, such as Australian sheepdogs, Dalmatians, and Huskies, as well as in cats and horses. 

What Is the Most Common Eye Color?

The most common eye color is brown. 

What Is the Rarest Eye Color?

Green is the rarest eye color.

Can Eye Color Change Overtime?

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, if you have blue eyes, they 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

Medical conditions can affect the color of the eyes, including albinism, cataracts, corneal arcus, uveitis, and Waardenburg syndrome. 

• Albinism: This is an inherited condition where individuals have very little or no melanin in their bodies. This affects the color of 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 conditions. The eyes may appear grayish or milky white color.

• Corneal arcus: With this condition, a light blue ring often appears around the cornea. It typically affects people over the age of 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.

• Waardenburg syndrome: This is a rare genetic condition where the eyes, hair, and skin have less pigment. 

Medications That Affect Eye Color

Medications may affect eye color. Prostaglandin, which is often used to treat glaucoma, may darken the color of the eyes.

Prostaglandins are the main ingredient in Latisse, an eyelash growth serum. If you are using prostaglandins, talk with your doctor about what to expect in terms of eye coloration.

Eye Color FAQs

What is the rarest eye color?

According to the American Academy of Ophthalmology, the rarest eye color is green. 

How many eye colors are there?

There are an infinite number of 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. 

What are the five most common eye colors?

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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6. Eye Colors: Rarest Eye Color, Baby Eye Color, Heterochromia. Cleveland Clinic.

7. Why Are Brown Eyes Most Common? American Academy of Ophthalmology.

8. Your Blue Eyes Aren’t Really Blue. American Academy of Ophthalmology.

9. The World’s Population By Eye Color. World Atlas.

10. Heterochromia Information. Mount Sinai.

11. Glaucoma. Mount Sinai.

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    (November 2020). Ophthalmology Times.

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16. Skin Discoloration & Pigmentation Disorders: Causes & Treatments. Cleveland Clinic.

17. Cholesterol: Types, Tests, Treatments, Prevention. Cleveland Clinic.

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20. Iris Colour Classification Scales: Then and Now. (January–March 2015). Romanian Journal of Ophthalmology.

21. Genome-Wide Association Study in Almost 195,000 Individuals Identifies 50 Previously Unidentified Genetic Loci for Eye Color. (May 2021). Science Advances.

22. The Genetic Overlap Between Hair and Eye Color. (November 2016). Twin Research and Human Genetics.