Understanding Eye Color

MenuPhoneAppointment
Seeing with Low Vision
March 12, 2018
How Smoking Causes Vision Problems
April 2, 2018
Show all

Understanding Eye Color

Six photos of different colored eyes

The colored part of your eye is called the “iris”. This part of your eye is pigmented depending on your genetics, which will determine what eye color you have. Many babies have blue eyes when they are born and for most of their first year of life. However, that might not be the eye color that they will always have, as pigmentation in the eye can change over time. There are only certain eye colors that people have such as green and blue instead of pink or red. Find out why that is and why you have the eye color that you do!

 

Regulating Light

You might be familiar with the terms “iris” and “pupil”. The iris is the colored ring of tissue that lies beneath the cornea and can be a range of colors. The pupil is located in the center of the iris and appears as a black hole. Just like a camera, the pupil will adjust how much light enters the eye so you don’t have too much light energy or too little hitting the tissues inside. In bright conditions, the pupil closes down, reducing the amount of light entering the eye and protecting the delicate nerves from being damaged. In the dark, the reverse happens to allow what light there is to enter the eye. The pupil gets bigger or smaller by way of the iris, which controls the diameter and size of your pupil.

 

What Determines Eye Color?

Your genetics largely determine your eye color. If everyone in a family has brown eyes, odds are that a new baby in the family will have brown eyes. However, there are families where everyone has different eye colors depending on how chromosomes combined when a baby was formed. In the past, many people used eye color charts to try to determine what eye color a child would have depending on the parents. These charts can be helpful at guessing an eye color, but can be wrong in many cases.

 

However, eye charts are helpful in determining what dominant eye color will likely be inherited, as brown is more likely to be dominant over blue in offspring. Each person inherits 23 chromosomes from each parent, which makes up 46 chromosomes total. These pieces of DNA determine eye color. You receive DNA from both parents, and the combination of those DNA strands in the chromosomes will determine your eye color.

 

close up of a woman's face and eye

Different Eye Color

In rare cases, people with albinism may have a lack of pigmentation in their iris, or will have a pinkish-white color. Some people are also born with two different eye colors, which is called heterochromia. One eye will be one color (such as brown), while another eye is a different color (such as blue). It is common for many people to be able to see several colors in their eyes at once (such as parts that look blue, while others look more green).

 

Depending on what you wear, your eyes may also appear to change shade to match what you are wearing. This is because the iris has 2 layers, both of which could have pigment. Depending on how much light there is and the diffraction it has in a person’s eyes, they may change pigment slightly. So, a person’s eyes may appear to change somewhat if they wear a certain color of clothing. You will never have pink or red eyes, or other colors, because eye color is a reflection of how much melanin your eyes have mixed with how much light is refracted. We only get the colors that we have because of it.

 

Brown Eyes

Brown is the most common eye color worldwide. Many cultures of people pass on brown to their offspring, as the color brown is the most dominant as far as genetics go. Two parents with brown eyes are most likely to have children with brown eyes. If you receive the gene for brown eyes from one parent and blue from another, you would have brown eyes. People with brown eyes have a high amount of melanin (a pigment) in their front layers of the iris, making the iris a darker color. This melanin amount is also what determines eye color. If you have more melanin in your eyes, they will be darker. If you have less melanin, they will be lighter. Genetics will determine how much melanin you have in your eyes.

 

Three people of different ethnicities with different colored eyes

Blue and Green Eyes

Lighter eye colors such as green and blue eyes are more common among people with European ancestry. Eye color is determined largely by genetics, and whole cultures of people can have a dominant color of eyes. Brown eyes will dominate genes over lighter colors. However, if blue and green eyes run in your family or culture, these will be more common among the people. Although brown is the most dominant eye color, green is more dominant over blue when it comes to genetics. Many studies suggest that if you have blue eyes, you share a common ancestor with everyone else that has blue eyes (even if it’s very far down the line).

 

Keeping Your Eyes Healthy

Hazel and gray eyes are also possible in many people, but the cause of these eye colors aren’t fully known. Many babies are born with blue eyes, only to have them change after several months or years depending on how much melanin the body begins to store in the iris. For all your questions about your eyes, call Optical Masters at (303) 377-0752!

Leave a Reply

Your email address will not be published. Required fields are marked *