A blue eye looks forward while text reads, "Eyes are unique to every individual person, almost like a fingerprint."

The Science Behind Eye Color

Eyes are unique to every individual person, almost like a fingerprint. But, have you ever found yourself wondering, for example, why your eyes are brown and your sister’s eyes are blue? Shouldn’t you have the same eye color if you are related? The science behind eye color is a little more complicated than what you may have learned in your high school biology class.

Basic Biology Breakdown

In high school biology you probably covered genetics and dominant and recessive genes. In order to fully understand this, you likely did an activity where you traced your eye color back to your parent’s. However, understanding how dominant and recessive genes play into eye color is just scraping the surface of the science behind your eyes.

Melanin and Genetics

Different eye color is caused by the melanin in your iris. The iris is a flat, colored, ring shape behind the cornea of the eye. Less melanin in the iris means lighter eye colors, like blue and green, and more melanin in the iris makes for darker eye colors, like hazel and brown. Melanin isn’t the only factor in determining eye color.

Like you learned in high school, genes do play a role, but it isn’t just the one gene you were taught. The gene OCA2 determines how much melanin you will have in the iris, because it produces protein. Less protein means blue or green eyes. The gene HERC2 limits the OCA2 gene. So, the more that HERC2 limits the OCA2 gene, means less melanin in the iris.

Melanocyte Activity

Melanocyte is the mature, melanin-forming cell. The activity level of melanocyte in babies can contribute to a change in eye color up until their 1st birthday. If melanocytes secrete only a small amount, a baby will have blue eyes. If melanocytes are very active, a baby will have brown eyes.

Did you know that most American Caucasian babies begin their life with blue eyes, but only 1 in 6 adults retain the blue eye color?

Anomalies

Sometimes, eye color is determined by anomalies in melanin and genetics. Heterochromia Iridium is a condition where each eye is a different color. Heterochromia Iridium occurs when there are anomalies in the iris. Only 6 in 1,000 have this condition.

Most people know that David Bowie has 2 different eye colors, so you may think that he has Heterochromia. Bowie’s condition, however, comes from eye damage from a fight as a teen over a girl, which led to a permanently dilated pupil, which is known as anisocoria. Max Scherzer, former Detroit Tigers pitcher, currently with the Washington Nationals, does, however, have Heterochromia.

 

At Rx Optical, we understand your eyes and the intricate science behind them. We would love to see you and learn more about your eye color and your eye health. Schedule your appointment with us online today.