Heterochromia: A Tale of Two Eye Colors

By Cole Purvis
Person with two colored eyes

July 12 is National Different Colored Eyes Day — a time of year where we recognize the individuals around the world who captivate us with one of nature’s most fascinating anomalies: heterochromia.

What is heterochromia?

Heterochromia refers to the condition where the color of a person’s two eyes are unique to each other or they have color variations within the one eye. The colorful part of your eye, or iris, ranges anywhere from light blue or gray to dark brown, and, typically, both of your eyes will match this color. With this condition, however, the iris in one eye may be a completely different color than the iris in your other eye. For example, you may have one eye that is green and one eye that is brown.

Heterochromia can also take place in just one eye when an iris contains two or more different colors. For instance, a brown eye could have a section that is blue, or a brown eye might have spikes of blue that radiate out from the center, or iris.

Types of heterochromia

Medical professionals, including those from Cleveland Clinic, agree that there are three types of of this condition based on their distinct visual patterns: complete, sectoral or central heterochromia.

Complete heterochromia (heterochromia iridum)

One eye is a completely different color than the other.

Sectoral — or partial — heterochromia (heterochromia iridis)

One iris has a section that is a color different from the rest.

Central heterochromia

One iris has an inner ring that’s a different color from the rest. This often looks like spikes extending outward from the pupil.

What causes it?

In the majority of cases, heterochromia occurs randomly. Most people are born with it and do not have any other health problems or symptoms — it’s simply a genetic mutation. However, heterochromia can develop later in life due to new underlying conditions, such as an injury or disease.

Is it a risk?

By all measures, most cases of heterochromia are perfectly safe and completely normal, albeit very rare. According to Cleveland Clinic, researchers and healthcare providers don’t know the exact likelihood of this condition, but some have estimated its chances to be near six in every 10,000 people.

As previously stated however, the condition can also come as a result of a disease of or injury to the eye. If you, a newborn child or other loved one develop heterochromia, immediately visit a doctor who can help identify the root cause of it, either an ophthalmologist or optometrist. There are several conditions, both congenital (present from birth) or acquired (after birth), that can cause it, including Horner syndrome, ocular melanosis and glaucoma among several others. The severity of these ailments can range from mild to severe, so identifying the culprit as soon as possible is essential to avoid any unwanted consequences.

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