Heterochromia: Why Some People Have Different-colored Eyes

Heterochromia is a rare condition characterized by different-colored eyes. The iris, or the colored part of the eye, is usually one color, but some people have different shades. The difference may be partial or complete. 

While some have different colors in one iris, others have each iris in a different color. Some people are born with the condition, but it develops later in life in others. Here is what you need to know about heterochromia and why some people have different-colored eyes. 

Understanding Heterochromia 

Eye color is determined by the amount of melanin in the eyes. The more melanin the eye has, the darker the iris will be. People with blue or grey eyes have less melanin than those with brown eyes. 

Heterochromia occurs when part or the entire iris has different melanin levels than the other. Heterochromia is an eye condition that affects about 0.06 percent of the population. The condition may be genetic but also due to injury or illness.

Types of Heterochromia 

There are three main types of heterochromia. They include:
 

• Complete heterochromia or heterochromia iridis. It is the most common type where each eye has a different-colored iris. One iris may be green and the other brown.
   

• Central heterochromia. It is a more subtle type where both eyes are similar, and the color difference is in the iris. The middle part is a different color from the outer edge. 
   

• Sectoral or partial heterochromia. A single eye can have more than one color, but the different-colored part is usually wedge-shaped. It can affect one or both eyes.  

What Causes Heterochromia 

A difference in melanin levels in the eyes can lead to heterochromia. In most cases, the condition is congenital, where an individual is born with it or develops in infancy. Genetic heterochromia is benign, which means it is not something to worry about. It is known as acquired heterochromia when the condition occurs later in life. It can be a sign of something serious that requires medical attention. 

Congenital Heterochromia 

Genetic heterochromia is usually random, but it may also be due to an underlying congenital disease. The diseases include Horner's syndrome, Waardenburg syndrome, Piebaldism, Hirschsprung disease, Sturge-Weber syndrome, tuberous sclerosis, Duane retraction syndrome, and Parry-Romberg syndrome. 

Acquired Heterochromia

Acquired heterochromia can develop due to various conditions. These include:
 

• Diabetes.
   

• Eye trauma or injuries.
   

• Benign or malignant tumors in the iris.
   

• Glaucoma or glaucoma medication.
   

• Complications of eye surgery.

When a change in eye color occurs later in life, it could be due to a severe disease such as cancer. If you notice differences in your eye color, visit your eye doctor immediately. 

Treatment for Heterochromia

Congenital heterochromia is usually of no medical concern and does not require treatment. Most people born with the condition do not have other eye or health issues. But if the condition develops later in life, treatment is necessary. 

It could be a sign of a severe eye condition. Treatment targets the underlying condition, which can involve treating diabetes, glaucoma, or tumors. Heterochromia due to eye trauma or injury is not reversible.

For more on heterochromia and why some people have different colored eyes, visit Paradise Canyon Eye Care at our St. George, Utah office. Call (435) 334-2331 or (435) 656-2003 to schedule an appointment today.

​​​​​​​

​​​​​​​

​​​​​​​