Heterochromia: What Is It?  

Seeing a person or an animal with different-colored eyes, or heterochromia is noticeable — and beautiful! Here, we’ll take a look at the different types of heterochromia, conditions associated with heterochromia, and how to decide whether treatment is necessary.

Types Of Heterochromia

There are three types of heterochromia: central, complete, and sectoral.

People who have central heterochromia have two different colors in the same iris: the inner ring of the iris is one color, and the outer ring of the iris is a different color. For people with this condition, the color of the outer of the iris is considered to be their true eye color. Many people who have this condition have the appearance of cat eyes. The inner color may radiate into the outer color in spike-like projections. This variety of heterochromia tends to occur more frequently in people who have green and blue eyes, rather than in people who have brown eyes.

Complete heterochromia is what many people think of when they learn of heterochromia: two completely different colored irises.

Sectoral heterochromia occurs when a segment of the iris is a different color than the rest of the iris. This is also known as partial heterochromia. The differently-colored area may be large or small and may occur in one or both eyes.

Heterochromia Causes and Related Conditions

Eye color is determined genetically and is created by melanin deposits in the eye. People with lighter-colored eyes have low levels of melanin in their eyes, while people with darker-colored eyes have higher levels of melanin in their eyes.

Heterochromia may simply be caused by an uneven distribution of melanin in the eyes. For most people who have heterochromia, there is no family history of unusual eye colors.

In other cases, however, heterochromia can be related to a disease or genetic condition. Some genetic conditions related to heterochromia include Parry-Romberg syndrome, Horner’s syndrome, Bourneville disease, Waardenburg syndrome, Hirschsprung disease, Block-Sulzberger syndrome, Sturge-Weber syndrome, and von Recklinghausen disease. Some people also develop heterochromia due to an eye injury or illness.

Do People With Heterochromia Need Treatment?

Most people who have heterochromia do not need treatment for the condition, as it does not cause any health issues (visual or otherwise). People who have acquired heterochromia should talk with both their eye doctor and their primary care physician about whether they need treatment for the health issue that caused the change in their eye color.