Heterochromia of the eye (heterochromia iridis) is a condition that leads to differently colored eyes or eyes with more than one color. It typically does not cause any issues and is merely a result of certain inherited genres or issues that emerge when the eyes are developing. In rare instances, it might be a symptom of an underlying condition. Nevertheless, heterochromia iridis is a rare condition, affecting less than 200,000 people in the country.

Causes
One could be born with heterochromia iridis or may develop it shortly after birth, also known as congenital heterochromia. Typically, kids born with the condition experience no symptoms or issues with their eyes or health. However, the difference in the color of both eyes could be a result of an underlying disorder, like Horner’s syndrome—a neurological condition affecting the eyes. Congenital heterochromia can also be a result of Bourneville disease, piebaldism, Sturge-Weber syndrome, and Waardenburg syndrome, among other conditions.

On the other hand, when a person develops the condition later in life, it is called acquired heterochromia. Here, eye surgery, bleeding or injury in the eye, or conditions like glaucoma (and its treatment), diabetes, neuroblastoma (cancer of the nerve cells), uveitis-induced swelling, or iris tumors are also likely causes. Additionally, undergoing a specific cosmetic treatment that helps eyelashes grow can be a risk factor for heterochromia iridis.

Types
The only heterochromia symptom is the difference in eye colors; however, the extent of color difference can vary. Consequently, heterochromia is classified into the following types:

Complete heterochromia: Here, the iris of one eye completely differs in color from the other. For instance, one iris may be black, and the other may be blue.

Segmented or partial heterochromia: With this type, a part of one iris varies in color from the remaining portion.

Central heterochromia: Here, the iris has an inner ring that has a different color than the outer area of the same iris.

Additionally, heterochromia may also be categorized into two types depending on the difference in the colors of the two eyes.

Hyperchromic heterochromia: When the affected iris is significantly darker than the normal one.

Hypochromic heterochromia: When the affected iris is significantly lighter than the normal iris.

The condition could be accompanied by other symptoms if certain health conditions are responsible for the color difference.

Diagnosis
One must schedule an appointment with an eye specialist or ophthalmologist if they notice a sudden change in the color of one or both eyes. Here, they can get a complete eye exam. Discussing details like when one noticed the color change and if they observed any other symptoms can help doctors determine the underlying cause. One may have to undergo genetic or blood tests to get a complete diagnosis.

Treatment
Typically, heterochromia is a harmless genetic trait, so it may not need treatment. However, underlying conditions, if any, may have to be treated once one gets a diagnosis. Further, one can get color contact lenses to address the difference in eye color following a consultation with an eye doctor.