Heterochromia is a condition that affects the colored part of the eye called the iris. The variations in the distribution and concentration of melanin, a pigment that gives color, result in different colored eyes. Heterochromia is more commonly seen in animals but can affect humans as well. It is not a severe condition and is usually caused by genetic variations. Read this article to learn about heterochromia, its symptoms, causes, and treatments.

Types of heterochromia
There are three variants for this condition, namely:

Complete heterochromia
When the entire iris in one eye is different in color than the other, it is called complete heterochromia or heterochromia iridis. For example, one eye may be green while the other is blue.

Partial or segmented heterochromia
When part or segment of an iris is different in color than the rest of it, it is called partial or segmented heterochromia. It is also known as heterochromia iridium. This type may be noticeable only when looking closely at the person’s eye.

Central heterochromia
In central heterochromia, the inner ring of the iris is different in color from the rest of it. For example, the outer ring may be blue or green, while the inner ring may be hazel.

Symptoms of heterochromia iridis
The common symptoms of heterochromia iridis is the appearance of different colors in the two eyes and rings of color around the pupil. If the variation is due to any inflammation or trauma, other signs may also be present.

Causes of heterochromia iridis
The uneven distribution of melanin causes heterochromia. Heterochromia iridis is genetic in the majority of cases. Rarely this condition can occur due to an underlying medical conditions.

Waardenburg syndrome
This genetic disease causes changes in the color of the eyes, skin, and hair. In some cases, it can also lead to hearing loss.

Piebaldism
In this condition, a lack of pigment causes some portions of the hair, skin, and eyes to become lighter than others.

Sturge Weber syndrome
This rare vascular disorder results in brain, skin, and eye abnormalities and is characterized by a port wine birthmark on the face.

Parry Romberg syndrome
Parry Romberg syndrome is a rare disorder that involves the gradual wasting away of the skin and soft tissues of one side of the face. Affected individuals may also develop several eye abnormalities, including heterochromia.

Hirschsprung disease
Hirschsprung disease is a bowel disorder that affects the large intestine. This is associated with sector heterochromia.

Tuberous sclerosis (Bourneville syndrome)
Tuberous sclerosis is characterized by multiple developmental tumors in all body organs, including the eye.

Congenital heterochromia
Congenital heterochromia is the most common cause of this condition. The majority of people are born with this condition, or it develops shortly after birth as a result of a benign mutation that impacts the development of melanin in the iris. It can occur in anyone, irrespective of whether or not there is a family history of heterochromia.

Causes of acquired heterochromia
Heterochromia iridis can also develop later in life because of an injury, illness, or due to certain treatments. However, acquired heterochromia is rare. Some of the causative factors of this condition are:

Eye injury
Injury or bleeding in the eye can influence color change in the iris.

Eye surgery
Certain eye surgeries can cause trauma affecting the eye color.

Diabetes
Diabetes causes an elevation of blood sugar in the body. In the long term, this can affect the eyes.

Horner’s syndrome
This rare condition is caused by damage to the nerves connecting the brain and eye. Horner’s syndrome affects one side of the face and eye.

Neuroblastoma
This cancer starts in the nerve cells of the sympathetic nervous system. If the tumors spread behind the eyes, it can result in changes in the organ, including a color variation of the iris.

Fuchs’ syndrome
This inflammatory syndrome affects the uvea. Usually, the lighter-colored eye is the one that is affected due to the loss of iris tissue.

Glaucoma
The treatment of glaucoma involves using eye drops that can stimulate the production of melanin in the iris but can result in darker eyes.

Melanoma of the eye
Melanoma of the eye is cancer that develops in the eye cells that produce melanin leading to changes in color.

Treatment
Generally, heterochromia iridis is a harmless condition and does not require any treatment. However, if one finds a change in the iris color later in life, it may be a sign of a medical issue. An eye examination will reveal whether the color change is caused by a health problem, and the root cause will be treated. If a person is bothered by this condition, one can wear colored contact lenses. There is no way to prevent heterochromia iridis, but the condition does not affect one’s quality of vision. However, regular eye check-ups can help detect any changes in the eye color.