Heterochromia: Eye Color, Types and Rarity

Published on March 28th, 2025

Heterochromia is an eye condition in which the irises are different colours. There are three different types of heterochromia; central, complete and sectoral. Ultimately, heterochromia is usually harmless as it doesn’t affect vision quality. However, in some cases, it can be a sign of underlying health conditions such as Horner syndrome or neuroblastoma wherein one of the symptoms is heterochromia. Heterochromia is a rare condition, more commonly occurring in cats and dogs than humans. Read on to learn more about heterochromia such as its appearance, types, rarity and causes.

What is Heterochromia?

Heterochromia is a condition in which the irises are different colours. The iris is the coloured part of the eye that surrounds the pupil. There are three different types of heterochromia; central, complete and sectoral. People can be born with heterochromia, known as congenital heterochromia, or develop it later in life, called acquired heterochromia, according to the American Academy of Ophthalmology.

What are the Different Types of Heterochromia?

The different types of heterochromia are central heterochromia, complete heterochromia and sectoral heterochromia. The types of heterochromia are listed below.

Central heterochromia: Central heterochromia refers to heterochromia occurring in the inner ring of the iris. With central heterochromia, the inner ring will be a different colour than the outer ring of the iris.
Complete heterochromia: Complete heterochromia is a type of heterochromia in which one iris is a completely different colour than the other iris.
Sectoral heterochromia: Sectoral heterochromia, also known as partial heterochromia, refers to heterochromia in which only a small section of the iris is a different colour than the rest, resembling a slice.

Three pictures of eyes, each with a type of heterochromia including complete heterochromia, central heterochromia and sectoral heterochromia.

What Causes Heterochromia?

The causes of heterochromia include an inherited gene, diseases and injuries. Heterochromia can be inherited or acquired later in life. The causes of heterochromia are listed below.

Inherited gene: An inherited gene or genetic mutation passed down from parent to child, is the most common cause of heterochromia.
Diseases: Diseases such as neurofibromatosis, Waardenburg syndrome or, neuroblastoma, can lead to heterochromia.
Injuries: Injuries such as ocular trauma or foreign objects in the eye, may lead to heterochromia.

What is the Difference Between Central Heterochromia vs Hazel Eyes?

The difference between central heterochromia and hazel eyes is that heterochromia is an eye condition stemming from causes such as gene mutation, eye diseases or eye injuries, whereas hazel eyes are a normal occurrence, determined by the amount of melanin in the eye. Central heterochromia is when one eye contains multiple pigments. It can cause a colour abnormality that stems from the pupil. The outer ring will almost always be blue or green however it's common for the inner ring to be gold or hazel, so the person may appear to have hazel eyes. Hazel eyes, on the other hand, are a mix of the colours brown, green and gold with brown or green the most predominant colours.

Is Heterochromia a Genetic Condition?

Heterochromia can be a genetic condition. According to the Cleveland Clinic, harmless genetic mutations can affect the genes related to producing melanin such as SLC45A2 which is notably involved in determining eye pigmentation. Heterochromia that is genetic and present from birth is called congenital heterochromia.

Can Heterochromia Be a Symptom of a Health Condition?

Yes, heterochromia can be a symptom of certain health conditions, such as eye injuries, or diseases. Certain health conditions or diseases such as Waardenburg syndrome and neurofibromatosis may result in heterochromia. This is known as acquired heterochromia.

What Are the Symptoms of Heterochromia?

There are generally no symptoms of heterochromia as a condition itself, outside of the different colours within the one eye, or over both eyes. If heterochromia is a symptom of another disease or eye injury, it may occur in conjunction with other symptoms of that disease.

Is Heterochromia Treatable?

Heterochromia is not treatable as It is often a harmless variation in eye colour. However, providers may treat heterochromia if it is caused by underlying conditions such as such as, Fuchs Iridocyclitis, an inflammatory condition that can cause heterochromia, cataracts and glaucoma. Heterochromia can also be a symptom of other eye diseases or injuries that may be treated.

Can Heterochromia Develop Later in Life?

Yes, heterochromia can develop later in life. This will happen due to an acquired condition, which is one that develops later in life, that causes heterochromia. Acquired conditions that can cause heterochromia include acquired Horner syndrome, neuroblastoma and intraocular melanoma. These conditions affect melanocytes. Conditions such as these disrupt the nerve-signalling pathway in your face, which leads your melanocytes to produce less melanin. As a result, the iris on the affected side of your face has less melanin, making it appear lighter and different in colour.

Is Heterochromia Dangerous or Harmful?

Heterochromia is generally not considered dangerous or harmful as it doesn’t affect the vision quality of a person who has it. However, if there is a sudden change in the colour of one or both eyes, it’s important to consult an eye health professional as this may be a sign of an underlying condition, disease or injury. Only an eye examination would reveal whether such changes were caused by a medical problem. A newborn or infant with a sign of heterochromia should be examined to be certain that there are no serious problems.

How Common is Heterochromia?

Heterochromia is not a common eye condition. According to the Optometrists Organisation heterochromia affects less than 1% of the population, making it a very rare condition. Heterochromia is more common in certain dog and cat breeds than in humans. Other eye colours that are rare include grey eyes and green eyes.

A person with complete heterochromia, or two different coloured eyes.

Can Heterochromia be Corrected with Contact Lenses?

Heterochromia cannot be corrected by coloured contact lenses, but they can give the appearance that both eyes are the same colour. This is a purely cosmetic choice and it is not required medically. Talk to an eye care specialist if you’re interested in coloured contacts. Coloured contact lenses are not the same as prescription contact lenses used for vision correction.

When Should You See a Doctor About Heterochromia?

You should see a doctor if you notice any sudden changes in your eye colour or overall eye appearance. Whilst heterochromia itself is harmless, certain health conditions or eye injuries can cause heterochromia to occur. This means, if you see your eye colour start to change, you should see a doctor as soon as possible.

Can Heterochromia Affect Vision?

Heterochromia does not affect vision or cause visual impairment. It will typically only affect the appearance of the eye. However, it can be a symptom of an underlying health issue, which could affect your vision. If you are having any vision issues and have noticed that your eye is changing colour, see your optometrist as soon as possible.

What Are the Cosmetic Solutions for Heterochromia?

The cosmetic solutions to heterochromia are limited to coloured contact lenses. There aren't many other recommended surgeries or treatments to change eye colour for aesthetic purposesIf a person has heterochromia as a result of eye diseases or eye injury, then treatment may help fix differing eye colour.