Heterochromia

What is heterochromia?

Have you ever looked a person in the eye and noticed that each eye is a different colour? If so, that person probably has a condition known as ‘heterochromia’ or is wearing coloured contact lenses!

Although it can refer to a patch of hair or skin (or fur) that is a different colour, heterochromia mainly refers to two different coloured eyes. If just part of the iris is different from the remainder of the eye, this is known as partial (or sectoral) heterochromia.

Causes of heterochromia

Heterochromia is the result of either an excess or lack of a pigment called melanin. In the case of eyes, the colour of the irises is mainly determined by the concentration and distribution of melanin.

For humans, an excess of melanin in the iris tissues is called hyperplasia, while a lack of melanin is called hypoplasia.

Most cases of heterochromia are hereditary, however, it can also be caused by certain diseases or injury that result in one eye changing colour.

The list of possible causes includes:

• Bleeding (haemorrhage)
• Foreign object in the eye
• Physical injury
• Inflammation affecting one eye
• Glaucoma (and some medicines used to treat glaucoma)
• Neurofibromatosis
• Genetic conditions present at birth such as Waardenburg syndrome (a rare group of conditions passed down through families that involve deafness and pale skin, hair and eye colour) or Sturge-Weber syndrome (a vascular disorder that causes abnormalities to the brain, skin and eyes).

Is there a treatment of heterochromia?

In itself, heterochromia is not a health risk and therefore does not require treatment. However, if there is a sudden change in the colour of one or both eyes, it’s important to consult an ophthalmologist 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 new born or infant with a sign of heterochromia needs to be examined to be certain that there are no related problems. Although there may be no sign of a disorder, it’s valuable to have an examination to be sure. In some instances, blood tests or chromosome tests may be required to confirm the cause.

Famous people with heterochromia

Interestingly, people with two different coloured eyes are often seen as being appealing. Film, fashion and the lifestyle media appear to have a fascination with famous personalities with heterochromia. Here are a few examples:

Actors:

• Simon Pegg
• Mila Kulis
• Keifer Sutherland
• Dan Akroyd
• Kate Bosworth
• Christopher Walken
• Josh Henderson
• Jayne Seymour
• Henry Cavill (partial heterochromia)

Dancer:

• Michael Flatley

Music:

• David Bowie (although both his eyes were blue, he appeared to have two different coloured eyes because one pupil was permanently dilated – the result of a fight in his younger years)

Heterochromia also produces some extraordinary looking animals. For many, the appearance of having two different coloured eyes is considered exotic and a quick Google search will provide an endless number of dramatic examples.