An Overview of Heterochromia

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Heterochromia

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Heterochromia is a disease that makes you have two different colors of irises. There are a few different variations of this condition. Complete heterochromia (heterochromia iridis) is when one iris is a totally different color from the other. For example, the iris in one eye may be brown while the other is green. Partial or segmented heterochromia is when part of one iris is different in color from the rest of that same iris, while central heterochromia is when you have a ring in one iris that’s a different color form the remaining parts of the same iris.

Heterochromia is also classified according to the difference in color of the irises. Hypochromic heterochromia is when the abnormal iris is of a lighter color than the normal one while hyperchromic heterochromia is when the abnormal iris is darker in color than the normal one.

The word heterochromia literally translates to "different colors" in Greek. Heterochromia is very rare in humans but it's quite often seen in animals like cats, horses, and dogs. If you’re born with it, or it manifests soon after your birth, it’s called congenital heterochromia.

Symptoms

The majority of cases of heterochromia are random and as such, they don’t come with any symptom other than the differently colored irises.

Causes

Most people born with heterochromia do not have any other health problems or symptoms, but in rare cases, it is a symptom of another congenital (present from birth) disease. Some of these diseases are:

  • Horner’s syndrome: A rare condition that’s caused by damage to the nerves connecting the brain and eye. It usually affects just one side of the face and is characterized by droopy eyelids and permanently small pupils on that affected side.
  • Waardenburg syndrome: A group of genetic diseases that result in changes in the color of the eyes, skin, and hair. It also sometimes leads to hearing loss.
  • Piebaldism: A relatively harmless condition that’s characterized by a lack of pigment in the skin, eyes, and hair. People with this condition usually have portions of their hair, skin, and eyes that are lighter than normal.
  • Sturge Weber syndrome: A condition where there are brain, skin, and eye abnormalities due to the abnormal development of certain blood vessels. People with this condition usually have a port-wine birthmark—a pinkish/reddish/purplish mark on their faces.
  • Parry-Romberg syndrome: In this condition, the skin, soft tissue, muscles and sometimes bones in one side of the face slowly weaken and atrophy. It’s a very rare disease and people with it often suffer from seizures as well.
  • Hirschsprung disease: A condition that affects the large intestine. Mainly newborn babies and toddlers have this condition and it makes them unable to pass stool easily and properly.
  • Tuberous sclerosis, also known as Bourneville syndrome: A rare disease that involves the formation of noncancerous tumors in many different body organs such as the brain, heart, skin, kidneys, eyes, and lungs.
  • Duane syndrome: Also known as Duane retraction syndrome, people with this condition have difficulty moving one or both eyes inward and/or outward.

When a person develops heterochromia later in life (acquired heterochromia), any of these could be the cause:

  • Neuroblastoma: A form of cancer that starts in the nerve cells of the sympathetic nervous system. It affects mainly infants and younger children.
  • Fuchs syndrome, also known as heterochromic cyclitis syndrome: This disease, affecting mainly older adults, is characterized by poor, cloudy vision, glare sensitivity, and eye pain. It’s caused by deterioration of the cells in the cornea whose main function is to regulate the amount of fluid in the cornea.
  • Glaucoma: This is a progressive disease where fluid builds up in the front part of your eye(s) and causes damage to the optic nerve there.
  • Central retinal vein occlusion: The blockage of the eye’s main retinal vein, which causes blood and other fluids to leak into the retina.
  • Melanoma of the eye: Also called ocular cancer, this is cancer that develops in the eye cells that produce melanin.
  • Eye injury or trauma
  • Certain types of eyedrops
  • Eye surgery
  • Some of the drugs used to treat glaucoma
  • Diabetes

There are generally no risk factors associated with heterochromia and it is also not an inherited disease. However, it is possible to have heterochromia because of inherited diseases like Waardenburg syndrome and piebaldism.

Diagnosis

Heterochromia is diagnosed by an ophthalmologist. They will examine your eyes to confirm that there is heterochromia present. Signs of underlying or causative diseases will also be looked out for.

If the ophthalmologist suspects that the heterochromia is indeed caused by or is a symptom of another disease, you will be referred to the particular doctor that's trained to treat such disease for further diagnosis. This could be either via blood tests or genetic tests. In most cases, however, this is not the case, and the different colored irises are not accompanied by any other health problems.

What to Expect From an Eye Exam

Treatment

Typically, there’s no need to treat heterochromia if it isn't caused by another condition. However, if you want both your eyes to have the same color, you may want to wear contact lenses.

If your heterochromia is as a result of any underlying disease or injury, treatment will be focused on said condition or injury.

A Word From Verywell

If you have benign heterochromia, that is, you don't have any other symptoms or a medical condition causing it, there’s no need for you to be concerned. You can go on living life normally. And if you don't like the way it looks, contact lenses are always an option. Custom-made contact lenses can be created to suit the particular kind of heterochromia you have. On the other hand, if you notice that you or your child's eyes have changed color all of a sudden, you should see an ophthalmologist as soon as possible because it could be a sign of eye damage or some other health condition.

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