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Heterochromia: When Does It Occur? (Types & Causes)

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Heterochromia describes both eyes being a different color. For example, the left eye is green, and the right eye is blue.

No study has been done to determine exactly how many people have the condition. However, some estimates state that approximately 1 percent of people throughout the entire world have this condition.

Some people are born with heterochromia, but it can occur later in life. When this happens, it is important to determine the underlying cause.

The diagnostic process is relatively simple to determine if someone has heterochromia. The specifics vary greatly if a doctor suspects one.

Heterochromia itself does not require any treatment. If there is an underlying cause, such as a disease, treatment for this issue is needed.

woman with heterochromia

Types of Heterochromia

There are three types of this condition.

  1. Partial: Only a portion of the iris is a different color from the rest.
  2. Complete: One eye’s iris is a completely different color compared to the other eye.
  3. Central: The part of the iris near the pupil is a different color that the outer part of the iris.

Causes of Heterochromia

Congenital heterochromia is a condition that babies are born with, or it starts very shortly after they are born. In most cases, these babies will not experience any other vision issues as a result of this condition.

Infants might also develop this condition as a result of another disease. These diseases are usually genetic.

  • Horner’s syndrome
  • Sturge-Weber syndrome
  • Piebaldism
  • Bloch-Sulzberger syndrome
  • Bourneville disease
  • Benign heterochromia
  • Waardenburg syndrome
  • Hirschsprung disease
  • Von Recklinghausen disease
  • Parry-Romberg syndrome

It is possible to develop this condition later in life. In these instances, it is referred to as acquired heterochromia. An injury or disease is usually responsible in these cases.

Healthy eye vs. Uveitis
  • Uveitis or iritis. These conditions can cause swelling, and this can contribute to a change in eye color. Uveitis is characterized by inflammation in the uvea. Iritis describes an inflamed iris.
  • Fuchs’ heterochromic cyclitis. This is a type of inflammatory syndrome that affects the uvea. Approximately 2 to 3 percent of cases of uveitis are attributed to this condition. The exact cause remains unknown, but ocular toxoplasmosis, rubella, and herpes simplex have been implicated in the disease.
  • Glaucoma. Both the condition and some of the drugs prescribed to treat glaucoma may cause this condition. This condition is characterized by the pressure in the eye becoming too high. It can lead to blindness, especially when it is not promptly treated.
  • Pigment dispersion syndrome. This is an eye condition that can result in pigmentary glaucoma. It is characterized by the pigment cells that are present in the iris sloughing off the back. Once they slough off, they start to float around in the fluid of the eye.
  • Iris tumors. It is possible for tumors to develop in the iris part of the eye. Some of these are malignant, but others are benign. One malignant type of tumor that can develop on this eye structure is melanoma.
  • Acquired Horner’s syndrome. This is a type of Horner’s syndrome that can occur later in life. The triad of symptoms that it can cause include miosis, eyelid ptosis, and facial anhidrosis. In most cases, only one side of the face is affected by this disorder.
  • Posner-Schlossman syndrome. This condition is characterized by attacks where someone’s intraocular pressure is elevated. It is unilateral, acute, and recurrent. The anterior chamber of the eye usually has inflammation too.
  • Diabetes mellitus. This causes blood sugar in the body to elevate. Some of the most common symptoms are increased thirst, being hungrier than usual, and frequent urination. When someone has diabetes, issues with their eyes are not uncommon. This is especially true if their blood sugar remains elevated long term.
  • Injury. In some cases, an injury to the eye may cause one of the eyes to change color. This is also possible with the trauma that can occur when someone has certain types of eye surgeries. Bleeding in the eye, due to a condition or an injury, may also influence a change in the color of the iris.

Diagnostic Process

The doctor can look at the eyes and determine if this condition is present. They may perform other testing to assess if there is an underlying cause that could be problematic.

An ophthalmologist should evaluate all infants if they have the congenital form of this condition. This will determine if there is an underlying cause.

An opthamologist is listening to the patient in an exam room.
For adults, a detailed eye exam is usually performed. While the cause is not always serious, it is still important to know why they acquired this condition later in life.

Heterochromia Treatment

It is not necessary to treat this condition itself. However, if there is an underlying condition that caused it, treatment will need to be provided for this. If people want to return their eyes to the same color, there are contact lenses that are colored that a doctor can prescribe.

The treatments for any underlying condition vary greatly. For some conditions, medications may be sufficient to help someone achieve better eye health. For other conditions, the treatment options many be more invasive. For example, certain tumors may need to be removed surgically to work toward greater eye health.

If someone develops heterochromia later in life, they should make an appointment with their doctor. The doctor can aid them in determining if there is an underlying cause that requires treatment.


  1. Central Heterochromia Statistics. Health Research Funding.
  2. Heterochromia: Why Do Some People Have Two Different Colored Eyes? All About Vision.
  3. Heterochromia. American Academy of Ophthalmology.
  4. An Overview of Heterochromia. Verywell Health.
  5. Fuchs’ Heterochromic Cyclitis. Seminars in Ophthalmology.

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