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Heterochromia: Types, Causes and Information

Author: Thomas C. Weiss : Contact: Disabled World

Published: 2015-09-29 : (Rev. 2018-01-06)

Synopsis and Key Points:

General information regarding Heterochromia, a difference in coloration, usually of the iris but also of hair or the skin.

Main Digest

'Heterochromia,' is a Greek word for differences in skin, hair and iris color. 'Heteros,' means different and, 'chroma,' means color. People who experience this usually have one iris that is a different color - darker or lighter than their other iris. The condition is caused by too much or too little pigmentation or melanin. The underlying causes include a number of things:

In anatomy, heterochromia is defined as a difference in coloration, usually of the iris but also of hair or skin. Heterochromia is a result of the relative excess or lack of melanin (a pigment). Heterochromia may be inherited, or caused by genetic mosaicism, chimerism, disease, or injury.

Heterochromia is a rare condition, it only affects around 11 people in 1,000 in America. Beside central heterochromia, there are two additional types of the condition. What follows is more in-depth information on heterochromia causes.

Causes of Heterochromia

Heterochromia is classified mainly by its time of onset as either genetic or congenital, present at or shortly after birth, or acquired. The majority of instances of heterochromia are hereditary and these might be associated with a congenital syndrome. Other instances are acquired and caused by an injury or disease. At times, one of a person's eyes might change color after certain injuries or diseases.

Heterochromia present at or shortly after a person's birth is usually hereditary, or due to intrauterine disease or injury. Congenital heterochromia might be familial and is inherited as an autosomal dominant trait. Inherited eye color is determined by a number of genes. Acquired or environmental factors may alter inherited traits. An infant with heterochromia should be examined by an opthalmologist as well as a pediatrician for other potential issues. If another disorder is suspected, diagnostic tests such as chromosome studies or blood tests might be performed to confirm the diagnosis.

Most instances of heterochromia at birth are genetic and not associated with any other form of systemic or ocular abnormality. The condition in this instance is simply referred to as, 'congenital heterochromia iridis.' The person's lighter eye often times shows some loss of iris and is therefore regarded as the eye that is affected. The lighter iris might be differently colored throughout, or only in part. Congenital syndromes which might be characterized by heterochromia iridis include the following.

Acquired Diseases or Conditions and Heterochromia Iridis

Some acquired conditions or diseases might be present in people with heterochromia iridis. These conditions or diseases include the following:

Clouding of a person's cornea or changes in color in their cornea from a number of conditions might cause their iris to falsely appear to be a different color. Conditions such as corneal scars, the common condition of, 'arcus senilis,' or the rare condition of Wilson disease might give the appearance of iris color differences.

Types of Heterochromia

Heterochromia manifests itself in one of three forms; sectoral, central and complete. It is also examined by how the onset occurred, genetic or acquired. While the majority of instances of this condition are genetic, there are also some instances where an eye changes color due to an underlying condition, or an eye injury. What follows are descriptions of the types of heterochromia.

Diagnosing Heterochromia

A health care provider might ask questions to help evaluate the cause such as, 'Did you notice the two different eye colors when the person was born, shortly after their birth, or recently? The health care provider may also ask if the person is experiencing any other symptoms. An infant with heterochromia should be examined by both an opthalmologist and a pediatrician for other potential issues.

A complete eye exam may rule out the majority of causes of heterochromia. If there does not appear to be an underlying disorder, no additional tests may be needed. If another disorder is suspected, diagnostic testing such as chromosome studies or blood testing might be performed in order to confirm the diagnosis.

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