Heterochromia is a difference in coloring at eye level. Each eye can present a different color or two colors can be present within the same eye. Heterochromia can appear in the baby’s first months or appear during life.

Definition of heterochromia

Heterochromia, or iris heterochromia, is the medical term for a difference in coloration at the level of the irises (colored circular discs located at the front of the eye).

To better understand this phenomenon, it is advisable to return to the appearance of the color of irises. At birth, the irises are poorly pigmented. Their coloration appears gradually with the multiplication of the pigmented cells of the iris. The higher the quantity of pigmented cells, the darker the iris. In heterochromia, there may be an alteration in the multiplication of pigmented cells and / or an alteration in the repair of pigmented cells in the iris.

There are two forms of heterochromia:

• complete heterochromia, also called iridium heterochromia, which results in a difference in color between the iris of each eye;
• partial heterochromia, also called heterochromia iridis, which results in the presence of two different colors within the same iris (two-tone iris).

Causes of heterochromia

Heterochromia can have a congenital or acquired origin, that is to say present from birth or occurring during life.

When heterochromia has a congenital origin, it is genetic. It can be isolated or associated with other symptoms. It can in particular be the consequence of a congenital disease such as:

• neurofibromatosis, a genetic disease affecting the nervous system;
• Waardenburg syndrome, a genetic disease resulting in various birth defects;
• congenital Claude-Bernard-Horne syndrome which is characterized by damage to the innervation of the eye.

Heterochromia can be acquired as a result of illness or injury. It can especially occur after:

• a tumor ;
• eye inflammation such as uveitis;
• glaucoma, a disease of the eye.

A simple clinical examination is enough to diagnose heterochromia.

Two irises of different coloring

Complete heterochromia, or iridium heterochromia, is characterized by a difference in color between the two irises. In common parlance, we speak of “wall eyes”. For example, one eye can be blue while the other is brown.

Two-tone iris

Partial heterochromia, or iridis heterochromia, is characterized by the presence of two different colors within the same iris. This form is more common than complete heterochromia. Partial heterochromia can be said to be central or sectoral. It is central when the iris presents a ring of a different color from the rest of the iris. It is sectorial when a non-circular section of the iris has a different color from the rest of the iris.

Possible aesthetic discomfort

Some people accept heterochromia and feel no discomfort. Others may see it as an aesthetic discomfort.

Other associated signs

Heterochromia can be the result of a congenital or acquired disease. It can then be accompanied by very different symptoms depending on the case.

To date, there is no specific treatment for heterochromia. Management generally consists of treating its cause when it is identified and when there is a therapeutic solution.

In case of aesthetic discomfort, the wearing of colored contact lenses may be proposed.

There is no prevention for heterochromia of congenital origin. Prevention applies to preventable acquired causes. For example, it may be advisable to limit the consumption of tea or coffee, which is a risk factor for glaucoma.