Heterochromia is�uncommon in humans, but�quite common in dogs (such as Dalmatians and Australian sheep dogs), cats, and horses.

Most cases of heterochromia are hereditary, caused by a disease or syndrome, or due to an injury. Sometimes one eye may change color following certain diseases or injuries.

Specific causes include:

• Familial heterochromia (autosomal dominant transmission)
• Waardenberg syndrome (congenital and autosomal dominant)
• Some medications used to treat glaucoma may cause the iris (colored part of the eye) to darken
• Neurofibromatosis (may cause the affected iris to darken)
• Injury, hemorrhage (bleeding), glaucoma, or foreign body in the eye

If you notice new changes in the color of one eye or that your infant has two differently colored eyes, consult your health care provider. A thorough eye examination is needed�to be sure this isn't a symptom of a medical problem.

Some conditions and syndromes associated with heterochromia, such as pigmentary glaucoma, can only be detected by a thorough ophthalmic exam.

The following questions may help evaluate the cause:

• Were the two different eye colors noticed when the child was born, shortly after the birth, or recently?
• Are any other symptoms present?

An infant with heterochromia should be examined by both a pediatrician and an ophthalmologist for other possible�problems.

A complete eye examination can rule out most causes of heterochromia. If there doesn't seem to be an underlying disorder, no further testing may be necessary. If another disorder is suspected, diagnostic tests may be performed to confirm the diagnosis. This may include various blood tests, chromosome studies, or others.