Heterochromia describes a variation in eye coloration, where an individual possesses irises of different colors or multiple colors within a single iris. The iris is the colored part of the eye, its color determined by melanin pigment.
Types of Heterochromia
Heterochromia can be categorized into three main types based on its visual presentation.
Complete heterochromia occurs when each eye is a distinctly different color, such as one blue and one brown. This type is the least common.
Sectoral heterochromia involves a segment of one iris being a different color from the rest. This can affect one or both eyes.
Central heterochromia is characterized by a ring of a different color around the pupil, while the outer edge of the iris maintains a separate color. Both eyes are typically affected similarly.
When Heterochromia is Present at Birth
When observed at birth or shortly thereafter, it is called congenital heterochromia. This form is typically a benign genetic trait, not indicating underlying health concerns, and often results from genetic factors influencing melanin distribution.
Congenital heterochromia can sometimes be associated with certain syndromes, although these are less common. For example, Waardenburg syndrome, a genetic condition, can cause changes in hair, skin, and eye color, including heterochromia, alongside potential hearing loss. Another condition, congenital Horner’s syndrome, can also lead to heterochromia if it occurs before approximately two years of age, causing the affected eye to be lighter in color. If a baby presents with different eye colors, a medical evaluation is often recommended to rule out any rare associated conditions.
When Heterochromia Appears Later in Life
Heterochromia that develops after infancy is known as acquired heterochromia. This type often warrants medical attention because it can signal an underlying health issue or injury.
Various factors can contribute to acquired heterochromia, including eye trauma or bleeding within the eye.
Inflammation of the eye, such as iritis or uveitis, can lead to changes in iris pigmentation. Fuchs heterochromic iridocyclitis, a chronic inflammatory condition, is specifically characterized by iris heterochromia. Certain medications, particularly some glaucoma eye drops like prostaglandin analogues, are known to cause iris darkening. This color change can be permanent. Other potential causes include eye tumors, diabetes, or pigment dispersion syndrome.
Seeking Medical Guidance
While heterochromia present from birth is frequently a harmless variation, any new development of different eye colors, or a noticeable change in existing heterochromia, should prompt a consultation with a healthcare provider.
An eye care specialist can determine the cause and rule out any serious underlying conditions. This is particularly important if the eye color change is accompanied by other symptoms.
Symptoms such as pain, redness, blurred vision, or sensitivity to light alongside a change in eye color necessitate prompt medical evaluation. A thorough eye examination can help identify whether the heterochromia is an isolated occurrence or a symptom of a condition requiring treatment. Addressing any underlying medical issues associated with acquired heterochromia is important for eye health.