What Causes Central Heterochromia?

Central heterochromia arises when melanin is unevenly distributed across the iris, with a higher concentration around the pupil that creates a distinct inner ring.

Multiple genes influence eye pigmentation; a small genetic variation can produce this rare pattern.

In most cases, central heterochromia is congenital, present from birth. It is more frequently observed in people of European descent and typically occurs without associated health issues.

Acquired Heterochromia

Acquired heterochromia can develop later in life due to eye injuries, medical conditions, or environmental factors.

Conditions such as pigment dispersion syndrome and certain glaucoma medications may alter iris pigmentation.

Uneven melanin distribution can produce color variations within a single iris.

Does Central Heterochromia Affect Vision or Eye Health?

Generally, central heterochromia is harmless and does not impact vision or eye health. Many individuals are unaware of the trait until someone points it out.

Sudden Changes in Eye Color

Sudden or later‑life changes warrant an eye exam, as they may signal underlying conditions like pigment dispersion syndrome or side effects of glaucoma drugs.

Eye color changes accompanied by light sensitivity or other symptoms should prompt medical evaluation.

How Is Central Heterochromia Different From Other Types?

Heterochromia iridum has three main forms:

• Complete heterochromia: each eye is a different color.
• Sectoral (partial) heterochromia: a portion of one iris differs in color.
• Central heterochromia: concentric rings of distinct colors within the same iris.

The variation depends on melanin distribution and may affect one or both eyes.

Can Lighting, Eye Makeup, or Other Factors Alter the Eye Color?

Light scattering and contact lenses can influence perceived eye color. In different lighting, the same iris may appear to have varying pigments.

Eye makeup can accentuate or diminish the visibility of central heterochromia. For example, complementary shades may highlight the inner ring.

While central heterochromia is not medically treated, cosmetic approaches can help emphasize or conceal the feature.

When to Talk to a Healthcare Provider

If you have had central heterochromia since birth without other symptoms, it is usually benign. However, any sudden change—especially in one eye—or accompanying symptoms such as light sensitivity or vision changes should prompt an eye examination.

An eye exam can rule out underlying conditions that affect iris pigmentation.

This article was prepared with AI assistance and reviewed by a HowStuffWorks editor.