Heterochromia
Two different eye colors on one person.
What are heterochromia irises?
Heterochromia iridum means having two different iris colors. Complete heterochromia is one blue eye and one brown eye, for example; sectoral (partial) heterochromia is a wedge of a different color within one iris; central heterochromia is a differently-colored ring around the pupil.
The science
The differences come from unequal melanin between (or within) the irises. Most heterochromia is congenital and benign — famous examples occur in both people and animals like huskies. Acquired changes in adulthood, by contrast, warrant an eye-doctor visit.
The genetics
Congenital heterochromia usually comes from uneven melanocyte behavior during development — the pigment cells in one iris (or one sector) simply produce more melanin than the other, sometimes following inherited variants, sometimes from spontaneous mosaicism where two cell populations carry slightly different genetics. Most congenital cases are isolated and harmless. Acquired heterochromia is different: injury, inflammation, or certain eye drops changing one iris's color in adulthood warrants a professional look.
How rare is it?
Complete heterochromia is one of the rarest eye traits in humans — far fewer than 1% of people. Sectoral and central forms are more common but still distinctive enough that most people who have them get asked about their eyes regularly.
Best colors to wear
With two different eye colors, neutrals plus one accent work best — let the eyes be the statement.
These are the classic picks for this eye color. Real irises mix several shades, and your exact mix decides which colors make your eyes pop. The Personal Eye-Pop Palette is built from your measured iris colors: five colors to wear, three to use carefully, plus makeup, hair and jewelry directions — $9.99, one-time.
Are your two eyes really different colors?
Free: your color mix in %, rarity score and Iris Card. Optional: the colors that make your exact eyes pop. Your photo never leaves your device.
Analyze My Eye Color FreeFrequently asked questions
What are the three types of heterochromia?
Complete (each eye a different color), sectoral (a wedge of different color in one iris), and central (a ring around the pupil differing from the outer iris). All three are pigment-distribution patterns.
How rare is complete heterochromia?
Very rare — well under 1% of people. Sectoral and central heterochromia are more common, and mild central heterochromia often goes unnoticed without a close-up photo.
Can an analysis detect heterochromia from a photo?
A per-eye color breakdown makes differences obvious: analyze each eye separately and compare the dominant families. Zone analysis of a single iris can reveal central and sectoral patterns.
Is heterochromia genetic or acquired?
Both exist. Congenital heterochromia — present from early childhood — is typically genetic or developmental and harmless. Acquired heterochromia, where one eye changes color later in life, has causes worth ruling out with an eye doctor.
Do animals have heterochromia more often than humans?
Dramatically so. Odd-eyed cats, huskies, and Australian shepherds carry coat-color genetics that frequently produce one blue eye. In humans complete heterochromia is far rarer — which is why it's so memorable when you meet it.