Green eyes with amber centers, also known as central heterochromia, are a rare and stunning eye color. This condition occurs when there is a ring of amber, brown, or gold around the pupil, while the rest of the iris is a different color like green, blue, gray, or hazel. The cause behind this eye color variation involves the concentration and distribution of melanin pigment in the iris.
What causes green eyes with amber in the middle?
Eye color is determined by the amount and type of melanin pigment in the iris. Melanin comes in two forms:
- Eumelanin – A brown/black pigment
- Pheomelanin – A red/yellow pigment
The combination and concentration of these two melanins produce different eye colors:
- Low melanin concentration produces blue eyes
- Moderate eumelanin produces green and hazel eyes
- High eumelanin concentration results in brown/black eyes
- High pheomelanin produces amber and gold eyes
In eyes with central heterochromia, there is a higher concentration of melanin pigment around the pupil compared to the outer iris. This results in the inner ring appearing darker or richer in color than the outer iris:
- Green outer iris + high central pheomelanin = amber ring around pupil
- Blue outer iris + high central eumelanin = brown ring around pupil
The distribution of melanin in the iris can be affected by:
- Genetics
- Ethnic background
- Hormones
- Age
This variation in melanin concentration and type across the iris leads to the two-toned or ring pattern in central heterochromia.
What causes the amber color in green eyes?
The amber, gold, or brown color seen in central heterochromia with green eyes is produced by pheomelanin pigment. Pheomelanin is a red/yellow pigment present in the iris in lower concentrations than brown eumelanin.
Green eyes have moderate amounts of eumelanin. When pheomelanin is also deposited around the pupil, it shows up as an amber/gold color against the outer green hue of the iris.
The higher concentration of pheomelanin near the pupil is likely influenced by genetics and family backgrounds that carry this pigment variation.
How rare are green eyes with amber centers?
Central heterochromia of any kind is relatively uncommon, occurring in less than 5% of the population. Green eyes themselves are also rarer, found in only 2% of the world’s population.
The combination of green eyes with central heterochromia is exceptionally unique. There are no statistics available on exactly how rare this eye pattern is. However, based on the rarity of both central heterochromia and green eyes in general, bi-colored green/amber eyes are likely found in less than 1% of people.
What ethnicities are associated with central heterochromia?
| Ethnicity | Likelihood of Central Heterochromia |
|---|---|
| Caucasian | More common |
| Northern European | Most common |
| Hispanic/Latino | Less common |
| African | Rare |
| Asian | Extremely rare |
Central heterochromia appears to be most prevalent in those of Northern European descent. The light eye colors common in this population provide the backdrop that allows central heterochromia to be visible.
The condition is less common in those with darker eye colors including Hispanic/Latin, African, and Asian ethnicities. However, central heterochromia can still occur in these populations.
Are there health concerns associated with central heterochromia?
Central heterochromia is considered a benign, cosmetic variation and not associated with any health or medical issues. It is different than other conditions that can affect the iris:
- Anisocoria – One pupil is permanently dilated due to disease or injury to the eye.
- Iris coloboma – A gap or hole forms in the iris during fetal development.
Central heterochromia does not affect vision or eye health. No treatment or intervention is necessary.
Is central heterochromia present at birth?
Central heterochromia is generally present from birth and is caused by genetic factors that affect melanin pigment production and distribution in the developing iris.
However, there are some cases where central heterochromia develops later in life. The melanin concentration in the eyes can shift over time due to factors like:
- Aging
- Disease
- Inflammation
- Injury
Iris pigmentation is not always static and can gradually change over the years. So while central heterochromia is usually present early on, it is possible for it to develop and become more distinct later in life.
Do the eyes of a baby change color from amber to green over time?
It is common for many babies to be born with darker gray/blue eyes that lighten during the first year of life. However, if central heterochromia is present at birth, the pattern is likely to remain as the eye color changes:
- Grayish blue eyes –> light blue with amber central ring
- Dark gray eyes –> green with golden ring
The outer iris may get progressively greener or bluer, but the central heterochromia remains consistent. The melanin concentration that causes the central ring effect is typically stable from infancy onward.
Can lasik or surgery change central heterochromia patterns?
Central heterochromia is often considered a desirable, cosmetic feature. There are no medical procedures to purposefully create or enhance central heterochromia if it is not already present:
- Lasik surgery only corrects refractive vision errors and does not alter iris pigmentation.
- Artificial iris implants for those with iris coloboma do not reproduce heterochromia.
- Tattooing to change overall eye color does not create central rings.
In very rare cases, laser surgery to correct glaucoma has been linked to inducing central heterochromia. But in general, the central heterochromia pattern remains unchanged before and after eye surgery or procedures.
How does hazel eye color differ from amber centers?
Hazel eyes appear light golden brown, amber, or greenish-brown. This happens when there is a very balanced mixture of melanin pigments in the iris. The melanin concentration is relatively uniform across the iris, so no distinct central ring pattern emerges.
Central heterochromia is different than hazel eyes in that there is a clear demarcation between the color of the outer and central iris. The distribution of melanin varies significantly within the iris, creating that ring effect.
While hazel eyes may contain amber coloring, there is no demarcation between the central and peripheral iris like in central heterochromia. The blending of melanin creates a more unified hazel effect.
Conclusion
Green eyes with amber or gold centers are an exceptionally rare variant of central heterochromia. The concentration and distribution of melanin pigments within the iris produce this stunning two-toned appearance. The exact genetics and origins behind central heterochromia are still being researched. But the amber ring remains consistent and stable over a person’s lifetime, creating a cosmetic anomaly that makes these multi-colored eyes captivating and unique.