Green and gold eye colors are quite rare and striking. While most people have brown, blue, or hazel eyes, green and gold eye colors stand out due to their vibrancy and uniqueness. The specific names used to describe these eye colors provide more detail about their appearance and help identify the causes behind them.
Central Heterochromia
One of the most common ways green and gold eye colors present themselves is through a condition called central heterochromia. This refers to when a person has two distinct colors within the same iris.
For example, someone with central heterochromia may have an inner ring of gold or amber around the pupil, surrounded by a larger outer ring of green. The two eye colors are very clearly defined and do not blend together.
This occurs when there is uneven distribution and concentration of melanin in the iris. Melanin is the pigment that gives eyes their color. Higher amounts of melanin lead to darker eyes, while lower amounts result in lighter eyes.
In central heterochromia, one part of the iris contains more melanin than the other part, leading to two distinct color zones. The difference in melanin content between the inner and outer iris causes one ring to appear lighter (gold) while the other appears darker (green).
Hazel Eyes
Hazel eyes are also commonly perceived as having a mix of green and gold. However, unlike central heterochromia, true hazel eyes have a blended, homogeneous appearance rather than defined rings of color.
Hazel eyes get their multi-colored look from a combination of melanin concentrations and the Rayleigh scattering of light. Areas with higher melanin content absorb more short wavelengths of light and appear darker. Areas with less melanin allow more light to scatter and reflect back, creating lighter, golden-brownish hues.
The net effect is an eye that can shift in appearance from brown to green to light amber depending on lighting conditions. But the colors mix together seamlessly rather than forming distinct bands like in central heterochromia.
Green Eyes
Solid green eyes with little to no gold, brown, or amber hues are very rare. Only about 2% of the world’s population has green eyes.
Emerald green eyes are prized for their dazzling color. This eye color is the result of extremely low levels of melanin in the iris, which allows light to scatter and reflect back more strongly to produce a pure green hue.
However, most eyes that appear green are actually greenish-hazel rather than a solid, vivid green. This means they have some concentration of melanin that dulls the green and adds underlying brown/gold tones.
Amber and Gold Eyes
Amber and gold eye colors also contain very little melanin. This allows more light to pass through and refract light back, producing golden and light brown hues.
Pure amber or gold eyes are very rare. Most that appear amber or gold also have darker flecks and gradients that create a hazel or light brown effect. The term “gold eyes” is also sometimes used to describe eyes with central heterochromia featuring a prominent golden ring around the pupil.
Rayleigh Scattering
Rayleigh scattering describes the way light interacts with particles and wavelengths. It helps explain how variations in melanin levels can produce different eye colors.
Light enters the iris and encounters melanin particles. Melanin absorbs higher energy short wavelengths of light. Lower energy long wavelengths pass through and reflect back out of the iris more easily.
The type of melanin also impacts the wavelengths absorbed. Eumelanin absorbs bluer wavelengths, while pheomelanin absorbs greener wavelengths.
The combination of melanin levels and type determines how much light is reflected back and what part of the spectrum that light is in. This creates the range and blending of colors we see in green, hazel, amber, and gold eyes.
Genetics and Ethnicity
Genetics play a major role in determining melanin levels and distribution in the eyes. Certain genetic factors can concentrate melanin in the anterior iris leading to central heterochromia. Others control how much melanin is produced overall.
Ethnicity is also a factor as certain populations tend to carry genes coding for less melanin production. Light eye colors including green and amber are most common in Northern and Eastern Europeans. Populations from Asia and Africa have higher instances of brown eyes.
That said, green and hazel eye colors can potentially occur in any individual regardless of race if the right genetic factors are present to limit melanin production in the iris.
Medical Considerations
While eye color variations like central heterochromia are usually harmless, some medical conditions can also produce similar effects. These include:
- Fuch’s heterochromic iridocyclitis – inflammation in one eye that can cause it to lose pigment
- Horner’s syndrome – disruption of nerves that control pupil size and pigment release
- Pigmentary glaucoma – buildup of pigment granules in the eye
Consult an ophthalmologist if you notice sudden changes in eye color that do not match your other eye. This can help rule out the possibility of an underlying medical issue.
Conclusion
In summary, green and gold eye colors can occur in several forms:
| Type | Description |
|---|---|
| Central heterochromia | Distinct inner ring around the pupil a different color from the outer iris |
| Hazel eyes | Green and gold tones blended together seamlessly |
| Green eyes | Pure green hue with little melanin and no brown/gold |
| Amber/gold eyes | Golden or light brown eyes with little melanin |
The combinations of melanin content and Rayleigh scattering determines how light is absorbed and reflected to produce these stunning eye colors.
While mostly genetic, some medical conditions can also impact eye color. Overall, green and gold eyes are beautiful and unique manifestations of the intricate biology that makes our eyes windows into the soul.