Having orange eyes is extremely rare but can occur in some cases. The color of our eyes is determined by the amount and quality of melanin pigments in the iris. More melanin leads to darker eyes, while less melanin results in lighter eyes. For eyes to appear orange, they need to have very low levels of melanin. Let’s explore how eye color works and if truly orange eyes are possible in humans.
How Eye Color Is Determined
There are two main factors that determine eye color:
- The amount of melanin pigment in the iris
- The way light scatters through the melanin
Melanin is the pigment that gives color to our hair, skin, and eyes. It comes in two forms:
- Eumelanin – A brown/black melanin that creates brown, black, or green eyes.
- Pheomelanin – A red/yellow melanin that makes hazel and amber eyes.
People with high levels of eumelanin tend to have very dark brown or black eyes. Those with low concentrations of melanin have blue or gray eyes. Most people are somewhere in between, with intermediate levels leading to green, hazel, or brown eyes.
The second factor is how light scatters through the iris. The stroma is the top translucent layer of the iris containing collagen fibers. Having less melanin and a thicker stroma layer results in more light scattering and lighter eye colors. Minimal light scattering creates darker eyes.
Genetics Behind Eye Color
Our eye color is inherited through genetics, mainly determined by two genes:
- HERC2 – Activates expression of the OCA2 gene.
- OCA2 – Responsible for melanin production.
The HERC2 gene turns on OCA2, which controls melanin levels. Specific variations in these genes are linked to different pigmentation levels and eye colors:
| Gene Variants | Eye Color |
|---|---|
| HERC2/OCA2 (high melanin) | Brown/Black |
| HERC2 (intermediate melanin) | Green/Hazel |
| HERC2 (low melanin) | Blue/Gray |
Other genes can also influence eye color, such as SLC24A4, TYR, TYRP1, and SLC45A2. But HERC2 and OCA2 are the main determinants.
Can Eyes Be Orange?
For eyes to appear orange, the iris needs to have extremely low levels of melanin. This reduces light absorption and makes the eyes look red/orange due to blood vessels and pigments showing through.
True orange eyes do not exist in humans. But some rare eye colors can appear reddish/orangeish:
- Red eyes – Albinism lacks melanin and makes eyes look red.
- Amber eyes – A solid golden/yellowish color.
- Yellow eyes – A light yellow/golden hue.
These eye colors only occur in a very small percentage of people. But certain conditions can make normal eyes look orangeish temporarily:
- Lighting – Strong lighting or sunlight reflecting in the eyes.
- Redness – Eye infections, inflammation, or conditions like albinism.
- Jaundice – Buildup of bilirubin in the body.
- Medications – Certain drugs and supplements.
While not fully orange, amber and yellow eyes are the closest thing found naturally in humans. Let’s look closer at these unusual eye colors.
Amber Eyes
Amber eyes have a solid orange, golden, or coppery color without flecks of other colors. This occurs from having low melanin levels combined with the yellowish pheomelanin pigment.
Only about 1% of the population has true amber eyes. They are most common in parts of Asia and South America among people with mixed Caucasian and Asian heritage. Amber eyes may reflect red in bright lighting.
Yellow Eyes
Yellow eyes are lighter than amber and have a bright golden or lemon hue. They are even rarer than amber eyes. True yellow eyes without specs of brown, green, or orange are almost non-existent.
In most cases, yellow eyes are not completely yellow. They tend to have bits of green and orange. The yellow color comes from having very low melanin levels and more pheomelanin pigment.
Certain health conditions like jaundice may temporarily make the eyes yellow. But permanent yellow eyes are extremely rare except in albinos.
Red Eyes
Having completely red eyes is often seen in albinism. Albinism is caused by inherited genes that limit melanin production. This results in very low pigmentation and makes the eyes look red because the blood vessels show through.
True red eyes are rare even among albinos. But eyes may look reddish or violet due to translucent irises and light refraction. Certain eye conditions like eye albinism primarily impact the iris and can make eyes look red.
Orange Eyes in Animals
Truly orange eyes are thought to only occur in some animals. Here are a few examples:
| Animal | Orange Eye Causes |
|---|---|
| Red squirrels | Lack of melanin |
| Albino rabbits | Albinism |
| Siamese cats | Albinism genes |
| Rats and mice | Red-eyed dilution gene |
The orange color comes from reduced melanin along with tyrosine and 3,4-dihydroxyphenylalanine (DOPA) pigments. But orange eyes in animals are still quite rare.
Conclusion
Truly bright orange eyes do not naturally occur in humans. But amber and yellow eyes with golden hues are possible. These develop from extremely low melanin levels combined with pheomelanin pigmentation.
Amber eyes are rare and found in about 1% of people worldwide. Pure yellow eyes without flecks of brown or green are even less common. While not fully orange, amber and yellow are likely the closest thing to orange eyes among humans.
Certain conditions like albinism and jaundice can temporarily make eyes orangeish. But permanent orange eyes remain elusive except in some animal species. So while orange eyes do not exist, golden amber and yellow hues are an intriguing and beautiful rarity.
