Blue eyes may sometimes appear to look grey or change between blue and grey. This is caused by a number of different factors relating to the amount of melanin pigment in the iris, the Tyndall effect, and the influence of surrounding colors. While true grey eyes are very rare, many blue-eyed people notice their eye color looking lighter or darker at times.
What determines eye color?
Human eye color is primarily determined by the amount and type of melanin pigment in the iris. There are two main types of melanin:
- Eumelanin: A brown/black pigment that produces brown or black eyes
- Pheomelanin: A red/yellow pigment that produces green, hazel, amber, and some blue eyes
The amount of melanin present is controlled by over 16 different genes. Blue eyes contain low levels of melanin and have less pigment than darker eyes. Having less melanin results in less color absorption and reflection, making blue eyes appear lighter.
How does light change the appearance of blue eyes?
The amount of light exposure impacts how dark or light blue eyes look. This effect is called the Tyndall effect. Longer wavelengths of light are absorbed by melanin, while shorter blue and violet wavelengths are reflected and scattered.
More light exposure causes the eye to reflect even more shorter wavelengths, making blue eyes appear lighter and greyer. Less light causes blue eyes to seem darker.
| Lighting Condition | Impact on Blue Eyes |
|---|---|
| Bright indoor or outdoor light | Eyes appear light blue-grey |
| Dark indoor lighting | Eyes appear darker blue |
Influence of surrounding colors
The colors around a person can also impact how blue eyes are perceived. This effect is caused by simultaneous contrast, where eye color is influenced by complementary colors in the environment.
Warm reddish, orange, or yellow tones make blue eyes look even cooler in comparison.Blue or purple hues can blend with and subdue the blue of the eyes. Green and hazel areas heighten the blue tone.
Grey is the complementary color of blue. When surrounded by grey, blue eyes will stand out more. Against a white background, blue eyes look intensely blue.
True grey eyes
While blue eyes may often look greyish, truly grey eyes are very rare. True grey eyes have an even, muted grey tone across the iris. They contain very low amounts of melanin and lack the vivid blue and green hues seen in most light eyes.
Grey eyes are not a separate eye color, but a variant of blue eyes. They make up around 1% of the population and tend to be found in Northern and Eastern Europe. Distinguishing grey eyes from blue can be somewhat subjective.
Blue-eyed people with temporary grey eyes
Many blue-eyed individuals notice their eyes looking particularly light grey or almost silver at times. This tends to happen more with light blue eyes versus darker blues.
Here are some of the main reasons blue eyes may temporarily appear grey:
- Exposure to bright sunlight washing out the iris color
- Reflection of white or grey surfaces in the eyes
- Bloodshot eyes diminishing the blue tone
- Pale skin and hair coloring reducing eye color contrast
- Albinism removing all iris pigment
- Advanced age reducing iris pigmentation
- Lasik surgery subtly changing the light reflection
- Cataracts forming over the lens
In most cases, the grey appearance resolves when the temporary cause goes away. The natural blue tone returns under normal conditions. However, some causes like aging have a progressive effect on eye color over time.
Can blue eyes turn grey permanently?
For most people, blue eyes turning permanently grey is unlikely. The main exceptions are:
- The development of complete heterochromia, where one iris loses almost all pigment
- Advanced cases of Horner’s syndrome, affecting iris pigmentation
- Late stages of ocular albinism, steadily reducing melanin over time
These rare conditions disrupt the formation and distribution of melanin in the iris, not just its concentration. In severe cases, permanent grey eyes can result.
Aside from those conditions, blue eyes turning completely grey permanently does not commonly occur. Even with aging, some residual hints of blue usually remain. The influence of lighting prevents blue irises from looking truly grey at all times.
Can you be born with grey eyes?
It is possible but extremely rare to be born with true grey eyes. For this to happen, an infant must have:
- Very low levels of iris pigment
- Little to no melanin variation across the iris
- A highly uniform grey/silver tone with no other colors visible
Grey eyes from birth may be a variant of blue eyes or a partial form of ocular albinism. However, most seemingly grey eyes in babies actually develop a bluer tone as melanin concentrations increase during infancy.
True grey eyes at birth are not fully understood. There are no specific genetic markers identified that cause them. Continued research is still needed.
Eye conditions that can cause grey eyes
While many conditions may make blue eyes temporarily appear more grey, some ocular disorders can permanently lead to greyish eye color:
| Condition | Effect on Iris Color |
|---|---|
| Horner’s syndrome | Reduced melanin on affected side |
| Heterochromia | Loss of pigment in one iris |
| Ocular albinism | Progressive loss of melanin |
The melanin loss is localized in heterochromia and can be global in ocular albinism. Horner’s syndrome typically impacts just one eye. In these disorders, blue eyes are the ones most likely to turn light grey.
Ethnicities associated with blue-grey eyes
Blue and grey eye coloration is most frequently seen in people of Northern European descent. Populations with the highest prevalence include:
- Scandinavia
- The Baltic region
- Finland
- Germany
- The Netherlands
- Russia
Lighter eye colors are believed to have evolved as an adaptation to allow better vitamin D absorption in areas with less sunlight. Northern indigenous populations needed lighter eyes to support healthier bone development.
Southern Europeans, like those from Spain, Portugal, and Italy, have very low rates of blue/grey eyes. It is also rarely seen in non-Caucasian ethnicities.
Can you permanently change blue eyes to grey?
There are currently no medically approved, safe methods to turn blue eyes permanently grey. However, there are some risky, controversial procedures that claim to lighten eye color by altering the iris. These include:
- Laser whitening treatment to remove pigment
- Iris implants made of artificial fibers
- Iris color contact lenses worn indefinitely
None of these approaches have enough clinical research to confirm long-term safety and effectiveness. They could potentially lead to:
- Infection
- Inflammation
- Cataracts
- Permanent eye damage or vision loss
Artificially lightening blue eyes is not recommended by any major medical organization. The risks outweigh any perceived cosmetic benefits.
Is there a diet or supplement to make eyes grey?
There are currently no special diets, natural supplements, or lifestyle changes known to turn blue eyes permanently grey. Products claiming to lighten iris color are not supported by rigorous research.
While some alternative medicine practitioners suggest camu camu, spirulina, and vitamin E for reducing melanin, this is not scientifically proven. Their long-term safety for eye color change is unknown.
Cosmetic companies market many topical serums, herbal extracts, and colloidal silver products to alter eye color. However, these lack clinical evidence and may be unsafe with prolonged use.
Conclusion
In summary, blue eyes may often appear greyish temporarily due to lighting conditions and other factors. Permanently changing blue irises to a true grey color is extremely rare without an underlying eye disorder.
While possible from birth in theory, grey eyes are not well understood scientifically. Purposefully making blue eyes grey involves significant risks and lacks medical oversight. For these reasons, blue eyes turning grey permanently should be viewed as highly improbable for most people.
