Hazel eye colour: What causes hazel eyes?
Hazel eyes are a bit of a mystery.
For starters, people describe this beautiful eye colour in many different ways. Some say it looks like hazelnut, while others call it golden or brownish green.
One of the reasons it's so hard to describe hazel-coloured eyes is that the hue itself seems to change, depending on what you wear and the type of lighting you are in.
Also, although hazel eyes appear to contain hues of green, amber and even blue, these colour pigments don't exist in the human eye.
So where does this stunning colour come from?
What determines eye colour?
Most of us were taught in high school science class that we inherit our eye colour from our parents, and that brown eye colour is dominant and blue is recessive. So two parents with blue eyes cannot have a child with brown eyes because neither parent carries the dominant form of the gene for brown eyes.
But it turns out the story is more complicated than that.
Recent research has shown that up to 16 genes (not just one or two) may influence eye colour, which makes predicting eye colour much more difficult.
Due to variations in the interaction and expression of multiple genes, it's hard to say for sure what colour a child's eyes will be based on the colour of his or her parents' eyes. For example, we now know it's possible for two blue-eyed parents to have a child with brown eyes — something the old model of eye colour inheritance would have deemed impossible.
Also, eye colour can change dramatically in the first few years of life. Many white, non-Hispanic babies are born with blue eyes and then develop brown, green or hazel eyes in childhood. This phenomenon has little to do with genetics, but it does help explain where hazel eyes come from.
What causes hazel eyes?
The pigmented structure inside the eye that surrounds the pupil and gives eyes their colour is called the iris. The pigment responsible for eye colour is called melanin, which also affects skin colour.
The reason many white, non-Hispanic babies are born with blue eyes is that they don't have the full amount of melanin present in their irises at birth. In the first few years of life, more melanin may accumulate in the iris, causing blue eyes to turn green, hazel or brown.
Babies whose eyes turn from blue to brown develop significant amounts of melanin. Those who end up with green eyes or hazel eyes develop a little less.
Babies of African American, Hispanic and Asian ethnicities usually are born with dark eyes that stay brown throughout life. This is because these individuals naturally have more melanin in their eyes and skin, compared with non-Hispanic whites.
Light absorption and scattering
There are no blue, green or hazel pigments in the eye. Eyes merely have different amounts of melanin, which is a dark brown pigment.
So how can a dark brown pigment create blue, green or hazel eyes? This is possible because of two processes:
Melanin in the iris absorbs different wavelengths of light entering the eye.
Light is scattered and reflected by the iris, and some wavelengths (colours) scatter more easily than others.
Eyes with high concentrations of melanin absorb more light entering the eye, so less is scattered and reflected back from the iris. The result is a brown eye colour.
In eyes with lower concentrations of melanin, less light is absorbed, and more is scattered and reflected by the iris. Since light rays with shorter wavelengths (blue and green light) scatter more easily than light rays with longer wavelengths (red light), eyes with less light-absorbing melanin appear green or hazel, and eyes with low concentrations of melanin appear blue.
Also, the distribution of melanin can vary in different parts of the iris, causing hazel eyes to appear light brown near the pupil and more green in the periphery of the iris.
Hazel eyes are a work of art
Hazel eye colour is both complex and magnificent, since its specific features are determined by many factors — including the amount and distribution of melanin in the iris, how scattering of light by the iris and pigment molecules affects colour, and how perception of eye colour is influenced by lighting and the colour of our clothing and surroundings.
Just as it takes many strokes of the artist's brush to produce a masterpiece, hazel eyes involve the dynamics of several elements to create the unique work of art that's represented in every hazel eye.
If you wear glasses, choose lenses with anti-reflective coating to eliminate distracting reflections in your glasses and allow others to see the beauty of your hazel eye colour.
Change your eye colour to hazel
If your eyes aren't naturally hazel, but you've always wanted them to be, you can achieve your wish with colour contact lenses. They won't actually change your eye colour, of course, just the appearance of it.
Colour contact lenses are available in many colours, so you'll have a choice of several shades of hazel. But it's not simply a matter of choosing a lens colour you like; the natural colour of your eyes has a role in determining which lenses will look best.
If you have very light eyes, colour contacts with an "enhancement tint" might be a good choice. These lenses have a translucent colour that lets some of your natural colour show through — to make your light blue eyes a deeper blue, for example. If your eyes are light enough, you might achieve the hazel eye colour you want with an enhancement tint.
More likely, you'll need lenses with an opaque tint to achieve a hazel eye colour. These lenses are designed to mask your natural eye colour with the colour you desire. These lenses work well if you have dark brown eyes and want to give them a lighter appearance, including hazel.
An optician can show you various colours and help you make the right choice.
Remember, contact lenses are a prescription item, and if you don't already wear contacts, you'll need an eye exam and a prescription before getting them — even if you have perfect vision without corrective lenses.
SHOPPING FOR COLOUR CONTACT LENSES? Find an eyewear store near you.
FUN FACTS: Which celebrities have hazel eyes?
Here's a short list of some well-known models and entertainers with hazel eyes:
Kelly Clarkson, Brooke Shields, Kristen Stewart, Ben Affleck, Jenny Mollen, Olivia Munn, Jason Statham, Tyra Banks, Jeremy Renner, Dianna Agron, Steve Carell, David Beckham, Heidi Klum, Jada Pinkett-Smith, Jessica Biel, Jason Bateman, Demi Moore, Rebel Wilson and Angelina Jolie.
Did having hazel-coloured eyes contribute to these celebrities' fame? We're not sure, but you could say that Kelly Clarkson's song "Behind These Hazel Eyes," from her Breakaway album, certainly did.
Page published on Monday, 27 July, 2020