What Causes Eyes To Appear Blue Or Brown?
- Pieter Maas
How Do Brown Eyes Get Their Color? – There are dozens of genes for eye color that contribute to how people get brown eyes. The amount of melanin, a pigment, in the iris determines eye color. If you have a larger amount of melanin, your eyes appear brown.
What causes eyes to be brown or blue?
Is eye color determined by genetics? A person’s eye color results from pigmentation of a structure called the iris, which surrounds the small black hole in the center of the eye (the pupil) and helps control how much light can enter the eye. The color of the iris ranges on a continuum from very light blue to dark brown.
- Most of the time eye color is categorized as blue, green/hazel, or brown.
- Brown is the most frequent eye color worldwide.
- Eye color is determined by variations in a person’s genes.
- Most of the genes associated with eye color are involved in the production, transport, or storage of a pigment called melanin.
Eye color is directly related to the amount of melanin in the front layers of the iris. People with brown eyes have a large amount of melanin in the iris, while people with blue eyes have much less of this pigment. A particular region on plays a major role in eye color.
Within this region, there are two genes located very close together: and HERC2, The protein produced from the OCA2 gene, known as the P protein, is involved in the maturation of melanosomes, which are cellular structures that produce and store melanin. The P protein therefore plays a crucial role in the amount and quality of melanin that is present in the iris.
Several common variations (polymorphisms) in the OCA2 gene reduce the amount of functional P protein that is produced. Less P protein means that less melanin is present in the iris, leading to blue eyes instead of brown in people with a polymorphism in this gene.
- A region of the nearby HERC2 gene known as intron 86 contains a segment of DNA that controls the activity (expression) of the OCA2 gene, turning it on or off as needed.
- At least one polymorphism in this area of the HERC2 gene has been shown to reduce the expression of OCA2 and decrease P protein production, leading to less melanin in the iris and lighter-colored eyes.
Several other genes play smaller roles in determining eye color. Some of these genes are also involved in skin and hair coloring. Genes with reported roles in eye color include ASIP, IRF4, SLC24A4, SLC24A5,, TPCN2,, and, The effects of these genes likely combine with those of OCA2 and HERC2 to produce a continuum of eye colors in different people.
Researchers used to think that eye color was determined by a single gene and followed a simple inheritance pattern in which brown eyes were dominant to blue eyes. Under this model, it was believed that parents who both had blue eyes could not have a child with brown eyes. However, later studies showed that this model was too simplistic.
Do Brown Eyes See Better?
Although it is uncommon, parents with blue eyes can have children with brown eyes. The inheritance of eye color is more complex than originally suspected because multiple genes are involved. While a child’s eye color can often be predicted by the eye colors of his or her parents and other relatives, genetic variations sometimes produce unexpected results.
- Several disorders that affect eye color have been described.
- Is characterized by severely reduced pigmentation of the iris, which causes very light-colored eyes and significant problems with vision.
- Another condition called affects the pigmentation of the skin and hair in addition to the eyes.
- Affected individuals tend to have very light-colored irises, fair skin, and white or light-colored hair.
Both ocular albinism and oculocutaneous albinism result from mutations in genes involved in the production and storage of melanin. Another condition called heterochromia is characterized by different-colored eyes in the same individual. Heterochromia can be caused by genetic changes or by a problem during eye development, or it can be acquired as a result of a disease or injury to the eye. Sturm RA, Duffy DL, Zhao ZZ, Leite FP, Stark MS, Hayward NK, Martin NG, Montgomery GW. A single SNP in an evolutionary conserved region within intron 86 of the HERC2 gene determines human blue-brown eye color. Am J Hum Genet.2008 Feb;82(2):424-31. doi: 10.1016/j.ajhg.2007.11.005.
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- Genetics of human iris colour and patterns.
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J Hum Genet.2011 Jan;56(1):5-7. doi: 10.1038/jhg.2010.126. Epub 2010 Oct 14. Review. PubMed: : Is eye color determined by genetics?
What causes some people’s eyes to appear blue?
The front layer of the iris (called the stroma ) can make eyes appear brown, blue or green –
For people with brown eyes, some of the cells also have brown pigment in them,
People with blue eyes have no pigment at all in this front layer, causing the fibers to scatter and absorb some of the longer wavelengths of light that come in. More blue light gets back out and the eyes appear to be blue. For people with green or hazel eyes, one or both of the layers of the iris contains light brown pigment. The light brown pigment interacts with the blue light and the eye can look green or speckled. Many people have variations in the color of their irises, often with one color near the pupil and another at the edge. This variation happens when different parts of the iris have different amounts of pigment in them.
What causes eyes to become brown?
Stay up-to-date with the latest from 20/20 Onsite – It’s not an uncommon thing to have wondered before if your eyes are capable of changing color. At some point or another, we’ve all wanted to have different eyes just to see what they’d look like. And as crazy as it may sound, eyes can absolutely change color! How does this happen? Let’s start with the basics. First of all, the iris is a muscle in the eye that gives it its color. With light, the iris can either expand or contract in order to control pupil size. The pupil shrinks when exposed to bright light, whereas it grows in dimmer lighting. When the pupil changes size, the pigments in the iris either compress or spread apart, which causes a slight change in perceived eye color,
- Age Babies are usually born with light blue or gray eyes, yet as they grow, their eyes often get darker. This is because eye color is determined by your genes and the melanin level on your body. As you grow up, the melanin level increases around your pupil, making the eye darker. However, 10-15% of Caucasian eyes change to a lighter color as they age, as pigment in the iris changes or degrades,
- Exposure to the sun Melanin production can be activated through solar exposure, meaning that a prolonged time exposure to the sun could make your eyes darker.
- Emotions Certain emotions can change the size of your pupil and the iris color. When you are happy, angry, or sad, your body releases a hormone that makes your pupil size change, When you’re happy or angry, your eyes usually become more vibrant, while when you cry, your eyes obtain a reddish color, making your eyes appear brighter.
- Clothing and makeup Darker clothes as well as some color makeup on your eyelids, or white eyeliner, are all things that can make your eyes look more vibrant and brighter, This is just a matter of perception, not reality, but your eyes will definitely pop a bit more than usual!
- Your diet They say you are what you eat, and for the eyes this is entirely true! The type of diet you keep will influence your eye color. Here are some of the foods that change your eye color if consumed often : Spinach: It’s richness in iron will make your eyes look younger and shine brighter! Organic honey: Regular consumption of honey could make your eye hue lighter and brighter. Fish: Consuming fish can increase your eye color strength and depending on the consumption, this changes could be permanent. Olive oil: Many people believe that adding olive oil to your diet could change the shade of your eyes. Onions: Regular intake of onion has shown gradual changes in eye and skin color. Nuts: Add different nuts to your diet and your eyes could gradually get a lighter color. * Note : Roasted nuts won’t affect your eyes since their nutrients (what might change your eye color) have already been destroyed by exposing them to high temperatures. Chamomile & Uva Ursi tea: eyes relax and pupil size changes, making the eye appear a different color (usually a warmer shade),
- Your health Your eye color can also change to a yellowish or greenish shade when you are unwell or if you have an eye disease such as : Horner’s Syndrome: A complication with the third cranial nerve. This disease could make the affected eye(s) change to a lighter color. Fuch’s Heterochromic Uveitis: A chronic mild inflammation of the front section of the eye. Pigmentary Glaucoma: In this type of glaucoma, the pigment on the back of the iris is disrupted and the loose pigment granules collect on the back of the cornea. This loose pigment could also collect on the front of the iris, changing the color. Medication for glaucoma c ould also affect the color of the eyes.
There are many reasons why your eyes may at least appear to change color. In certain cases, like eye disease and changes in your diet, your eye color may truly change. However, many times it is only a matter of perspective and elements that can reflect into your eyes, tricking the mind of those looking at you into thinking your eyes just changed into a different shade.
Are brown eyes actually blue?
Story highlights – Blue eyes have long been associated with movie star good looks, but why they make hearts throb is open to conjecture An estimated 17% of the world’s population has blue eyes. The color is an illusion created by light refracting in clear eyes Stroma Medical has developed a laser system that agitates the pigmentation in irises to reveal the clear blue eyes underneath While the company says tests have shown the treatment to be safe, critics say that there may be a risk of developing glaucoma CNN — From the piercing blue eyes of Paul Newman to the steely gaze of Daniel Craig, blue eyes have always been a measure of attractiveness.
But exactly why they make hearts throb and catapult actors and models to stardom is a point of conjecture. Theories range from evolutionary psychologists who say that blue-eyed women in Palaeolithic societies had a better chance of standing out in the crowd, others posit that pupil dilation – a signifier of attraction – is easier to see in lighter eyes.
Either way, just 17% of the world’s population has blue eyes. For the majority of the world’s population – an estimated 80% – those elusive movie star eyes can usually only be obtained with the aid of colored contact lenses. But today there’s a medical procedure that can permanently turn your brown eyes blue.
- Pioneered by Stroma Medical, the laser procedure works by eliminating the brown melanin that’s present in the anterior layers of the iris.
- The fundamental principle is that under every brown eye is a blue eye,” Dr Gregg Homer told CNN, adding that there is no actual blue pigmentation in the eye.
- The only difference between a brown eye and a blue eye is this very thin layer of pigment on the surface.
“If you take that pigment away, then the light can enter the stroma – the little fibers that look like bicycle spokes in a light eye – and when the light scatters it only reflects back the shortest wavelengths and that’s the blue end of the spectrum.” He said the effect is similar to the Rayleigh scattering of sunlight in the sky – the physics that makes our sky appear blue.
- The company says it has developed a laser treatment that disrupts the layer of pigment, causing the body to begin removing the tissue naturally.
- While the procedure takes all of 20 seconds, the blue eyes lurking underneath do not emerge for several weeks.
- He said that Stroma Medical wanted to develop a procedure that was safer, cheaper and more convenient than any of the alternatives on the market.
While it has yet to get the green light from regulatory bodies in the United States, the company’s medical board has said that preliminary studies show the surgery is safe. So far, just 17 patients in Mexico and 20 in Costa Rica have undergone the treatment.
- It’s difficult to work out a way to injure someone with this laser because the energy is so low,” he said.
- The laser treats only the iris and does not enter the pupil or treat any portion of the inside of the eye where the nerves affecting the vision are located.
- The company is still in the fundraising stage but hopes to have completed clinical trials within several years.
And the cost of turning your brown eyes blue? Dr Homer says Stroma Medical would charge around $5,000 (£3,120) for the procedure. Industry reaction to the process has been muted. Ophthalmologists who deal with people’s eyes, Homer concedes, have every right to be skeptical for the simple fact they are dealing with one of the most sensitive organs in the human body.
Saj Khan, an ophthalmologist at the London Eye Hospital, told CNN the treatment raised some red flags. ‘The main concern with any procedure that involves releasing pigment inside the eye is that the pigment can clog up the normal drainage channels which can in turn cause the pressure inside the eye to go up,” he said.
“If that happens significantly enough, for long enough, it’s how patients develop glaucoma.” He said that while Stroma Medical claims that the particles released by the process are too fine to cause glaucoma – and that any complications were likely to be short-term and easily remedied – a risk still remains.
- Theory has some sense to it, but without seeing long-term outcomes and without seeing patients that have been treated in this way I wouldn’t commit myself to it,” Khan said.
- In the meantime, Homer says there are no shortage of potential customers wanting to have the irreversible procedure.
- It’s not a goal of our company to promote blue eyes,” he said.
“From my experience what most people are after is the translucence of the blue eye rather than the color of the blue eye. “The people who seem most vigilant about pursuing this always have a story about being young and in the presence of a sibling or a friend who had light eyes and the friend is being told how beautiful their eyes are and it sticks with them.
Why are my eyes getting lighter?
What Causes Eye Color to Change? Changes in eye color can be as captivating as they are concerning. By understanding what can cause eye colors to change, you can determine if what you’re experiencing is typical or if you should see a visionary eye doctor.
- Here is a look at common causes of eye color changes.
- Natural Age-Related Eye Color Changes One of the most common situations that leads to changes in eye color occurs in children.
- When a baby is born, their eyes are usually lighter or bluer.
- Mainly, this is because a newborn hasn’t had sun exposure, so the melanin in their eyes isn’t fully developed.
As they are exposed to light, melanin production increases, causing the color of their eyes to shift. However, eye color changes can also occur as a person ages. Those with lighter color eyes – especially Caucasians – may see their eyes lighten over time.
- The pigment slow degrades over time, resulting in less color.
- Other Situations Leading to Eye Color Changes Sun Exposure Since melanin plays a role in eye color, exposure to the sun can lead to eye color changes.
- Usually, it requires prolonged exposure and results in the irises darkening.
- Medical Treatments Some medications may alter eye color.
One prime example was a name-brand eyelash growth serum that was available by prescription. While the side effect was rare and usually required the drops to be applied to the eye – not the lash line, as it was meant to be used – a chemical in the serum could have the ability to impact eye pigments.
It’s also possible for other medications and surgeries to result in eye color changes. If that’s a potential side effect of a treatment, your eye care specialist will discuss it in advance. Nearby Colors In some cases, it may look like your eye color has changed when, in reality, your eyes are the same color.
Changes to the size of your pupils can cause your eye color to appear slightly different. Partially, this is because your limbal ring (the darker ring on the outside of the iris) is closer to the pupil’s edge. This can make your eye color appear darker because less of the iris is visible.
Additionally, other colors near your eyes may impact how your eye color is perceived. For example, your clothing, makeup, hair, and glasses frame color may all influence the apparent hue of your irises. However, most of that is an illusion. When a different color is near your eye, slight reflections of those shades might make your eye color seem different, even though it isn’t.
In a similar vein, changing the colors that are near your eyes may create more or less contrast than is usually there, making the hue seem stronger or weaker due to an adjustment in the comparison. Similarly, crying, allergies, or other activities that cause the sclera – the white part of the eye – to redden may make the irises seem slightly different.
Again, this is because the area near the iris changed hues, not because the iris itself is a new color. Medical Conditions There are medical conditions that can lead to shifts in eye color. Heterochromia – a condition that causes a person to have two different colored irises or more than one color in a single iris – may result in color changes.
Horner’s syndrome may cause the eyes to lighten. Pigmentary glaucoma and Fuch’s heterochromic uveitis – an inflammatory condition – may also result in changes to the iris. The same goes for eye melanoma, a type of cancer. Consult a Reputable Eye Doctor The eye care specialists in Buffalo, NY at ECVA take the safety and health of our patients’ eyes seriously.
Can trauma cause your eyes to change color?
Health Problems That Can Affect Eye Color – In some cases, health problems can affect or change the color of your eyes. Trauma. An injury or trauma to the eye can result in iris damage. Any tissue loss that occurs can alter the appearance of the eye’s color.
- Neurofibromatosis is a condition that affects the nervous system.
- It can cause small tumors to grow on nerve cells throughout the body and may lead to small nodules on the irises.
- These generally harmless growths are called Lisch nodules.
- While they don’t affect your vision, they can alter the color of your eyes.
Uveitis, Uveitis is a term used to describe a group of inflammatory diseases that cause swelling in the eyes. It can affect your vision and even lead to loss of sight. You may also notice changes in the color of the affected eye. Fuchs’ heterochromic iridocyclitis.
- Also called FHI, this condition is a form of chronic uveitis.
- It can lead to atrophy of the iris, cataracts, and eye inflammation.
- The condition can also cause pigment loss, which can change the color of one eye, leading to heterochromia, or two differently colored eyes.
- Horner’s syndrome.
- Horner’s syndrome is a rare condition that may occur as a result of a stroke or spinal cord injury that damages facial nerves.
Signs include pupil constriction (miosis), eyelid drooping, and a lack of sweating on one side of the face. It may also cause depigmentation in the iris, causing the color of the eye to change. Cataracts. A cataract is the clouding of the eye’s lens, which is behind the pupil.
What do amber eyes look like?
What Color Are Amber Eyes Exactly? – If we’re talking about the color amber in general, it falls somewhere between yellow and orange on the color wheel. It gets its name from the material amber, which is actually fossilized tree resin (remember the mosquitos trapped in amber in Jurassic Park ?).
Amber is valued as a gemstone for its striking color, and it has been used to craft jewelry and all kinds of decorative items for ages. Amber can be found in a wide range of colors, but most commonly, it’s some shade of a yellow-orange-brown mix. Like the gemstone they’re named for, amber eyes can exist in a variety of shades.
You can think of amber eyes as being a light brown color with either a golden or copper tint to them. Amber eyes are sometimes called golden eyes when their shade leans toward the yellow hue.