What Colour Are My Eyes?
When it comes to human diversity, eye colour stands out as one of the most visually captivating traits. From the deep browns of the majority to the rare hues of green and gray, our eyes are windows not only to our souls but also to a fascinating genetic palette. In this blog post, we'll explore the most common eye colours, delve into the percentages of the global population that possess them, and provide insights into the genetics behind these colours.
The Spectrum of Eye Colours
Brown Eyes: The Global Majority
Brown is the most common eye colour worldwide, with estimates suggesting that 70% to 80% of the global population boasts this warm hue. The prevalence of brown eyes varies significantly by region, reaching nearly 100% in Africa and Asia. This dominance is attributed to the high concentration of melanin in the iris, which not only determines the darkness of the brown but also offers protection against harsh sunlight, a trait likely favoured by evolution.
Blue Eyes: The Northern Charm
Approximately 8% to 10% of people have blue eyes, a trait most commonly found in Northern and Eastern European countries. Blue eyes result from a lower concentration of melanin in the iris combined with light scattering effects, which give the iris its blue appearance. Countries like Estonia, Finland, and Iceland boast a significant majority of blue-eyed individuals, often exceeding 80% of their populations. People with blue eyes frequently experience increased light sensitivity outdoors or when working under bright lights.
Green Eyes: The Rare Gem
Green eyes are among the rarest worldwide, with only about 2% of the population sporting this enchanting colour. The green hue is achieved through a similar scattering of light as seen in blue eyes but with a higher amount of yellow-coloured pigment called lipochrome. The highest concentration of green-eyed individuals is found in Northern, Central, and Western European countries.
Hazel Eyes: The Multifaceted Beauty
Hazel eyes, characterized by a combination of green, brown, and gold tones, account for approximately 5% of the global population. This eye colour exhibits a multicoloured appearance that can change under different lighting conditions, making it unique. Hazel eyes are most commonly found in regions that border areas with high concentrations of green—and brown-eyed populations.
Gray Eyes: The Enigmatic Shades
Gray eyes are relatively rare, with around 3% of the world's population possessing this elusive colour. Like blue eyes, gray eyes have a low melanin concentration but with a different composition of collagen in the stroma, leading to light scattering in a way that produces a gray appearance. Gray eyes are most commonly found in Eastern European countries and regions where blue eyes are prevalent.
Amber and Other Colors: The Exotics
Amber eyes, often mistaken for hazel, are a solid golden to coppery shade without green, blue, or gray influences. This eye colour is rare, found in less than 1% of the global population. Other unusual eye colours include red or violet, typically seen in individuals with albinism (as you're seeing a reflection of the retina), and heterochromia, where each eye is a different colour.
The Genetics Behind Eye Color
The genetics of eye colour are complex, involving multiple genes and their interplay. The OCA2 gene on chromosome 15 significantly influences the amount of melanin in the iris, but it's the interaction between this gene and others, such as HERC2, that determines the spectrum of eye colours. Recent studies suggest that up to 16 genes could be involved in determining eye colour, highlighting the intricate genetic dance behind this captivating human trait.
Why Do Some People Have Different Coloured Eyes?
Having different-coloured irises, a condition known as heterochromia, is a rare and fascinating phenomenon. This condition can present in several forms: complete heterochromia, where each iris is an entirely different colour; partial heterochromia, where part of one iris is a different colour from its remainder; and sectoral heterochromia, where one iris contains a segment of a second colour. Heterochromia can be congenital (present from birth) or acquired due to an injury or medical condition.
If you have iris heterochromia, it is important to see your optometrist regularly for eye exams. You may be showing signs of another underlying eye condition, which can increase your risk of developing glaucoma.
Do All Babies Have Blue Eyes?
Not all babies are born with blue eyes, and this is a common misconception. The colour of a baby's eyes at birth is mainly influenced by genetics and the amount of melanin present in the iris.
And yes, two brown eye parents can have a blue-eyed baby. But, it depends heavily on the genetic makeup of the parents.
Factors Influencing Eye Color at Birth:
Genetics: The genetic makeup received from both parents plays a crucial role in determining a baby's eye colour. Genes involved in eye colour can lead to a wide range of shades, from very light to very dark, even at birth.
Melanin Production: Melanin is the pigment responsible for giving colour to the eyes, skin, and hair. The amount and distribution of melanin in the iris will affect the eye colour. Babies with more melanin will have darker eyes and those with less will have lighter eyes.
Ethnic Background: Babies of African, Asian, and Hispanic descent are often born with brown or dark gray eyes due to higher melanin levels in the iris from birth. In contrast, Caucasian babies are more likely to be born with lighter eye colours, including blue, green, or gray, due to lower initial melanin levels.
Development After Birth: For many babies, especially those born with lighter eyes, eye colour can change in the first few years of life as melanin production increases. This can result in the darkening of the eye colour from blue or gray to green, hazel, or brown.
Understanding the Timeline
Birth: Many babies, especially those of Caucasian descent, are born with blue or gray eyes due to a lack of melanin.
3-6 Months: You might start to see changes in your baby's eye colour as melanocytes respond to light and produce more melanin.
6-12 Months: Most babies have developed their true eye colour by this time, although subtle changes can continue for several years.
Can I Get Contact Lenses That Change My Eye Colour?
Yes, you can get contact lenses that change your eye colour. These are known as coloured contact lenses, and they come in a wide variety of shades, ranging from natural colours like blue, green, brown, and gray to more exotic hues and patterns for costume or cosmetic purposes. Coloured contact lenses are available in both prescription and non-prescription forms.
Always purchase coloured contact lenses from a reputable supplier like your optometrist. Never buy cosmetic lenses without a prescription or from a non-reputable vendor, as poorly fitted lenses or those made from inferior materials can seriously harm your eyes. In Canada, coloured or decorative contact lenses are considered a class II medical device and must be approved by Health Canada. As of 2018, the only companies that sell lenses approved by Health Canada are:
Alcon Laboratories
Bausch & Lomb
Ciba Vision
Coopervision
Geo Medical Co.
Johnson & Johnson Vision Care (Acuvue)
Les Lesieur Enterprises Inc.
Neo Vision Co.
Unicon Optical Co.
Can I Change My Eye Colour With Surgery?
Yes, it's possible to undergo eye surgery to change your eye colour, but it's important to approach this cautiously. Eye colour surgeries are still relatively new and come with significant risks. In fact, we do not currently know of any eye surgeons in Edmonton that offer these types of procedures for cosmetic purposes, and we do not recommend them to our patients. The two main types of procedures available, however are:
Iris Implant Surgery
This procedure involves inserting an artificial iris, made of a thin, flexible, biocompatible silicone, into the eye over the natural iris. It was originally developed to treat eye injuries or medical conditions affecting the iris, but it has been used cosmetically to change eye colour. However, this procedure has been associated with a high risk of complications, such as reduced vision, glaucoma, cataracts, injury to the cornea, and even blindness. Due to these risks, many medical professionals advise against iris implant surgery for cosmetic purposes. In some countries, the procedure is not approved or is highly regulated.
Laser Surgery
Another method involves using a low-energy laser to disrupt the thin layer of pigment on the iris's surface, revealing the underlying tissue, which is usually a blue or grey colour. This method is typically used to turn brown eyes blue and is based on the principle that all brown-eyed individuals have a blue iris underneath the brown pigment. The long-term effects and safety of this procedure are still under scrutiny, and it remains controversial within the medical community. There is a risk of glaucoma, inflammation, and other sight-threatening complications.
Seeing Beyond the Surface: Understanding Eye Colour and Vision Health
No matter what your eye colour is, it's crucial not to overlook the importance of maintaining optimal eye health. Regular eye exams with your optometrist are the cornerstone of proactive eye care, offering invaluable insights into vision clarity, ocular health, and potential concerns that may otherwise go unnoticed. At Helio Optometry in Edmonton, our team of optometrists, opticians and optical assistants are committed to preserving and enhancing your vision, ensuring that every aspect of your eye health is meticulously examined and addressed. Don't wait until your vision becomes blurry or uncomfortable—schedule your comprehensive eye exam today and embark on a journey towards clearer, healthier vision. Your eyes deserve the best care, and at Helio Optometry, we're here to provide just that.
Do you have a favourite eye colour? Leave us a comment below.
