Why Do We Have Different Eye Colours

Have you ever looked into the eyes of your friends, family members, or even strangers and wondered what makes their eye colours so diverse? Some people may have piercing blue eyes, others commanding brown, or even captivating green. What is the science behind this phenomenon? Let’s explore the various factors contributing to the unique colours of our eyes.

 

Which Factors Affect Your Eye Colours?

 

The key component determining eye colour is melanin, a pigment responsible for the colour of our skin, hair, and eyes. Produced by special cells called melanocytes, the amount and distribution of melanin in your iris – the coloured part of your eye – is responsible for determining your eye colour.

Genetics plays a significant role in determining how much melanin is produced and distributed in your iris. It is widely believed that eye colour inheritance follows a simple pattern; however, it's a complex process involving multiple genes. Researchers have identified at least two primary genes on chromosomes 15 and 19 that influence the melanin levels within your iris.

One might assume that siblings would share the same eye colour due to genetics, but unfortunately, it's not that straightforward. The genes related to eye colour can combine in various ways, leading to greater variations in families. This genetic lottery means that even two brown-eyed parents could have a blue-eyed child.

It's also important to note that a new-born’s eye colour can change during their first few years of life. This is because melanocytes become more active as children grow older, resulting in an increase in melanin production. A baby born with blue eyes may develop brown eyes as they grow up because of this surge in melanin.

There are external factors such as sun exposure and certain medical conditions that may alter an individual’s natural eye colour over time too. Increased sun exposure can stimulate melanocytes to produce more melanin and cause subtle changes in eye colour. Medical conditions, such as Horner's syndrome and pigmentary glaucoma, can also lead to changes in eye colour.

 

How Do Children Get Different Eye Colours from Their Parents?

 

Eye colour is one of the most fascinating aspects of genetics, with each person possessing a unique combination of colours. Many people wonder how children can inherit different eye colours from their parents and what factors determine the appearance of these shades.

The Role of Genetics in Eye Colour:

Eye colour is determined by the combination of multiple genes, with the most significant being the OCA2 and HERC2 genes on chromosome 15. These genes affect the production of melanin, which is responsible for pigmentation in various parts of our body, including our eyes. The more melanin present in the iris, the darker the eye colour.

There are three primary pigment colours found in human eye melanin: brown, blue, and green. While there are other factors influencing eye colour, most variations result from the amount and type of these pigments.

How Do Children Inherit Eye Colour from Their Parents?

Each person has two copies of each gene associated with eye colour – one inherited from each parent. The expression of these genes interacts to determine a person's eventual eye colour but isn't as straightforward as once thought.

Previously, it was believed that eye colour followed a simple dominant-recessive pattern where brown eyes were dominant over blue. More recent discoveries have shown that multiple genes play a part in determining eye colour inheritance. This complex interaction between several genes often results in unexpected eye colours that might not precisely match either parent.

For example, suppose one parent has brown eyes and another has blue eyes. In that case, it's possible for their child to have brown or blue eyes, depending on which gene alleles are inherited and expressed more prominently.

Different Eye Colours:

In addition to the three base colours mentioned earlier – brown, blue, and green – variations and combinations can occur. Hazel eyes, for instance, create a unique blend of pigments and can manifest as a mixture of green, blue, or brown hues.

Similarly, amber eyes contain a higher concentration of the lip chrome pigment, giving an eye colour that ranges from golden-yellow to brownish-honey. There are even cases where a person may have heterochromia, resulting in two different eye colours within one individual.

 

Why The Babies Start With The Blue Eyes? 

 

Many parents are astonished to see their new-borns with bright blue eyes, even when neither one of them has the same eye colour. Within the first few weeks or months, the eyes of a baby undergo a metamorphosis to their true tone. But why do babies start with blue eyes, and is there any impact of eye colours on eyesight?

The reason behind new-borns beginning with blue eyes lies in the melanin pigment. At birth, the baby's irises contain minimal melanin, and the blue colour comes from the scattering of light through various layers of the iris. As they grow older, they get exposed to natural light, which triggers melanin production and deepens their eye colour.

 

Do Eye Colours Affect Eyesight?

 

Now, let's dive into another intriguing question: do different eye colours affect our vision? The truth is that though there seems to be a correlation between the two, it is not definitive. Darker-eyed individuals tend to have slightly better visual acuity due to increased pigment concentration in their irises. This extra pigment blocks more light and provides them somewhat better protection against harmful rays.

Conversely, lighter-eyed individuals may be more sensitive to bright lights and glare due to lesser pigmentation. However, this does not imply that people with blue eyes have poor vision by default. Our vision comprises numerous factors such as eye health, genetics, and lifestyle habits.

Technology has stepped in to aid these varying needs with advancements such as Smart Audio Glasses and ROKiT Smart Glasses. These innovative eyewear solutions can accommodate different eye colours and provide personalized experiences catering to individual visual requirements.

Polarized Sunglasses hold vital importance for individuals wanting clearer vision during daytime activities regardless of their eye colours. They reduce glare and enhance clarity making it easier for people with lighter-coloured eyes to handle bright surroundings.

In conclusion, while babies typically start with blue eyes due to lower melanin concentration at birth, their true eye colour will usually emerge within the first year of life. Although there is a small correlation between eye colour and visual acuity, it does not significantly impact overall eyesight. Technological advancements such as Smart Audio Glasses and Polarized Sunglasses ensure that everyone can enjoy optimal vision regardless of their eye colour.