There is no more expressive part of our body than our eyes. These complicated windows to our soul come in all shapes, sizes, and colors. They’re cause for fascination when we’re born, with our parents guessing whose eyes we’ll have. Will we have mom’s, dad’s, or catch the random gene bouncing around from our grandparents? From chocolate brown to icy blue and every shade of hazel in between, everyone’s eyes are different, telling their own story. But just how do we get our unique eye color?
The color of our eyes is determined by the pigmentation of our iris. The iris is the circular tissue surrounding the hole in the center of our eyes, called the pupil. Within the iris are muscles that regulate the amount of light entering our eyes, by constricting or dilating the pupil. In short, the iris is the most colorful and noticeable component of our vision and is critical to healthy eyes. The front layer of the iris contains a pigment called melanin. This is the ingredient most important in determining eye color. Storage, production, amount, and quality all play an important role in determining if our eyes are light or dark. Typically, larger amounts of melanin result in brown eyes, where less melanin result in lighter, blue or green eyes. The amount and quality of pigment is determined by the genetics passed onto us by our parents.
Have you ever noticed that all baby’s eyes are blue? This is because melanin production doesn’t begin right at birth. It isn’t until around the age of three that a baby’s true color is apparent. Believe it or not, some people’s eyes actually change color, or appear to anyway. The iris of our eyes has two layers and sometimes pigments find themselves in both. Depending on melanin levels in each layer and the amount of light diffraction at any given moment, some eyes are able to shift in hue. There is also a condition which allows certain individuals to have one eye a different color from the other. This condition, called heterochromia is rare and usually harmless.
To take a trip back to biology class, we can remember that our cells are made up of chromosomes, 46 to be exact. These chromosomes are separated into 23 pairs and contain genes that will later determine most of our physical characteristics. Within these genes are alleles that ultimately decide which of these characteristics will actually appear. When we’re born, we inherit one chromosome from each parent to create a complete original, us!
The two major genes involved with eye color are OCA2 and HERC2, both within chromosome 15. Previously it was thought a simple genetic pattern dealing with dominant and recessive traits was the sole determinant of light or dark eyes. Under this model, it was thought to be rare for blue eyed parents to conceive a brown-eyed child and vice versa. However, today we believe it’s a little more complicated than that. It is believed we have upwards of 15 different genes that play a role in the color of our eyes. Though brown eyes are traditionally more dominant than blue and our parent’s genetics are an effective way to predict eye color, the color of our eyes doesn’t quite work like mixing paint swatches at Home Depot. Because our eyes rely on so many more than two genes to decide color, there is simply a much wider range of possibilities in determining our baby blues or beautiful browns than we previously thought. Scientists continue to research what exactly causes the probabilities of being born with certain eye colors over others.
For a consultation towards clear vision, or to clear up any questions you may have regarding healthy eyes, contact Advanced Eye Medical today. We are standing by to answer any of your concerns, and to help you get your vision back to where you want it. Join our growing family of happy customers who trust us with their eyes.