What Causes Different Eye Colors?

Eye color is a big deal. Along with being an identifiable feature listed on drivers licenses, eye color can be a distinguishing attribute that shows family resemblance or even makes someone appear more attractive.

While eye color is highly variable amongst the population, and the patterns within the eye can be very complex, there is very little that an eye exam could tell you about how your eyes got their color. The answer lies deep in your DNA, and is decided long before you are even born.

The Simple Answer

The region of your eyes that holds color is called the iris. This ring surrounding the pupil contains varying levels of melanin – the pigment responsible for hair and eye color – from person to person.

In simplest terms, eye color is determined entirely by genetics. There are no external factors such as geography or sun exposure that have any meaningful impact on expressed eye color. While certain regions of the world have similar eye colors, this reality is due more to genetic clustering of like individuals rather than the region having an impact on the eyes. The color of one’s eyes are directly related to the amount of melanin their body produces, which is determined by genetics.

The More Complex Answer

To dig into the nitty gritties, a wide variety of genes have an effect on eye color. While it was once thought that a single gene determined eye color, with brown dominating blue, further research has concluded over time that 11 or more genes have some impact on the expression of this trait. While current models that take these genetic components into account can predict eye color of offspring relatively consistently, there is still room for error.

Furthermore, genetic mutations (unforeseen changes in the genetic code) can create even more possibilities. For example, it is widely agreed that 10,000 years ago, all humans had brown eyes. Blue eyes emerged as a result of a genetic mutation that caused an individual to produce less melanin than normal, and thus the recessive blue-eyed gene was born.

Fast forward to today, and the population is much more varied. In the United States, just under 50% of people have brown eyes. 25% have blue, 18% have hazel, and less than 9% have green. Across the world, there are also extremely rare colors such as amber, gray, and violet!

In reality, the variance in these colors is simply due to the level of melanin in an individual’s system and the unique shape and configuration of their irises. As the light reflects across the fibers of the eye, we see a wide scale of colors, with each being uniquely beautiful.

Protect Your Eyes with Complete Eye Care of Medina

Curious about your eyes? The local vision care specialists at Complete Eye Care of Medina have the technology and diagnostic experience to help correct any vision issues and clarify any questions you may have. We take a consultative, one-on-one approach to family eye care, working alongside you to manage your vision eye health needs. Whether you need a standard eye exam, new contact lenses, or corrective surgery, we will keep you and your family informed and protected so you can pursue the right treatments. Contact us to schedule an appointment.