Do you look in the mirror every morning to see two different colored eyes staring back to you? Do you know someone who does? This exquisite trait, which affects only .67% of America’s population, is called heterochromia iridum and is one of the most complex, unique, intriguing elements of human anatomy.
Let’s take a closer look at this extraordinary effect on the eyes.
Derived from the Greek words heteros meaning ‘different’ and chroma meaning ‘color’, heterochromia iridum is the difference in iris coloration. Similar to the way baby’s eyes change with the influx of melanin (or pigment), heterochromia iridum is a result of too much or not enough melanin in the iris.
Heterochromia iridum can present in two separate ways: complete heterochromia and sectoral heterochromia. The latter of the two typically exhibits one (or both) iris with two different colors. For example, perhaps the left half of the iris is blue while the right half is brown. Complete heterochromia is the entire color difference between irises; maybe the left eye is green while the right eye is grey.
Eye color is determined by the unique distribution and concentration of melanin in the iris. The more melanin an eye contains, the darker the color will be. Eyes affected by heterochromia are either hyperchromic (the iris lacks pigment) or hypochromic (the iris has an abundance of pigment).
The three most common causes of heterochormomia iridum are from a disease, an injury, or because of hereditary traits passed down by your parents.
Hereditary cases are typically the result of a genetic condition where the eye’s cells are polychromatic. Eyes with sectoral heterochromia usually come from illnesses like Waardenburg syndrome or Hirschsprung’s disease. The biggest injury that leads to eye color differentiation is bleeding, normally from a hemorrhage or a foreign object in the eye.
Whereas humans are rarely affected by heterochromia iridum, other species – mainly animals – are frequently seen with this unique feature. Oddly enough, animals with two different colored eyes typically always contain one blue, or lightly pigmented, eye.
Cats like the Japanese Bobtail and Turkish Van lack melanin from the skin or hair, which inevitably results in at least one blue eye as a result of low pigmentation. Dogs breeds like the Siberian Husky, Australian Shepard and Catahoula Leopard Dog also experience this lack of melanin and are commonly seen with different colored eyes.
Horses like pintos and palominos are also known for frequent cases of heterochromia iridum. Other creatures like ferrets, owls, cattle and water buffalo are also known for displaying different colored eyes.
Below are four famous faces that have two different eyes:
Though no symptoms are typically associated with genetically passed heterochromia, visiting an optometrist is advisable if your eyes have changed colors due to an illness or injury.
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If you or a loved one has been or may potentially be affected by heterochromia iridum as a result of an illness or injury, consider looking into the benefits of vision insurance. VSP Individual Vision Plans offers a reliable, affordable vision insurance plans that can provide comfort and coverage for all eye-related needs. Learn more about your vision insurance plan options today. Once you’ve completed your vision plan enrollment, keep your eyes open for dental insurance plan options from Guardian Direct®. Get the care your eyes and smile both need.