Celebrities like Mila Kunis, Kiefer Sutherland, Jane Seymour and David Bowie all likely have more money in the bank than the average Joe or Jane. But they also all have more of something else compared to most of us: eye colors. And apparently, today we’re supposed to celebrate them.
Those celebs are part of a tiny group of humans on Earth that have different-colored eyes — a condition known as heterochromia iridis. That could mean, for example, that one eye is blue and the other is green. While we can more easily notice it in public figures on our giant high-definition TVs, it’s something that’s so rare that there are no credible records of just how many people exhibit this interesting human phenomenon. But Dr. David Sendrowski, a fellow with the American Academy of Optometry, estimates that less than 1 percent of people are born with different-colored eyes.
Eye color is dictated by the amount of melanin in our eye’s iris. Some babies are initially born with blue or brown eyes, depending on ethnicity. But it’s not always apparent at birth what our DNA has in store for our permanent eye color, since that can change as we develop from infancy. Heterochromia iridis can even occur in cats and dogs.
Sendrowski, who is also a professor in Marshall B. Ketchum University’s Southern California College of Optometry, explained that there are two types of heterochromia: one in which each eye is a different color (iridis), and another in which one eye has different colors within it (iridum). And while some are born with this condition, others’ eye colors actually grow into their multiplicity.
How can it happen? “Inflammation, infection or other sorts of hereditary disease,” says Dr. Brad Sutton, a practicing eye doctor and clinical professor at the Indiana University School of Optometry.
Experts say conditions like Horner’s syndrome, Waardenburg syndrome or even the virus that causes shingles and chicken pox can lead to heterochromia iridis. A condition called Fuchs heterochromic iridocyclitis can cause chronic inflammation in the eye that lightens the iris over time. And then there’s possible trauma during birth that affects the sympathetic nervous system (the part of your nervous system that is like a car’s gas pedal, responsible for fight-or-flight responses).
If you’re noticing changes in your eye color, don’t assume you’re just getting prettier — Sendrowski recommends seeing your eye doctor. While different-colored eyes could be something benign, it’s always worth checking out with an expert.
Plus, be aware that sketchy colored contact lenses sold without a prescription at places like gas stations or beauty parlors can be downright dangerous. Sutton notes that they can lead to infections or may not fit your eyes properly. Remember: Contact lenses are medical devices — and we can’t all be as creative as this Brazil fan every day.
Vignesh Ramachandran is a tech buff and journalist living in the Bay Area. Follow him on Twitter @VigneshR.
Why you should care
You probably know someone with different-colored eyes — and it turns out it’s a pretty rare condition.