You would definitely know if you’d met someone with heterochromia because it’s hard to miss when someone has two different colored eyes! We’re talking something like one blue eye and one brown eye, but it can get even more complex than that. These people can also have one part of their eye be a different color than the other! “It’s also possible for small segments of the same iris to be different colors. For example, half of your left eye could be blue and half could be brown,” says Healthline. Sometimes referred to as heterochromia iridis and heterochromia iridum, this condition has been around long before there were ever cosmetic colored lenses.
Unlike other conditions on this list, most of the time heterochromia is not serious. It’s not a result or symptom of any underlying medical issues. It’s just a genetic fluke and in very rare cases it can be “a sign of a congenital (present from birth) condition or the result of an injury or illness.”