Cats have beautiful eyes, and many cats will happily stare at you while you eat dinner and show you their eyes. But did you know that some cats have more striking eyes than others? Although this condition is very rare, a condition called heterochromia can cause cats to have two different colored eyes. These odd-eyed cats usually have one iris (the colored part of the eye) that is blue, while the other is either green, brown, or yellow. Heterochromia can also affect dogs and even humans.
All kittens are born with blue eyes due to a lack of pigment within the iris. During their first few weeks or months of life, a pigment called melanin spreads across the iris, causing the eyes to discolor. This usually occurs in both eyes, but if the cat is heterochromatic, the melanin is distributed on only one iris, leaving the other one to appear blue.
It's unclear what causes some cats to develop heterochromia while others don't. It appears to be a developmental condition, and while it may be genetically related, no one really knows what causes this strange and beautiful phenomenon. While some breeds of cats seem to be more prone to heterochromia than others, it can happen to any cat.
Fortunately, heterochromia does not have any effect on cats' visual abilities, nor does it seem to affect their hearing. Although white cats with one or two blue eyes are more likely to be deaf, non-white cats with only one blue eye do not appear to have a higher risk of deafness than normal cats.