Cats’ eyes are incredible. As well as looking beautiful and being almost hypnotic, they enable cats to see in very low levels of light, although it is a myth that cats can see in total darkness. Because their pupils react more quickly to a change in light conditions, they can better adjust to sudden light changes than humans are, too.
In terms of physical appearance, cat eyes can be blue, green, yellow, brown, or a combination of these colors. Rarely, we even see cats with two different colored eyes, a condition known as heterochromia. Although the exact cause of heterochromia is unknown, it means that melanin is only delivered to one eye and not the other, and it is most often found in white cats or those that have at least some white on their bodies.
Interestingly, a white cat with heterochromia is likely to be deaf in the ear on the same side of the head as the blue eye.
Cat Eye Color
All kittens are born with blue eyes and their eye color only changes as they age. Melanin is slowly delivered to the irises as they age: a process that usually begins at around eight weeks and can continue until they reach three months of age. Once your cat reaches this age, they should have fully developed their eye color and this is the color they will remain.
Cats’ eyes come in a myriad of colors from blue to brown and yellow to amber.
Different Colored Eyes
Very occasionally, we see cats with two different colored eyes. This is most commonly seen in white cats. White cats have the epistatic gene, which produces the white coat color, or a white spotting gene, which usually causes a bicolor coat that includes white. In both cases, the gene prevents the melanin pigment from reaching their coat, giving them their distinctive white fur. These same genes also prevent melanin from reaching the eyes. This means that one or both eyes will not change from the original blue color.
Does Heterochromia Cause Any Problems?
Heterochromia does not affect a cat’s vision in any way, and it won’t cause a cat to have any sight difficulties or be deaf. Because it is most often found in white cats, a cat with odd-colored eyes may be deaf, because congenital deafness is associated with the same genes that cause the white coat color, but it is not a result of eye color.
Approximately 10% of white cats with no blue eyes are born deaf, while 40% of those with one blue eye will be deaf in at least one ear. This number rises sharply for cats with two blue eyes: approximately 80% will be deaf in one or both ears.
Why Do Some Cats Have Two Different Colored Eyes?
Cats come in many different shapes and sizes, including having different colored eyes. Kittens are born with blue eyes but as they age, melanin spreads into the irises, changing the color from the original blue to various shades of yellow, green, brown, and orange.
However, the same gene that causes white cats to have their white coat, can also prevent color pigmentation from reaching their eyes. In some cases, pigment might spread to one eye but not the other, which causes the cat to have two different color eyes. The condition is not dangerous and doesn’t affect the cat’s vision, but the same gene that gives the cat its white coat and unusual eyes can also cause congenital deafness.
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