What Determines a Cat’s Eye Color?

December 1, 2015

cat eye dawnBy Langley Cornwell

How many of us have stared into our cat’s eyes trying to read their minds, attempting to understand their innermost thoughts or simply appreciating their catness? You know I have! And as my cat and I are making earnest eye contact, I always marvel at the gorgeous color of his eyes. They are a deep, rich emerald green.

Cat eyes can be a number of colors including light brown, yellow, orange, green and blue. And each of these colors comes in a variety of intensities and hues. This is why it appears that there are so many different feline eye colors. To further complicate the matter, some cats even have odd colored eyes.

A feline’s eye color is determined by many factors, and it’s not always related to the animal’s coat color. In fact, the major contributors to the ultimate color of a cat’s eyes are blue refraction, iris pigmentation and breeding.

Blue Refraction

Similar to infant children, newborn kittens start out with blue eyes. This is no indication of the eye color the adult cat will end up having. Their natural color can usually be determined by around the 8 to 12 week mark. There are several cat breeds, however, that do keep blue eyes throughout their lives, notably the Siamese, Javanese, Balinese, Tonkinese, Himalayan, Birman, Ragdoll and the rare Snowshoe.

Blue eyes can also be found in white cats and are linked to the dominant white gene. I wrote more about dominant white genes and how they affect cats in this article: White Cats and Deafness – What’s the Connection?

Kittens are born with no pigment in their irises. Therefore, much like the way a clear, colorless window pane can look blue or greenish around the edges, a kitten’s eyes look blue under most circumstances. This is because their eyes are round so light refracts through the spherical surface and the result is a blueish tint. The depth and richness of the blue color depend on the strength of the blue refraction.

Iris Pigmentation

The center of a cat’s eye is the elliptical black pupil. The colored part surrounding the pupil is the iris. The iris is colored because it is made up of pigment-containing cells called melanocytes. I’m not trying to get too scientific here, but this is interesting because the number of melanocytes (pigment-containing cells) present in your cat’s cat eye Kateeyes is what determines his eye color. It works this way: the fewer the number of melanocytes found in your cat’s iris equals the lighter his eye color. Conversely, the greater the number of melanocytes equals the darker your cat’s eye color.

No matter how dense the iris pigmentation is, however, cats do not get deep brown or blackish colored eyes. The darkest colored eyes a cat can have are an opulent, deep orange. This color is often referred to as copper, and if you’ve ever seen a cat with this color of eyes you know they are stunning.

As an aside, I learned in my research that the word iris means rainbow in Greek.

The Purebred Connection

Breeders breed purebred cats to conform to breed standards. Feline breed standards often include the shape of a cat’s ears, head, body, legs, paws and tail. They also include the coat texture and color as well as the eye shape and color. Additionally, I’ve seen this in almost every breed standard: “Clarity of eye color is desirable.” Therefore, breeders choose which cats to breed based on many things, including particular eye color and/or eye color intensity.

This is interesting if you like to know the reason why things are what they are. But when I’m gazing lovingly into my mixed breed rescue cat’s eyes, I’m not thinking about all this. I’m just enjoying the moment and relishing the powerful connection we have.

Top photo by Dawn Ellner/Flickr
Bottom photo by Kate Brady/Flickr

Read more articles by Langley Cornwell

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