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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  1. Alexfighter13 says:

    My cat is a gray female (Breed unknown) with bright, round green eyes. She’s had four kittens, two ending up with her same green eyes. One had brown-ish eyes and the other has a darker green-gold eye color. Now I know each kitten could have a different father each, but what’s the odds each one had green eyes. Would her green eyes be more dominate than, say, gold or brown eyes? Probably a stupid question, but just wondering.

    1. Jennifer says:

      Spay our cats!!

  2. Nora Coombs says:

    Thank you for your informative article. I was talking with a fellow cat rescue person about cats’ eye colors, and was wondering what determined this. Of course genetics has hand in it, I’m sure, but it seems that some color fur has common eye colors. I have 4 all black cats and 3 have yellow eyes, and the 1 has gold eyes. I’ve yet to run into a green eyed black cat here, but I’m sure they exist. I also noticed that Buster, who has the gold eyes is more sensitive and loving than the other 3. Coincidence? You mentioned color hues too. Some of my cats with green eyes have the normal green, yet a couple have what I call mint green eyes. Those are stunning. One of them with the mint green eyes is a grey and white tux, which goes beautifully with the eye color. We used to have a cat that came to visit and eat with my tnr cats, that was white with black spots and it had one blue eye and one green eye. Now that makes me wonder what would cause that. Thank you again for your interesting and informative article.