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The Peculiar Case of your Cats Eye Color

MEOW!!! Do you have a kitty that has very special eyes? Have you ever been mesmerized by your kitties eyes? Well, this is just the article for you! Here we’re going to briefly cover how your kitty gets his beautiful eyes.

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Understanding How Cats Get their Eye Color

There are three genetic components that determine your cat's eye color:

  • Breed
  • Iris Pigmentation
  • Blue Refraction

The colored part of the eye is called the iris. Your, and your kitties, eye color is determined by the number of melanocytes present in the eye. For example, if your cat really has intense, bright amber eyes, this does mean that his iris produces a lot of melanin.

The second important genetic factor includes the level of blue refraction. To best understand this, imagine looking at your kitties eyes from a side-view point. Notice that glassy, globe-like structure? That’s essentially what determines how intense the blue eyes would be on your cat. In simple, the degree to which light scatters or absorbs corresponds to the different eye colors we see in cats. For example, reds, oranges, yellow are colors with long wavelengths while blue has a short wavelength.

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Cats with blue eyes actually don’t have any pigment! In fact, there is virtually little to no melanin production in the iris. Similarly, darker eye colors occur as a result of the pigmentation absorbing the light reflected on it. This is simply because darker eyes have a higher concentration of melanin.


Blue Eyed Cats

The really pawesome thing about blue-eyed cats is that their iris is actually not able to make much pigment, and the blue in their eyes is actually due to the level of refraction. This means your beautiful Siamese, with those mesmerizing deep blue eyes, actually has low pigment but high refraction and therefore you’re simply perceiving those eyes as blue, when in fact they are essentially colorless.


All kittens have those baby blues

Kittens are similar to human babies - all are born with essentially no pigment in their iris. This means that neonatal kittens will all have blue eyes. However, as they begin to age, their individual breed genetics will take over. This means that by 6 to 7 weeks of age your cats eyes will change color as their melanocytes begin to mature and produce melanin. Dark eyes mean high production of melanin, blue or green eyes, mean the iris is not producing much melanin.


How Is Coat Color Associated with Eye Color?

white cat-blue eyes

The genetic link between eye color and coat color is actually minimal. In general, only blue eyes have an association with a specific coat type or color. The most well-known example seen in cats is the white coat / blue-eye association. You’ve probably seen yourself that cats with white coats tend to have blue eyes and that the majority of these white haired fur babies tend to be deaf. This is because the gene that codes for white fur coats will essentially mask all other eye colors like amber, hazel, green.


Why Do Siamese Have Blue Eyes?

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Ever wonder why Siamese cats have blue eyes. If you’ve got a Siamese, Burmese, Birmans, Himalayas, or a Tonkinese then it’s very likely that they’ll either have or carry the pointed coat pattern. The pointed coat is essentially a form of albinism which is temperature sensitive, what this means is that the warmer parts of the body have pigment while the cooler parts of the body do not. Similarly, this albinism is carried onto their eyes. So, essentially Siamese, Birmans, and the Himalayas will have no pigment cells in their eyes thus making it appear blue.


Heterochromia: Odd-colored eyes

Heterochromia simply means that some cats inherit more than one eye color. Heterochromia can either be classed as complete or sectoral. Complete heterochromia simply means that each eye will be a unique color, for example one eye may be blue whilst the other may be amber. Sectoral heterochromia is actually pretty unique - cats with sectoral heterochromia will have a split in eye colors, for example one eye can contain both blue and amber colors.

sectoral heterochromia

complete heterochromia

How does complete heterochromia work? Kittens are all born with blue eyes, but as they age melanin begins to mature and reach their eyes. When melanin reaches only one eye, this is referred to as complete heterochromia. Sectoral heterochromia occurs when there is a varying concentration of melanin in each eye. Heterochromia isn’t restricted to cats. Humans are prone to it to, and there we think there is simply something very meowgical about cats who have these unique genetics.