What does it mean if a cat has one blue eye and one green eye?

What does it mean if a cat has one blue eye

Once in a while, you’ll come across a cat with visuals unlike any other.  One set of eyes with two different colors.  These cats are what people lovingly call “odd-eyed”.  They have a condition called heterochromia iridis.

Odd balls with odd eyes

Cats with heterochromia typically have one eye blue and the other green, brown or yellow.  They’re usually have white fur all over, or in some parts of their bodies.  The gene responsible for the white fur and odd eyes are the same.  While it can happen to cats with colors other than white, it’s extremely uncommon for black cats to have heterochromia.

When they’re born, kittens will always have blue eyes.  After six weeks or so, the melanin hits and they develop eye colors.  For cats with heterochromia iridis, the color changing only happens to one of their eyes.  The other eye will always be blue, unless if a little bit of melanin moves to the blue eye, turning it green.  On their 12th week, their eye colors are permanent.

Because it is their genes that determine what their coloring is, some breeds are more prone to having heterochromia.  The notable breeds are: Japanese Bobtail, Turkish Angora and Turskish Van – although, this genetic mutation could happen in any breed as long as the cat has the right genes for it.

By the way, of your cat’s eyes changes color when they’re passed their 12th week, it could be due to a health problem.  Please get in touch with your vet right away.

Degrees of odd-eyedness

There are two different types of heterochromia in cats.  One is Complete heterochromia, and the other is sectoral heterochromia.  Complete heterochromia happens when one of their eyes is a different color from the other.  Sectoral heterochromia, on the other hand, is when one eye contains two colors.  Their eyes would look like a pie cut in two.  One blue slice, and the other, green.

Complete heterochromia happens when melanin is blocked from reaching the other eye.  Sectoral heterochromia occurs if melanin isn’t able to spread throughout the whole eye.  Both look bizarrely gorgeous.

Health problems associated with having odd eyes.

In general, heterochromia is only an aesthetic mutation.  It itself will not cause any harm on your cat’s health.  It has been noted that white cats with blue eyes are at a higher risk of being deaf.  However, this isn’t really the case for cats with odd eyes.  70% of odd-eyed cats will not develop any hearing problems during their lifetimes.  Cats with odd eyes will also have normal vision.

As mentioned above, if your 1 year old cat suddenly develops heterochromia, you must visit a vet immediately.  The changes in their eye color could be caused by inflammation, iron deposits, uveitis, or even blood in their eyes.  Older cats are also at risk of developing glaucoma – which makes their eyes a bit cloudy.  In any of these cases, please visit your vet as soon as possible.


Common questions about cats’ eyes

Do cats have third eyelids?

When your cats are just waking up from their afternoon nap, you can sometimes see a milky white film pass through their eyes.  It looks a little weird, but it’s completely normal.  This is your cat’s third eyelid, medically called the nictitating membrane.

The purpose of this third eyelid is to protect their cornea, and for keeping their eyes moist while they have their eyes “open”.  This is particularly helpful to cats when they were hunting in the wild.

By the way, if you’re seeing their third eyelid more than that brief moment when they wake up, take your cat to the vet as your cat may have suffered a trauma or an infection in their eyes.

Are cats colorblind?

Cats see the world differently from humans – that is unless the human in question has a red-green color blindness.  Color blindness doesn’t mean that your cat is blind – it only means that they see the world with a limited range of hues.

Blue and yellow pop much better in your cat’s eyes.  That being said, your cat will love toys that are in these colors.

Can cats see in complete darkness?

Cat vision is so much better than human vision – especially in the dark.  When you see a cat in the dark, you’ll often see their eyes looking like they’re glowing.  What their eyes are doing at this moment is that they’re reflecting the light back out of their eyes.  This way their eyes could have twice the chances of absorbing the information, therefore seeing better in the dark.

However, cats’ eyes don’t actually glow.  Their eyes don’t emit light; they only reflect it.  So, in complete darkness, your cat can see as well as you and I, meaning they can’t see anything at all.


Heterochromia is one very beautiful mutation cats can have.  It’s most common to white cats, and is not related to any sort of health issue if your cat was genetically blessed to have multicolored eyes.  Cats that develop heterochromia when they’re older than 1 year old must be looked at by the vet as this is a sign of some serious health problem.

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