Example of bad strabismus in a longhaired Oriental cat

Strabismus is the scientific term for a squint and this Oriental Longhair has a very bad one. It is the worst example I have seen. As you might know, the Siamese cat is predisposed to the squint. And the Oriental cat both long and shorthair is part of the Siamese cat family by which I mean they inherit a similar set of genes i.e. the genotype is similar. And for this reason, I think it is fair to say that you will see the squint in Oriental Shorthair and Longhair cats more often than is typically encountered amongst the general domestic cat population.

Oriental Longhair with an enormous squint. Screenshot.

I have a page on what causes this condition which you can read by clicking on this link if you wish. The important fact about the squint in cats is that they compensate for the optical and brain wiring that has gone wrong and scientists believe that they are able to see normally which is hard to imagine when you look at this guy with his enormous squint.

The Siamese cat spawned a lot of other cat breeds such as the Oriental and cat breeds such as the Javanese and Thai.

RELATED: Thai cats – describing their place in the Siamese cat family.

The experts might be incorrect about the squint not affecting vision for the Siamese and cats in the Siamese cat family. I say this because humans can also develop a squint particularly in children. And it is corrected in various ways because if it is not dealt with, they say that it might cause "persistent blurred or double vision". 

This implies that humans are not able to correct for the squint. Perhaps this is because the cause of a squint in humans is different to that in cats? Or there are different causes. The cause for the squint in this Oriental Longhair will almost certainly be congenital i.e. inherited due to faulty 'wiring'.

But the main reason why the squint is rectified in humans is because of the appearance. This can cause embarrassment or low self-esteem. Clearly, we do not place that much importance on a squint in domestic cats.

Siamese Cat Binocular Vision

The Siamese cat is well known for a squint and a kinked tail. Both have been bred out by breeders over the years as they are considered "defects" but they are nonetheless part of this cat breed's heritage. The kinked tail in cat show competition is reason to disqualify the cat as I recall.

There are colorful legends regarding the squint that are usually about Siamese cats who defended temples and valuables. The task was arduous and it caused the cats to develop a squint!

The question on some people's minds is, "does the Siamese cat squint affect normal vision and particularly binocular vision?" Let's first say that it isn't just Siamese cats that have squints but they have a genetic predisposition to acquiring the squint. The cat below is not a Siamese but has a clear squint. Perhaps she is a Siamese mix (lynx point)

Not Siamese but clear squint - Photo by fazen (Flickr)

Cats have two eyes to allow them to judge distance and depth. Two eyes give animals a form of three dimensional vision. This is important to cats in making judgements on tracking objects, jumping and hunting etc.

It transpires that the squint is apparently a compensation for defective wiring of the nerves that go from the eyes to the brain. In normal cats half the optical nerves cross over to the side of the brain opposite to the position of the eye. This provides binocular vision.

In Siamese cats the nerve fibres that were not meant to cross over, do in fact cross over. This causes "the faulty positioning of the retinal map on the tectum". The tectum is a region of the brain, specifically the dorsal part of the mesencephalon (midbrain). The squint cancels out the effects of the faulty positioning on the tectum by "altering the positioning of the retina".

So there you have it. The squint develops over the first six to eight weeks of the kitten's life to make this compensation.

Siamese cat binocular vision is maintained by the famous Siamese cat squint. That's how nature has compensated for a genetically inherited neurological defect. Incidentally, the Siamese and Persian cats have the most genetically inherited diseases and are two of the most long standing purebred cats.

The references are from the New Scientist Aug 17, 1972. Thanks to Google Books.

Blue Point Traditional Siamese with Mild Squint

Che Che's photo set, a photo by AJ Franklin on Flickr.

The title says it all. It is hard to tell but this nice looking Applehead Siamese does have a slight squint (cross-eyed gaze).

This is not uncommon in Siamese cats. The cross-eyed look and kinked tail are part of the breed as are the pointed extremities.

Breeders of this cat breed out these so called defects.

My research indicates that the squint does not affect binocular vision (depth assessment).

Feral Cross-eyed Blue Pointed Bobtail Cat

Siamese Bobtailed Cat, a photo by KaCey97007 on Flickr.

Wow....this cat that looks like a feral Siamese cat that has blue pointing and a bob tail.

Both cross-eyes (squint) and a shortened tail (or a kinked tail) are known to exist in the Siamese cat. See Siamese cat kinked tail.