Eye anomalies and hereditary vision problems that can affect Siamese cats

Eye anomalies and hereditary vision problems that can affect Siamese cats

The Siamese cat breed is one of the most popular pedigree cat breeds in the UK, and as most owners will tell you, they are very unique cats with highly individual personalities, as well as having a distinctive and instantly recognisable appearance.

Cats of the breed need a lot of love and attention and thrive under the care of an owner that will spend lots of time with them, and treat them as one of the family. They also tend to be lively, playful and active, as well as very vocal!

The Siamese cat breed is certainly not a good fit for everyone – and many first-time Siamese owners often find themselves rather daunted when they first bring their new companion home and come to realise just how individual and unlike the average moggy they really are. However, for the many fans of the breed, no other cat will do – it’s Siamese for life.

Like all pedigree cat breeds, Siamese cats have rather elevated risk factors for a range of specific hereditary and conformation problems and health conditions that can affect their appearance, lifespan and quality of life, which any potential Siamese cat owner should research carefully before making a purchase.

Eye problems such as conformation anomalies and hereditary vision issues of certain types tend to crop up more in Siamese cats than in most other cat breeds – and so in this article, we will look at the main eye problems and conditions that Siamese cats are more susceptible to inheriting. Read on to learn more.


Nystagmus is a congenital neurological disorder that causes involuntary movements of the eyes, and many Siamese cats inherit the condition to some extent. In some breed populations, the condition is so prevalent that it is considered to be a regular albeit anomalous feature of the breed, but it is not necessarily recognisable nor obvious in the majority of cats.

A cat with nystagmus will exhibit eyes that seem to move independently, potentially flickering from left to right like a pendulum, or in a pattern of slow and fast movements in opposite directions. In more severe presentations of the condition, your cat may also tilt or bob their head as well as exhibiting the signature eye movements.

Whilst the appearance of nystagmus can be unnerving, it is not painful for your cat and they probably won’t even be aware that it is happening.

Crossed eyes

Old films and TV shows, as well as cartoons and other media used to display Siamese cats with a stereotypical cross-eyed expression, and historically, a significant percentage of cats of the breed were indeed cross eyed, and this was considered to be a normal breed trait.

However, it is less common today, and truly cross-eyed Siamese cats are now few and far between – and the condition is hereditary and so, likely to appear only in certain breed lines and populations. Again, this is not painful, but can affect your cat’s ability to focus and perceive depth without deliberately adjusting their eyes to compensate for it.


Strabismus is similar to crossed eyes in that one or both of the eyes will focus and move independently, or point in different directions. Generally, Siamese kittens with strabismus will be obvious from soon after they first open their eyes, but the condition can potentially develop later in life within the breed too.

If both of the cats’ eyes point outwards, this is called divergent strabismus, while both eyes pointing inwards is called convergent strabismus.

Once more, this condition won’t cause your cat any pain, unless they suffer from eye strain as a result of attempting to focus.


Glaucoma is a feline eye condition that can arise for a variety of reasons, including heredity. The Siamese cat breed has been identified as one of the breeds with risk factors for primary glaucoma, which is a hereditary form of the condition that is still reasonably uncommon.

When glaucoma develops (which can occur at any stage in the cat’s life, and affect one or both eyes), pressure builds up behind the eye as a result of poor drainage from the tear ducts, which in turn, places pressure on the optic nerve. This can cause pain, as well as affecting the cat’s vision, as the messages transmitted from the optic nerve to the brain are interrupted.

Left untreated, glaucoma can result in total and irreversible blindness.

Progressive retinal atrophy

Finally, progressive retinal atrophy is a progressive and painless disorder that leads to complete blindness over time, which cannot be reversed or cured. A reasonable number of pedigree cat breeds have elevated risk factors for progressive retinal atrophy, and the Siamese is one of them – in fact, around a third of all cats of the breed carry the gene mutation that can result in the condition.

However, for a cat to be affected by the condition themselves, they need to inherit two copies of the gene, otherwise they will be unaffected themselves and simply be a carrier for the condition. The risk of passing on the condition to offspring is fairly acute, however, as so many cats of the breed have carrier status, and inadvertently mating two seemingly healthy cats who are carriers can lead to affected litters.

Pre-breeding health screening can help to determine the status of any two potential parent cats, enabling breeders to make an informed decision about proceeding.

If you are considering buying a Siamese kitten, ask the breeder about health testing for progressive retinal atrophy in the parent stock, and don’t proceed with a purchase until you examine the results.



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