Eye problems in the Sphynx

There are two eye problems that are particularly worth knowing about in the Sphynx: corneal sequestrum and lower eyelid entropion. And in this case we do actually have research showing a breed predisposition rather than simply reports of these conditions occurring in individual Sphynx cats.

Sarfaty, Ezra-Elia and Sebbag looked at 110 Sphynx cats seen at a veterinary ophthalmology referral centre between 2012 and 2021 and compared them with non-Sphynx cats seen at the same centre.

Their conclusion was quite straightforward:

“Corneal sequestrum and entropion were overrepresented and diagnosed at an earlier age in Sphynx cats.”

The difference was not particularly small either. The odds of corneal sequestrum were eight times higher in the Sphynx group and for lower eyelid entropion they were about four times higher.

There is one thing we need to be careful with here though. Forty-two of the 110 Sphynx had a sequestrum, but these were cats attending an ophthalmology referral centre. It would be completely wrong to take 42/110 and turn it into a claim that around 38% of Sphynx cats develop sequestra.

What the study gives us is evidence of predisposition. It does not give us prevalence for the whole breed.

Corneal sequestrum

A sequestrum is probably easier to recognise than the name makes it sound. It is an area of damaged cornea that develops a brown or black appearance, sometimes starting as a very small dark mark.

There may be tearing, squinting, discharge or obvious discomfort, although pain should not be the thing we wait for before having it checked. A small spot can look fairly unimpressive from the outside and still need proper examination.

This is particularly relevant in Sphynx because they were not only overrepresented in the study, they were also much younger when diagnosed. The average age was 2 years in Sphynx compared with 5.9 years in non-Sphynx cats.

Recurrence was higher too. Among surgically treated eyes it was recorded in 19.4% of Sphynx eyes and 6.4% of non-Sphynx eyes.

Again, we should not turn 19.4% into an individual Sphynx cat’s chance of recurrence. It is simply what was found in this particular study population.

How a sequestrum is treated depends on the lesion. They are not all the same size or depth and this is where an ophthalmologist looking at the actual cornea matters considerably more than photographs on the internet. Some require surgery to remove the affected tissue and, where the defect left behind is deeper, a graft or another form of corneal support may be needed.

For an owner, the useful message is much shorter: if a new brown or black spot appears on the cornea, have it looked at.

It should not simply be assumed to be harmless pigmentation and left until the eye becomes obviously painful.

Entropion

Entropion starts with the eyelid rather than the cornea.

The lid turns inwards and ends up sitting against the surface of the eye. If that contact continues, it can obviously become irritating and the cornea can be damaged as a result.

Twenty-five Sphynx in the study had lower eyelid entropion and the odds were about four times higher than in non-Sphynx cats.

The age is interesting here as well. The average Sphynx was only 0.9 years old when diagnosed, compared with 3.5 years in the other cats. And in 80% of the affected Sphynx, both eyes were involved.

So eyelid position is something worth looking at in kittens and young cats. Persistent watery eyes or squinting should not automatically be dismissed as something Sphynx simply do, particularly if the eyelid itself appears to be turning towards the eye.

More significant entropion may need surgical correction, especially where the position of the lid is continually irritating the cornea.

What about the other eye problems?

There were plenty of other diagnoses in the paper.

The researchers recorded presumed herpetic keratoconjunctivitis, conjunctivitis, corneal ulcers, nasolacrimal duct problems, corneal dystrophy, eosinophilic keratitis and uveitis, amongst others.

But we should not put all of those on a list called “Sphynx predispositions”, because that is not what the study showed.

The strong comparative finding was for corneal sequestrum and lower eyelid entropion. Those are the two conditions the authors found to be overrepresented compared with non-Sphynx cats.

That distinction matters because there is a big difference between a disease being found in a Sphynx and having evidence that Sphynx are actually predisposed to it.

What should we watch for?

Mostly changes. Sphynx can have visible eye discharge and individual cats differ, so every bit of discharge does not need to be turned into a medical problem. What matters more is something changing from what is normal for that particular cat.

An eye suddenly being held partly closed, persistent squinting, much more tearing than usual, redness, rubbing, cloudiness or any obvious change to the corneal surface deserves attention.

The eyelids are worth looking at as well, rather than concentrating only on the eye itself.

And a new brown or black mark on the cornea should be checked sooner rather than later, particularly knowing what we now know about sequestra in this breed.

None of this means that Sphynx cats are destined to have eye problems. That isn’t what the research says.

What we can say is much more specific: Sphynx have a documented predisposition to corneal sequestrum and lower eyelid entropion, and both were diagnosed at a younger age than in non-Sphynx cats in the comparative study.

References:

Sarfaty H, Ezra-Elia R, Sebbag L. Prevalence and characteristics of ocular diseases in Sphynx cats: A retrospective assessment (2012–2021) and comparison with non-Sphynx cats. Veterinary Ophthalmology. 2022;25(5):367–375.

BSAVA — Corneal sequestrums in cats: diagnosis and treatment options⁠; https://www.bsavalibrary.com/content/chapter/10.22233/9781913859008.Ch73