Browsing tag: enucleation

Why cats go blind.

Blind cat showing dilated pupils

Blind cat showing dilated pupils

One of the most common causes of sudden blindness in an elderly cat is due to high blood pressure (hypertension). The increased pressure pushes the light sensitive layer (retina) away from the back of the eye and this can happen literally overnight.

The affected cat will have very widely dilated pupils even in bright sunlight and there might be some blood visible when looking into the eyes. They will appear to be disorientated, bump into things and might vocalise excessively.

Monitoring a cat's blood pressure

Monitoring a cat's blood pressure

The usual cause of raised blood pressure in cats is an excess of thyroid hormone (hyperthyroid) but it can also be due to kidney disease or diabetes. This is why it’s important for the vet to take blood tests to decide which condition to treat.

We monitor cats’ blood pressure in a similar way to human doctors by inflating a cuff just above the paw on a front leg but we listen for blood flow with an ultrasonic probe rather than a stethoscope. Some cats are calmer if the cuff is placed around the tail base. A few readings are usually taken to make sure that the blood pressure has not been raised through stress.

blood pressure kit

Blood Pressure Monitor

Drugs are very successful in bringing a cat’s blood pressure down to normal but the blindness is usually permanent. Cats are extremely adaptable when it comes to finding their way around the house and finding their food but they are not safe to allow outside due to all the dangers out there.

There are a number of other causes of blindness but these generally come on more slowly:

Glaucoma is the same condition as people get where there is an increased pressure within the cat’s eye. This is usually seen as a very angry painful eye and the white of the eye appears red due to the many new blood vessels. Drops can control the condition if caught early enough but if it reaches the stage where the eye is visibly swollen or ulcerated, then removal of the eye (enucleation) will usually be suggested. Glaucoma can be found in just one eye or both.

Cataracts are much less common in cats than dogs and would be seen as a misty or pearly lens. Tests would be required to rule out diabetes which can be a cause.

Tumours within the cat’s eye are occasionally discovered when the eyes are examined with an ophthalmoscope. Loss of vision would be slow to develop in these cases and often in only one eye initially.

If you have a pedigree cat (particularly an Abyssinian) who starts to slowly lose vision early in life, there is a possibility of Progressive Retinal Atrophy (PRA) which is a genetic disease, very similar to the condition in some pedigree dogs. There is no treatment but the cat usually has time to adapt to the slow loss of vision.

Something we hardly ever see these days is Taurine (an amino acid) Deficiency. Modern complete diets have all the taurine a cat needs but it is just possible that a cat fed exclusively on tinned tuna could develop slow onset blindness due to this deficiency. If caught early enough, the loss of vision can be stopped or even reversed.

Most cats adapt very well to blindness and go on to enjoy a good quality of life. Some adapt so well that it would be hard for a casual observer to know they were blind.

If you are worried about any problems with your cat’s eyes, please contact your vet or use our interactive Cat Symptom Guide to help you decide what to do next.

Cat Eye Operation

Joe Inglis BVSc MRCVS is the vet for the One Show, This Morning and BBC Breakfast. He runs his own line of natural pet food called Pet’s Kitchen

I often find myself sympathising with my patients, and feeling for their distress and pain when they are suffering from illnesses or injuries – and never more so than when their problem involves their eyes. There’s something about injuries and diseases of eyes that really affects me more than almost any other type of problem and I can really empathise with how my patient must be feeling. Having an ulcer or other injury to an eye must be horribly painful, not to mention the psychological impact of dealing with the loss of some or all of your sense of sight.

When Sylvester the cat came into the consulting room last week and clambered miserably out of his wicker basket, my heart sank and I felt an immediate sense of shock and distress when I saw his problem. His left eye was barely recognisable, with a large grey ulcer dominating the cornea and angry red blood vessels invading the usually clear surface of the eye from the sides. This was not Sylvester’s first visit to the surgery for this problem, but it was the first time that I’d seen him, and I immediately knew that we needed to do something drastic if we were going to save his eye – and bring his obvious suffering to an end. Looking at his records it was clear that this ulcer had been grumbling on for a couple of weeks by this stage, and despite ongoing treatment with medicated drops it was getting worse rather than better.

At this stage we had a couple of options to consider. One was to refer Sylvester to an eye specialist, but this was quickly ruled out by his owner on the ground of cost and lack of pet insurance cover. The second option would be to continue with medical therapy, taking a swab to find out exactly which bacteria were causing the ongoing damage and preventing the ulcer from healing and potentially changing the eye drops once these results were known. The downside of this course of action was that it would do little to alleviate Sylvester’s discomfort in the short term, but after talking to his owner and explaining that the only other option would be surgery to remove the eye, we agreed that we would try this first.

So I took a swab from Sylvester’s eye and sent it away to the laboratory to see what they could tell us about the infection. While we waited for the results we did what we could to manage Sylvester’s discomfort with painkillers and anti-inflammatories, and then as soon as the results were in we started him on an aggressive course of antibiotics that were targeted specifically at the bacteria the swab had isolated. At this stage I was still optimistic that we could save Sylvester’s eye, but unfortunately things didn’t work out as planned and despite our new treatment regime, the ulcer stubbornly refused to respond and after a week of treatment it became clear to me that we were left with only one option – to remove Sylvester’s eye.

Breaking this news to his owner was not easy, but she did appreciate that it wasn’t fair to let him continue to suffer as he was doing given the now very slim chance that we would be able to save his eye. After a couple of long – and emotional – consultations, we agreed to go ahead and last Friday Sylvester came into the surgery for his operation.

Sylvester the cat after the operation to remove his eye

Sylvester the cat under anaesthetic after the operation to remove his eye

Removing an eye is an operation I really don’t enjoy, as I can’t help but really feel for the poor animal that is losing such a crucial part of their anatomy, and the operation itself is also technically tricky and pretty gruesome. Sylvester’s operation went as well as I could expect, but it was not one that I finished with a sense of satisfaction – I felt good that we had brought Sylvester’s suffering to an end, but I also felt as though we’d failed him by having to resort to such a procedure.

If you have any concerns about your cat’s eye please contact your vet or use the interactive cat symptom guide to help you decide what to do next.

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