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.


36 thoughts on “Why cats go blind.

  1. Hi my cat just a stroke but I note he banging in things I think he blind if so can he get it back he is 15 he went to have a tooth out and I was told he had a stroke

  2. Hi my cat just a stroke but I note he banging in things I think he blind if so can he get it back he is 15 he went to have a tooth out and I was told he had a stroke

  3. Our 18 year old cat Dotty, who is totally deaf, quite suddenly became blind. Amazingly, after only 2 or 3 days, she had sufficient confidence to climb up and down the stairs. Equally amazingly, after taking Amlodipine tablets for 7 days, her sight just as suddenly returned. She is now on regular medication (Semintra) and a special renal diet and is back to her old deaf self.

    1. Hi Pete. Our sweet little girl went blind yesterday 1/4/20. She went from a vibrant playful kitty to a terrified girl in just one day. We took her to an emergency clinic today. They ran a bunch of tests & diagnosed her with high blood pressure.
      We are now giving her Amlodipine. 1/4 tab once a day. Is this the dosage you gave Dotty? Zoee is 12. Please let me know. My husband & I are devastated.

      1. High blood pressure is often clinically silent (showing no symptoms) in cats – until it causes a stroke or damage to the retina in the eye 🙁
        Good luck with her.

    1. This suggests a serious medical condition, probably kidney failure leading to high blood pressure and bleeding in the retina. I strongly advise you to seek medical attention for him as soon as possible, if you haven’t already, as this is NOT a normal old age change, and is a serious animal welfare issue if untreated. In many countries, for example, it would be a criminal offence not to seek veterinary treatment for a cat in that state.

      1. My cat is 19. The veterinarian said she has kidney failure & put her on a special diet. Two days ago, she suddenly went blind. At her age, should I still take her to the vet? Is there anything they can do? Shouldn’t I just keep her stress-free & comfrotable as possible?

        1. Sudden blindness is common in kidney failure secondary to dangerously high blood pressure. I would very strongly advise contacting your vet because if not addressed, the next symptom could be a stroke.

  4. My coworker and I rescued a cat that was abandoned for days without food or water. Found the owner who had moved out of state and was no interested in the cat anymore. The cat is 12 and very friendly. Both his pupils are very dilated. At first we thought it was due to him being scared in a new environment. But we noticed that he’d bump into the wall occasionally. His hearing is very keen but we don’t think he can see well if not at all. He doesn’t follow a toy waved in front of his face unless he hears it. He can’t follow a laser pointer in a dark room. This blindness doesn’t seem sudden. He’s very adept at walking around and rubbing against objects to Mark their location. My coworker and I are saving money to bring him to a vet for a wellness exam. Is there anything we should look out for that would warrant an emergency vet visit?

    1. From what you’ve said, I don’t think this sounds like an emergency, as it does look like he’s lived with this for a while. If anything changes, though, especially in terms of his behaviour, drinking and urinating, then definitely get him checked ASAP.

    2. Hello. My female Siberian cat, loved family member, is 10 years old, going on 11.
      She came from a very conscientious breeder that minimized inbreeding in Siberian Cats.
      She has been mostly problem free. I noticed that she was not seeing the cat treats she loves. I have done a Blood test and she has been found in good health, no kidney problems nor diabetes. She functions well and jumps to areas without missing, but more hesitation and calculation.
      I want to do for her everything possible to help her out of this situation. What is available for her ailments?

      1. There are a wide range of causes of blindness, and while some are treatable, most are not. It might be worth having a chat with your veterinarian about getting her eyes checked, either by them or by a specialist. This will hopefully allow you to determine the exact cause, how good her vision is currently, and if there are any treatments that might help or slow down the progression. Good luck!

  5. My cat will be is 16 yrs. old and on low thyroid medication. They just increased his dose a week ago. When I got home from work and I could not find him and my husband had not seen him all day. He was hiding and came out but he seems to be blind. I am not giving him any more Thyroid medication tonight. Just went to the doctors last week and was told to increase dose. Did this cause his blindness and is there anything I can do to reverse it?

    1. Are you sure your cat has a low thyroid? Because overactive thyroid is MUCH more common in cats. Assuming that’s what it is, the medication is unlikely to have caused blindness, but the underlying condition could well have resulted in a bleed in the retina or even in the brain. Get in touch with your vet as soon as possible and get him checked out immediately.

    1. Get her checked by your vet as soon as possible – acute onset blindness usually means a serious underlying health issue that needs urgent attention.

  6. My cat is 19 1/2 years old and about a month ago she suddenly went blind her eyes were totally black then the next day she could see again and has been fine since until tonight and she has gone blind again I’m worried what could be causing this.

    1. At that age, the most likely explanation would be a series of mini-strokes, probably due to high blood pressure. If so, she needs veterinary attention as soon as possible to reduce the risks of a catastrophic stroke or bleed.

  7. My 16 years female cat had 10 teath removed a month ago. She recovered slowly but developed reverse sneezing attacs after eating and drinking. Also, her left eye syarted a clear fluid infectef situation. Today we itentified cmplrte acute blindness which, looking back at her photoes, happened gradually in the last ten days. After she eats she shakes her head and skreems with pain. The vet thinks it is a brain tumor. Any other suggestions ? She is 16.

    1. I’m so sorry to hear that.
      Yes, a brain tumour definitely sounds possible; other causes would include some disorder of the nerves in her head and neck. However, whatever the cause, I think you and your vet are rapidly running out of options for how to manage the condition; I think you need to have a chat with your vet, quite urgently, about her quality of life.

  8. Our cat is 20 years old. Recently, she started bumping into thinks and seemed to be going blind. She recovered for a day and then went blind again. The color of her eyes is different, and they seem cloudy. We cannot take her to the vet now due to having to stay home. Any suggestions? Thanks.

    1. Unfortunately, there’s no way to know what the cause is. Possibilities would include cataracts, but in cats, other issues such as eye infections, high blood pressure and diseases of the cornea are also possibilities. We’d strongly suggest giving your vet a ring though for advice – they may be able to do a video or phone consult, and in any cat of that age, sudden blindness may suggest a more serious underlying health issue.

  9. If its due to high blood pressure and you don’t take your cats to the vets straight away and treat your cat with high blood pressure medication then your cat will be blind permanently.
    The blood pressure forces your cats retina to peel away and once its fully detatched it cannot be healed.
    I was lucky, the first time it happened to my cat on Boxing day I got her into the vets the day after and she recovered because the retina still had attachment, she goes blind from time to time but I just up her dosage to allow the retina to heal.
    If you leave it, your cat will have no chance to regain their sight ………. take them to the vet!

    1. This is definitely the risk without veterinary intervention! Make sure you follow the vet’s advice on drugs and doses though, as the medication can cause side effects if the dose isn’t just right.

  10. I have 3 yrs old male cat. He went suddenly blind on 15may. In the morning he was started throwing out and lose motions. We took him to the vet till that time he was fine (i think I’m not sure). In evening time i noticed he was sitting at one place no movement that when i realise he not able to see. What to do.

    1. Back to the vet – if he’s suddenly developed a new symptom, it needs checking, especially one so serious.

    2. Something similar just happened to my three year old cat a few days ago. Took him to the vet all blood work came back fine, but he still cannot see. They think it’s from trauma. Any word on your fur baby yet.

  11. Hi my cat is about 8 and I’ve noticed his eyes are developing cataracts, it seemed to come on quickly over the last year. Any advice to slow it down or stop it?

    1. Definitely a vet check – true cataracts are quite uncommon in cats unless they have uncontrolled diabetes. So, the underlying cause needs to be diagnosed and if possible treated.

  12. Hi there,
    We moved almost 2 months ago and have been attesting my 2 years old male cats hiding to the new move. He’s recently started to come out more, but I’ve noticed he can’t see well. Over the last 2 weeks it has become obvious he is hiding his eyes, won’t make contact, flinches if touched, whimpers a little when picked up(which he loved before), he sneezes a lot and now has slight eye mucus showing. His appetite is great still, very good motivated, still drinking water well… most things seem the same and normal, but his actual eyes are not the same. They’re distant, a slight cloudiness maybe, and his favorite toys have no bearing on him. We been scheduled for a vet check in 2 weeks but I’m not sure I should wait that long? He doesn’t seem like he’s declining, but he’s not happy, he’s not playful and moving around like usual. Really hoping this is something I can reverse 😞

    1. I’d say try and get him seen sooner if you can – it sounds like he’s painful, and eye problems can worsen dramatically in a very short time.

  13. My 19 year old cat has started to go blind at night. The vet put her on blood pressure medicine after the first incident and her pressure is controlled, but she still loses her sight for short or long periods at night. She doesn’t have kidney disease or glaucoma. We are stumped. What could be happening?

    1. Hypertension is really confusing; other possibilities might be chronic vascular disease, overactive thyroid, or idiopathic hypertension – however, a very real possibility in a cat of that age is that she’s suffering from mini-strokes. If so, over time, the medication will reduce their frequency, but there may be some permanent damage. Sadly, it’s one of the things elderly cats are prone to.

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