I have a beautiful long haired tabby/ tortoiseshell cross 1 year old but her right eye pupil is wide open and does not dilate, the left eye is similar but not as bad, the vet finds this ‘strange’ but is obviously not familiar with the problem. Can anyone help please?
Derek

Hi Derek: I am not sure that you have described the problem accurately. If the pupil is wide open it is dilated. Perhaps you mean that the pupil does not change shape or narrow. The pupil is the opening in the center of the eye through which the light passes and which is narrowed or enlarged to control the amount of light entering the eye. The iris (a muscular structure) opens and closes the pupil. In the cat the pupil is slit like and the amount of light entering the eye can be further controlled by the eye half closing and going over the slit.
Iris not responding to light input
If the iris is not responding to different light levels by closing and opening the pupil it might indicate that your cat is blind or partially blind i.e. light is not being received and no signal is being sent to the brain to regulate its impact on the retina. Blind or partially sighted cats can cope very well and therefore hide the problem.
Hypertension
Sudden blindness is often caused by untreated feline hypertension. Early signs to watch for include dilated pupils which don’t respond to light. It appears that this is what is happening with your cat but I am not a veterinarian. Seek veterinary advice please.
Hypertension can damage the blood vessels in the retina and it can cause the retina to detach which in turn can cause partial or complete blindness on my understanding of this disease.
Any disease that reduces the sensitivity of the retina to light impulses such as retinal atrophy or a disease which affects the optic nerves or that part of the brain which processes information from the optic nerve (e.g. brain trauma) can produce visual disturbance including blindness which can cause the operation of the irises to change which in turn can lead to the pupil being in an always dilated position.
Retinitis
High blood pressure (hypertension) is one of the most common causes of retinitis which is a disease of the eye in which inflammation of the retina leads to the degenation and destruction of the light receptors. There are various causes including toxoplasmosis, feline infectious peritonitis, lymphoma, and systemic fungus infections but, as mentioned, one of the most common causes is high blood pressure.
Test
Shining a light into your cat’s eyes is not a guaranteed test of whether they are partially or completely blind. It is not exact enough because the pupil may become smaller because of a reflex action. In which case it doesn’t tell you if the brain is receiving visual images.
Perhaps a more general way to diagnose if a cat is blind is through their behaviour and activity. Activities that require good body coordination such as jumping from a sofa to a chair may show that the cat’s abilities are impaired. And sometimes in a dimly lit room cats with limited or no vision may bump into furniture. They may hold their noses close to the ground and feel ahead with their whiskers which are pointed forward.
Deafness
Sometimes, with older cats their eyesight might fail soon after they become deaf. They then have to rely more on memory to find their way around their home. Many blind cats get along quite well because they are familiar with the surroundings and they can use their other senses. Everything in the home should be kept in its place this reason.
Of couse there is no substitute for a good vet providing advice on the spot.
From My cat has dilated pupils to cat health problems.
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Marianne, your story is touching. You have a wonderful cat. I find it strange that your vet found permanently dilated pupils to be OK. That can’t be right surely? The brain closes down the iris in bright light so there is some sort of neurological problem. There has to be even if he is not blind. Has he been tested for blindness? Thanks for sharing.
Miss Ashleigh, I hope your cats eyes are not from inbreeding.. I have a 16 yr old male mackerel tabby. this past january he had a runny eye, vet treated it with drops. two weeks later he had a huge lup on his brow, it was soft-like and spongy. vet said it was cancer and my husband wanted an antibiotic. (couldn’t hurt) . one week later the lump was gone. he is still with us today except now he has fixed and dialated pupils.. even in the light. the vet has no concern with this.. I do!!.. he stopped playing and I have to point and tap for him to get his food. vet checked the eyes and examined the optic nerves in the back and are clear… . my cat had no inbreeding and was in a litter of 3 kittens that burned in a fire except for him.. he is a very special cat. and has fought off a lot of medical problems that the vet said he would never live thru. he is getting weaker now but my concern is that he cant see and is scared. he is always in my face to smell my lips when I talk to him.. I wish I knew what the dilated pupils ment…
This is the article and response…
The response to this is in a post: My cat has constantly enlarged pupils. Any ideas?
Hi Miss Ashliegh, I have a response prepared. I have decided to convert your comment to an article and respond to it by adding my own text. I’ll do this in the morning GMT (about 12 hours time).
Thank you Miss Ashleigh. I’ll read your comment carefully this evening and respond as fully as I can then.
I realize this post is old, but just in case people are still reading…
I have a 7yo cat who was the runt. She weights ~3.5lbs. A mini-kitty. Bottle-fed as her ma didn’t allow her to feed. I took her in after living with her for a year as the roommate was just going to ‘let her go in the woods.’
She is highly skittish (more so than most cats,) and it’s taken me all these years to gain her trust. She sleeps on me & kneads, etc, and is the sweetest, and weirdest, cat I’ve ever had.
I found out a few years ago that she was ‘a baker,’ as we affectionately call her, instead of inbred ( mother/son.) She goes feral when taken out of her environment, even vets are scared of her; her tone gets low & she won’t allow touching & forgets who her protectors are.
As she’s so tiny, we’ve always referred to her as being ‘all eyes and whiskers.’ It wasn’t until about a month ago when we took in a stray (doppelgänger, but growing,) that I realized her constantly enlarged pupils weren’t normal. (@ first I thought something was wrong with the other cat.) Then it slowly dawned on us that her vision may be compromised. She’s clumsy, but so are we, so we always joked she took after us.
Big, round, black pupils. All the time. When calm, loving, active, spazzing, half-asleep.
I’m afraid the vet brings so much trauma (lasts for days. & vets have to ‘gas her’ to get near,) so I don’t subject her to visits unless she’s sick, which she rarely has been. She does not adapt to change well. She seems to be in good health, and is a loving sweetheart, and I am also very poor right now, so unless she showed signs of illness, I wouldn’t be able to take her to the vet (& she’s ‘flagged’ at local vets.)
However this’s pupil thing has me questioning her vision. She doesn’t walk into walls but she misses jumps & is timid navigating.
Any ideas? Could this be from the inbreeding & not a sign of blindness? She’s always been this way, since she was months old.
Thanks,