Is My Cat Blind?

There have been several posts or comments from visitors throughout the website asking questions about their cat’s eyesight. The most common is that the pupils of their cat’s eyes do not change, constrict or become smaller, when the light becomes brighter. The pupil is the hole located in the center of the eye that lets light into the eye to fall on the retina at the back of the eyeball. The iris is the part of the eye that controls the size and shape of the iris. When the pupil is fixed despite changes in light levels, what is happening?

Blind Cat

Blind Cat. Due to high blood pressure (BP)? Photo courtesy Vetlive

For me the obvious reason why the pupil does not contract when light falls onto the eye is because the light is not registering with the cat’s nervous system and therefore the natural reflex to narrow the pupil is not instigated.

The obvious reason why the nervous system has not registered light is because the retina is not working properly due to retinal disease such as retinal atrophy. Another reason is that something is wrong with the optic nerves that run from the retina to the brain. If the retina is working but the optic nerve is not functioning for whatever reason the brain will not receive the signals that is the image formed by the retina and lens.

The layperson’s test for checking for blindness is to shine a bright light into a cat’s eyes to test for pupillary constriction. If the pupils do not constrict I think you can make an initial diagnosis of some sort of blindness. This though is not an exact test for blindness. Apparently the pupil may contract due to a simple reflex but that does not mean the cat is seeing. However, I would have thought that if the pupil does not contract the first conclusion is blindness to some degree.

That initial assessment could be backed up by other observations such as:

  • In low light a cat with impaired vision might bump into furniture and
  • hold their head close to the ground to employ their sensitive whiskers to feel what is before and around them or
  • may hesitate to go out if she went out before or
  • be unwilling to jump on or off furniture.

It would seem that retinal degeneration is perhaps one of the most common causes. In some purebred cats it is a genetically inherited disease. Bengal cats and Abyssinians can have the problem (see Progressive retinal atrophy (PRA) in Bengal cats). Some authors also say it can affect Siamese and Persian cats too.

Another disease of the retina is retinitis. This is inflammation of the retina which leads to its degeneration. There are a number of causes including feline infectious peritonitis (FIP) and toxoplasmosis. Pulmonary hypertension can cause the retina to detach. If a cat has a deficiency in his diet of taurine it can result in retinal degeneration of the central part of the retina. The cat will have some peripheral vision. The same sort of partial blindness can be caused by an antibiotic called enrofloxacin.

Cataracts are obvious. Anyone can tell if a cat has cataracts. This is because the lens of the eye becomes opaque (cloudy rather than clear). Cats have very clear bright eyes usually. Cataracts will impair vision in varying amounts.


Comments

Is My Cat Blind? — 5 Comments

  1. Another obvious cause is some disrespectful and irresponsible pet-owner let their cat roam free. A neighbor who got fed-up with their cat destroying their property and animals aimed a high-powered pocket-laser laser into the eyes of their cat.

    If blinded in one eye a cat will lose depth-perception and no longer be able to capture wildlife as easily. The wandering cat otherwise senselessly destroying all valuable native wildlife if both eyes are functioning properly. If a cat is blinded by a laser in both eyes the cat will stay home where it belonged in the first place. Plus the owner can still show it all the affection it ever needed and wanted, only more now because the cat is finally staying home where it belonged to begin with. A win-win situation for everyone, cat and wildlife included.

    Blinding cats with high-power pocket-lasers is quite a popular method today to train someone’s cat to stay home where it belongs. Completely anonymous 99.99% of the time, inexpensive, silent, instant, and completely painless; even more pain-free and humane than having a cat declawed, spayed, or neutered.

    Is YOUR cat not blind yet? Keep it home while it still has its eyesight! Simple as that.

      • I hadn’t seen this article! How very cruel Woody is, only the most depraved sick in the mind person would think about deliberately blinding living creatures!
        Leanne I would gladly hold this scumbag down while you shone a laser beam into his eyes.
        I agree with Michael, he is a sh*t and a coward and has nothing better to do than look for places to vent his spite and hatred.

  2. April 1985 we adopted a kitten for a friend but that friend had been adopted out by a momma cat with kittens. As cat lovers/rescuers/helpers decision was made to adopt the young kitten, named Snuggles, a lover & hunter. Our male Russian Blue about 7 yrs old quickly adopted her. March 1990 we moved to a smaller town, Snugles & our senior Tortie moved with us during 2 separate trips. Our Tortie took the 2 hr trip very well, she decided nap till her owners reached their new home. Following trip Snugles came along, she absolutely made the trip memorable by her sheer screaming for 2 hrs. October 1996 a friend of our son “Carmen, what’s wrong with Snuggles eyes, they’re huge ? I called our vet & few minutes later were on route to have her eyes checked. Less than half hour later Dr Sugasky told us that Snuggles had a high degree of Glaucoma & would be blind in a very short time. She knew exactly where cat door was, never had an accident inside the house. A great hunter. Very territorial she would fight off large males that entered our property & climb up on the roof for better protection. She died peacefully in her sleep underneath her masters dining room chair close to 20 yrs old. Her picture sits on our mantle along the family.
    keenpetite
    Southeast Arizona (USA)

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