Yes, Siamese cats have eye problems relating to vision. They are quite well known because of the Siamese cat’s squint. However, the extent of the eye problems are probably not fully appreciated by most cat owners.
Line breeding – aka inbreeding – of Siamese cats has perpetuated the genes that are a disadvantage to the cat and which would have been selected out if these genes had been carried by free-roaming stray cats. Genes which cause problems get in the way of survival and therefore they are selected out over time.
Siamese cats have poor stereoscopic vision2. This is because of a lack of nerves in their brains designed to compare the signals coming from the left and right eyes. Stereoscopic vision provides 3-D vision giving depth to the image.
This results in Siamese cats seeing double. Or Dr Bradshaw says, ‘one eye may shut down completely, sometimes causing a squint to develop’.
There is another Siamese cat eye problem. A malformation in the retina1 which may cause a temporary impairment in their vision by blurring when they move their attention from one object to another.
A condition called nystagmus is also quite common in Siamese cats. The eyes jerk back and forth. This condition is not confined to Siamese cats. This is may be caused by vestibular disease (disease of the inner ear where a cat’s balance is regulated).
Note 1: the retinas of cats contain two types of ganglion cells, Y-type and X-type. Y-type responds to movements and inhibit the output of X-type cells when the eyes are moving. Siamese cats have about 14% of Y-cells compared to 35-45% in cross-breed non-orientals.
Note 2: Normally around 35% of the cat’s nerve fibres stay on the same side of the brain. This allows comparisons to be made between the images from each eye. However, in Siamese cats ‘few binocular driven calls can be detected….’. Behavioral evidence suggests that they do not have stereoscopic vision.
Source: Cat Sense by Dr John Bradshaw and The Behavior of the Domestic Cat by the same author and Rachel Casey and Sarah Brown.
I’m an optometrist and multiple-cat owner. I also have crossed eyes. It’s been established in the scientific literature that cross-eyed cats, like many humans, do not see double, nor do they suppress an eye. They are wired from the optic chiasm and/or lateral geniculate nucleus of the thalamus to see single with their eyes crossed. The debate will continue about purebred pets in an age of overflowing shelters, but from the cats point-of-view, their vision is not a problem.
Thanks James. I did know that Siamese cats see okay because they have processed the cross-wires. I think the following post covers the point.
https://pictures-of-cats.org/why-siamese-cats-are-cross-eyed.html
I have these same eye problems and always greet color-point cats with, “Hello, Nystagmus-Twin.” The vision problems mostly cause me trouble with reading. I wouldn’t exactly call that a reason to stop breeding Siamese, haha!
My “Siamese”, is not a purebred, however I found this website because I was concerned about my siamese-looking street cat Monkey. He came from a mixed litter trapped by a kitty rescue place, I also have his pure grey sister. I noticed some peculiarities about him, how he liked to spend days when the house was busy under the bed, (not with the other cats at the patio door watching the squirrels), not in the thick of things, only coming out when the routine was quiet. He also would shy away and run if you approached him to quickly or did not announce yourself or call out his name when you entered the room. The final straw came when I was playing with the other cats with the laser pointer and I realized he did not see it even when I pointed it right in front of him. It finally dawned on me that his vision was very poor, so he was nervous because he could not figure out what that big thing coming at him was unless you announced yourself first. Poor kitty!
I believe that this is true. Many Siamese cats have eye related problems, but certainly not all of them. My kitty, Nikki Hana, is nearly 19 years and 4 months old. She is the traditional Siamese, also known as “applehead” Siamese. I have not noticed any problems with her eyes per se, although she has other health problems. I am thinking that maybe the traditional siamese have less eye problems than the “modern” siamese, due to all the breeding that has taken place, as you stated.
Thanks for your information on Siamese. I think back to a Siamese mix female I had and realize maybe she had Nystagmus. Her blue eyes would rapidly move like you describe. Her head would bob slightly left and right too at times. My current Siamese has microphthalmia..”tiny eye.” But it doesn’t seem to be a breed related problem. He cannot see out of his right eye but it doesn’t bother him.
now THAT is sad! when i read things like THIS it just proves to e how inhumane we r to these “purebreed” cats to where we INSIST on inbreeding them so we get specific traits, but which also cause others that put them in danger & lessen their quality of life, cuz im sorry but i cant imaine acat out there that would say, “sur i will keep the eye problems so i see the world around me in a COMPLETELY messed up way just so i can look ‘cute’ to YOU.” its cruel! would WE allow OURSELVES to go through life like THAT(no stereoscopic vision, etc)? yeah, i think NOT! how can WE do stuff like THAT, or even say, “awww that looks sooo cute!” knowing just how impaired the cat is & STILL call ourselves “cat LOVERS”?! of course the upper-class cat-breeding/showing world WONT stop it cuz they make to much MONEY off of it, & have)too much power within said world(which means they have too much to lose if/when others disagree & get snotty over it. its sad when that kind of thing happens. its just like with that other breed where theyre eyes r too far apart which makes it harder for them to see too!
these animals r so loving, & caring, & they depend on US for everything. we have a HUGE influence on their lives because of it. all they ask us is that we love & protect them. we love them so much we insist that they live their lives handicapped cuz WE like it. makes me wonder if they dont need to be protected from US. yes i know, MANY of us DONT like it & say so, but isnt there a way to contact the breeding clubs & tell THEM that its wrong? or start up a petition to get that practice stopped? i mean, when i was a kid i had an English Boxer & unlike the American version only their tails were docked cuz ear docking is considered barbaric(or was i dont know if thats still the case now-a-days. tail docking is necessary cuz they can break their own tails just by wagging it sometimes). so if a common practice can change in the dog breeding community then we SHOULD be able to change THIS as well. i hope im not out of line by putting THAT out there, but i feel like WE should DO something about THIS. if im out of line cuz THIS isnt the place for that then i apologize. i remember how much it sucked when i had to wear an eye-patch for a few weeks. my vision was so messed up. i HATED it! yet these poor kitties have to live like this their WHOLE lives, & , to me, that is sad, heartbreaking even. knowing theyll live their WHOLE LIVES this way cuz the people they loved & trusted did it to them & wouldnt let them change it.
I agree with you Ed. We should do something about this. But we (the public) accept it. We are passive about it. And breeders certainly accept it and sometimes promote ill-health in cat breeds. The Persian is another example. And breeders often keep their breeding cats in poor conditions. I accept the views of others but if I had my way I’d ban all cat and dog breeding.