Strabismus is another name for eyes that are fixed in the wrong position. Astigmatism is another term for a vision problem where the cat cannot see the world accurately. Cats with strabismus have problems with depth perception and other vision problems, so all cats with strabismus have astigmatism, but not all cats with astigmatism have strabismus.
There are several causes for strabismus in cats. The most common is due to a genetic defect of the eyes. But other potentially lethal conditions such as encephalitis, injury to the eye or brain, feline leukemia virus and cancer can cause the cat's eyes to cross. The resulting eye position will cause the cat to stumble into things and perhaps be fearful to move.
Some cat breeds are predisposed to getting strabismus and astigmatism, but the Siamese breed seems to have been the originator. Any breed where the Siamese played a large part in original breeding stock may be prone to strabismus and astigmatism. These breeds include the Himalayan, the Thai cat, the Tonkinese, the Balinese, the Ragdoll and the colorpoint shorthair. According to veterinarian Dr. John McDonnell, one color in Persians, the flame or red point, also is prone to being cross-eyed. Albino cats may also be prone to strabismus.
There are two types of strabismus in cats -- divergent and convergent. In divergent strabismus, the eyes are turned abnormally, as if trying to look sideways, downwards or upwards at an object. With convergent strabismus, the pupils have a more familiar cross-eyed gaze, where the pupils are fixed close to the nose. Another name for convergent strabismus is medial strabismus.
Strabismus and astigmatism can happen at any point in a cat's life, depending on the cause. Even if the cause is genetic, the cross eyes may manifest at birth, or during development and aging of the eye muscles or the brain. It can happen to both eyes or to just one eye.
If the cause of strabismus and resulting astigmatism is due to genetics, then there is no cure. These cats should be neutered so as not to pass the gene along. But if the strabismus is due to an underlying medical condition, then treatment of that condition should allow the eyes to go back to a normal position.