Siamese cats can inherit genes from parents that result in eye problems including progressive retinal atrophy, glaucoma, strabismus and nystagmus. The first two problems can render your kitty blind, while the second two give him a personality with misdirected and moving eyes.
Progressive Retinal Atrophy
About 33 percent of Siamese cats carry one mutated gene associated with progressive retinal atrophy. This disease will not affect a cat who only has one gene, but will make him a carrier. If a kitten receives two of these genes, he will suffer from progressive retinal atrophy. The eyesight is normal when born, and then the rods and cones in the retina degenerate and cause vision loss with the onset of blindness between the ages of 3 and 5 years.
Siamese cats suffer from primary glaucoma, which is rare and is inherited through the bloodlines. The watery fluid in the front of the eye, behind the lens doesn't drain well and puts pressure on the optic nerve. This nerve connects the eye and the brain for vision. The nerve damage prevents normal vision that can result in total blindness.
Strabismus is when one or both eyes are misdirected. The eyeball sits normally in the socket, but the direction of the eye can turn inward toward the nose, outward toward the sides of the head, upward or downward. Siamese cats are often born "cross-eyed," with both eyes affected by strabismus and pointing inward at the nose, or convergent strabismus. When both eyes are affected and point outward, it is categorized as divergent. This condition can be apparent at birth or it may develop later in life in felines. Strabismus that appears suddenly in an adult cat can be a sign of a serious eye problem, which needs veterinary attention.
Siamese cats may inherit nystagmus as a congenital condition. This is actually perceived as "normal" for a Siamese cat. The eyes involuntarily swing from side to side in a rhythmic motion. A slow movement in one direction then a quick motion in the opposite direction characterizes jerk nystagmus. Pendular nystagmus is when the eyes move slightly back and forth at the same rate of speed. Jerk nystagmus is more common and can include a Siamese cat who circles often or tilts his head to one side.