Did you ever wonder why Siamese Cats appear to be cross-eyed? Did you know that it is really a function of the coat color rather than any problem with their eyes. Well, it’s true – the gene that causes the beautiful coat color possibilities in the Siamese and Himalayan also affects their eyes and the “routing” of visual pathways in their brains.
The color variations in Siamese and Himalayan cats are caused by pigment production that varies with temperature. Pigment is produced in areas of greater heat loss, such as the extremities and is absent elsewhere. The Siamese trait therefore represents an imperfect form of albino in which there is some pigment but not a full complement as seen in other breeds.
Siamese cats, because they are deficient in pigment production, lack pigment on the retinas at the back of their eyes and therefore fail to develop normal visual pathways.
These pathways are abnormal in all Siamese cats but vary amongst individuals in degree. As a consequence of this misrouting from the eyes to the brain, a portion of the visual field is opposite of normal or inverted.
Siamese cats have learned to compensate for such misinformation by some brain “rewiring” but all Siamese cats lack binocular vision, the ability to form one picture from two eyes. The visual fields are therefore altered in Siamese cats, and their visual precision is decreased.
Siamese cats often develop a cross-eyed appearance (convergent strabismus) during their third month of life in an effort of their brains to create a complete visual field; abnormal eye position is necessary to optimize visual perception. Although we don’t tend to think of Siamese cats as any real kind of albinos, they do represent an important model of the effects of pigment and the genes that control them.