Anomalous retinal pathways in the Siamese cat: an inadequate substrate for normal bioncular vision.

All major retinal pathways in the Siamese cat are abnormal, with almost total crossing of the projections to the pretectum and superior colliculus. These projections represent a marked disruption in the customary neural substrate for binocular vision, which implies a consequent impairment in stereoscopic depth perception. Crossed eyes, commonly seen in the Siamese cat, may therefore arise from a neuroanatomical defect in the primary visual pathways.