Abnormal visual resolution in the Siamese cat.

When tested behaviorally, Siamese cats display marked differences in contrast sensitivity compared to ordinary cats. Overall sensitivity is depressed, the high-frequency cutoff point is lower, and there is less falloff in sensitivity at low spatial frequencies. Optical factors may contribute to these differences, or they may be attributable to the well-established anatomical abnormalities within the visual system of the Siamese cat.