Acuity in cats is 0.2 times that of people, 0.33 times that of horses, and 0.5 times that of dogs. Aphakic condition in dogs and horses is hyperopic. Aphakic horses are 8-10 D hyperopic. A small pupil would help correct some of the aphakic hypermetropia. The preponderance of large diameter axons and large ganglion cells indicate that the dog should have good motion detection and high temporal contrast capabilities.
Acuity is less than humans and horses, but greater than the cat.
Siamese cats have fewer ganglion cells, little stereopsis, less acuity and too much crossing over of optic nerve axons at the optic chiasm. The vertical stenopaic slit pupil of the cat allows for maximum light control and optically decreases astigmatic scatter in the horizontal meridian. The horizontal pupil of the horse would minimize scatter in the vertical meridian. The lens of dogs and cats has weak accommodative ability and therefore they have limited near focus capability. The minimum threshold of light for vision in cats is 6X lower than that of humans.