I think the tweet above should get you past the paywall. Here is the paragraph I love in this article:

A cat—like its fellow nighttime predators—effectively has a narrow pupil in the horizontal direction but a wide pupil in the vertical direction. So anything along the horizontal plane is in beautiful sharp focus, and the image is more blurred in the vertical direction. But at the right focal length, the image will be perfectly in focus in both directions, and that gives the cat an extra way of judging distance.