Actually, I suspect the world looks like collection of Cat Toys. (Anything not nailed down is a Cat Toy).
As far as the slit pupil thing goes, the quotation above about horizontal vs. vricalmotion comes close, bt doesn’t quite get to the truth. Here is the real deal:
The resolving power of a optical system depends upon a number of factors, but all other things being equal, the larger the aperture is, the greater the resolving power (perversely, the larger the aperture, the smaller the f/# is. Don’t blame me for this – I didn’t come up with the definitions.).
However, when your system gets flooded with light, you have to close the aperture (“stop down” the system, to you photographers). You trade off being able to see against better resolution. The human eye, and most animal eyes, and camera lenses all solve thi problem with a aperture that remains cicular, but shrinks down in diameter. You lose resolution eqally in all directions.
The cat eye, however, along with snake eyes and a few others, keeps the same vertical dimension, and only shrinks horizontally, frming a vertical slit. As a result, the cat retains excellent vertical resolution (it can see really fine detail of horizontal objects), but has even worse horizontal resolution than your eyes.
Why is this? It may soundcorny, but it’s the only solution that makes sense to me – cats want to be able to see things like mouse tails, that are really small verticaly and lie out horizontally, but they don’t care about seeing grass, which is very fine horizontally. In fact, it works to the cat’s advantage to be able to see the mouse tail and NOT see the grass. Snkes, too, would like to be able to see mice and other prey amidst the grass.
I have to point out tha Big Cats, like lions and tigers, don’t have vertically-slitted “cat’s eyes”. (Look closely at photos of them sometime, or go to the zoo.) This, I think, means that they don’t particularly want to see fine vertical detail – ions don’t hunt mice, for the most art. Ths also means that those reconstructions of T. Rex and other big dinosaurs that show them with snake-like vertical pupils are almost certanly off the mark.
For the record, the frequency response of an optical system i called the Modulation Transfer Function, or MTF. I worked for a company that measured this for eight years, but we never discussed the issue of cat’s eyes. I ant to write a detailed article about t someday.