Cats are crepuscular, meaning they are active at dawn and dusk which may be why they need such good night vision. Their eyes have six to eight times more rod cells, which are more sensitive to low light, than humans do. Scientists know a lot about what cats see.
Unlike humans who can see more vibrant colors during the day, cats have the edge when it comes to peripheral vision and night vision.
Cats have a wider field of view, about 200 degrees, compared with humans' 180-degree view. In addition, cats' elliptical eye shape and larger corneas and tapetum, a layer of tissue that may reflect light back to the retina, help gather more light. The tapetum may also shift the wavelengths of light that cats see, making prey or other objects silhouetted against a night sky more prominent.
Because the human retina has about 10 times more cones, the light receptors that function best in bright light, give us the edge in the day time and w humans have 10 to 12 times better motion detection in bright light than the cat or dog, since bright-light vision is a cone function.
Humans have three types of cones, allowing them to see a broad spectrum of colors, with sensitivity peaks at red, green and blue. While cats may have three types of cones, the number and distribution of each type varies. In behavioral tests, cats don't seem to see the full range of colors that most humans do.
Humans also can see with much greater resolution, with a greater range of vibrant colors, thanks to their eyes' many cones. Humans can see objects clearly at 100 to 200 feet away, but cats need to be no more than about 20 feet away to see those same things sharply.
Some experts believe cats' color vision is limited to blue and grays, while others believe it is similar to dogs', but with less richness of hues and saturation of the colors. Dogs see the world in fewer hues than humans do and cannot distinguish between red, yellow.
Because cats lack the muscles necessary to change the shape of their eye lenses, they can't see things clearly quite as close as humans can and need to be further away. Cats may be better at picking up the darting and scurrying of a mouse, but there are many slow-moving objects that humans can detect that look stationary to cats.
How does the world actually look to a cat? See this Popular Science article.