Animals see the objects around them due to the fact that the light that passes into the eye irritates the retina. These irritations are transmitted along the fibers of the optic nerve directly to the brain, which translates them into an image. If there is no light in the room at all, that is, it is pitch darkness, the cat, contrary to popular belief, will not be able to distinguish objects, because light does not enter the eyes. So in complete darkness all animals and people see equally badly.
However, in the twilight, sometimes absolutely impenetrable for humans, cats are much better oriented in space, especially if they are in motion. There are three reasons for this phenomenon.
The ratio of rods to cones
In the retina, there are two types of nerve endings - cones and rods, the names of which correspond to their shape. Cones react most strongly to bright light; they are responsible for color vision and the eye's perception of fine details. Rods respond best to low-intensity light, and they cannot reproduce harsh images. So it is the functioning of the rods that determines the twilight vision. The ratio of rods to cones in humans is only 4: 1, while in cats it is 25: 1. As you can see, the difference is palpable.
The presence of a reflective layer
Unlike humans, a cat has a reflective layer (“blanket”) that is located just behind the retina. This layer reflects light rays entering the eye and irritating nerve endings back to the same endings. That is, each ray of light has a double effect on a specific nerve ending. It is thanks to this layer that the effect of the "cat's eye" can be observed, when a ray of light directed from darkness directly into the eyes of the animal, reflecting from the "veil", creates the impression that the eye glows in the dark.
Dilated pupils
In all animals and humans, the pupils of the eyes tend to dilate in low light and shrink in bright light, trying to keep the amount of light directed into the eye at a constant level. So in a cat, the pupils can expand and contract very significantly. In bright light, the cat's pupil turns into a narrow slit, and in the dark it expands so much that it reaches almost a centimeter in diameter. Thus, at dusk, much more light enters the eyes of a feline than, for example, humans.
Combining all these three factors, we can say with confidence that a cat sees much better than a person in poor lighting conditions - about 5 times.
