The structure of a dog's eyes is practically no different from human eyes. They also have a cornea and a lens. The elements that make up the retina are also similar. The only thing that distinguishes a dog's eyes from human eyes is the set and arrangement of retinal elements.
Surely many have noticed that the pupils of a dog's eyes are more dilated than those of humans. This suggests that such eyes are more adapted to low light, which is especially important for dogs that are active at night.
Dogs, however, like humans, are characterized by such deviations in vision as farsightedness and myopia. So, for example, farsightedness in most cases manifests itself in dogs of wild breeds, such as wolves, jackals and others. But in domestic dogs, such a deviation is extremely rare and in most cases in breeds such as retrievers and greyhounds. As for myopia, until recently there was an opinion that this deviation is characteristic of all breeds of dogs, but in the course of the conducted studies, it was found that myopia is manifested only in such breeds as schnauzers, Rottweilers, and German shepherds.
Also in the course of the research, scientists have found that visual acuity in dogs is about six times lower than in humans. For example, dogs from a distance of one meter can notice an object in motion, and if the object is stationary, then only from a distance of six hundred meters. If the object is from the dog at a distance of thirty-five to fifty meters, the clarity of its vision is sharply reduced. But then the viewing area of her vision is larger than that of a person. It is two hundred and fifty degrees, which is about seventy degrees larger than the human field of view.
As for the perception of colors by a dog, unlike humans, it distinguishes only three colors: gray, yellow, blue. Here, for example, an object painted in red is seen by a dog in yellow, and green is distinguished by it as grayish-white. But unlike a person, a dog distinguishes a large number of shades of gray, which make up for it an absolutely complete picture of its environment.