Why can dogs see at night?

Dogs have more photoreceptor cells in their eyes.

For dogs, its world is not as colorful as ours, but its advantages are obvious, and it is unrestricted to come in and out at night. The light at night is very weak, and it is basically dark in our eyes at night, but the dog's light sensitivity is very strong, and the world it can see is different from ours.

The existence of reflective tissue gives the retina two chances to capture the light entering the eyeball, thus improving the dog's vision in low light. The dog's eyes will shine in the dark, which is caused by this reflective tissue. However, this kind of reflective tissue, which is very useful at night, is not so powerful during the day. It will scatter some light and reduce the dog's vision in normal light.

In the dark and dim light, dogs' eyesight is also better than people's. Dogs are naturally occurring carnivores and make a living by hunting, so they also have proper eyesight in the dark. Dogs' eyes can see short-wavelength colors.

There is an extra choroidal layer on the dog retina, which has strong reflection and can also improve the dog's night vision. Because light entering the eye will hit the photoreceptor on the retina, but it may also miss and penetrate the retina; But for dogs, because of the choroidal layer, even if the light misses and does not hit the photoreceptor, it will still reflect back to the retina, resulting in the so-called second vision.

Therefore, at sunrise or sunset, dogs can see more clearly than people, but they can't see in the darkness where there is no light at all. In addition, the dog's cornea is larger, allowing more light to enter the eyes, so it is easier to see things in dim light.