#Cats have some of the most unique eyes in the animal world. Instead of having circular pupils like humans, the black parts in the centres of their eyes are vertical which can adapt quickly and can open and close like the aperture of a camera. Pupil shape and size determines how much light gets to the eyes and is then translated by the brain into a picture of the world around us. When it’s dark out, pupils expand to let in more light and enhance our vision, but when it’s bright out, our pupils get smaller to prevent overstimulation.
Source: Cat Eyes by Adriano