Why do cats’ eyes glow in the dark?

The tapetum lucidum, Latin for “bright tapestry”, acts like a mirror behind the retina. Light that passes through the retina without being absorbed is reflected back for a second chance at being detected, greatly improving night vision. When a torch or car headlight shines on a cat at night, some of that reflected light exits the eye, causing the eerie glow called eyeshine. Cats can see in light levels about six times dimmer than humans need. Many other animals, including dogs, deer, cows and crocodiles, also have a tapetum, while humans do not.