The tapetum lucidum is an organ at the back of the eyes of many animals like cats and dogs that reflects back light that passed by the retina to have a higher chance of being absorbed again, which helps them see better in the dark. This can give the appearance of glowing eyes in flash photography or if a light is near the viewer.

As such, you should use this tag if a character is reflecting light from their eyes, otherwise use glowing eyes.

Humans do not have a tapetum lucidum, but may reflect light from blood vessels in the back of their eye in photos where red eye shows up.