The glowing eyes effect is a result of the tapetum lucidum.It is a tissue layer in the eye that reflects light visible light back through the retina, thus increasing the light for the photoreceptors. It is often found in nocturnal animals, especially carnivores, thus allowing for their increased night vision.(Not my gif. Spazzy computer was having issues with the original reblog. If yours, let me know and I’ll add credit.)

The glowing eyes effect is a result of the tapetum lucidum.
It is a tissue layer in the eye that reflects light visible light back through the retina, thus increasing the light for the photoreceptors. 
It is often found in nocturnal animals, especially carnivores, thus allowing for their increased night vision.

(Not my gif. Spazzy computer was having issues with the original reblog. If yours, let me know and I’ll add credit.)