21

Multiple sources on the internet (including answers on this site) claim that red-eye is created by light from the flash reflecting on the blood vessels in back of the eye.

So, why do animals like dogs, that I believe also have red blood (I'm not going to injure my dog in order to test this, but I'm pretty sure the blood is red) have green-eye?

  • 2
    Maybe some sort of vegetation growing on the back of pet's eyes reflecting the light? – Nir May 2 '11 at 13:35
  • 1
    ...and lets not forget Riddick – Jakub Sisak GeoGraphics May 2 '11 at 15:24
  • +1 for not injuring your dog. (Also, good question :P) – poke May 2 '11 at 17:59
20

Many animals, including cats and dogs, have a reflective layer of cells at the back of the eye called the tapetum lucidum ('the tapestry of clarity'). This reflects the light back through the light-sensitive cells in the retina for a 'second pass', allowing the animal to see better at night.

  • You don't have to do photography to notice this green reflective layer; staring into a cat's eye at exactly the right angle will let you see that at naked eye :) – badp May 2 '11 at 18:17
  • Yup, headlights are particularly effective at showing them up. – ElendilTheTall May 2 '11 at 18:49
  • Nice answer, +1, but no one as yet has explained why the color is green specifically... – Uticensis May 2 '11 at 20:47
  • 2
    @billare: actually, eyeshine can be white, green, blue, yellow or pink, depending on the angle you view it at. – ElendilTheTall May 2 '11 at 20:57
9

According to Wikipedia it seems that animals that exhibit this phenomenon ("eyeshine") have an extra layer of tissue within their eyes that cause light to be reflected in a different way.

enter image description here
Source: Wikipedia

  • 1
    Wikipedia has a picture of a cat which dramatically illustrates red eye and "eyeshine" occurring simultaneously. – Please Read My Profile May 2 '11 at 14:03

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.