22

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?

Improve this question
3
  • 2
    Maybe some sort of vegetation growing on the back of pet's eyes reflecting the light?
    – Nir
    May 2, 2011 at 13:35
  • 1
    ...and lets not forget Riddick
    – Jakub Sisak GeoGraphics
    May 2, 2011 at 15:24
  • +1 for not injuring your dog. (Also, good question :P)
    – poke
    May 2, 2011 at 17:59

2 Answers 2

Reset to default
21

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.

Improve this answer
4
  • 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, 2011 at 18:17
  • Yup, headlights are particularly effective at showing them up.
    – ElendilTheTall
    May 2, 2011 at 18:49
  • Nice answer, +1, but no one as yet has explained why the color is green specifically...
    – Uticensis
    May 2, 2011 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, 2011 at 20:57
10

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

Improve this answer
1
  • 1
    Wikipedia has a picture of a cat which dramatically illustrates red eye and "eyeshine" occurring simultaneously.
    – mattdm
    May 2, 2011 at 14:03

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

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