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You are here: MacNN Forums > Community > MacNN Lounge > Red eye effect result of blood? I call BS

Red eye effect result of blood? I call BS
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design219
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Jun 23, 2015, 12:07 PM
 
Yesterday Jeopardy had a question (answer) that said the "red eye" effect is caused by blood in the back of the eye. I immediately thought, no, it's refraction and splitting of the spectrum like a prism. I'm sure of this because I've seen the effect be blue in dogs and even greenish/cyan in cows.

But just to verify, I started looking around the web and almost everything explains it as excessive blood in the back of the eye. Even if that were right, I always thought blood was rather dark until exposed to oxygen.

Does anyone have a good answer to this question?
( Last edited by design219; Jun 25, 2015 at 02:13 PM. )
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Doc HM
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Jun 23, 2015, 02:05 PM
 
I'm with you mr the Kidd.

Afaik the red blood explanation is just pop science. Cats and dogs have the same colour blood but show blue and green eye.

I had always thought this was due to refraction but also like you am finding Google a tad light on the subject.
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ghporter
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Jun 25, 2015, 05:23 PM
 
Retinal reflection is why humans have "red eye" in photos. Blood flow isn't going to effect the reflective quality of the retina much. It had [u]better[/i] have good blood flow, but the retina is reflective for a number of reasons. One is the interface between the vitreous and the retina itself; that transition from viscous liquid to cells is a natural reflective layer.

Different cats typically have different reflected colors. Most reflect green. Except Siamese cats; their eyes reflect red. It's a genetic thing not as much related to eye color as being Siamese.

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