Monday, October 28, 2013

Monday Medical: Why do cat's eyes glow?

Many of you have seen the recent article that's been making the rounds, where photographer Nickolay Lamm produced a series of photographs that are his visual interpretation of the way cats see differently from humans. It's hit all the major news outlets - Huffington Post, NBC,, and others.

While I'm not completely convinced of its accuracy, it did spawn a lot of discussion.

So I thought I'd add to the discussion by re-running an article from last summer on why cats' eyes glow in the dark. It was a lot of fun to research and write. Enjoy!


If you’ve taken many pictures of your dog, cat or ferret, then you’ve seen it: laser eyes!

It’s a phenomenon specific to only a handful of animals; other species like rabbits, guinea pigs – even humans – just don’t genetically have that "special glow."

Those that do are gifted with a unique surface in the eye behind the retina called the tapetum lucidum. This special surface is composed of 15 layers of glittery cells that combine to create a single reflective layer to capture and enhance light.

Any light that gets past the retina is bounced back at it, giving the photoreceptors in the retina more data - and a second chance - to resolve the image.

Basically it functions a bit like nature’s very own night vision goggles! Cool, huh?

Why do Siamese eyes
glow red instead of green?

I had never really paid any attention to the color of the boys' eyes when they glowed until someone mentioned this to me. The claim was that Siamese eyes glowed red while all other breeds glowed green.

Of course, I had to test this empirically. So out came the el-cheapo camera (you know, the one guaranteed to get the bad photos - and red eye - every time!).

Test Subject One: Allie

Yep, green!

Test Subject Two: Faraday

Look! Red eyes!

Test Subject Three: Maxwell

Seriously red eyes! We were shocked at how red, in fact.
Of course, that begs the question, what causes this?

Contrary to what Wikipedia states (you do know Wikipedia can be wrong, don't you?) Siamese cats do have that cool night vision layer behind their retinas. But unlike other breeds, there is a hereditary abnormality in Siamese that weakens the tapetum lucidum. So a Siamese cat probably won't see as well in the dark as other kitties.

Since Faraday is a Tonkinese (a blend of Siamese and Burmese), you'll notice his eyes are less red than Maxwell's. He probably sees better at night that Maxie.

So there you have it.
Cats: cool, built-in night vision goggles.
What's not to love?
"Hereditary abnormality in tapetum lucidum of the Siamese cats. A histochemical and quantitative study,"  Histochemistry, 1982;75(1):1-9. Published by National Institute of Health's PubMed site 

"Why do animals' eyes glow in the dark?" - NPR

"How Stuff Works" 


  1. That was very interesting. Wonder what colour ours are. Have a marvellous Monday.
    Best wishes Molly

  2. Great share. Thank you for pointing out how Siamese cats have a different glow. I have read before how the glow in our pets eyes make them see better in the dark (like glow in the dark stickers retaining more light) but the Siamese thing was new.

  3. "Hereditary ABNORMALITY"??? No no no...yoo see we ARE special and our eyes glow red because the '15 glittery layers' of cells in our eyes are RUBIES! Burmese rubies at dat. So....tanks for da info, I'm so proud of my not 1..not 2 but 15 glittery layers! Pawsome!

  4. Mommy says every time she sees the word tapetum, it immediately makes her think tapeworm. Silly Mommy!
    Thank you for posting about this. It's very interesting!

  5. Äiti says this is most interesting, but she has photos of Mirsku taken with the same camera but his eyes staring back at different angles, showing different colours of 'red eye' from him. This made her think, and she could not solve the problem. And she did do a blog post about it but cannot remember when! It was a couple of years back.

  6. Wow, that's fascinating! Moosey's (blue) eyes glow red when a flash is used, too.

  7. Did you know that blue eyes tend to create more red eye in pictures then eyes of a different color.. (said the red headed blue eyed woman)

  8. Yes! That's because with blue eyes there is no melanin in the iris to partially block the light. Melanin is also responsible for all eye colors aside from blue. Blue is technically the absence of color (aka melanin). We wrote about that, too. We may have to get mom to re-run that article sometime soon, because it was another fun one!!

  9. How fun! Quill has really strong lasers.

  10. That really was cool info, but we always thought it was a poor photographer!

  11. We had heard some of that, but not all of it. Really cool stuff!

  12. The Human said this was fascinating reading but me, I just wanted to bat around that thing that Maxwell was playing with.

  13. fab, I feel so much wiser when I pop by and say hi to your guys!

  14. That was so interesting, never thought about it before. I always try and catch Alfie with lazer eye'z. xxooxxx

    Mollie and Alfie

  15. This is very interesting!!! I never realized that Siamese Cats eyes glowed a different color. I think cat's eyes are fascinating. I do wish I could figure out how to take a picture of my cats without the glowing eyes. It worked out great for Halloween but I wish I could take some pictures of my kitty's where they dont look like they are possessed. Cali, Andy, Tater and Shelly (C.A.T.S) and Judy

  16. We had noticed that Marley's eyes glow green while ours glow red, but we had thought it was because his eyes arent blue like ours. Now we know the difference. Thanks. ~ Ayla and Iza

  17. SO interesting!!!
    And your timing is perfect! Just this past weekend, I was working on my photography session powerpoint and I had to get a really bad picture of Waffles using a flash. So I pulled out the dusty P&S and sure! Poor Waffles...he doesn't even look like the same cat his pic is so bad.

    Those red lasers are COOL!!!!

    ; )


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