reflective retina

[rpames]

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I saw the movie Pitch Black yesturday night. In the movie, one charcter had a doctor make his retinas reflective, like a deer's. I was surprised when a friend of mine, one of the smartest people I know, asked me how the reflective retinas worked. I was just curious about how many of you knew.

 

[r_salis]

(possible spoilers below...)
(I wasn't sure if you meant for us to post our replies)









Are you talking about the tapetum lucidum? We dissected a sheep's eye in lab last year and got to see this membrane, uh, "in person". 🙂

 

[rpames]

That is exactly to what I am refering. Nice job r_salis!

So does anyone else know how it works?

 

[cpw]

It is the tapetum ... but I'm not sure how it works... I would venture a guess that it's the same kind of thing that makes the foveal reflex... but again, it's just a guess. (an educated one.. but a guess none the less). Any vet students out there want to help us out.. 😀

 

[rpames]

I as hoping some one else would post it, but he it is:

Basically it works like an amplifier, the photon passes through the retina and excites a rod or con, just like a human eye. Here comes the cool part, that same photon is then reflected directly back off the tapetum at the same nerve and stimulates it again. Essentially it is like putting a candle infront of mirrior to increase the light. This then of course allows these animals to see very well low light situations. I think it is very cool. I guess it shows why I like optometry.
😎

The fovea reflex on the other hand does reflect light, but not in a way that re-stimulates the retina, nor is light reflected by the entire retina. The tapetum bounces the light all over the inside of the eye while the fovea focuses the light into a point within the vitreous.