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01-20-2012, 03:12 PM
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#61
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I just dissected two dragon eyes. I found sclera and goo. Nothing that resembles an iris. The eye was frozen and denatured and I have still not reached a conclusion.
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01-20-2012, 03:14 PM
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#62
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tell me how to upload a pic then i will help you make a conclusion.
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01-20-2012, 03:14 PM
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#63
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are you a surgeon or pathologist?
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01-20-2012, 03:18 PM
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#64
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wait i figured it!
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01-20-2012, 03:30 PM
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#65
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Ok here are the pics. After these it is fairly conclusive that bearded dragons do have an Iris (Irises? plural? Haha English is not my first language.)
The first photo is from "Infectious diseases and pathology of Reptiles" by Elliott R Jacobson. It shows the histopathology of the cornsnake eye.
I encircled the IRIS. Thus we now KNOW that cornsnakes have an iris.
From my picture uploaded above we can see that cornsnake eyes are very similar to bearded dragon eyes. We can thus CONCLUDE that bearded dragons also have IRISES?
The second picture is a PM I have done several years ago. (This female is the great great grandmother to the Witblits bearded dragons).
The tags are obvious.
Now I have PROVEN (almost) that bearded dragons have an iris.
Ok so that is out of the way now. Back to the oroiginal discussion. Why are some bearded dragon eyes BLUE?
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01-20-2012, 03:55 PM
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#66
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"Why wouldn't the iris respond to light?"
The iris would (and does) respond to light. That is the main purpose of the iris. To control the amount of light that enters the eye via the pupil. This miosis is quite obvious in mammals. In the dragon it is quite subtle. I suspect it is because they are more used to sharp light conditions.
What I have noted is how reponsive their iris is to focussing. The iris/pupil would react more towards different focus levels than towards light sharpness.
This is different than in mammals. Our iris/pupil plays a small role in focus. The ciliary muscles of the lens does the work here. I think once again it is due to the fact that beardeds eyesight is their main sense.
Why is the iris vascular and white?"
I dont know why it is so vascular. In humans the sclera is quite vascular. Perhaps these bloodvessels are not on the iris but rather part of the cornea in the bearded dragon. This will have to be shown by histopathology.
White. I havent seen one that is white. They have an off-white (which means there are pigment in them) background colour but the majoroty of the eye is 'coloured', either brown or yellow.
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01-20-2012, 04:14 PM
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#67
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Bearded dragons eyes DO NOT respond to light. Check your dragons with a light.
Here are some images of my dissection.
http://bloodbankdragons.com/2011photos/ziris.htm
I think they have a scleral ring. when I cut front half in half again it was crunchy like it was made of bone.
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01-20-2012, 04:16 PM
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#68
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If the iris responds to light I cant see it. It must be very very subtle.
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01-20-2012, 04:23 PM
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#69
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The striated muscles typically associated with reptilians eyes iris make it possible that the contraction/dialation may actually be a voluntary responce. The dragon may have control over this function.
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01-20-2012, 04:26 PM
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#70
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Steven here it is agian, on your own pic...
Are you an opthalmologist?
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