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Overview of eye
http://www.youtube.com/watch?NR=1&feature=endscreen&v=0HzWmldLDHI
A good overview of the physiology of the eye – well worth a visit.
Focussing light on the retina
http://www.youtube.com/watch?v=AsKeu4wm3XI
How the lens helps us to focus light on the retina and why we sometimes need help through glasses.
Pupil Dilation
By light – Gecko
http://www.youtube.com/watch?v=uYmqbZk-uvs
Cute little Gecko – jump to 1.50 to see the action when lights are turned on and off.
By excitement – pounce
http://www.youtube.com/watch?NR=1&feature=endscreen&v=i1znmh8d7U4
Quick video showing a cat about to pounce – see the changes in pupil size that are not related to changes in light level.