I got this picture from http://www.nei.nih.gov/health/glaucoma/glaucXsection.gif
What's the Optic nerve?
The Optic nerve is a bundle of more than 1 million nerve fibers
in the back of the eye that connects the retina to the brain.
What's the retina?
The retina is the light sensitive tissue in the back of the eye
that is connected to the brain.
If you look in the diagram below you can see the Optic nerve towards
the back and the retian that circles the eye.
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I got this picture from http://www.nei.nih.gov/health/glaucoma/glaucXsection.gif