Can you give me some info on optical discs and what it means if there flat, but deep?

Clue to disease: The optic disc is the site at the back of the eye where the nerves of vision carry information to the brain. The color and contour (depth) can give the ophthalmologist clues as to the health of the nerve, whether there has been glaucoma damage, or nerve damage. It can also be a clue to intracranial pressure. A deep disc (cupping) can be normal but can be a sign of glaucoma.