What is the Optic Nerve
This is the nerve that carries the electrical signals produced by the retina towards the brain, where they are interpreted so that we can see. The optic nerve is usually round and has no retina over it. This means that light landing on the optic nerve is not seen so each eye has a blind spot in its vision.
Each optic nerve is about 1.5mm in diameter inside the eye and looks like a doughnut, where the outer ring is made up of nerve fibres and the central hole is a space without nerve fibres. The central retinal artery and the central retinal vein run through the centre of the optic nerve.