The optic disc is the area at the back of the eye where the optic nerve leaves, taking the visual information to the brain from the retina. The optic disc is roughly 1.5mm in diameter. In a healthy eye, as many as 1.5 million nerve fibres pass through this point!
The above picture was taken with a scanning laser ophthalmoscope, which allows us to build up a 3-dimensional image of the back of the eye. The picture shows the area around the optic nerve head, and the stump of the optic nerve at the bottom. The nerve fibre runs across the back surface of the eye until it gets to the nerve head. At this point, the fibres bend through a hole in the casing of the eye and bundle together to form the optic nerve. The green line marks out the edge of the optic disc.
