What exactly is a tilted optic nerve?

Can be normal: Tilted optic nerves are a normal part of eye anatomy. It can be benign.

Tilted: Most optic nerves enter the eye straight on, like a cable pushed into a styrofoam ball perpendicular to the surface. In some eyes, the optic nerve enters at an angle, leading to a tilted appearance. This occurs most commonly in nearsighted people (myopes).

Angled nerve head: The ophthalmologist examines the optic nerve head with the ophthalmoscope. This structure is usually flat although it may vary in interior detail. In some people the blood vessels exit the nerve in a tilted manner which gives the whole disk the appearance of tilt. This can also occur in high myopia. By itself, it is not pathologic.