The good news?  This finding is very normal, but can give you quite a start when you see it for the first time! Myelinated nerve fiber layer is a benign finding where the myelin sheath that typically lines and insulates the optic nerve when it exists the eye, persist even inside the eye. Normally, the myelin sheath stops before the nerve enters the eye because myelin (the dense white material you see above the nerve in this photo) will prevent light information from reaching any retinal cells underneath it. Myelin sheathing of the nerve is essential to visual function because it speeds up the transmission of information from the eye to the brain.  But if it exists inside the eye, there may be some (usually very subtle) visual loss since myelin is not clear and therefore any cells stuck behind it won't be able to detect light when it enters the eye.