Nerve myelination in glaucoma. Ophthalmoscope image of the retina of an eye with glaucoma, showing optic nerve myelination. Nerve myelination appears bright white around the optic disc (lower centre) where blood vessels and the optic nerve enter the retina. Myelin is a protein laid down normally as a nerve sheath, enabling impulses to be conducted more rapidly. Here, due to glaucoma (high fluid pressure inside the eye) myelinated nerve fibres on the retinal surface are damaged. This damage has caused them to become exposed, showing their myelin sheaths. Glaucoma typically results in atrophy of the optic nerve, and is an important cause of blindness.