As a consequence, the fibers of the optic nerve are covered with myelin produced by oligodendrocytes, rather than Schwann cells of the peripheral nervous system, and are encased within the meninges.

[2] From the lateral geniculate body, fibers of the optic radiation pass to the visual cortex in the occipital lobe of the brain.

In more specific terms, fibers carrying information from the contralateral superior visual field traverse Meyer's loop to terminate in the lingual gyrus below the calcarine fissure in the occipital lobe, and fibers carrying information from the contralateral inferior visual field terminate more superiorly, to the cuneus.

The type of visual field loss will depend on which portions of the optic nerve were damaged.

In general, the location of the damage in relation to the optic chiasm (see diagram above) will affect the areas of vision loss.

Damage at the optic chiasm itself typically causes loss of vision laterally in both visual fields or bitemporal hemianopsia (see image to the right).

Finally, damage to the optic tract, which is posterior to, or behind the chiasm, causes loss of the entire visual field from the side opposite the damage, e.g. if the left optic tract were cut, there would be a loss of vision from the entire right visual field.

Injury to the optic nerve can be the result of congenital or inheritable problems like Leber's hereditary optic neuropathy, glaucoma, trauma, toxicity, inflammation, ischemia, infection (very rarely), or compression from tumors or aneurysms.

Glaucoma is frequently associated with increased intraocular pressure that damages the optic nerve as it exits the eyeball.

The presence of excess aqueous humor, increases IOP, yielding the diagnosis and symptoms of glaucoma.

Tumors, especially those of the pituitary gland, can put pressure on the optic nerve causing various forms of visual loss.