Glaucoma is a general term used to describe the various ways a patient can have a damaged optic nerve.

This optic nerve is the connection of the eye to the brain.

Early optic nerve loss will lead to peripheral vision loss first but if left uncontrolled near complete nerve loss effectively is blindness.

While optic nerve diseases can be things other than glaucoma such as papilledema or NAION, glaucoma is more typical.