If glaucoma is not diagnosed and treated, it can progress to loss of central vision and blindness. Glaucoma is usually, but not always, associated with elevated pressure in the eye (intraocular pressure). Generally, it is this elevated eye pressure that leads to damage of the eye (optic) nerve.In some cases, glaucoma may occur in the presence of normal eye pressure.laucoma is a disease of the major nerve of vision, called the optic nerve. The optic nerve receives light-generated nerve impulses from the retina and transmits these to the brain, where we recognize those electrical signals as vision.