Glaucoma is a disease of the optic nerve which results in slow unnoticed loss of visual fields. If a patienthas glaucoma, the fluid does not drain properly out of the eye. The increased pressure, called intraocular pressure, can damage the optic nerve, which transmits images to the brain. If damage to the optic nerve from high eye pressure continues, glaucoma will cause permanent loss of vision. Without treatment, glaucoma can cause total permanent blindness.