Glaucoma is a disease of the optic nerve of the eye, which is basically the structure that relays what the eye sees to the brain. The major risk factor is represented by the intraocular pressure (IOP) that, when sufficiently elevated, will damage the optic nerve. If left untreated, continued damage to this structure may lead to visual field defects, visual impairment (noticed as foggy/cloudy vision), and blindness.