Glaucoma is an eye disease that damages the optic nerve and causes vision loss - often without warning and symptoms. Like a cable wire, the optic nerve is responsible for carrying the images we see to the brain. Damage to the optic nerve can occur when the pressure within the eye increases, usually due to a build-up of aqueous fluid inside the eye. This leads to the development of blind spots in our field of vision. However, damage may occur without elevation of the intra-ocular pressure. Conversely, the pressure may at times be elevated without damaging the optic nerve. This is a condition known as Ocular Hypertension. Blind spots in the field of vision usually go undetected by the individual until the optic nerve is significantly damaged and a great loss of peripheral or central vision has occurred. A Visual Field evaluation can detect glaucomatous damage in its very early stages. If the disease is untreated the optic nerve may be damaged to a point that irreversible blindness will result.