Glaucoma results from damage to the optic nerve which can impair vision. Glaucoma is the second leading cause of blindness, and is commonly referred to as the “Silent Thief of Sight” because it damages vision so gradually that you do not notice it until the advanced stages.
It is usually associated with elevated intraocular pressure or reduced circulation to the optic nerve. Another mechanism is when the microscopic drainage system in the eye is partially obstructed, the intra-ocular pressure increases causing damage to the optic nerve. However, even people with normal eye pressures can have glaucoma.