Glaucoma is a group of eye diseases that damage the optic nerve. The optic nerve is the main nerve to the eye (located in the back of the eye) that is responsible for transmitting electrical impulses to the brain. Damage usually occurs as a result of elevated pressure of the fluid (aqueous humor) in the eye. This damage results in gradual visual changes and then loss of vision.

The eye is protected by the sclera (the white covering of the eye). At the front of the eye is a clear window (the corne...