Glaucoma is a disease of the major nerve of vision, called the optic nerve. The optic nerve receives light from the retina and transmits impulses to the brain that we perceive as vision. Glaucoma is characterized by a particular pattern of progressive damage to the optic nerve that generally begins with a subtle loss of side vision (peripheral vision). If glaucoma is not diagnosed and treated, it can progress to loss of central vision and blindness.
Glaucoma is usually, but not always, associated with elevated pressure in the eye (intraocular pressure). Generally, it is this elevated eye pressure that leads to damage of the eye (optic) nerve. In some cases, glaucoma may occur in the presence of normal eye pressure. This form of glaucoma is believed to be caused by poor regulation of blood flow to the optic nerve.
The treatment is aimed to keep eye pressure in normal range. For any individual the normal or "target pressure" is different, which is decided by the eye surgeon after studying the reports of all above mentioned tests. The lowering of eye pressure is achieved by eye drops or medicines alone or in combination with laser procedure. If the eye pressure is not controlled by above, surgery is required. The modality of treatment is decided by factors like type & stage of glaucoma, damage already done at the time of presentation, response to prior treatment, patients ability to put medication regularly etc.