Glaucoma is an eye disease that causes loss of sight by damaging a part of the eye called the optic nerve. This nerve sends information from your eyes to your brain. When glaucoma damages your optic nerve, you begin to lose patches of vision, usually side vision (peripheral vision). Over time, glaucoma may also damage straight ahead (central) vision. You may not notice a loss of side vision until you have lost a great deal of your sight. When checking for glaucoma, eye doctors usually look for damage to the optic nerve and any loss of side vision. They may also check your eye pressure. Glaucoma is often called the ‘silent killer’ because people usually do not notice any signs of the disease until they have already lost significant vision. Once lost, vision cannot be restored.
This is the most common type. In open-angle glaucoma, aqueous fluid drains too slowly and pressure inside the eye builds up. It usually results from aging of the drainage channel, which doesn't work as well over time. However, younger people can also get this type of glaucoma.
This is a form of open-angle glaucoma not related to high pressure. People with normal tension glaucoma may be unusually sensitive to normal levels of pressure. Reduced blood supply to the optic nerve may also play a role in normal tension glaucoma.
Less than 10 percent of people have this form, but It causes a sudden rise in pressure, requiring immediate, emergency medical care. The signs are usually serious and may include blurred vision, severe headaches, eye pain, nausea, vomiting or seeing rainbow-like halos around lights. Occasionally, the condition may be without symptoms; similar to open angle.
Another 10 percent of glaucoma cases come from certain diseases and conditions that damage the eye's drainage system. These include diabetes, leukemia, and sickle-cell anemia also some forms of arthritis, cataracts, eye injuries or inflammation of the eye plus steroid drug use and growth of unhealthy blood vessels.