It was once thought that the loss of these fibers was due to strictly to high pressure in the eye. But now it is known that even patients with normal eye pressure can have glaucoma and loss of these nerve fibers.
In many patients, the disease is not noticed in the early stages, because there is no pain and no noticeable changes in the vision. Early detection by an eye doctor is the key to the prevention of vision damage from glaucoma. Routine eye examinations are recommended.
The reason that eye pressure is high in many glaucoma patients is that the drainage system in the eye is not working properly. The fluid in the eye, called aqueous humor, does not flow out of the eye as quickly as it should. The drainage system lies in a part of the eye called the angle, which is between the outer layer and the iris of the eye. This angle can be open or closed.
There are several kinds of glaucoma. The most common form of glaucoma is called chronic open angle glaucoma. The drainage angle is open in these patients, but the eye fluid does not drain as quickly as it should. Closed-angle glaucoma occurs when the drainage angle closes, and almost no eye fluid can escape. During closed-angle glaucoma, eye pressure can get very high and there is pain. Angle closure glaucoma is an emergency and must be treated immediately. If the high pressure is allowed to continue for too long, blindness can result.
Some persons are more likely to have glaucoma. These include persons who are older, have nearsightedness, have a family history of glaucoma, have had past eye injury, have diabetes or have a past history of vascular shock. Also, African-Americans are six times more likely to have the disease.
Glaucoma is treated with eye drops that lower the eye pressure. If the pressure does not fall to a low enough level with drops, then surgery may be necessary. Glaucoma surgery opens up the drainage system in the angle so that the eye fluid can flow more freely.