Glaucoma is a group of diseases that can lead to damage to the eye's optic nerve and result in blindness. Open-angle glaucoma, the most common form of glaucoma, affects about 3 million Americans--half of whom don't know they have it. It has no symptoms at first. But over the years it can steal your sight. With early treatment, you can often protect your eyes against serious vision loss and blindness. In many people, increased pressure inside the eye causes glaucoma. In the front of the lens of the eye is a space called the anterior chamber. A clear fluid flows continuously in and out of this space and nourishes nearby tissues. The fluid leaves this anterior chamber at the angle where the cornea and iris meet. When the fluid reaches the angle, it flows through a spongy meshwork, like a drain, and leaves the eye.

Open-angle glaucoma gets its name because the angle that allows fluid to drain out of the anterior chamber is open, as it should be. However, for unknown reasons, the fluid passes too slowly through the meshwork drain. As the fluid builds up, the pressure inside the eye rises. Unless the pressure at the front of the eye is controlled, it can result in damage to the optic nerve at the back of the eye and cause vision loss.

At first, open-angle glaucoma has no symptoms. Vision stays normal, and there is no pain. As glaucoma remains untreated, people may notice that they get tunnel vision - although they see things clearly in front of them, they miss objects to the side and out of the corner of their eye. Over time, without treatment, the remaining forward vision may decrease until there is no vision left.

Conventional treatment by doctors includes medications for newly diagnosed glaucoma, laser surgery (a safe and effective alternative) or conventional surgery to create a new drain to relieve the pressure.

Although open-angle glaucoma is the most common form, some people have other forms of the disease.

Low-tension or normal-tension glaucoma: Optic nerve damage and narrowed side vision occur unexpectedly in people with normal eye pressure. People with this form of the disease have the same types of treatment as open-angle glaucoma.

Closed-angle glaucoma: The fluid at the front of the eye cannot reach the angle and leave the eye because the angle gets blocked by part of the iris. People with this type of glaucoma have a sudden increase in pressure. Symptoms include severe pain and nausea as well as redness of the eye and blurred vision. This is a medical emergency. Without treatment, the eye can become blind in as little as one or two days. Usually, prompt laser surgery can clear the blockage and protect sight.

Congenital glaucoma: Children are born with defects in the angle of the eye that slow the normal drainage of fluid. Children with this problem usually have obvious symptoms such as cloudy eyes, sensitivity to light, and excessive tearing. Surgery is usually the suggested treatment, because medicines may have unknown effects in infants and be difficult to give to them. The surgery is safe and effective. If surgery is done promptly, these children usually have an excellent chance of having good vision.

Secondary glaucomas: Can develop as a complication of other medical conditions. They are sometimes associated with eye surgery or advanced cataracts, eye injuries, certain eye tumors, or uveitis (eye inflammation). One type, known as pigmentary glaucoma, occurs when pigment from the iris flakes off and blocks the meshwork, slowing fluid drainage. A severe form, called neovascular glaucoma, is linked to diabetes. Also, corticosteroid drugs - used to treat eye inflammations and other diseases - can trigger glaucoma in a few people.