Glaucoma usually occurs when the pressure in your eye increases. This can happen when eye fluid isn’t circulating normally in the front part of the eye.

Normally, this fluid, called aqueous humor, flows out of the eye through a mesh-like channel. If this channel becomes blocked, fluid builds up, causing glaucoma. The direct cause of this blockage is unknown, but doctors do know that it can be inherited, meaning it is passed from parents to children.

Less common causes of glaucoma include a blunt or chemical injury to the eye, severe eye infection, blockage of blood vessels in the eye, inflammatory conditions of the eye, and occasionally eye surgery to correct another condition. Glaucoma usually occurs in both eyes, but it may involve each eye to a different extent.

There are two main types of glaucoma:

• Open-angle glaucoma. Also called wide-angle glaucoma, this is the most common type of glaucoma. The structures of the eye appear normal, but fluid in the eye does not flow properly through the drain of the eye, called the trabecular meshwork.
• Angle-closure glaucoma. Also called acute or chronic angle-closure or narrow-angle glaucoma, this type of glaucoma is less common but can cause a sudden buildup of pressure in the eye. Drainage may be poor because the angle between the iris and the cornea (where a drainage channel for the eye is located) is too narrow.

Glaucoma most often occurs in adults over age 40, but it can also occur in young adults, children, and even infants. In African-Americans, glaucoma occurs more frequently and at an earlier age and with greater loss of vision.

You are at an increased risk of glaucoma if you:

• Are of African-American, Irish, Russian, Japanese, Hispanic, Inuit, or Scandinavian descent.
• Are over age 40.
• Have a family history of glaucoma.
• Have a poor vision, especially the field of vision.
• Have diabetes.
• Take certain steroid medications, such as prednisolone, for a long time.

For most people, there are usually few or no symptoms of glaucoma. The first sign of glaucoma is often the loss of peripheral or side vision, which can go unnoticed until late in the disease. Detecting glaucoma early is one reason you should have a complete check-up with an eye specialist every one to two years. Occasionally, intraocular pressure can rise to severe levels. In these cases, sudden eye pain, headache, blurred vision, or the appearance of halos around lights may occur.

If you have any of the following symptoms, seek immediate medical care:

• Seeing halos around lights
• Vision loss
• Redness in the eye
• The eye that looks hazy (particularly in infants)
• Nausea or vomiting
• Pain in the eye
• Narrowing of vision (tunnel vision)

To diagnose glaucoma, an eye doctor will test your vision and examine your eyes through dilated pupils. The eye exam typically focuses on the optic nerve which has a particular appearance in glaucoma. In fact, photographs of the optic nerve can also be helpful to follow over time as the optic nerve appearance changes as glaucoma progresses.The doctor will also perform a procedure called tonometry to check for eye pressure and a visual field test, if necessary, to determine if there is loss of side vision. Glaucoma tests are painless and take very little time.

Glaucoma treatment may include prescription eye drops, laser surgery, or microsurgery.

• Eye drops for glaucoma. These either reduce the formation of fluid in the front of the eye or increase its outflow. Side effects of glaucoma drops may include allergy, redness of the eyes, brief stinging, blurred vision, and irritated eyes. Some glaucoma drugs may affect the heart and lungs. Be sure to tell your doctor about any other medications you are currently taking or are allergic to.
• Laser surgery for glaucoma. Laser surgery for glaucoma slightly increases the outflow of the fluid from the eye in open-angle glaucoma or eliminates fluid blockage in angle-closure glaucoma. Types of laser surgery for glaucoma include trabeculoplasty, in which a laser is used to pull open the trabecular meshwork drainage area; iridotomy, in which a tiny hole is made in the iris, allowing the fluid to flow more freely; and cyclophotocoagulation, in which a laser beam treats areas of the middle layer of the eye, reducing the production of fluid.
• Microsurgery for glaucoma. In an operation called a trabeculectomy, a new channel is created to drain the fluid, thereby reducing intraocular pressure that causes glaucoma. Sometimes this form of glaucoma surgery fails and must be redone. For some patients, a glaucoma implant is the best option. Other complications of microsurgery for glaucoma include some temporary or permanent loss of vision, as well as bleeding or infection.

Open-angle glaucoma is most commonly treated with various combinations of eye drops, laser trabeculoplasty, and microsurgery. Traditionally, medications are used first, but there is increasing evidence that some people with glaucoma may respond better with early laser surgery or microsurgery.

Infant or congenital glaucoma — meaning a child is born with it — is primarily treated with surgery since the cause of the problem is a much distorted drainage system.

Talk to your eye doctor to find out which glaucoma treatment is right for you.

Glaucoma cannot be prevented, but if it is diagnosed and treated early, the disease can be controlled.

Adopting an active lifestyle (as opposed to a sedentary one) is supposed to reduce the risk of glaucoma to some extent, but no definite data is available on the extent of risk reduction.

At this time, loss of vision caused by glaucoma is irreversible and cannot be restored. However, successfully lowering eye pressure can help prevent further visual loss from glaucoma. Most people with glaucoma do not go blind as long as they follow their treatment plan and have regular eye check-ups.