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What is glaucoma?
Glaucoma is a group of eye diseases that can damage the eye’s optic nerve and result in vision loss and blindness. However, with early treatment, you can often protect your eyes against serious vision loss.
What is the optic nerve?
The optic nerve is a bundle of more than 1 million nerve fibers. It connects the retina to the brain. (See diagram below.) The retina is the light-sensitive tissue at the back of the eye. A healthy optic nerve is necessary for good vision.
A cross-sectional diagram of the eye, showing the optic nerve at the back (left side of diagram)
How does open-angle glaucoma damage the optic nerve?
In the front of the eye is a space called the anterior chamber. A clear fluid flows continuously in and out of the chamber and nourishes nearby tissues. The fluid leaves the chamber at the open angle where the cornea and iris meet. (See diagram below.) When the fluid reaches the angle, it flows through a spongy meshwork, like a drain, and leaves the eye.
Sometimes, when the fluid reaches the angle, it passes too slowly through the meshwork drain. As the fluid builds up, the pressure inside the eye rises to a level that may damage the optic nerve. When the optic nerve is damaged from increased pressure, open-angle glaucoma—and vision loss—may result. That’s why controlling pressure inside the eye is important.
Does increased eye pressure mean that I have glaucoma?
Not necessarily. Increased eye pressure means you are at risk for glaucoma, but does not mean you have the disease. A person has glaucoma only if the optic nerve is damaged. If you have increased eye pressure but no damage to the optic nerve, you do not have glaucoma. However, you are at risk. Follow the advice of your eye care professional.
Can I develop glaucoma if I have increased eye pressure?
Not necessarily. Not every person with increased eye pressure will develop glaucoma. Some people can tolerate higher eye pressure better than others. Also, a certain level of eye pressure may be high for one person but normal for another.
Whether you develop glaucoma depends on the level of pressure your optic nerve can tolerate without being damaged. This level is different for each person. That’s why a comprehensive dilated eye exam is very important. It can help your eye care professional determine what level of eye pressure is normal for you.
Can I develop glaucoma without an increase in my eye pressure?
Yes. Glaucoma can develop without increased eye pressure. This form of glaucoma is called low-tension or normal-tension glaucoma. It is not as common as open-angle glaucoma.
Who is at risk for open-angle glaucoma?
Anyone can develop glaucoma. Some people are at higher risk than others. They include the following:
- African Americans over age 40
- Everyone over age 60, especially Mexican Americans
- People with a family history of glaucoma.
A comprehensive dilated eye exam can reveal more risk factors, such as high eye pressure, thinness of the cornea, and abnormal optic nerve anatomy. In some people with certain combinations of these high-risk factors, medicines in the form of eyedrops reduce the risk of developing glaucoma by about half.
“A comprehensive dilated eye exam can reveal risk factors, such as high eye pressure, thinness of the cornea, and abnormal optic nerve anatomy.”
Can glaucoma be cured?
No. There is no cure for glaucoma and vision lost from the disease cannot be restored.
How is glaucoma treated?
Immediate treatment for early stage, open-angle glaucoma can delay progression of the disease. That’s why early diagnosis is very important.
Glaucoma treatments include medicines, laser trabeculoplasty, conventional surgery, or a combination of any of these. While these treatments may save remaining vision, they do not improve sight already lost from glaucoma.
Medicines. Medicines, in the form of eyedrops or pills, are the most common early treatment for glaucoma. Some medicines cause the eye to make less fluid. Others lower pressure by helping fluid drain from the eye.
Before you begin glaucoma treatment, tell your eye care professional about other medicines you may be taking. Sometimes the drops can interfere with the way other medicines work.
Glaucoma medicines may be taken several times a day. Most people have no problems. However, some medicines can cause headaches or other side effects. For example, drops may cause stinging, burning, and redness in the eyes.
Many drugs are available to treat glaucoma. If you have problems with one medicine, tell your eye care professional. Treatment with a different dose or a new drug may be possible.
Because glaucoma often has no symptoms, people may be tempted to stop taking, or may forget to take, their medicine. You need to use the drops or pills as long as they help control your eye pressure. Regular use is very important.
Make sure your eye care professional shows you how to put the drops into your eye. See How should I use my glaucoma eyedrops?
Laser trabeculoplasty. Laser trabeculoplasty helps fluid drain out of the eye. Your doctor may suggest this step at any time. In many cases, you need to keep taking glaucoma drugs after this procedure.
Laser trabeculoplasty is performed in your doctor’s office or eye clinic. Before the surgery, numbing drops will be applied to your eye. As you sit facing the laser machine, your doctor will hold a special lens to your eye. A high-intensity beam of light is aimed at the lens and reflected onto the meshwork inside your eye. You may see flashes of bright green or red light. The laser makes several evenly spaced burns that stretch the drainage holes in the meshwork. This procedure allows the fluid to drain better.
Like any surgery, laser surgery can cause side effects, such as inflammation. Your doctor may give you some drops to take home for any soreness or inflammation inside the eye. You will need to make several followup visits to have your eye pressure monitored.
If you have glaucoma in both eyes, only one eye will be treated at a time. Laser treatments for each eye will be scheduled several days to several weeks apart.
Studies show that laser surgery is very good at reducing the pressure in some patients. However, its effects can wear off over time. Your doctor may suggest further treatment.
Conventional surgery. Conventional surgery makes a new opening for the fluid to leave the eye. (See diagram below.) Your doctor may suggest this treatment at any time. Conventional surgery is often done after medicines and laser surgery have failed to control pressure.
Conventional surgery is performed in an eye clinic or hospital. Before the surgery, you will be given medicine to help you relax. Your doctor will make small injections around the eye to numb it. A small piece of tissue is removed to create a new channel for the fluid to drain from the eye.
For several weeks after the surgery, you must put drops in the eye to fight infection and inflammation. These drops will be different from those you may have been using before surgery.
As with laser surgery, conventional surgery is performed on one eye at a time. Usually the operations are four to six weeks apart.Conventional surgery is about 60 to 80 percent effective at lowering eye pressure. If the new drainage opening narrows, a second operation may be needed. Conventional surgery works best if you have not had previous eye surgery, such as a cataract operation.In some instances, your vision may not be as good as it was before conventional surgery. Conventional surgery can cause side effects, including cataract, problems with the cornea, and inflammation or infection inside the eye. The buildup of fluid in the back of the eye may cause some patients to see shadows in their vision. If you have any of these problems, tell your doctor so a treatment plan can be developed.
“Immediate treatment for early stage, open-angle glaucoma can delay progression of the disease. That’s why early diagnosis is very important.”
Conventional surgery makes a new opening for the fluid to leave the eye.
read more at nei.nih.gov/glaucoma