Glaucoma is caused by increased intraocular pressure in the eye. The optic nerve, which is responsible for carrying all visual information to the brain, is damaged by increased pressure, and the damage is irreparable.
The most common form is called open-angle glaucoma, which represents about 90% of all cases. In this case, the condition is painless and begins by affecting vision on the periphery of the visual field. The other 10% of cases are caused by closed-angle glaucoma, which occurs suddenly with extreme pain, visual disturbances like lights and halos, and nausea and vomiting. Closed angle glaucoma is a real emergency and must be treated in the emergency room to prevent permanent blindness. People of East Asian descent are at the highest risk for developing closed angle glaucoma.
At first, open-angle glaucoma has no symptoms. It causes no pain. Vision stays normal. glaucoma can develop in one or both eyes. Without treatment, people with glaucoma will slowly lose their peripheral (side) vision. As glaucoma remains untreated, people may miss objects to the side and out of the corner of their eye. They seem to be looking through a tunnel. Over time, straight-ahead (central) vision may decrease until no vision remains.
Glaucoma is detected through a comprehensive dilated eye exam that includes the following:
- Visual acuity test. This eye chart test measures how well you see at various distances.
- Visual field test. This test measures your peripheral (side vision). It helps your eye care professional tell if you have lost peripheral vision, a sign of glaucoma.
- Dilated eye exam. In this exam, drops are placed in your eyes to widen, or dilate, the pupils. Your eye care professional uses a special magnifying lens to examine your retina and optic nerve for signs of damage and other eye problems. After the exam, your close-up vision may remain blurred for several hours.
- Tonometry is the measurement of pressure inside the eye by using an instrument called a tonometer. Numbing drops may be applied to your eye for this test. A tonometer measures pressure inside the eye to detect glaucoma.
- Pachymetry is the measurement of the thickness of your cornea. Your eye care professional applies a numbing drop to your eye and uses an ultrasonic wave instrument to measure the thickness of your cornea.
Nearly 2.2 million people have glaucoma, a leading cause of blindness in the United States. Although anyone can get glaucoma, some people are at higher risk. They include:
- African-Americans over age 40
- everyone over age 60, especially Mexican-Americans
- people with a family history of glaucoma.
Studies show that glaucoma is
- five times more likely to occur in African-Americans than in whites
- about four times more likely to cause blindness in African-Americans than in whites
- fifteen times more likely to cause blindness in African Americans between the ages of 45-64 than in whites of the same age group.
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, in the form of eyedrops or pills, are the most common early treatment for glaucoma. Taken regularly, these eyedrops lower eye pressure. 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 and supplements that you are taking. Sometimes the drops can interfere with the way other medicines work.
Glaucoma medicines need to be taken regularly as directed by your eye care professional. 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 medicines 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 medicine 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.
Laser trabeculoplasty helps fluid drain out of the eye. Your doctor may suggest this step at any time. In many cases, you will need to keep taking glaucoma medicines after this procedure.
Laser trabeculoplasty is performed in your doctor’s office or eye clinic. Before the surgery, numbing drops are applied to your eye. As you sit facing the laser machine, your doctor holds a special lens to your eye. A high-intensity beam of light is aimed through 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 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 follow-up visits to have your eye pressure and eye monitored.
If you have glaucoma in both eyes, usually 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 can be 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 makes a new opening for the fluid to leave the eye. (See diagram on the next page.) Your doctor may suggest this treatment at any time. Conventional surgery often is done after medicines and laser surgery have failed to control pressure.
Conventional surgery, called trabeculectomy, is performed in an operating room. Before the surgery, you are given medicine to help you relax. Your doctor makes 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. This fluid will drain between the eye tissue layers and create a blister-like "filtration bleb."
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.
Conventional surgery is performed on one eye at a time. Usually the operations are four to six weeks apart.
Sometimes after conventional surgery, 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, inflammation, infection inside the eye, or low eye pressure problems. If you have any of these problems, tell your doctor so a treatment plan can be developed.
What are some questions to ask?
About my eye disease or disorder...
- What is my diagnosis?
- What caused my condition?
- Can my condition be treated?
- How will this condition affect my vision now and in the future?
- Should I watch for any particular symptoms and notify you if they occur?
- Should I make any lifestyle changes?
About my treatment...
- What is the treatment for my condition?
- When will the treatment start and how long will it last?
- What are the benefits of this treatment and how successful is it?
- What are the risks and side effects associated with this treatment?
- Are there foods, medicines, or activities I should avoid while I’m on this treatment?
- If my treatment includes taking medicine, what should I do if I miss a dose?
- Are other treatments available?
About my tests...
- What kinds of tests will I have?
- What can I expect to find out from these tests?
- When will I know the results?
- Do I have to do anything special to prepare for any of the tests?
- Do these tests have any side effects or risks?
- Will I need more tests later?
- If you don’t understand your eye care professionals responses, ask questions until you do understand.
- Take notes or get a friend or family member to take notes for you. Or, bring a tape recorder to help you remember the discussion.
- Ask your eye care professional to write down his or her instructions to you.
- Ask your eye care professional for printed material about your condition.
- If you still have trouble understanding your eye care professional’s answers, ask where you can go for more information.
- Other members of your healthcare team, such as nurses and pharmacists, can be good sources of information. Talk to them, too.
In the United States, glaucoma represents about 9% to 12% of blindness, affecting over 100,000 people. It's also the leading cause of blindness for African Americans and Hispanics in the US. Over 4 million people in the US are diagnosed with it.
The use of cannabis (marijuana) as a treatment for glaucoma has received much press over the years, usually as a point of contention in the larger debate over the legalization of the drug. While the American Academy of Ophthalmology (AAP) has acknowledged that ingestion of cannabis derivatives does reduce intraocular pressure, their official position is that there is no scientific evidence that cannabis is better for glaucoma treatment than the current FDA approved pharmaceuticals.
If you are being treated for glaucoma, be sure to take your glaucoma medicine every day. See your eye care professional regularly.
You also can help protect the vision of family members and friends who may be at high risk for glaucoma-African Americans over age 40; everyone over age 60, especially Mexican Americans; and people with a family history of the disease. Encourage them to have a comprehensive dilated eye exam at least once every two years. Remember that lowering eye pressure in the early stages of glaucoma slows progression of the disease and helps save vision.
Medicare covers an annual comprehensive dilated eye exam for some people at high risk for glaucoma. These people include those with diabetes, those with a family history of glaucoma, and African Americans age 50 and older.