Glaucoma

What is glaucoma?

Glaucoma is a group of diseases that result in degeneration of the optic nerve and many are caused by increased pressure inside the eye. Glaucoma can lead to vision loss and even blindness.

In most patients, glaucoma occurs when pressure inside the eye is at a level sufficient to damage to 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.

 The Human Eye
The Human Eye

Glaucoma is one of the leading causes of blindness. Glaucoma causes blindness in little over 12 percent of people with the condition. However, early treatment can often prevent serious vision loss.

What causes optic nerve damage in glaucoma?

Glaucoma is often associated with increased pressure inside the eye.

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. In normal eyes, fluid leaves the chamber through the open angle, the area 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.

In eyes with glaucoma, the drainage of fluid is either slowed down or blocked. The pressure inside the eye then rises to a level that can damage the optic nerve. When the optic nerve is damaged from increased pressure, it can cause vision loss. This is why controlling pressure inside the eye is important.

What are the types of glaucoma?

There are three main types of glaucoma:

  • Open-angle glaucoma – In this type, the angle in the eye is open, but it does not function properly. This prevents the fluid inside the eye from draining and causes the pressure in the eye to rise.
  • Closed-angle glaucoma – In this type, the angle in the eye is closed, or blocked. This prevents the fluid inside the eye from draining and causes the pressure in the eye to rise. In some people, the blockage happens very suddenly and causes severe pain and vision loss. This is called "acute closed-angle glaucoma." In other people, it happens slowly over time, and might cause periods of headaches. This is called "chronic closed-angle glaucoma."

    Closed-angle glaucoma is a serious condition and needs to be treated immediately.

  • Congenital glaucoma – This happens when a child is born with a defect in the angle of the eye that slows the normal drainage of fluid. These children usually have obvious symptoms, such as cloudy eyes, sensitivity to light, and excessive tearing.

Other types of glaucoma include:

  • Low-tension or normal-tension glaucoma – In this type, the optic nerve is damaged without an increase in eye pressure. People with this condition might also have problems with side vision. In some people with this type of glaucoma, medications or surgery can lower the eye pressure and slow the disease. In other people, lowering the eye pressure will not stop the glaucoma from getting worse.

    If you have low-tension or normal-tension glaucoma, make sure your eye doctor knows your complete medical history. This can help him or her identify other risk factors that might be contributing to your condition, such as low blood pressure. In people with no other risk factors, treatment options for low-tension or normal-tension glaucoma are the same as those for open-angle glaucoma.

  • Secondary glaucoma – These are types of open-angle glaucoma that are caused by medication or other medical conditions. They include:
    • Pseudoexfoliative glaucoma – People with this type have deposits of a protein-like material in their eye.
    • Pigmentary glaucoma – In this type, pigment from the iris flakes off and blocks the meshwork of the angle. This slows fluid drainage.
    • Neovascular glaucoma – This is a severe form of glaucoma that can happen in people with diabetes.
    • Uvetic glaucoma – This type of glaucoma can happen from eye inflammation.

In some people, corticosteroid drugs used to treat eye inflammations and other diseases can also cause secondary glaucoma.

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. Your eye doctor can help you understand whether or not you have glaucoma.

Will 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 might be too high for one person but normal for another.

Whether or not you develop glaucoma depends on the level of pressure your optic nerve can tolerate. That's why it is important to have a comprehensive dilated eye exam. It can help your eye doctor determine what level of eye pressure is right for you.

Can I develop glaucoma without increased eye pressure?

Yes. 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 glaucoma?

Anyone can develop glaucoma, but a person’s risk increases with age.

In addition, some people are at higher risk for developing the condition than others. They include:

  • People with a family history of glaucoma
  • African Americans
  • Hispanics

Among African Americans, research shows that glaucoma is:

  • Five times more likely to occur than in Caucasians
  • About four times more likely to cause blindness than in Caucasians
  • Fifteen times more likely to cause blindness between the ages of 45 to 64 than in Caucasians of the same age group

What can I do to protect my vision?

Studies have shown that the early detection and treatment of glaucoma, before it causes major vision loss, is the best way to control the disease. If any of the risk factors above apply to you, make sure to see an eye doctor for a comprehensive dilated eye exam at least once every two years.

If you are being treated for glaucoma, be sure to take your glaucoma medicine as directed and see your eye doctor regularly.

You also can help protect the vision of family members and friends who might be at high risk for glaucoma. Encourage friends and family at risk to have a comprehensive dilated eye exam at least once every two years. Remember that lowering eye pressure in glaucoma's early stages slows progression of the disease and helps save vision.

What are the symptoms of glaucoma?

When it first starts, glaucoma has no symptoms. Vision stays normal, and there is no pain most of the time. However, as the disease progresses, a person with glaucoma might notice his or her side vision gradually failing. Objects in front might still be clear, but objects to the side might be missed. Glaucoma can develop in one or both eyes.

A person whose glaucoma remains untreated might routinely miss objects to the side and out of the corner of his or her eye. Without treatment, the person will slowly lose his or her peripheral (side) vision. Vision appears as if it is through a tunnel. Over time, straight-ahead vision might also decrease, leaving no vision remaining.

In acute closed-angle glaucoma, symptoms include severe pain and nausea, as well as redness of the eye and blurred vision. In chronic closed-angle glaucoma, symptoms include periods of headaches or eye pain. If you experience any of these symptoms, you should seek treatment immediately. Closed-angle glaucoma is a medical emergency.  

If you have symptoms of closed-angle glaucoma and your doctor is unavailable, go to the nearest hospital or clinic. Without treatment to improve the flow of fluid, the eye can become blind in a short period of time. Usually, prompt laser surgery and medicines are needed to clear the blockage and protect sight.

How is glaucoma detected?

Glaucoma is detected through the following tests:

  • Comprehensive eye exam - This includes:
    • Visual acuity test - This test uses an eye chart to measure how well a person sees at various distances.
    • Tonometry – For this test, an instrument measures the pressure inside the eye. Numbing drops might be applied to the eye beforehand.
    • Pachymetry – For this test, the eye doctor uses an ultrasonic wave instrument to measure the thickness of the cornea. A numbing drop is applied to the eye beforehand.
    • Dilated eye exam – For this exam, drops are placed in the eyes to widen, or dilate, the pupils. The eye doctor then uses a special magnifying lens to examine the retina and optic nerve for signs of damage and other eye problems. After the exam, the person’s close-up vision might be blurred for several hours.
  • Visual field test - This computerized test measures peripheral vision. It helps the eye doctor determine if a person has had loss of peripheral (side) vision, which can be a sign of glaucoma.
  • Optical coherence tomography – This test measures optic nerve thickness. In glaucoma, the nerve fiber layers (the fibers that make up the optic nerve) can get thinner as the disease progresses.
  • Pictures – The eye doctor might take a picture of the optic nerve. This picture can serve as a baseline to see if changes happen over time.

Can glaucoma be treated?

Yes. Immediate treatment for early stage, open-angle glaucoma can slow progression of the disease. That's why early diagnosis is very important.

There are many different treatments for glaucoma. However, while these treatments might save remaining vision, they do not restore sight already lost from glaucoma:

  • Medication - Medication, in the form of eyedrops or pills, is the most common early treatment for glaucoma. Some medications cause the eye to make less fluid. Others lower pressure by helping fluid to drain from the eye. Glaucoma medications might need to be taken several times a day.

    Before you begin glaucoma treatment, tell your eye doctor about other medications you are taking. Sometimes the drops can cause problems with the way other medications work.

    Most people have no problems with these medications, but in some people they can cause side effects such as fatigue, low heart rate and drowsiness. For example, drops can cause stinging, burning, and redness in the eyes. Many medications are available to treat glaucoma. If you have problems with one medication, tell your eye doctor. Treatment with a different dose or a new medication might be possible.

    Because glaucoma often has no symptoms, people might be tempted to stop taking, or might forget to take, their medication. But regular and correct use is very important to control eye pressure. Your eye doctor can show you how to put drops into your eye.

  • Laser surgery - There are different kinds of laser surgery doctors can use to treat glaucoma. They include:
    • Laser trabeculoplasty – This can help fluid drain out of the eye in open angle glaucoma. It is a surgery that the eye doctor performs in his or her office. If you have open-angle glaucoma, your eye doctor might suggest this as an option at any point in your treatment. In many cases, a person needs to keep taking glaucoma medication after this procedure.

      Before your surgery, your doctor will apply numbing drops to the eye. You will sit facing the laser machine and the doctor will hold a special lens to your eye. The doctor will then use the laser to make several evenly-spaced spots in the meshwork inside your eye. This will allow the fluid to drain better. You might see flashes of bright green or red light during this part of the surgery.

    • Laser iridotomy - This treatment is used for closed-angle glaucoma. It can create a hole in the iris to help relieve the blockage of the angle.

    Like any surgery, laser surgery can cause side effects, such as inflammation. The doctor might give you drops to take home for soreness or inflammation inside the eye. Several follow-up appointments might be needed to monitor your eye pressure. Usually, if a person has glaucoma in both eyes, one eye will be treated at a time. But some people will have both eyes treated at the same time. If you have your eyes treated separately, the laser treatments for each eye will be scheduled several days to weeks apart.

    Studies show that laser surgery is very good at reducing eye pressure in some people. However, its effects can wear off over time. If this happens, further treatment might be needed.

  • Conventional surgery – Most eye doctors will only do conventional surgery for glaucoma after medications or laser surgery have failed to control eye pressure. Surgery is about 80 to 95 percent effective at lowering eye pressure. The types of conventional surgeries for glaucoma include:
    • Trabeculectomy – In this surgery, the eye doctor makes a new opening for the fluid to leave the eye. (See diagram.) Your eye doctor might suggest this treatment at any time.
    • Glaucoma drainage implant – For this surgery, the eye doctor places an implant inside the eye to help fluid drain. There are different types of implants eye doctors can use for this treatment. Your eye doctor can help you decide which type is best for you.
    • Trabectome – For this surgery, the eye doctor removes the meshwork inside the eye to help fluid drain.
     The Human Eye

    Conventional surgery is performed in the hospital. Before the surgery, you will be given medicine to help you relax. Your doctor will also numb your eye. If you need surgery in both eyes, your doctor will perform surgery on one eye at a time.

    For several weeks after your surgery, you will have to put drops in your eye to fight infection and inflammation. These drops will be different from those you might have used before surgery. You will also need to avoid strenuous activity, such as bending, lifting, and straining. You will be able to read and watch TV normally after surgery.

    If you have severe pain or vision loss after surgery, contact your eye doctor immediately. This might be a sign of infection, which can have major consequences for your vision.

How should I use my glaucoma eyedrops?

If your eye doctor gives you eyedrops for treating your glaucoma, you must use them exactly as instructed. Correct use of your glaucoma medication can improve its effectiveness and reduce your risk of side effects.

To use your eyedrops, follow these steps:

  • First, wash your hands.
  • Hold the bottle upside down.
  • Tilt your head back.
  • Hold the bottle in one hand and place it as close as possible to the eye. Do not touch your eye with the bottle, as this can contaminate the bottle.
  • With the other hand, pull down your lower eyelid. This forms a pocket.
  • Place the prescribed number of drops into the lower eyelid pocket. If you are using more than one eyedrop, be sure to wait at least five minutes before applying the second eyedrop.
  • Close your eye or press the corner of the eye that is nearest to your nose lightly with your finger for at least one minute. Either of these steps keeps the drops in the eye and helps prevent the drops from draining into the tear duct and through the nose, which can increase your risk of side effects.

What can I do if I already have lost some vision from glaucoma?

If you have lost some sight from glaucoma, first see your eye doctor. He or she can help prevent further loss of vision by controlling your glaucoma with treatment.

You can also talk to your eye doctor about low vision services and devices that can help you make the most of your remaining vision. Ask him or her to refer you to a specialist in low vision.

Many community organizations and agencies offer information about low vision counseling, training, and other special services for people with visual impairments. A nearby school of medicine or optometry might provide low vision services.