What Is Glaucoma?

Glaucoma is the name for a group of diseases that can destroy the optic nerve, the main nerve of the eye. The word glaucoma means “hard eyeball.” Any one of the conditions classified as glaucoma can lead to irreversible blindness by damaging the optic nerve.

Glaucoma sneaks up on people. There are no symptoms other than loss of vision, which can occur so gradually that many people do not realize it is happening. The first vision loss is usually peripheral vision (what you can see off to the sides when you are looking straight ahead).

Even though glaucoma cannot be cured, it can be treated. If it is spotted in its early stages, before any sight is lost, blindness can almost always be prevented. But the longer glaucoma remains untreated, the more vision can be lost.

Glaucoma is considered a thief of eyesight. The only way to make sure that it doesn’t sneak up is to have regular eye exams. This is especially true for people who:

  • Have a family history of the condition
  • Are black
  • Are over age 40

For reasons still unknown, some people have optic nerves that are more likely to be damaged-usually when fluid pressure in the eye increases. Some experts speculate that these people may have an inadequate blood supply to the optic nerve, or that the tissues supporting the nerve are weak. But no one really knows for sure.

In most cases, there is no pain associated with glaucoma and no early warning signs. That is why it is so important to have regular eye exams.

How Glaucoma Progresses

  • The first time many people realize that there might be something wrong with their eyes is when they begin to lose their vision.
  • The first to go is peripheral vision, which is what you see on the sides when you look straight ahead.
  • Left untreated, glaucoma will eventually lead to tunnel vision, where all a person can see is what is directly in front of the eye.
  • From there it can deteriorate to complete blindness.

There are several different types of glaucoma. The most common is called “open-angle” or “chronic simple” glaucoma. It occurs in 80 percent of all people with glaucoma.

Other types of glaucoma are:

  • Angle-closure glaucoma, of which there are two types: acute angle-closure and chronic angle-closure
  • Neovascular glaucoma
  • Pigment dispersion and exfoliation glaucoma
  • Normal-pressure, or low-pressure, glaucoma
  • Infantile glaucoma

Facts About Glaucoma

  • More than three million Americans have glaucoma, but half of them don’t know it yet.
  • Glaucoma damages the optic nerve, which is the bundle of more than 1.2 million different nerve fibers that transmit to the brain what the eye sees.
  • Everyone should have a glaucoma check by the time they are 40. They should do so even earlier if they are black or if glaucoma runs in their family.


What Causes Glaucoma?

The eye is filled with aqueous humor and vitreous humor.

  • Aqueous humor is a clear fluid in the front part of the eye.
  • Vitreous humor is a clear, jelly-like substance that fills the eye behind the lens and helps the eyeball keep its shape.

In a normal eye, aqueous humor is produced, circulates through the eye, and then drains out through the trabecular meshwork, which is the eye’s filtration system. This is a series of tiny channels near the angle formed by the cornea (the clear portion of the eye), the iris (the colored portion of the eye), and the sclera (the white of the eye).

If there is any sort of blockage in these channels, pressure builds up inside the eyeball.

Nice To Know:

Imagine a garden hose with water flowing through it. If you plug the hose, the water pressure builds up. Eventually it will damage the hose.

Untreated pressure in the eye can damage and eventually destroy the optic nerve, leading to blindness. But, surprisingly, there are some people who suffer from glaucoma even though they have normal pressure in their eyes. There also are people who have pressure in their eyes and yet do not suffer from glaucoma. Researchers are still trying to figure out why.

  • Somewhere between 20 and 25 percent of people with glaucoma have normal (and maybe even low) eye pressure.
  • Some people with high eye pressure, which is also called ocular hypertension, do not have glaucoma, and never will.

Nice To Know:

What is normal eye pressure?

Eye pressure is measured in numbers, but there is no “normal” number for eye pressure. The average pressure, however, is about 16.

High eye pressure doesn’t guarantee that a person will develop glaucoma. But it is one of the risk factors. A person with an eye pressure of 25, for example, is 13 times more likely to have glaucoma than a person with an eye pressure of 15.

Glaucoma can be hereditary, although having people in your family with glaucoma does not necessarily mean that you will develop it.

Who Gets Glaucoma?

Black people are more likely to develop glaucoma than any other race. No one fully understands why this is so. Black people are also more likely to develop glaucoma at a younger age and will experience more damage to their vision because of it.

  • One out of every 100 Black people age 40 and above has glaucoma. This is also true of Caucasians.
  • By age 80, those numbers jump to 11 out of every 100 for Black people, but only 2 in 100 for Caucasians.
  • Black people between the ages of 45 and 65 are much more likely to go blind from glaucoma than are members of other races.
  • People of Asian descent and other races have figures more in line with Caucasians than with Black people.

Other factors can increase the likelihood of developing glaucoma. The risk is higher if a person has:

  • A family history (glaucoma seems to trace in families)
  • Diabetes
  • Nearsightedness (myopia)
  • A previous eye injury

Some researchers believe there may be a link between glaucoma and high blood pressure, but this has not been proven.

Can Children Get Glaucoma?

While glaucoma is very rare in infants and children, some specific types do show up. So it is important that children be tested, too.

When Should People Have Their Eyes Checked For Glaucoma?

Ophthalmologists recommend that Black people without any symptoms of the condition have regular glaucoma exams every three to five years starting at age 29. Once they reach age 40, they should be examined every one to two years.

For members of other races, specialists recommend regular eye exams every three to five years starting at age 39. Once they reach age 50, they should be examined every one or two years.

You should also have a check-up every one to two years, regardless of your age, if:

  • Someone in your family has glaucoma.
  • If you have ever had a serious eye injury.

If you regularly take steroid medication, you should have your eye pressure checked even more frequently. Discuss this with your doctor.

Do I Have Glaucoma?

The only way for people to determine whether or not they have glaucoma is to be examined by an ophthalmologist, a medical doctor who specializes in eye care. The doctor will perform a number of tests. If there are indications that glaucoma is present, other tests can confirm it.

Checking For “Cupping”

Doctors use eye drops to dilate (enlarge) the pupil so they can look through it to the back of the eye. What they are looking for is abnormal “cupping” at the end of the optic nerve that is visible along the back wall of the eyeball. There is usually a slight depression there. If this depression is abnormally large, it is referred to as cupping. Cupping is often the first indication of glaucoma.

Visual Field Test

The doctor will also perform a visual field test to check your peripheral vision (what you can see on your sides while you are looking straight ahead), since that is the vision that glaucoma destroys first.

Measuring Eye Pressure

The doctor uses a simple and painless technique to measure the pressure within the eye. An anesthetic eye drop is given first, to ease any possible discomfort.

If the first three tests indicated that glaucoma might be developing, there are two more tests that can be performed.

  • Gonioscopy. In this test, doctors place a lens on the surface of the eye to study the drainage channels that should be taking aqueous humor out of the eye. This can help determine whether glaucoma exists and, if so, what type it is.
  • Photographing the optic nerve. While the eyes are dilated, photographs are taken of the optic nerve. These are studied and kept so the doctor can determine if the condition is changing.

The Most Common Type Of Glaucoma

Open-angle glaucoma, which is also called chronic simple glaucoma, is the most common form of the condition. This is the type experienced by 80 percent of glaucoma sufferers.

Open-angle glaucoma often runs in families, but does not always affect every member of the family. It can also skip one or more generations. When it does strike, it almost always affects both eyes.

The aqueous humor drains out of the eye near the “angle” formed by the cornea, the iris, and the sclera. Open-angle glaucoma gets its name because although it looks as if this angle is open-there is no visible blockage-something is preventing fluid drainage.

From somewhere inside the meshwork of channels, there seems to be some sort of increased resistance to the flow of fluid. This could be caused by:

  • An injury
  • Inflammation
  • Reaction to various medications
  • The aging process
  • Unknown reasons

How Is Glaucoma Treated?

Glaucoma can be treated, and the sooner the better. The damage that has already occurred from glaucoma cannot be repaired-it will either stay the same or get worse. Catching glaucoma at its earliest stages and treating it promptly will increase the odds of keeping one’s vision.

All of the various glaucoma treatments and procedures are aimed at reducing eye pressure. Eye pressure doesn’t necessarily cause glaucoma, but once it develops, eye pressure speeds up the destructive process.

There are a number of different treatments for glaucoma:

The type of treatment depends upon individual conditions.

Eye Drops

Eye drops are used to reduce eye pressure by either increasing the eye’s ability to drain or by decreasing the amount of fluid it produces.

If you notice any side effects from any eye drops you use, contact your doctor. If one medication is causing problems, there are usually others that can be used.

You also should also talk to your doctor or pharmacist before using a new drop, to make sure it doesn’t conflict with anything else you are taking.

How-To Information:

To give the eye drop more time on the surface of the eye, where it can do the most good, try the following:

  • Close your eyes after putting in the drops.
  • Leave your face turned up so the drop is more likely to stay on the eye.
  • Apply gentle pressure on the skin between the eye and nose.

Medications that are applied directly to the eye are usually in the form of eye drops, but sometimes ointments may be prescribed. There are six different types of medications that are administered to the eye to treat glaucoma:

  • Beta-blockers cause little discomfort and work by decreasing the production of aqueous fluid. However, they can make breathing and heart problems worse in people with heart or lung conditions.
  • Prostaglandins increase drainage. They can cause blue and green eyes to become darker.
  • Alpha-stimulators are used with other medications to lower eye pressure. These can cause allergic reactions in and around the eyes.
  • Carbonic anhydrase inhibitors decrease fluid production. Because they are sulfa based, they should not be used by people allergic to sulfa.
  • Miotics increase fluid drainage. They can, however, cause headaches when first used. They also cause the pupil to constrict-shrink-which can cause blurred vision.
  • Epinephrine increases fluid drainage. Although there are not usually any major complications, it can cause temporary redness of the eye and blurred vision.

Oral Medication

Pills are usually used to decrease fluid production. They can be very effective in lowering eye pressure, but they also cause side effects in about half of the people who take them. For this reason, your doctor may want to try other options first.

Possible side effects of glaucoma pills are:

  • Tingling in the fingers and toes
  • Fatigue
  • Loss of appetite
  • Mood changes

Less common side effects include:

  • Blood chemistry imbalance
  • Kidney stones
  • Aplastic anemia, an extremely rare but possibly life-threatening condition in which the bone marrow no longer produces blood cells

Surgical Procedures For Glaucoma

Various surgical procedures-both traditional surgery and laser surgery-can make a major difference in a glaucoma sufferer’s life. A possible side effect of glaucoma surgery is the development of cataracts in some eyes. However, cataracts are easier to treat than glaucoma.

Laser surgery involves the use of a bright and highly focused light to destroy tissue or fix tissue in place.

Surgical procedures for glaucoma include:

  • Laser trabeculoplasty, a laser surgery procedure that is now a standard treatment for open-angle glaucoma. A safe and fast outpatient procedure that requires almost no recuperation, it normally takes about five minutes per eye and is usually painless.

    First, the eye is numbed with an anesthetic. The laser is aimed at the drainage channels in the eye, in order to make a tiny hole and let the fluid drain more easily. It normally works for 80 percent of people, and the effects last for five years.

    Most people will need to continue their medications even after laser treatment. After the operation a person may have slightly blurred vision and some redness in the eyes that lasts a day or so.

  • Trabeculectomy is a traditional surgical procedure. In trabeculectomy, a tiny hole is made in the sclera (the white part of the eye) out of which fluid drains. It may take six to eight weeks for vision to return to the same level as before the operation.

    This procedure is used to provide long-term relief from high eye pressure without the use of medication.

  • Drain implantation involves placing a microscopic plastic tube, or drain, within the eye to improve drainage and lower eye pressure.
  • Ciliodestructive surgery, sometimes called cyclophotocoagulation, is a procedure in which a laser is used on the surface of the eye. The goal is to disrupt the process within the eye that produces the aqueous fluid. This reduces fluid production.

    Because this procedure can cause a decrease in vision, it is usually used as a last resort when other procedures have failed.

Combining Glaucoma And Cataract Surgery

Glaucoma and cataracts (clouding of the lens) are both common among older persons. In people who have both conditions, surgeons often perform both cataract and glaucoma surgeries at the same time.

However, while the vision lost due to cataracts can be restored, vision lost because of glaucoma is gone forever.

Medications You Need To Avoid if you have Glaucoma

You should always make sure that your different doctors and pharmacists know all the medicines you take. This is especially important if you have glaucoma.

As a rule, people with glaucoma can safely use most other medications. There are, however, two special cases.

Cold And Allergy Medication

People with angle-closure glaucoma should avoid taking over-the-counter cold and allergy remedies. These can cause the pupils to dilate and, in rare instances, can cause people with chronic angle-closure glaucoma to have an attack of acute angle-closure glaucoma. This could lead to an increase in eye pressure.


Corticosteroids are used to treat inflammations. If used for prolonged periods, they may raise eye pressure in people who suffer from any form of glaucoma.

Do People With Glaucoma Have To Change The Way They Live?

As a rule, no. People with glaucoma can continue to read, do fine detail work, and use their eyes the way they always have.

Some things you can do to help are:

  • Have your blood pressure checked regularly
  • Quit smoking
  • Get regular exercise

However, a person with glaucoma should avoid activities such as yoga, which may require you to stand on your head. This can raise eye pressure.

Less Common Types Of Glaucoma And Their Treatments

Open-angle glaucoma is the most common form of the disease and generally does not affect people until they are in their 40s. But there are other types that can strike earlier-some even start in childhood.

Angle-closure, Or Closed-angle, Glaucoma

In closed-angle glaucoma, the inside of the eye is too crowded. There is not enough room for the normal flow of aqueous humor, either through or out of the eye. The fluid has problems passing from behind the iris (colored part of the eye), through the pupil (the hole in the center of the iris), and to the anterior chamber (the fluid-filled area between the iris and the cornea, which is the clear front part of the eye through which light passes). The fluid just won’t drain properly, which can lead to two serious problems:

  1. Acute angle-closure glaucoma. reasons not known, the eye pressure increases rapidly. The person notices eye pain, eye redness, blurred vision, and haloes around lights. This is often accompanied by nausea and vomiting. Since the pressure can lead to blindness, this is a real emergency and requires an immediate visit to the doctor or emergency department.

    No one knows why, but acute glaucoma tends to be more common among middle-aged women. And just as open-angle glaucoma is more common among blacks, acute glaucoma tends to be more prevalent in Eskimos and in the people of Southeast Asia than in other races.

    Doctors will sometimes use a hyperosmotic agent, a sugar-based medication, to quickly lower eye pressure. It is a temporary measure and not useful for long-term treatment.

  2. Chronic angle-closure glaucoma. The drainage tissues gradually start to scar. This blocks the flow of fluid, and the eye pressure rises slowly. This condition is generally silent, and severe glaucoma damage can occur without the person’s knowledge.

    People suffering from closed-angle glaucoma might need an iridotomy, a laser surgical procedure. A small hole is created in the iris, which improves fluid flow through the eye and reverses the crowding problem that causes the condition. This is a painless outpatient procedure that only takes a few minutes and has few complications. If a person needs treatment in one eye, it will most likely be needed in the other.

Neovascular Glaucoma

Neovascular glaucoma develops when blood vessels grow in the front part of the inside of the eye. This abnormal growth can block the drainage channels, which leads to a pressure buildup.

This type of glaucoma can develop as a result of diabetes, insufficient blood flow to the arteries in the neck, or as a result of other eye conditions.

Once neovascular glaucoma is fully developed, it is extremely difficult to treat and usually results in irreversible vision loss. So, it is best to prevent it or treat it as soon as possible.

Although eye drops and pills may help, laser surgery is usually the treatment of choice. A laser will sometimes cause the abnormal blood vessels to disappear. If it is done early enough, eye pressure may return to normal with little or no permanent damage. In eyes in which the eye pressure remains high despite laser treatment and medicine, conventional surgery may be performed to open up the draining channels.

Pigment Dispersion And Exfoliation Glaucoma

Pigment dispersion glaucoma and exfoliation glaucoma are both similar to open-angle glaucoma. What sets them apart is the presence of abnormalities in the front part of the eye.

  • In pigment dispersion glaucoma, pigment is lost from the iris and is deposited on other structures, including the drainage channels. It is more common in younger persons, in males, and in near-sighted people.
  • In exfoliation syndrome glaucoma, abnormal deposits are found on the surface of the lens and on other structures inside the eyeball. This can sometimes lead to a rapid increase of eye pressure. It is more common in older people and among people of Scandinavian descent.

Both are treated in much the same way as open-angle glaucoma.

Normal-pressure, Or Low-pressure, Glaucoma

Normal-pressure, or low-pressure, glaucoma is sometimes called low-tension glaucoma. It is the type of glaucoma that develops where there is no increase in eye pressure. Many experts say that people who develop this condition have unusually sensitive optic nerves. But other factors-still unknown-may also contribute to their damage. This type of glaucoma is treated by lowering the eye pressure.

Glaucoma In Children

In infantile or congenital glaucoma, eye pressure is elevated at birth. Or, it starts to climb within the first months of life. It is a rare condition that may affect one or both eyes. It seems to run in some families.

Babies with congenital glaucoma dislike bright lights and sunlight and tend to have a lot of tearing. They may also appear to have big eyes or one eye that is bigger than the other. In some cases the cornea (the clear front part of the eye) may be cloudy.

The primary treatment for congenital glaucoma is surgery. The procedure has a high success rate.

Nice To Know:

In babies under age 3, the increased pressure will actually stretch the eye, which is why it is sometimes referred to as buphthalmos, or ox eyes.


What Does The Future Hold For Glaucoma Research And Treatment?

Hundreds of laboratories and clinical investigators around the world are searching for the causes of glaucoma as well as for better ways to treat it. In recent years, these researchers have given us:

  • A better understanding of the different types of glaucoma
  • Improved detection methods
  • Computerized visual field testing
  • New and innovative laser and conventional surgical techniques


Before glaucoma can ever be prevented and cured, more research is needed to determine why eye pressure climbs and what makes the optic nerve susceptible to eye pressure.

Many of the most important advances in the diagnosis and treatment of glaucoma have come out of clinical studies. If you have glaucoma, you may wish to consider joining a clinical study. Your doctor can provide more information.

Glaucoma: Frequently Asked Questions

Here are some frequently asked questions related to glaucoma.

Q: Is glaucoma related to stress?

A: At this point there is no definite evidence linking the two. But some research seems to indicate that stress can either aggravate the problem or make a person more likely to develop it, possibly by causing either congestion or spasms among the blood vessels. None of this, however, has been conclusively proved. In any case, stress can damage the entire immune system and lead to other physical and emotional problems. So while reducing stress level might not do anything for glaucoma, it can do a lot for the rest of the body.

Q: Is glaucoma linked to smoking?

A: There is no direct link to smoking, but smoking is hazardous to your health and can lead to other diseases and conditions. Smoke can also irritate the eyes.

Q: Is it true that marijuana and alcohol can help glaucoma?

A: Some research has shown that using marijuana and drinking alcohol will lower eye pressure by reducing the amount of aqueous humor the eyes produce. But neither one lowers it as much as conventional medications. More importantly, marijuana and alcohol use can also lead to other problems.

Q: Are migraines related to glaucoma?

A: Migraine headaches, like glaucoma, can lead to a loss in peripheral vision. But with migraines, the loss is usually temporary. Although doctors aren’t sure why this happens, they think it’s because migraines can reduce the amount of blood that flows into the brain, which affects the optic nerves. The lost peripheral vision normally returns after the migraine is over.

Q: Is there a “normal” eye pressure?

A: No, but there is an average pressure. For adults that number is around 16, but there are “normal” eyes with pressure as low as 10 and as high as 23. A better question to ask is, “Is my eye pressure at a safe level?” Only your doctor can answer that.

Q: Will reading or using my eyes make my glaucoma worse?

A: No. Reading or using your eyes does not wear them out.

Q: Is glaucoma hereditary?

A: It can be. It does run in some families, although it does not necessarily affect everyone in the family. It has also been known to skip a generation or two.

Q: What is the difference between glaucoma and cataract?

A: A cataract develops when the lens of the eye grows thicker, losing its transparency by becoming cloudy and opaque. Cataracts do not affect the optic nerve, but glaucoma does. Since both tend to happen to people once they get older, it is common for a person to have both.

Q: Does having diabetes put someone at greater risk for glaucoma?

A: Being diabetic leaves a person susceptible to a number of medical problems, and some of them affect the eye. People with diabetes can develop neovascular glaucoma, when abnormal blood vessels grow inside the eye.

Glaucoma: Putting It All Together

Here is a summary of the important facts and information related to glaucoma.

  • Glaucoma is actually the name for a group of diseases that can destroy the optic nerve, the main nerve of the eye. Any one of them can lead to irreversible blindness by damaging the optic nerve.
  • Glaucoma is one of the leading causes of blindness in the world today. It doesn’t have to be.
  • Any vision lost to glaucoma is lost for good. It does not come back.
  • Glaucoma cannot be cured, but it can be treated and controlled.
  • Early detection and prompt treatment can save eyesight.

Glaucoma: Glossary

Here are definitions of medical terms related to glaucoma.

Anterior Chamber: The part of the inside of the eye that is in front of the iris (the colored tissue in the eye).

Aqueous Humor: The watery fluid that circulates throughout the eye supplying nutrients and also providing enough pressure to keep the eyeball in its normal shape.

Cornea: The clear front surface of the eye that you “see” through.

Cup: A slight depression normally present in the part of the optic nerve that can be seen by looking inside the eye. In glaucoma, the cup is larger than it should be.

Dilation:: To make the pupil bigger with the use of eye drops.

Gonioscopy: A technique that allows the eye doctor to see the drainage channels that carry the aqueous humor out of the eye.

Iridotomy: Laser procedure in which a hole is made in the iris.

Iris: The colored tissue within the eye.

Laser: A bright and highly focused light.

Optic Nerve: The bundle of nerve fibers that transmits what you “see” with your eyes to your brain.

Pupil: The round hole in the center of the iris.

Sclera: The white of the eye.

Trabeculectomy: An operation for glaucoma in which a hole is made in the coating of the eye to increase drainage.

Trabeculoplasty: Laser procedure in which the drainage channels are treated to increase drainage.

Vitreous Humor: A clear, jelly-like substance that fills the eye behind the lens and helps the eyeball keep its shape.

Glaucoma: Additional Sources Of Information

Here are some reliable sources that can provide more information on glaucoma.

The Wilmer Eye Institute at Johns Hopkins is one of the foremost eye centers in the world, acclaimed for its research and cutting-edge technology.

American Academy of Ophthalmology

Glaucoma Research Foundation

Prevent Blindness America

Research to Prevent Blindness


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