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Glaucoma
The word glaucoma means \”hard eyeball.\” Glaucoma is a group of eye disorders that gradually steal sight without warning increasing the pressure inside eye and thus affects the optic nerve which consists of a bundle of nerve fibers that sends signals to brain and also causes the loss of retinal ganglion cells.
In the early stages of the disease, there may be no symptoms. This is because glaucoma is a painless but progressive loss of vision which is quite hard to detect for a patient. According to the experts, half of the people affected by glaucoma may not identify that they have this disease.
Damage to the optic nerve can initially lead to blind spots at the outer surface of the field of vision known as peripheral or side vision. Optic nerve acts similar to an electric cable that has over a million wires. It is in charge of carrying images from the eye to the brain.
Normally, it is this increased eye pressure that cause damage to the eye (optic) nerve which is made up of the bundle of more than 1.2 million different nerve fibers that pass on to the brain what the eye sees. In some cases, glaucoma may also occur even in the presence of normal eye pressure. This form of glaucoma is supposedly caused by poor circulation of blood flow to the optic nerve.
If glaucoma is not diagnosed and left untreated, it can progress to loss of central vision and blindness.
It was once considered that high pressure within the eye, (intraocular pressure or IOP), is the main reason behind this damage of optic nerve. Although IOP is a definite risk factor, it is now known that other factors must also lead to glaucoma because even people having “normal” levels of pressure can suffer from vision loss due to glaucoma.
Even though glaucoma is not curable, it can be treated. If it is diagnosed in its early stages, before experiencing any sight lost, blindness can be prevented. But the longer glaucoma remains untreated, the more will be the vision loss.
Glaucoma is called “sneak robber of sight” as the disease progresses gradually over a long period of time and is often detected when the condition the disease is quite advanced. The only way to prevent it is regular eye check ups. This is especially necessary for people who:
- Have a family history of the condition
- Are black
- Are over age 40
For reasons are still unknown, some people have optic nerves that are more likely to be damaged typically when fluid pressure in the eye elevates. Some experts guess that these people may experience insufficient blood supply to the optic nerve, or that the tissues supporting the nerve are fragile. But this can’t definitely be said.
As in most cases, there is no pain associated with this eye disease and no early symptoms it becomes so important to undergo regular eye exams.
What causes glaucoma?
The eye consists of aqueous humor and vitreous humor. Aqueous humor is a clear fluid in the front part of the eye and vitreous humor is clear, jelly-like substance filling the eye behind the lens. It helps the eyeball retain its shape.
In a normal eye, aqueous humor is produced and it circulates through the eye. Then it drains out through the trabecular meshwork (the eye\’s filtration system). This is a series of small channels close to the angle created 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 occurs any sort of blockage in these channels, pressure increases consequently inside the eyeball.
Untreated pressure in the eye can harm and ultimately destroy the optic nerve, causing blindness. But, surprisingly, some people suffer from glaucoma even though they have normal pressure in their eyes. There also are people who have elevated pressure in their eyes and yet do not experience glaucoma. Researchers are still trying to discover the reason.
Nearly 20 to 25 percent of people with normal (and maybe even low) eye pressure have glaucoma. On the other hand, some people with increased eye pressure, (which is also termed as ocular hypertension), do not have glaucoma, and will never have.
What is normal eye pressure?
Eye pressure is generally measured in numbers. There is no \”normal\” number for eye pressure. The average pressure, however, is about 16.
High eye pressure not necessarily causes glaucoma. But it is surely one of the risk factors. A person having eye pressure of 25, for instance, is 13 times more likely to have glaucoma than a person with an eye pressure of 15.
Glaucoma can be hereditary. But having a family history of glaucoma does not necessarily indicate that you will develop it.
How Glaucoma Progresses?
The first time many people start realizing that there might be something wrong with their eyes is when they start losing their vision.
The first thing to lose is peripheral vision, which is actually what you see on the sides when you look straight ahead.
If glaucoma is left untreated, it will finally lead to tunnel vision, in which a person can see is only what is directly in front of the eye.
From there it can progress to absolute blindness.
Types of Glaucoma:
Primary Open Angle Glaucoma
This is the most common type of glaucoma that happens when the eye’s drainage canals become clogged in due course. The inner eye pressure (also called intraocular pressure or IOP) increases because the proper amount of fluid can’t drain out of the eye. In case of open angle glaucoma, the entrances to the drainage canals are clear and should be working properly. The clogging problem takes place further inside the drainage canals, just like a clogged pipe below the drain in a sink. Most people have no symptoms and no early signs of caution. If open angle glaucoma is not diagnosed and treated on time, it can lead to a slow but sure loss of vision. This type of glaucoma develops gradually and sometimes without visible sight loss for many years. It generally responds well to medication, especially if diagnosed early and treated.
Secondary Glaucoma
Glaucoma can also occur due to an eye injury, inflammation, and tumor or in advanced cases of cataract or diabetes. It can also be the side effects of certain drugs such as steroids. This form of glaucoma may perhaps mild or severe. The choice of treatment will depend on the understanding whether it is open angle or angle closure glaucoma.
Pseudoexfoliative Glaucoma
This form of secondary open angle glaucoma causes when a flaky, dandruff-like substance peels off the outer layer of the lens within the eye. The material gathers in the angle between the cornea and iris and can block the drainage system of the eye. This evidently leads to elevated eye pressure.
Pseudoexfoliative Glaucoma is more common in those of Scandinavian descent. Treatment usually involves medications or surgery.
Pigmentary Glaucoma
It is a form of secondary open angle glaucoma which occurs as the pigment granules in the back of the iris (the colored part of the eye) break into the transparent fluid formed inside the eye. These minuscule pigment granules flow toward the drainage canals in the eye and gradually choke them, causing increased eye pressure.
Treatment generally includes medications or surgery.
Traumatic Glaucoma
Injury to the eye may result in secondary open angle glaucoma. This type of glaucoma occur either right after the injury or sometimes even years later.
Traumatic glaucoma can be caused by blunt injuries which “bruise” the eye (blunt trauma) or by injuries that penetrate the eye.
Moreover, conditions such as severe nearsightedness, previous injury, infection, or prior surgery may make the eye more susceptible to a severe eye injury.
Neovascular Glaucoma
The unusual development of new blood vessels on the iris and over the eye’s drainage channels can lead to a form of secondary open angle glaucoma.
Neovascular glaucoma is always related with other abnormalities, mainly diabetes. It never occurs on its own. The new blood vessels obstruct the eye’s fluid from exiting through the trabecular meshwork (the eye’s drainage canals), causing an elevation in eye pressure. This type of glaucoma is very hard to treat.
Irido Corneal Endothelial Syndrome (ICE)
This rare form of glaucoma usually occurs in only one eye, rather than both. Cells on the back surface of the cornea advances over the drainage tissue of the eye and across the surface of the iris, mounting up eye pressure and damaging the optic nerve. These corneal cells also produce adhesions that bind the iris to the cornea, and further clog the drainage channels.
Irido Corneal Endothelial Syndrome is more common in light-skinned females. Symptoms may comprise of hazy vision upon awakening and the appearance of halos around lights.
Treatment may include medications and filtering surgery. Laser therapy is not useful in these cases
Angle Closure Glaucoma
This type of glaucoma is also called acute glaucoma or narrow angle glaucoma which is much rarer and is quite different from open angle glaucoma in that the eye pressure usually increases rapidly.
This happens as the drainage canals get clogged or covered over, like a sink with something covering the drain.
In case of angle closure glaucoma, the iris is generally not as wide and open as it should be. The outer edge of the iris mounts up over the drainage canals, when the pupil enlarges too much or too swiftly. This can occur while entering a dark room.
A simple test can be done to examine if your angle is normal and wide or abnormal and narrow. Treatment of angle closure glaucoma is followed by a surgery to remove a small portion of the outer edge of the iris. This helps clear the drainage canals to facilitate the drainage of extra fluid. Normally, surgery is effective and long lasting. However, you should still go for regular eye examination.
Symptoms of angle closure glaucoma may include:
- Headaches
- Eye pain
- Nausea
- Rainbows around lights at night
Very blurred vision
Normal Tension Glaucoma (NTG)
Normal tension glaucoma is also called low-tension glaucoma or normal pressure glaucoma. In this form of glaucoma, the optic nerve gets damaged although intraocular pressure (IOP) is not very high. Doctors are still under the dark to answer why some people’s optic nerves experience damage even though pressure levels are in the “normal” range (between 12-22 mm Hg).
People with a family history of normal tension glaucoma, people of Japanese ancestry, and people with a history of systemic heart disease, such as irregular heart rhythm are more vulnerable to this disease. Normal tension glaucoma is usually diagnosed after a test of the optic nerve.
The Glaucoma Research Foundation sponsored a collaborative international study to help find out the most appropriate treatment for this type of glaucoma. The study revealed that eye drops used to limit intraocular pressure were helpful even in cases of normal tension glaucoma. At present, most doctors prefer to treat normal tension glaucoma by keeping normal eye pressures as low as possible with medicines, laser surgery, or filtering surgery.
Pediatric Glaucoma
The pediatric glaucomas consist of:
- Congenital glaucoma (present at birth)
- Infantile glaucoma (appears during the first three years)
- Juvenile glaucoma (age three through the teenage or young adult years)
- All the secondary glaucomas occurring in the pediatric age group.
Congenital glaucoma occurs at birth and in most cases is diagnosed during the first year of life. Sometimes symptoms are not visible until later in infancy or early childhood.
The signs of Pediatric Glaucoma include:
- Unusually large eyes
- Excessive tearing
- Cloudy eyes
- Light sensitivity
The range of treatment is differs widely from that for adult glaucoma. It is very vital to detect pediatric glaucoma early to prevent blindness.
Who Gets Glaucoma?
Glaucoma is one of the leading causes of blindness in the United States. At least 2 million Americans suffer from glaucoma. It is the most frequent reason of blindness in black Americans.
Black people are more susceptible to develop glaucoma than any other race. But the reason behind this is still not known. Black people are also more likely to suffer from glaucoma at a younger age and will receive more damage to their vision due to it.
One out of every 100 Black people age 40 and above suffers from glaucoma. This is also applicable to Caucasians.
By age 80, the number increases 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 under the risk of going blind from glaucoma than the members belonging to other races.
People of Asian origin and other races have figures more in line with Caucasians than with Black people.
Recent studies reveal that the risk for Hispanic populations is higher than those of chiefly European ancestry. The risk is high among Hispanics over age 60.
Glaucoma is more common among older people. Person ages over 60 are six times more likely to get glaucoma.
Some evidence associates steroid use to glaucoma. A study reported in the Journal of American Medical Association, March 5, 1997, demonstrated a 40% increase in the incidence of ocular hypertension and open angle glaucoma in adults who require about 14 to 35 puffs of steroid inhaler to control asthma. This is a very high dose and is only necessary in cases of severe asthma.
People of Asian descent appear to develop angle closure glaucoma. Angle closure glaucoma is found in less than 10% of all diagnosed cases of glaucoma. Otherwise there is no known greater risk in Asian populations.
While glaucoma is very rare in infants and children, some specific types may occur. So it is important for the children to get tested, too.
Other factors can increase the risk of developing glaucoma include:
- A family history (glaucoma seems to trace in families)
- Diabetes
- Nearsightedness (myopia)
- A previous eye injury
Some researchers suspect a link between glaucoma and high blood pressure, but this has not been confirmed.
Eye check up
Ophthalmologists recommend that Black people without any symptoms of glaucoma should have regular glaucoma exams every three to five years from age 29 onwards. Once they reach age 40, they should be tested every one to two years.
For members of other races, specialists advise 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, especially when:
- 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 if you take steroid. Still it is better to consult your doctor.
How is glaucoma diagnosed?
The only means for people to confirm whether they have glaucoma is to get examined by an ophthalmologist, (a medical doctor specialized in eye care). The doctor will generally perform a number of tests.
Checking For \”Cupping\”
Doctors use eye drops to enlarge the pupil so that they can look through it to the back of the eye. What they are searching is abnormal \”cupping\” at the end of the optic nerve. This can be seen along the back wall of the eyeball. There is normally a minor depression there. But if this depression is unusually large, it is called cupping which is often the first indication of glaucoma.
Visual Field Test
The doctor will also do a visual field test to examine your peripheral vision (what you can see on your sides while you are looking straight ahead), because glaucoma first destroys this vision.
Measuring Eye Pressure
The ophthalmologist follows a simple and painless technique to measure the pressure within the eye. An anesthetic eye drop is applied first, to reduce any possible discomfort.
If the first three tests indicate that development of glaucoma, there are two more tests to perform.
Gonioscopy
In this test, doctors place a lens on the surface of the eye in order to study the drainage channels that should be taking aqueous humor out of the eye. This is useful to determine whether glaucoma exists and, if so, what type it is.
Photographing the optic nerve
While the eyes are enlarged, photographs of the optic nerve are taken. These are examined and kept in order to determine if the condition is changing.
How Is Glaucoma Treated?
Although glaucoma can’t be cured it can be treated, and the sooner the better. But the damage caused due to glaucoma cannot be repaired- it will either remain the same or get worse by time. Detecting glaucoma at its earliest stages and treating it on time will facilitate retaining one\’s vision.
All of the diverse glaucoma treatments and procedures are aimed at limiting eye pressure which doesn\’t necessarily cause glaucoma, but once it develops, eye pressure turns out to be the destructive process.
There are a number of different treatments for glaucoma:
Eye drops are recommended in order to reduce eye pressure either by raising the eye\’s ability to drain or by diminishing the amount of fluid it produces.
If you notice any side effects from any eye drops you use, contact your doctor immediately. If a medication is causing problems, there are usually substitutes that can be used.
You also should also consult your doctor or pharmacist before using a new drop, to determine it doesn\’t clash with anything else you are taking.
To give the eye drop more time on the surface of the eye, for the best result, try the following:
- Close your eyes after receiving the drops.
- Leave your face turned up so that the drop can stay longer on the eye.
- Pressure gently on the skin between the eye and nose.
Medications that are applied directly to the eye are generally in the form of eye drops. Sometimes ointments may also be prescribed. There are 6 different types of medications that are applied to the eye to treat glaucoma:
Beta-blockers cause little uneasiness and work by reducing the production of aqueous fluid though; they can make breathing and heart problems worse especially in people with poor heart or lung conditions.
Prostaglandins enable drainage. They can cause blue and green eyes to become darker.
Alpha-stimulators are used coupled with other medications to reduce eye pressure. Be cautious as these can cause allergic reactions in and around the eyes.
Carbonic anhydrase inhibitors reduce fluid production. As they are sulfa based, they should be avoided by people allergic to sulfa.
Miotics facilitate fluid drainage. They can, on the other hand, cause headaches when first used. They also cause the pupil to constrict-shrink leading to blurred vision.
Epinephrine increases fluid drainage. Although there are not usually any major complications related to its use, it can still cause transitory redness of the eye and blurred vision.
Oral Medication
Pills are usually recommended to reduce fluid production. They can be very useful in decreasing eye pressure, but they also show side effects in about half of the people who take them. For this reason, your doctor may wish to try other options first.
Possible side effects of glaucoma pills include:
- Tingling in the fingers and toes
- Fatigue
- Loss of appetite
- Mood changes
Less common side effects include
Blood chemistry imbalance
Kidney stones
Aplastic anemia (extremely rare but possibly life-threatening condition in which the bone marrow no longer produces blood cells).
Surgical Procedures for Glaucoma
Various surgical procedures including traditional surgery and laser surgery can make a large difference in a glaucoma sufferer\’s life. A possible side effect of glaucoma surgery includes formation of cataracts in some eyes. But yes, cataracts are easier to treat than glaucoma.
Laser surgery involves the use of a bright and highly focused light to destroy tissue or attach tissue in place.
Laser trabeculoplasty
A laser surgery procedure is now considered a standard treatment for open-angle glaucoma.
It is a safe and quick outpatient procedure that needs almost no recuperation; it usually requires
about five minutes per eye and is normally painless.
To perform the laser surgery, the eye is first anesthetized with an anesthetic. The laser is targeted
at the drainage channels in the eye to make a little hole and let the fluid drain out more easily. It
usually works for 80% of people, and the effect lasts for five years.
Remember, most people will require continuing their medications even after laser treatment. Once the operation is over, a person may experience slightly blurred vision and some redness in the eyes that lasts a day or so.
Trabeculectomy- 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 out. It may take 6 to8 weeks for vision to return to the similar level as before the operation.
This procedure is useful to provide long-term relief from increased eye pressure without using medication.
Drain implantation
It is also called cyclophotocoagulation. In this procedure a laser is used on the surface of the eye to disrupt the production of the aqueous fluid in your eye. This decreases fluid production.
As this procedure can cause low vision, it is usually used as a last option when other procedures have failed.
Glaucoma and cataracts (clouding of the lens) both of these eye diseases are common among older persons. In case of the patient who have both conditions, surgeons often perform both cataract and glaucoma surgeries simultaneously.
However, while the vision lost due to cataracts can be recovered, vision lost because of glaucoma can not be cured.
Medications You Need To Avoid
People with glaucoma can safely use most other medications. Though there are two special cases that include:
Cold and Allergy Medication
People with angle-closure glaucoma should not take over-the-counter cold and allergy remedies because these can cause the pupils to enlarge and, in rare ceses, can cause people with chronic angle-closure glaucoma to have an attack of acute angle-closure glaucoma. This could also elevate eye pressure.
Corticosteroids
Corticosteroids are used as remedy to inflammations. If used for extensive period, they may increase eye pressure in people suffering from any form of glaucoma.
Future studies on glaucoma:
Many researchers are studying the therapeutic role of neuroprotection of the optic nerve, especially in patients having progressive nerve damage and loss of visual field, despite relatively normal intraocular pressures (IOP). Animal models have shown that certain chemical mediators can decrease the risk of injury or death of nerve cells.
Hundreds of laboratories and clinical investigators around the world are trying to find out the causes of glaucoma as well as better ways to treat it. In recent years, these researchers have given us:
A better understanding of the different types of glaucoma
Improved detection procedure
Computerized visual field testing
New and innovative laser and conventional surgical techniques
More research is required to determine why eye pressure increases and what makes the optic nerve vulnerable to eye pressure.
Many of the vital advances in the detection and treatment of glaucoma have come out of clinical studies. If you have glaucoma, you may join a clinical study.
Frequently Asked Questions
Q: Do people with glaucoma have to change the way they live?
A: As a rule, no. People with glaucoma can continue with reading, doing fine detail work, and can use their eyes the way they always have.
- Some things you can do to help are:
- Have your blood pressure checked regularly
- Quit smoking
- Do regular exercise
However, a person with glaucoma should avoid activities such as yoga that may require you to stand on your head because this can increase eye pressure.
Q: Is glaucoma related to stress?
A: At this point there is no definite proof linking the two. But some research seems to indicate that stress can either intensify the problem or make a person more likely to develop it, perhaps by causing either jamming or spasms among the blood vessels. None of this, however, has been decisively proved. Anyhow, stress can damage complete immune system and make a way to other physical and emotional problems. So while reducing stress level might not prove effective 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 injurious to your health and can cause other diseases and unfavorable conditions. Smoke may irritate the eyes too.
Q: Is it true that marijuana and alcohol can help glaucoma?
A: Some study has shown that using marijuana and drinking alcohol will decrease eye pressure by dropping the amount of aqueous humor the eyes produce. But neither one reduces it as much as conventional medications. More significantly, marijuana and alcohol use can also cause other troubles.
Q: Are migraines related to glaucoma?
A: Migraine headaches, like glaucoma, can cause a loss in peripheral vision. But with migraines, the loss is generally transitory. Although doctors aren\’t sure about the causes behind it, they think as migraines can lessen the amount of blood flowing into the brain, it also affects the optic nerves. The lost peripheral vision normally recovers 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.
Q: Will reading or using my eyes make my glaucoma worse?
A: No. Reading or using your eyes does not aggravate glaucoma.
Q: Is glaucoma hereditary?
A: Glaucoma can be hereditary. It does occur in some families, although it does not necessarily impinge on everyone in the family. It has also been reported 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 becomes thicker on losing its transparency by turning cloudy and opaque.
Cataracts do not damage 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 glaucoma and cataract.
Q: Does having diabetes put someone at greater risk for glaucoma?
A: Being diabetic makes a person vulnerable to a number of medical complications, and some of them affect the eye. People with diabetes can develop neovascular glaucoma in which abnormal blood vessels grow inside the eye.
Putting It All Together
Here is a summary of the important facts and information related to glaucoma.
Glaucoma is a group of diseases that may destroy the optic nerve (the main nerve of the eye). Any one of them can lead to permanent blindness by damaging the optic nerve.
Glaucoma is one of the principal causes of blindness in the world today.
Any vision lost to glaucoma is lost forever. It can’t be recovered.
Glaucoma cannot be cured, but it can be treated and restricted.
Early diagnosis and prompt treatment can save eyesight.
More than 3 million Americans suffer from glaucoma, but half of them aren’t aware of it yet.
Glaucoma damages the optic nerve, which is the bundle of more than 1.2 million nerve fibers that transmit the vision to the brain.
Everyone should have a glaucoma check by the time they reach 40. They should do so even earlier if they are black or if glaucoma is in their family history.
In babies under age 3, the increased pressure will actually widen the eye, which is why it is sometimes referred to as buphthalmos, or ox eyes.
Glossary
Here are definitions of medical terms related to glaucoma:
Anterior Chamber: The space behind the cornea and in front of the iris (The colored tissue in the eye).
Aqueous Humor: The thick watery fluid filling the space between the lens and the cornea. It 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. It is that transparent front portion of the eye that covers the iris, pupil, and anterior chamber.
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 the usual.
Dilation: To make the pupil larger with the use of eye drops.
Gonioscopy: A technique that helps the eye doctor seeing 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. It is a thin circular structure in the eye controlling the diameter and size of the pupils.
Laser: A bright and highly focused light.
Optic Nerve: The bundle of different nerve fibers that transmits what you \”see\” with your eyes to your brain.
Pupil: The opening in the center of the iris of the eye. It allows light to enter the retina.
Sclera: The white, tough wall 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 enhance drainage.
Vitreous Humor: Clear, jelly-like substances that fills the posterior portion of the lens and helps the eyeball keep its shape. It also transmits light to retina.
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