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  GlaucomaHighlightsGlaucoma Glaucoma is one of the leading causes of blindness. While glaucoma can develop in anyone, people over age 60, who have a family history of glaucoma, or who are African-American are at especially high risk. Certain types of medical conditions, such as diabetes or extreme near-sightedness, can also increase the risk for glaucoma. Glaucoma is actually a term used to describe several types of eye conditions that affect the optic nerve. In most cases, damage to the optic nerve is caused by increased pressure in the eye, also known as intraocular pressure (IOP). Primary Open-Angle Glaucoma
Treatment There is no cure for glaucoma, but treatment can help reduce intraocular pressure thus preventing optic nerve damage and blindness. Glaucoma is usually treated with medications, although surgery may also be recommended for some patients. Medication Most glaucoma medications are usually given in the form of eye drops. Make sure your doctor or ophthalmologist explains to you the correct way to administer these drops. A number of different medications are used to treat glaucoma. They include:
IntroductionGlaucoma is a disease of the optic nerve, in which the nerve cells in the front of the optic nerve (the ganglion cells) die. The process is irreversible. Previously, it was believed that glaucoma was almost always due to increased intraocular pressure. However, glaucoma has occurred in many patients with normal and even low eye pressure, so damage to the optic nerve is now key for diagnosis. The Aqueous Humor. To understand glaucoma, it is important to first consider aqueous humor, the clear, watery fluid that circulates continuously through the front (anterior) chamber of the healthy eye and is a primary focus of glaucoma research. (This fluid is not related to tears, nor is it the dense jelly-like substance called vitreous humor that is contained in the rear chamber.) Aqueous humor serves two important functions in the eye:
Draining the Fluid and Intraocular Pressure. The aqueous fluid is continuously produced within the front of the eye, causing pressure known as intraocular pressure (IOP). To offset the in-flowing fluid and to maintain normal IOP, the fluid drains out between the iris and cornea (an area known as the drainage angle). It does so through two channels within this angle:
Intraocular Eye Pressure. Previously, it was believed that glaucoma was almost always due to an abnormal rise in intraocular pressure.  Glaucoma is a term used to describe several types of eye conditions that affect the optic nerve. In most cases, damage to the optic nerve is caused by increased pressure in the eye, also known as intraocular pressure (IOP). Glaucoma can cause partial vision loss, with blindness as a possible eventual outcome. Increased IOP is, indeed, present in most cases of glaucoma, but some patients have normal IOP, which is usually maintained at measurements of 10 - 20 mmHg. Measurements above this, however, do not necessarily predict glaucoma. For example, only about 10% of people with IOP levels of 21 - 30 mmHg will actually develop glaucoma. This still puts such individuals at considerable risk for glaucoma, however. Primary Open-Angle GlaucomaMost people with glaucoma have the form called primary-open-angle glaucoma (also called chronic open-angle glaucoma). Open-angle glaucoma is essentially a plumbing problem. The disease process may occur as follows:
Optic nerve damage is the basic glaucoma condition. If it is untreated, eventually the nerve deteriorates until a person loses sight, first in the peripheral vision (the vision in the "corner of the eyes"). If it becomes severe, the person loses central vision (in the middle of the eyes), and may eventually become blind. (Blindness is fortunately nearly always preventable with early treatment.) Primary open-angle glaucoma tends to start in one eye but eventually involves both. About half of patients have gernalized (spread out) nerve damage. In the other half the disease is localized, causing wedge-shaped abnormalities in the nerve fiber layers of the retina. Normal Tension GlaucomaIntraocular eye pressure is normal (12 - 22 mmHg) in about 25 - 30% of U.S. glaucoma cases, a condition known as normal-tension glaucoma. (In Japan, the rates may be as high as 70%.) Other factors are present that cause optic nerve damage but do not affect IOP. Closed-Angle GlaucomaClosed-angle glaucoma (also called angle-closure glaucoma) is responsible for 15% of all cases. It is less common than open-angle glaucoma in the U.S., but it constitutes about half of the world's glaucoma cases because of its higher prevalence among Asians. The iris is pushed against the lens, sometimes sticking to it, closing off the drainage angle. This can occur very suddenly, resulting in an immediate rise in pressure. It often occurs in genetically susceptible people when the pupil shrinks suddenly. Closed-angle glaucoma can also be chronic and gradual, a less common condition. Congenital GlaucomaCongenital glaucoma, in which the eye's drainage canals fail to develop correctly, is present from birth. It is very rare, occurring in about 1 in 10,000 newborns. This may be an inherited condition and often can be corrected with microsurgery. The EyeThe Light-Processing Parts. To understand sight, one begins with light and its passage through the eye's sensitive camera-like structures:
The Supportive Chambers. To help support and protect these sensitive structures, the eye contains two fluid-filled chambers:
CausesNo single factor has been identified as a cause of primary open-angle glaucoma. A number of conditions, alone or in combination, are needed to trigger the processes leading to pressure in the first place and then to the nerve damage that destroys sight. The damage done to the optic nerve in glaucoma is triggered in most cases by the excessive pressure on the optic nerve that, over time, causes damage. Because optic nerve damage occurs in patients with normal as well as high intraocular pressure, however, researchers are investigating several other abnormal events that occur and can damage the optic nerve. Genetic FactorsA number of genes have now been identified as possible factors in many cases of glaucoma. Researchers hope that identification of genes will help improve screening of high-risk patients. Syndromes Associated with Increased Optic Pressure and GlaucomaSpecific syndromes have been identified with glaucoma. Many have an inherited component, although in most cases other factors must be present to activate the disease process. Pseudoexfoliation Syndrome. Pseudoexfoliation (PEX) syndrome (also known as exfoliation syndrome) is the most common identifiable condition associated with glaucoma. The substance is composed of proteins produced by the lens, iris, and other parts of the eye. People can have this condition and not develop glaucoma, but they are at high risk. PEX has a strong genetic component but other factors (possibly sunlight, an autoimmune response, or slow virus) may be needed to trigger the disease. Pigment Glaucoma. Pigment glaucoma starts with a condition called pigment dispersion syndrome, an inherited condition in which granules of pigment (the substance that colors the iris) flakes off into the intraocular fluid. These fragments clog the trabecular meshwork and pressure builds up, causing glaucoma. In one study, 2% of patients had this form of glaucoma. Irido Corneal Endothelia Syndrome. In irido corneal endothelial syndrome (ICE), cells on the back surface of the cornea spread to the drainage angle, sometimes forming scars that connect the iris to the cornea. Neovascular Glaucoma. Neovascular glaucoma is always associated with other disorders, usually diabetes, that result in abnormal formation of new blood vessels on the iris and in the drainage system. Aniridia. Aniridia is a rare inherited disorder (in which the iris is abnormal and increases the risk for glaucoma) that is difficult to treat. (A surgical approach called goniosurgery may help prevent glaucoma in young people with aniridia.) Congenital Glaucoma. When an infant is born with glaucoma (congenital glaucoma), it is usually caused by an inherited abnormality in the drainage canal. Researchers have identified the gene responsible for 85% of these cases. Causes of Nerve Cell Death (Apoptosis) and Optic Nerve DamageA natural process called apoptosis (cellular self-destruction) may contribute to damage in the retinal ganglion nerve cells, the nerve cells that are the front line of the optic nerve. Cell death can occur with or without elevated eye pressure. It is not clear what triggers apoptosis and cell death in such cases, but there are a number of suspects. Excess Glutamate. Researchers have observed abnormally high levels of glutamate in people and animals with glaucoma. Glutamate is an amino acid that excites nerve cells. In the eye this occurs during vision. Some experts theorize that in glaucoma, either reduced blood flow or increased pressure on nerve cells triggers the release of excess glutamate. In large amounts, glutamate causes the nerve cells to fire intensively, which eventually destroys them. Reduced Blood Flow. Researchers have observed reduced blood flow to the optic nerve in patients with glaucoma associated with both high and normal IOP. Less blood flow suggests oxygen loss, which may play a role in the destructive process. Some studies suggest that the greatest risk factor for nerve damage in patients is when blood pressure to the eye drops during the night. Ocular pressure at this time is highest, so the risk for nerve damage becomes intensified. Of interest in this regard are reports finding a significant reduction in eye blood pressure at night in patients with normal-tension glaucoma. Excess Nitric Oxide. Elevated levels of nitric oxide, another nerve-stimulating compound, also play a role in the nerve-damaging process. Nitric oxide is critical for nerve function and flexible blood vessels, but excess amounts may be toxic to nerves. Glaucoma and Alzheimer's Disease. Some research has pointed out similarities in the process leading to cell death in glaucoma and Alzheimer's disease. Specifically, in both diseases activation of certain enzymes called caspases occurs and leads to accumulation of fragments of beta amyloid, an insoluble protein that forms sticky patches. Autoimmunity. Some experts are studying the possibility that normal tension glaucoma may be an autoimmune disease; that is, factors in the immune system, including antibodies, attack cells in the person's own body as if they were foreign substances. In the case of glaucoma, such antibodies would damage parts of the optic nerve. Causes of Closed-Angle GlaucomaPeople with acute closed-angle glaucoma often have a structural defect that causes a narrow angle between the iris and cornea where the aqueous humor circulates. Conditions that suddenly dilate the pupils may cause this shallow angle to close and precipitate attacks of acute glaucoma in susceptible people. Such conditions may include:
Causes of Secondary GlaucomaWhen intraocular pressure leading to glaucoma is caused by other diseases or conditions, it is known as secondary glaucoma. Secondary glaucoma may be chronic or acute, mild or severe. Medical Conditions. A number of diseases can contribute to the development of intraocular pressure leading to glaucoma:
Corticosteroids. Corticosteroids, commonly called steroids, have multiple effects on the trabecular meshwork and may even cause genetic changes. In fact, studying the effects of steroids on the eye is helping researchers understand the glaucoma disease process. Steroids pose a higher or lower risk depending on the form:
SymptomsChronic glaucoma is insidious. If the pressure increases slowly, it will not produce any symptoms until it has done irreversible damage. In such cases, people may notice visual problems at first only when light is dim. Patients are often sensitive to glare. Eventually they may have trouble differentiating between varying shades and brightness (contrast sensitivity). Symptoms of Closed-Angle GlaucomaIn acute closed-angle glaucoma, the pressure inside the eye increases quickly, and the symptoms are dramatic. Intense pain in the eyebrow area and blurred vision develop usually in one eye, and the patient often feels like the eye will burst (although it won't). The eye usually reddens. A person may see rainbow-like halos around lights. Sometimes nausea and vomiting occur. These symptoms may occur on and off and not appear as a full attack. In either case, they indicate a medical emergency. In chronic closed-angle glaucoma, the process is gradual and painless. Symptoms of Congenital GlaucomaAlthough congenital glaucoma is usually present at birth, symptoms generally don’t develop in the infant for a few months. If parents notice that an infant’s eyes are enlarging, becoming cloudy, often watering, or tending to close in the presence of light, they should have an ophthalmologist examine the child’s eyes. Port-wine stains on an infant’s face could indicate Sturge-Weber syndrome, a disorder that occasionally causes glaucoma. OutlookWorldwide, glaucoma ranks as one of the leading causes of blindness. Even if people with glaucoma do not become blind, vision can be impaired. In developed countries, most people get treatment in time to preserve their vision. Even so, glaucoma causes 3 - 6% of blindness cases in Caucasians, and even more cases in African-Americans. In a 20-year study of Caucasian patients with glaucoma, blindness in at least one eye occurred in 27% of patients, and blindness in both eyes occurred in 9% of patients. Blindness rates in African-Americans are most likely higher. In fact, glaucoma is the leading cause of blindness in African-Americans. Despite this higher prevalence, this ethnic group receives surgical treatment at half the rate of Caucasians. Outlook for Primary Open-Angle GlaucomaThe Process Leading to Vision Loss. Chronic glaucoma is often called “the silent thief of sight" because the patient has no warning sign, no hint that anything is wrong. Untreated, the destruction develops slowly over time:
Although there is no cure for open-angle glaucoma, a number of treatments are available that lower intraocular pressure and slow progression of vision loss. Risk Factors for Vision Loss. Estimates of progression rates in vision deterioration range from 9 - 30% over a 2 - 7 year period. According to a study on patients with elevated IOP, for every 1 mmHg increase in IOP, there is a 10% higher risk of disease progression. A very elevated IOP (above 30 mmHg) is certainly hazardous. An elevated IOP that is below 30 mmHg, however, is not necessarily the most important factor in determining the risk for disease progression. Some evidence suggests that frequent and large daily fluctuations in intraocular pressure, not simply high IOP, are associated with the greatest risk for loss of vision. Having normal-tension glaucoma with optic nerve damage highly increases the risk for progression, even if eye pressure is reduced. In any case, factors other than IOP play a role in increasing the chances for progression and vision loss in patients with slightly elevated IOP and normal tension glaucoma:
Non-eye related factors associated with disease progression include being elderly, African-American, female, or having a history of migraines. Severity of Acute Closed-Angle GlaucomaAcute closed-angle glaucoma is a medical emergency. If the high pressure is not reduced within hours, it may permanently damage vision. Anyone with symptoms of acute closed-angle glaucoma should immediately contact an ophthalmologist or go to a hospital emergency room. Risk FactorsAbout 2 million Americans have open-angle glaucoma, but an exact count is unclear. Experts estimate that by 2010, more than 60 million people worldwide will have glaucoma, with 74% of these cases due to open-angle glaucoma. Half of people with glaucoma are unaware of this problem because the condition causes no symptoms. Elevated intraocular pressure in the eye occurs in 5 - 10 million Americans, but only about 10% of such people develop glaucoma because of this pressure. And, in 15% of actual glaucoma cases, IOP is normal. Major studies are helping to clarify the people who are at highest risk for glaucoma and optic nerve damage, including those with normal tension glaucoma. Elderly. The prevalence of chronic glaucoma increases with age. In a major study, 0.6% of people age 60 - 64 had primary open-angle glaucoma. Among people who were 10 years older, the prevalence had more than doubled to 1.3%, and among those who were age 80 - 84, it had more than doubled again to 3%. People of African Descent. Across all age groups, the prevalence of glaucoma in African-Americans is about 3.5% compared to about 1% in Caucasians. In addition, U.S. studies suggest that glaucoma develops earlier in African-American population groups (starting at age 45 instead of age 60 in Caucasians). And, their risk for blindness once they have glaucoma is 14 - 17 times that of Caucasians with glaucoma. African-American men are at higher risk than women. African-American children who are extremely near-sighted and have relatives with glaucoma should begin regular eye examinations for glaucoma as early as possible. In a major glaucoma study in Barbados, where most people are of African descent, over 10% of those age 50 and older had open angle glaucoma, and over 15% were afflicted after age 70. About half of the cases had normal or lower eye pressure. One study suggested that African-Americans tend to have significantly thinner central corneas than Caucasians. This could lead to misleadingly lower pressure scores in African-American patients who actually may have high IOPs. Family History. Glaucoma tends to run in families. Brothers and sisters of patients with open angle glaucoma are 5 times more likely to develop glaucoma by the time they are 70 years old than people whose siblings do not have the disease. Previous studies have also found that people with family histories of glaucoma are more likely to already have some vision loss when they are first diagnosed with glaucoma. Effects of Blood Pressure. The association between a person's blood pressure and intraocular pressure in the eye is not entirely clear. A number of studies have found a higher risk for glaucoma in people with high blood pressure. Having Certain Medical Disorders. Individuals with certain medical or physical conditions, including diabetes, migraine, nearsightedness, and sleep apnea, appear to have a higher risk. Conditions that require the use of any oral or inhaled steroid, particularly high doses for prolonged periods of time, can cause glaucoma. Previous eye surgery also puts people at risk. Other Risk Factors for Normal-Tension GlaucomaWeightlifting. Holding your breath while weightlifting may increase the risk for developing normal-tension glaucoma. Weightlifting causes temporary increases in eye pressure. Holding your breath during this exercise leads to even greater intraocular pressure. Risk Factors for Other Forms of GlaucomaRisk Factors for Closed-Angle Glaucoma. Chronic closed-angle glaucoma tends to be more common in people of Asian and African descent. Those who have this condition are often extremely farsighted. Acute closed-angle glaucoma occurs much more frequently in women than in men. Risk Factors for Normal Tension Glaucoma. Risk factors for normal tension glaucoma include Japanese ancestry and a family history of the disease. It is more common in women than in men. A family history of cardiovascular disease also increases the risk. Risk Factors for Pigmentary Glaucoma. Pigmentary glaucoma occurs three times more often in men then in women and at a younger age. Risk Factors for Irido Corneal Endothelial Syndrome. This condition occurs more often in light-skinned women. DiagnosisA diagnosis of glaucoma no longer simply relies on the presence of pressure within the eye. Optic nerve damage or a strong suggestion of damage must also be present. This damage can be clearly seen during a dilated eye examination of the optic nerve. In general, the hallmark sign of this condition is a loss of peripheral vision. With peripheral vision loss, a person can see in front of him- or herself but has lost the vision to the side.  The optic nerve carries the information of vision from the eye to the brain. Because chronic glaucoma has no warning symptoms, half of its victims are unaware they have the condition. Early diagnosis, however, is the key to successful treatment of glaucoma. One study reported that the longer it's been since a glaucoma patient's last visit to an eye professional, the greater their risk of visual loss. Recommendations for Glaucoma ScreeningThere has been some debate about the relative benefits and risks of routine glaucoma screening in adults. Glaucoma screening in adults can help identify signs of increased intraocular pressure (IOP) and the early stages of primary open-angle glaucoma (POAG). However, treatment of IOP and early POAG can potentially result in harmful effects, such as eye irritation and increased risk for cataracts. Because of this uncertainty, the United States Preventive Services Task Force has not found sufficient evidence to recommend for or against routine screening for glaucoma in adults. In contrast, the American Academy of Ophthalmology strongly supports glaucoma screening, with the following specific recommendations:
Tonometry and Pressure TestsDoctors determine the intraocular pressure (IOP) of the aqueous humor inside the eye using tonometry, which measures the force necessary to make an indentation in the eye. There are several methods:
Attempting to close the eyelids during the test can increase eye pressure and produce errors in the results. In general, normal IOP is usually maintained at measurements of 10 - 20 mmHg. Glaucoma pressure over 21 mmHg indicates a potential problem. The test is not completely accurate, however. Only about 10% of people with IOP levels of 21 - 30 mmHg will actually develop glaucoma and optic nerve damage. On the other hand, many people with glaucoma have normal pressure, at least for part of the time. Changes in posture may also affect IOP. A recent study indicated that IOP increases during sleep or when a person is lying down. As IOP tests are generally given in a doctor’s office when a patient is sitting up, they may not provide a completely accurate evaluation of eye pressure. Measurement of Cornea ThicknessThe cornea thickness may be an important indicator of disease progression in patients with elevated IOP. According to some research, patients with thinner corneas have a significant risk for developing damage from glaucoma, while those with thicker corneas have a low risk. Tests for Optic Nerve DamageIn order to determine early damage in the optic nerve, a number of diagnostic instruments have been developed to assess the nerve fiber layers at the back of the eye (the fundus) and to check for optic disk cupping. (The cup of the optic disc is the center portion, which enlarges as nerve damage progresses.) The two most common procedures for identifying nerve damage are ophthalmoscopy and fundus photography. Other instruments have been developed, including those that use laser technology and computers, but none have proved to be infallible. No test has proven to be completely accurate, however, and none is routinely performed by all eye professionals. In order to be accurate, the tests require a skilled professional and there are certain common factors:
If IOP is low or normal and tests report optic nerve damage and peripheral visual loss, doctors should also check for other conditions before starting any treatment for glaucoma. Such problems include steroid use, anemia, and previous hemorrhage or severe low blood pressure. Ophthalmoscopy. The eye professional (or even a primary care doctor) uses an ophthalmoscope to peer through the pupil directly at the optic nerve. The examiner can then check the shape and color of the nerve fibers to evaluate whether they have been damaged by the high pressure of glaucoma. Damaged nerve fibers may be indicated by:
If results show no optic nerve damage in patients who have mild elevations in pressure, the ophthalmologist may want to retest frequently but delay drug treatment, unless the patient has significant risk factors. Fundus Photography. Fundus photography may be used to take pictures of the optic nerve and can reveal changes years in advance of vision loss. It is an unpleasant procedure requiring drops and a bright flash. This procedure has the same limitations as ophthalmoscopy. Laser Polarimetry. Polarimetry uses laser technology to scan the eye and does not require any response from the patient. It is reported to be able to measure nerve fiber thickness in the eye and so be able to reveal early signs of deterioration. Preliminary studies have indicated that it has a diagnostic accuracy of over 90% for both confirming and ruling out glaucoma. One study, however, reported that laser polarimetry was sensitive enough to detect glaucoma in only up to 57% of patients with early glaucoma, 71% of those with moderate disease, and 81% of those with severe glaucoma. More research is needed. Other Devices. Computer-assisted devices, such as the confocal scanning laser ophthalmoscope, are now available that may be useful for evaluating the retinal nerve layer. Another instrument, the optical coherence tomograph, measures the echo time delay of light that is scattered back from different layers in the retina. The value of these tests has not yet been determined. Perimetry and Other Tests of the Visual FieldsIf there is indication of optic nerve damage, the eye professional will conduct tests of the visual fields (the areas that the patient can see). In most people with glaucoma, the first areas to become noticeably impaired are the peripheral visual fields (areas of sight that are not directly in front of a person but more to the sides).  Click the icon to see an image of the visual field test. Standard Perimetry Tests. Perimetry tests are used to check peripheral vision. One variation of this test is as follows:
The test is complex and lengthy. Elderly people and those with short attention spans may be inappropriate candidates. Other perimetry tests, some requiring less time to administer and some using "virtual reality" techniques, are currently being developed. Other Tests. Other visual field tests are being developed that can detect abnormalities years before they can be detected by standard perimetry. Experts recommend some of these tests in selected patients with suspected glaucoma. For example, a screening test called frequency doubling technology (FDT) checks for changes in particular cells in the retina that are indications of early glaucoma. It takes less than a minute to perform. Another test called short wave automated perimetry (SWAP) uses colors (blue-on-yellow) and also detects very early abnormalities in the visual field. Testing time is longer than with FDT, however, and the presence of certain types of cataracts can interfere with its accuracy. MarkersELAM-1. Endothelial leukocyte cell adhesion molecule 1 (ELAM-1) is a molecule that has been found in glaucoma but not in healthy eyes. This molecule may prove to be a "marker," and its presence may be helpful in diagnosing glaucoma. Test for Acute Closed-Angle GlaucomaA simple test using a penlight helps determine the risk for acute closed-angle glaucoma. A beam of light is directed from the side of the face toward the patient's iris. If no shadow appears on the nose, then most likely the angle is wide enough to dilate. Using an instrument called a gonioscope, ophthalmologists can also inspect the front of the eyes and assess the drainage angle between the cornea and the iris and the channels in the trabecular meshwork. This test can differentiate between closed- and open-angle glaucoma. TreatmentMost treatments for glaucoma aim to reduce ocular pressure and its fluctuations. Early treatment with medications, surgery, or both can nearly always maintain safe pressure of the aqueous humor, thus preventing optic nerve damage and blindness. The choice between surgery and medications and when to start treatment is not always straightforward. For example, with the introduction of beta blockers and newer glaucoma drugs, there has been a decline in surgeries. It is not clear, however, which drugs are more effective than others and if, over time, any will actually prevent surgery. Patients should discuss all issues with their doctors and ophthalmologists. Decision to Start TreatmentMany people have high IOP but no sign of nerve damage. Over the course of 20 years, only 10 - 30% of these people will actually develop glaucoma. Nevertheless, once glaucoma has destroyed optic nerve fibers, no known treatment can reverse the damage. Indeed, studies suggest that in people with glaucoma, even very small differences in pressure may mean the difference between disease progression and stability. An important trial reported that, on average, treating patients when their glaucoma was first detected reduced IOP by 25%. In addition, treatment reduced the risk for progression by 17%. This study confirmed previous findings supporting early treatment for glaucoma. Another study found that treatment with eye drops halved the risk of developing open-angle glaucoma in African-Americans who had elevated IOP. Some evidence suggests that early treatment to lower IOP may be beneficial even in patients with normal tension glaucoma. However, not all individuals with early signs of glaucoma (elevated IOP or normal-tension glaucoma) develop optic nerve damage and serious vision problems. Nor does treatment prevent progression in a large minority of patients. Medications used for glaucoma also can carry significant side effects and risks. Some experts suggest that treatment is warranted only in people with early signs of glaucoma who have risk factors for progressive disease and vision loss (thinner corneas, larger cup to optic disc ration, older age, and elevated pressure). Considerations for Drug TreatmentsA number of effective drugs are now available for treating glaucoma. The drugs reduce pressure in the eye but all have a number of side effects that affect other parts of the body. Some of these side effects can be quite severe. Many of the drugs used for glaucoma also interact with common medications for other conditions. To compound the difficulties, many patients require multiple drugs. As a result, only about half of patients comply with their treatments. Experts generally recommend topical drugs (such as eye drops or ointments) first.
Combinations. Combinations of these drugs can be very effective, because they tend to have different actions. Single medications that contain two drugs are becoming available. For example, Cosopt combines timolol and dorzolamide; Timpilo is a combination of timolol and pilocarpine. Studies of these and other combinations compared to each other to single drugs are ongoing. To date, results on any superior combinations have been mixed. It should be noted that the side effects of each drug apply to any combination. Treating Pregnant Patients. Considerations for a pregnant woman with glaucoma can be complicated. All of the drugs used for glaucoma are absorbed by the body, cross the placenta, and are excreted in breast milk. Many have effects that can interfere with or adversely affect pregnancy. Women should discuss going off medication, particularly during the first trimester, and be monitored during that time for increasing eye pressure. IOP tends to drop during pregnancy, although usually not to a significant degree. In addition, changes in IOP and visual loss vary greatly. Some women have no IOP change or visual loss during pregnancy, while others may experience an increase in IOP or worsening of visual loss. Your ophthalmologist must carefully consider your case and talk with you about the risks and benefits of continuing glaucoma medication during pregnancy. If women need to take medications, they should try to achieve the lowest dose possible. Some drugs have fewer side effects than others. Pregnant women must also be very careful about administering eye drops to allow as little medication as possible to enter the body. When taking eye drops, press your index finger against the corner of the eye near your nose. This helps prevent the eye drop from passing down into the tear duct where it is easily absorbed through the rest of the body. Even this approach, however, does not guarantee complete safety. Women with glaucoma who are planning to become pregnant might want to consider surgery before they conceive. Considerations for SurgeryThe object of standard glaucoma surgery is to reduce pressure in the eye by increasing the outflow of the aqueous fluid. Two methods are commonly used:
Both are effective, but certain patient groups may respond to one more than the other. For example, African-Americans may do better with laser surgery while trabeculectomy may be a better choice for Caucasians with no serious medical problems. In general, surgery is a last resort. Doctors may, however, recommend surgery before drug therapies for patients unlikely to comply with difficult drug regimens or for patients who may have severe reactions from the glaucoma drugs. Women who plan on becoming pregnant should also discuss surgery with their doctor. Some studies indicate that laser treatment performed as the initial treatment for glaucoma is as effective as medications in some cases. One major comparison study suggested that 4 years after surgery there was little difference in visual field loss between trabeculectomy and medical treatment. There was, however, a higher risk for cataracts and loss of vision sharpness with surgery. On the other hand, side effects from medications may be ongoing and troublesome. It is important to note that even surgery does not cure glaucoma, and over half of patients will need medication within 2 years. Experts who are against early surgeries also argue that studies on their success often omitted quality of life assessments and serious postoperative problems, such as late-onset infection. MedicationsNearly all glaucoma medications are prescribed for reducing eye pressure. Lowering IOP is even proving to be beneficial for about two-thirds of patients with normal-pressure glaucoma. Beta-blockers (Timolol and Others)Topical beta adrenoceptor blockers (commonly called beta-blockers) are the drugs most often prescribed to treat glaucoma. They lower the pressure inside the eye by inhibiting the production of aqueous humor. Brands. These drugs are categorized as either nonselective or selective beta-blockers:
All beta-blockers are effective and generally well tolerated. Because they cause less eye irritation than many other glaucoma medications, they are often prescribed for patients who also have cataracts. Side Effects and Complications. After the beta-blocker is administered, only a tiny amount of the drug is absorbed by the cornea. Most of it enters in the bloodstream. These drugs, therefore, can cause side effects in parts of the body other than the eyes ("systemic" side effects):
Interactions with Other Medications. The effects of the eye medication may be additive to other oral medications, such as oral beta-blockers, calcium-channel blockers, or the antiarrhythmic drug quinidine. People with diabetes who take insulin or hypoglycemic medications should realize that beta-blocker side effects may mask the symptoms of hypoglycemia (low blood sugar). ProstaglandinsProstaglandins are hormone-like substances that help open blood vessels. Drugs that resemble prostaglandins increase outflow of aqueous humor (the watery substance in the eye). Drainage of aqueous humor helps reduce intraocular pressure. Brands. Latanoprost (Xalatan) and unoprostone (Rescula) are the standard brands. Latanoprost was the first prostaglandin to be approved as first-line treatment for elevated eye pressure. Two newer prostaglandins, travoprost (Travatan) and bimatoprost (Lumigan), may help some patients who do not respond to latanoprost. These drugs may also benefit patients with normal-tension glaucoma. Latanoprost, travoprost, and bimatoprost need to be taken only once daily. Unoprostone needs to be taken twice a day and is not as effective as others, but it still can reduce IOP significantly. It is the least expensive of these drugs. Latanoprost has been shown to reduce pressure by 45 - 70%. Some studies have suggested that newer prostaglandins travoprost (Travatan) and bimatoprost (Lumigan) are more effective than latanoprost, but the older drug appears to be better tolerated. All of these drugs may be work better than timolol in lowering IOP. The newer prostaglandins may be especially superior to timolol in treating African-American patients. In comparison studies, latanoprost achieved better IOP pressure reduction than brimonidine. Studies have suggested that bimatoprost is more effective in lowering eye pressure than a combination of timolol and dorzolamide (Cosopt). Studies have been mixed on whether latanoprost is superior to the combination. Side Effects. These drugs do not slow down the heart rate and also appear to be safe for people with asthma. Side effects include itching, redness, and burning during administration. Muscle and joint pain may also occur. All of these drugs may permanently change eye color from blue or green to brown. To date, such color changes do not seem to be hazardous. (The only significant problem may be cosmetic in people who treat only one eye, since the color may differ from the other.) These drugs can increase blood flow in the eye and also make eyelashes become thicker and longer in some patients. (These latter effects are more common with bimatoprost and travoprost than with latanoprost.) Carbonic Anhydrase InhibitorsCarbonic anhydrase inhibitors (CAIs) decrease eye pressure by reducing the fluid in the chambers of the eye (aqueous humor). Research suggests that CAIs reduce aqueous humor fluid by as much as 40%. These drugs are used for glaucoma when other drugs do not work. They may be combined with other medications. CAIs may also improve blood flow in the retina and optic nerve (beta-blockers do not). Improving blood flow can keep the disease from getting worse. Brands and Side Effects. CAIs are available in the following forms:
Adrenergic AgonistsAdrenergic agonists activate muscles in the eye that dilate pupils and, therefore, increase outflow of aqueous fluid. Newer variations called alpha 2-adrenergic agonists reduce production of aqueous humor and also increase outflow through the uveoscleral pathway (the alternative channel to the trabecular meshwork). Older adrenergic agonists include epinephrine. Alpha 2-Adrenergic Agonists. Apraclonidine (Iopidine) and brimonidine (Alphagan) are alpha 2-adrenergic agonists. These have generally been used before glaucoma surgery, but a number of studies are indicating that they may even be useful as primary therapy when used in combination with beta-blockers or other standard drugs. Brimonidine is proving to be particularly effective for long-term therapy. (Apraclonidine is used for the short term.) It also may have nerve-protecting properties and may be safer than other drugs during pregnancy and for patients with asthma. The most common side effects of brimonidine and apraclonidine are dry mouth and altered taste. They also commonly trigger an allergic reaction that causes red and itching eyes and lids, a major drawback. Brimonidine causes less of an allergic response than apraclonidine. Unlike apraclonidine, however, it can cause lethargy and mild low blood pressure. It also appears to remain effective longer. Miotics (Pilocarpine and Others)Miotics, also called cholinergic agonists, narrow the iris muscles and constrict the pupil. This action pulls the iris away from the trabecular meshwork and allows the aqueous humor to flow out through the drainage channels, reducing the pressure inside the front of the eye. Brands. Pilocarpine (Pilocar, Adsorbocarpine, Almocarpine, Isoptocarpine, Ocusert) was the most widely used anti-glaucoma drug before timolol was introduced. It is the preferred miotic. Because pilocarpine is used up by the body fairly quickly, however, patients must take it several times a day; many people, therefore, fail to take their medication regularly. A combination of timolol or latanoprost with pilocarpine is more effective than either drug used alone. Carbachol is another miotic. Demecarium (Humorsol), isoflurophate (Floropryl), and echothiophate (Phospholine) are a group of long-acting drugs known as anticholinesterase miotics. Because of their potential for serious side effects, however, some authorities even prefer surgery to their use. Epinephrine and its derivatives are the older anticholinergics. Epinephrine is now rarely prescribed because of side effects. Dipivefrin (Dipivefrin), a newer form of epinephrine, remains inactive until it reacts with enzymes in the cornea. It is effective in low doses and causes few systemic side effects. Side Effects. Side effects include:
Experimental TherapiesCannabinoids. Cannabinoids, compounds in marijuana (cannabis), are being studied for their effects on glaucoma. For example, oral or inhaled tetrahydrocannabinol (THC), the active ingredient in marijuana, has been shown to reduce IOP in 60 - 65% of patients. The effects of smoking marijuana on IOP last only 3 hours, however. THC also increases the release of glutamate -- a nerve-protecting chemical. Experts are hoping that topical use of THC or other cannabinoids may help prevent optic nerve damage without the widespread effects of oral or inhaled administration. Managing Drug RegimensReasons for Noncompliance. Studies indicate that more than 40% of patients miss 10% of their doses, and 15% of patients miss more than 50% of their doses. Noncompliance is very high for many reasons:
Patients who do not regularly take their glaucoma medication are at high risk for blindness. If you have problems taking your medications or sticking to the dosing regimen, talk with your doctor. Hints for Managing a Regimen.
Administering Eye Drops. A common reason that medicine does not work is that patients do not take it correctly. Patients should ask the ophthalmologist to watch while they place the drops in their own eyes to make sure the procedure is being done correctly. The following are some recommended steps:
Drug Therapy for Acute Closed-Angle GlaucomaIn this emergency situation, ophthalmologists may administer a combination of two or more anti-glaucoma medications to reduce eye pressure quickly before it can damage the optic nerve and cause visual loss. Apraclonidine (Iopidine) is a powerful drug used before and after laser surgery to prevent an increase in fluid pressure and is more effective than other medications. In addition to standard drugs, doctors may also administer glycerin (Glyrol, Osmoglyn) by mouth or mannitol or acetazolamide intravenously. Surgery is almost always performed once the pressure is reduced. Therapies for Less Common GlaucomasMost rare forms of glaucoma respond to the same medications and surgery used for open angle glaucoma. Irido corneal endothelial syndrome (ICE) is difficult to treat and if surgery is required, filtering surgery is the best choice. Neovascular glaucoma is also very hard to treat; researchers are investigating drainage implants for this disorder. SurgeryIf medications do not control eye pressure, or if they create intolerable side effects, surgery may be necessary in a small percentage of people with chronic glaucoma. It may be particularly helpful for patients with pseudoexfoliation glaucoma. The standard procedures are usually one of the following:
African-Americans may respond better to initial laser surgery than to conventional trabeculectomy, while the opposite may be true in Caucasians. Some experts now recommend that, in most circumstances, African-Americans should start with laser surgery, and Caucasians with no serious medical problems should have trabeculectomy first. In addition, a number of experimental and less invasive procedures are under development. Filtration Surgery (Trabeculectomy)The Procedure. Filtration surgery has been used for more than 100 years with only minor modifications. It uses conventional surgical techniques known as full-thickness filtering surgery or guarded filtering surgery (trabeculectomy).
The procedure has a high success rate. About 50% of patients no longer need medication after surgery. Thirty-five to 40% of those who still need medication have better control of their glaucoma. A new instrument called a trabectome has allowed for a less invasive type of trabulectomy surgery. The trabectome procedure appears to be a safe and simple way to lower eye pressure. It can be performed before a traditional trabulectomy, if needed. Side Effects. Many of the serious side effects or complications that occur with filtration surgery involve blebs (blister-like bumps).
 Click the icon to see an illustrated series detailing cataract surgery. Supportive Medication for Preventing Scarring. Specific drugs, usually mitomycin C, are often used in conjunction with the procedure to prevent scarring and closure. A large review of studies of mitomycin C supported its effectiveness in increasing surgical success in nearly all patients. Fluorouracil (5-FU) appears to be similar in effectiveness but has a high risk for complications and is not used as often as in the past. Laser TrabeculoplastyThe Procedure. Laser trabeculoplasty involves the following steps:
Laser surgery is not a cure. Patients still need to take anti-glaucoma eye drop medications every day. Within 2 - 5 years, about half of patients need either additional surgery or new medications. Complications. In about 35% of patients, pressure increases after surgery. In most cases it is temporary, but in rare cases the increased pressure is permanent and vision loss can occur. Use of the drug apraclonidine (Iopidine) or pilocarpine can help prevent this elevated pressure. About a third of patients also develop adhesive-like substances called peripheral anterior synechiae that cause the iris to stick to part of the cornea. Drainage Implants (Tube Shunts)Drainage implants, also known as tube shunts, may be used to drain fluid in certain cases, such as if glaucoma is not responsive to any standard procedure or is caused by certain conditions. Tube shunts may work better than filtration surgery (trabulectomy) for some patients. In one study, patients who received tube shunts had more stable IOP over the course of a year than patients who underwent trabulectomy. Candidates. Drainage implants may be useful in the following conditions:
The Procedure. In general, the procedure involves:
Complications. Complications include:
The implant often becomes blocked, and repeated operations are needed. Some researchers are studying the use of a drug called tissue plasminogen activator (tPA) to open up tubes that have been blocked by blood or blood factors. (This so-called clot-busting drug is normally used to break up blood clots during heart attacks.) Nonpenetrating Surgical Techniques: Deep Sclerectomy and ViscocanalostomyDeep sclerectomy and viscocanalostomy are less invasive techniques than filtering surgery that leave the anterior chamber (front of the eye) intact and avoid creation of blebs. In deep sclerectomy, the surgeon removes a deep piece of the sclera (the white part of the eye), part of the trabecular meshwork, and the front of Schlemm's canal (the vessels that return fluid into the bloodstream).
Many variations are under investigation. In general, the procedures have fewer complications afterward than standard filtering surgery, although they require excellent surgical skill. Nonpenetrating techniques do not lower IOPs as much as conventional surgery does, however. In time, however, these nonpenetrating techniques are expected to be as effective as filtration surgery. Treatment for Patients with both Glaucoma and CataractsCataracts and Glaucoma. For patients with both glaucoma and cataracts, experts recommend the following:
Some evidence indicates that the combined approach generally offers better control over eye pressure for patients with both cataracts and glaucoma. However, it is still unclear which specific type of surgical procedure works best. [For more information, see In-Depth Report #26: Cataracts.] Laser Cyclophotocoagulation (or Cycloablation) for End-Stage GlaucomaDiode laser transscleral cyclophotocoagulation (TSCPC), also called laser cycloablation, reduces aqueous production by destroying the muscles that control the lens for near and far vision (the ciliary body). There is a chance of vision loss with this procedure, so it is reserved for people with end-stage glaucoma or those who fail to benefit from any other therapies. Nevertheless, researchers continue to explore the possibilities for this effective procedure, especially for people who may not have access to expensive medications. Studies have suggested it may even be suitable as first-line surgery for some patients. Surgery for Acute Closed-Angle GlaucomaFor an acute closed-angle glaucoma attack, emergency microsurgery is usually necessary after reducing pressure with medications. Iridotomy or Iridectomy. Either laser (iridotomy) or conventional (iridectomy) surgery may be used. With either procedure an ophthalmologist makes a tiny opening in the iris to let the aqueous humor flow out more freely. Because acute glaucoma commonly occurs later in the other eye, surgeons will often recommend surgery in the unaffected eye to prevent a second attack. Laser iridotomy almost never requires hospitalization, and postsurgical treatment includes only aspirin and eye drops. It has almost completely replaced conventional surgery, which requires anesthesia and hospitalization. Vision will be blurred, and recovery can take 4 - 8 weeks. Following surgery, patients can usually use previously restricted anticholinergic medications, such as antihistamines and certain antidepressants, with safety. Phacoemulsification and Intraocular Lens Implantation. Phacoemulsification and intraocular lens implantation, a procedure ordinarily used for cataracts, may prove to be beneficial for some patients with acute angle-closure glaucoma requiring surgery. [For more information, see In-Depth Report #26: Cataracts.] Lifestyle ChangesStudies suggest that patients with glaucoma who exercise regularly (at least 3 times a week) may be able to reduce their intraocular pressure by an average of 20%. If they stop exercising for more than 2 weeks, pressure increases again. In one study, those who walked briskly 4 times a week for 40 minutes were able to go off their medications. (Although not confirmed by any evidence, yoga or other exercises that involve head-down or inverted positions may be harmful for patients with glaucoma and should be discussed with the doctor.) Exercise has no effect on closed-angle glaucoma. It may, in fact, increase eye pressure in patients with pigmentary glaucoma. Vigorous high-impact exercise may cause more pigment to be released from the iris in these patients. Patients should talk to their doctor about an appropriate exercise program. DietAntioxidants in Foods and Supplements. Diet most likely plays very little role in glaucoma. There has been no definitive evidence for an association between important nutrients associated with protection against other eye disorders, including vitamins C, E, A, and carotenoids. Caffeine. Some studies have shown that large amounts of caffeine drunk in a short period of time can elevate eye pressure for up to 3 hours. Fluids. Drinking large amounts (a quart or more) of any liquid within a short time, about 30 minutes, appears to increase pressure. Patients with glaucoma should have plenty of fluids, but they should drink them in small amounts over the course of a day. SunglassesGlaucoma can cause the eyes to be very sensitive to light and glare. Medications can worsen this problem. Sunglasses solve this problem and are important for prevention of cataracts. Protective sunglasses do not have to be expensive. Sunglasses are classified into three categories based on protection against ultraviolet radiation (UV) A or B:
Nontraditional TreatmentsAcupuncture, meditation, biofeedback, and relaxation methods can help counteract stress, and there are some anecdotal reports that they may help some people with open-angle glaucoma, but no rigorous evidence confirms their benefit. A number of herbal and nontraditional remedies have been advertised as glaucoma remedies. A few studies have reported that the herbal remedy ginkgo biloba may have properties that offer benefits to patients with glaucoma, including increasing blood flow in the eye without altering overall blood pressure, heart rate, or intraocular pressure. More research is, however, needed. Herbs and SupplementsGenerally, manufacturers of herbal remedies and dietary supplements do not need FDA approval to sell their products. Just like a drug, herbs and supplements can affect the body's chemistry, and therefore have the potential to produce side effects that may be harmful. There have been a number of reported cases of serious and even lethal side effects from herbal products. Always check with your doctor before using any herbal remedies or dietary supplements. The following is of special concern for people with glaucoma:
Resources
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Review Date:
8/9/2008 Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-
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