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FAQ's:
Amblyopia | Common Glasses Problems and Solutions
Cataract | Diabetic Eye Disease | Macular Degeneration | Strabismus |
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1. What is glaucoma, and how prevalent is the disease? 3. Are there different kinds of glaucoma? 5. Are there risk factors for the development of glaucoma? 6. What's the difference between a glaucoma suspect and a glaucoma patient? 7. How can I tell if I have glaucoma? 10. What is the treatment for glaucoma? 11. How does laser treatment work for glaucoma? Is the treatment painful?
1. WHAT IS GLAUCOMA, AND HOW PREVALENT IS THE DISEASE?
Glaucoma is a disease that causes damage to the optic nerve which threatens blindness. The optic nerve is the "cable" that connects the eye with the brain and which carries visual information from the retina (back of the eye) to the seeing centers of the brain. (See Eye Anatomy for details.) The optic nerve is composed of over one million nerve fibers and is approximately 1/16th of an inch in diameter. There are many forms and causes of glaucoma (see below) which can be extremely difficult disease to diagnose at times. Glaucoma is considered a major health problem, and it is estimated that over 2 million Americans have the disease, and as much as half of them may be unaware of the problem. Every year, as much as 100,000 Americans develop glaucoma. According to the American Academy of Ophthalmology, in the United States alone, glaucoma of all types is the second most common cause of legal blindness, and is the leading cause of legal blindness among African Americans. Approximately 80,000 Americans are legally blind from glaucoma, and many more have visual impairment. Glaucoma is one of the most common causes of preventable blindness. There is no cure for glaucoma. However, with proper treatment, blindness can be prevented in 90% of the cases. The eye is a closed cavity that has its own internal fluid circulation which bathes and nourishes the internal eye. This fluid is called aqueous humor and is made by tiny glands in the ciliary body, a muscle that helps the eye focus. This muscle is located behind the iris (the colored part of the eye).
Aqueous (red arrows) then flows from behind the iris, through the pupil, and into the front compartment of the eye (called the anterior chamber) where is nourishes the cornea and lens. From there, it is normally drained out of the eye through a filtering drain called the trabecular meshwork. The trabecular meshwork is situated in the angle of the eye (where the colored and white parts of the eye meet. In many cases of glaucoma, this "drain" becomes clogged such that fluid cannot leave the eye as fast as it is produced. This causes fluid pressure to build up in the eye. Optic nerve damage in glaucoma is usually caused by this elevated fluid pressure within the cavity of the eye.
Although most cases of glaucoma are related to abnormally elevated fluid pressure in the eye, the degree of fluid pressure elevation necessary to cause optic nerve damage varies from individual to individual. Many people tolerate elevated pressures without any optic nerve damage at all. Still others can have severe optic nerve damage with normal or only mild elevations of pressure. In these types of patients, it is thought that optic nerve damage is a result of poor blood flow to the nerve making the nerve very sensitive to pressure in the high normal range. 3. ARE THERE DIFFERENT KINDS OF GLAUCOMA? The word "glaucoma" is like the word "automobile." Many forms and types exist. Below is a discussion of the most common forms. If you have glaucoma, it is important that you know which type you have. Some forms of glaucoma, for example, can be affected by certain medications. Each of these are discussed below. Just scroll down or click on any of the items below for discussion. It will be helpful if you read the section on Primary Open-Angle Glaucoma before reading about the other types of glaucoma.
PRIMARY OPEN-ANGLE GLAUCOMA (POAG) POAG is the most common form of glaucoma, and usually occurs in adults over the age of 45-50 years of age. It is a chronic problem of unknown cause resulting from increased fluid pressure within the eye which causes damage to the optic nerve and vision. This form of glaucoma is "silent" meaning that there are no early symptoms. The pressure rises slowly, and various components of the eye such as the cornea adapt well without signaling any pain. The disease often goes undetected, and patients can lose large amounts of their vision without being aware of any damage. This is because initial loss of vision occurs in the periphery. It is not until central vision becomes involved that patients realize that there is something wrong. Even then, there's a tendency to believe that there's only a minor problem such as needed their glasses adjusted. By then, however, the damage is irreversible. There is much still to be learned about POAG. We do know that in this form of glaucoma elevated pressure causes damage and deterioration to the optic nerve. The average pressure in the normal population is 14-16 millimeters of mercury, although the normal range can vary from 8 to 21. Pressures or 22 are considered suspicious, and beyond that point, abnormal. What is not understood well is why persons with clearly elevated pressures do develop optic nerve damage, and why some others do not. This is the subject of active research.
In this disease, it is thought that the drainage portion of the eye and trabecular meshwork (please see question 2 - What Causes Glaucoma?) does not allow outflow of internal fluid (aqueous) normally. The reasons for this are not clear, and there are several theories being considered. Because aqueous continues to be formed, pressure within the eye increases. Once a sufficient number of optic nerve fibers are destroyed, blind spots begin to develop in the peripheral vision. This peripheral field loss is often undetected by the patient, but can easily be mapped out by a visual field test (please click Diagnostic Services for a description of a visual field test). It is important to realize that damage at any level is permanent, and that the goal of treatment is to slow or arrest the disease so that no further damage is done. (Question 7 talks of ways your ophthalmologist has to detect problems before they lead to visual damage.) While there is no "cure" for POAG, treatment is often highly successful is slowing or arresting the disease. Many patients do not understand the necessity for lifelong treatment, especially when they sense that their vision is good, and they "feel" nothing wrong with them. It is important however that treatment is taken according to your doctor's instructions to prevent further damage. If you are having side effects from your medicines, you need to discuss this with your doctor. If you are not confident with the recommendations or diagnosis, a second opinion may be helpful. By no means should you ignore the problem because of lack of symptoms. Remember, glaucoma treatment is a very individualized process. Please see question 10 for more details about treatment.
NORMAL OR LOW TENSION GLAUCOMA LTG is a form of glaucoma where there is progressive optic nerve damage and deterioration resulting in loss if vision, but in which there is no elevation of intraocular fluid pressure. This form of glaucoma can be very difficult to diagnose, and is often not recognized until some form of damage results. LTG is becoming increasingly recognized as an important type of glaucoma to look for, especially in persons with vascular disease such as hypertension, diabetes, heart disease, etc. LTG is thought to be due in part to poor circulation to the optic nerve head, making it very sensitive to any form of pressure, even pressure that is well within normal range for the general population. In these very sensitive eyes, it is thought that a pressure lower than normal is necessary to prevent further damage and visual loss. The target pressure to minimize any further optic nerve damage is different for different individuals, and treatment can never be a "cook book" approach. There is much research being done in the field of optic nerve blood flow, and much has yet to be learned about this form of glaucoma. For treatment details, please see question 10.
ACUTE ANGLE-CLOSURE GLAUCOMA (AACG) Unlike POAG where intraocular fluid pressure rises slowly, in AACG, the pressure rise is sudden and can become extremely high. This results in pain, redness, blurred vision, and may cause nausea and vomiting. The cornea often swells causing halos in addition to blurred vision.
What causes an attack of acute glaucoma? Please refer to question 2 for details of anatomy. As discussed, the aqueous (red arrow) is drained through the trabecular meshwork located in the angle of the eye. The angle is where the iris (colored part of the eye) and the white part (called the sclera or "wall" of the eye) meet. In some individuals, the angle of the eye is very narrow. This could be as a result of the way their eye is built, or it may be due to problems such as thickened cataracts which begin to crowd the front part of the eye. Under these conditions, anything that dilates the pupil will cause the iris to crowd the angle.
When crowding becomes critical, the trabecular meshwork may become completely and suddenly obstructed by iris that fluid pressure begins to build up rapidly, causing the attack. Things that can cause pupillary dilation include being in the dark, certain types of medication such as anti-histiminics, cold preparations, anti-depressants, anti-nauseants, and some others. Stress can cause pupillary dilation as well. Attacks usually occur in the evening or at night. AACG is an emergency, and must be treated promptly before optic nerve and trabecular meshwork damage occur. Permanent damage to these structures can result quickly. Treatment begins with a combination of drops to both constrict the pupil (thereby "pulling" the iris away from the trabecular meshwork) and decrease the eye's fluid production. Once the intraocular fluid pressure is within normal range, your ophthalmologist will perform a laser iridotomy. A laser iridotomy is a procedure in which a laser beam is used to create a small opening in the iris, near the angle. This allows pressure to equalize in the eye, and allows the aqueous to flow more freely. This laser treatment is a painless outpatient procedure, and can be done in less than 10 minutes. An attack usually occurs in only one eye, even though it is very common that both eyes have narrow angles. Therefore, most of the time, your ophthalmologist will recommend that the uninvolved eye also undergo a laser iridotomy procedure to prevent such an attack in that eye too. Routine comprehensive examinations can be helpful in determining if an individual is at risk for AACG. If your ophthalmologist is suspicious of narrow angles, he will perform a gonioscopy exam, a painless procedure in which a special mirrored lens is placed gently on the surface of the eye that allows visualization of the angle. (See Diagnostic Services page for a description of gonioscopy.) Patients with narrow angles can then be warned of symptoms. Your doctor may even recommend that you undergo laser iridotomy if he feels that the risk for attack is great.
This is an uncommon form of glaucoma that is caused by NEW blood vessel growth in the iris (colored part of the eye) which leads to bleeding and scarring of the angle. When the angle scars, the aqueous cannot exit via the trabecular meshwork and Schlemm's canal causing relentness increased intraocular pressure. (See question 2 for details of the anatomy of the angle.) This is an uncommon form of glaucoma and is usually due to other problems of the eye related to its circulation or even more rare, chronic inflammation. This is considered a type of SECONDARY GLAUCOMA (see below) meaning that NVG has occurred due to another problem with the eye. There are two main circulation problems that can lead to NVG. Diabetic Retinopathy in its advanced form, if untreated, can lead to NVG. Central Retinal Vein Occlusion (CRVO) is a circulatory problem in which the main vein draining blood out of the eye becomes occluded or "stopped up," leading to a back flow of blood and hemorrhaging into the eye. If severe and untreated, NVG can develop. There are many systemic problems that are associated with CRVO such as hypertension, heart disease, diabetes, and other vascular problems. Rarely does CRVO occur in healthy persons. There are other less common causes of NVG such as carotid artery occulsive disease, chronic uveitis, and others. If caught in time, laser treatment can usually successfully treat NVG. The goal of treatment is to save the eye, not to restore vision since vision is usually permanently damaged by this time.
Pigmentary glaucoma is a type of open-angle glaucoma that is caused the shedding of iris pigment into the anterior chamber fluid (aqueous) which then accumulates into the drainage structures of the eye called the trabecular meshwork. (See question 2 for details of the anatomy of the drainage system of the eye.) With the trabecular meshwork "clogged up," aqueous produced in the cavity of the eye cannot drain out into Schlemm's canal thereby causing increased fluid pressure in the eye. Pigmentary glaucoma is relatively uncommon and occurs more in men than women. It is an inherited form of glaucoma and begins usually in the 20's or 30's. Because it begins so early in life, it represents a real threat to long term normal vision. The vast majority of cases of pigmentary glaucoma occur in nearsighted persons. It is thought that in certain nearsighted individuals, the anterior chamber is deeper than normal causing the iris to rub up against other structures in the eye such as the lens and zonules (fibers in the eye behind the iris which hold the lens in proper position). This constant rubbing action causes the iris pigment to flake off into the aqueous. This form of glaucoma can be treated successfully (see question 10).
This form of glaucoma is common, and occurs in approximately 10% of persons over the age of 50. For reasons that are not clear, a whitish dandruff-like material builds up in the eye and accumulates on the lens surface. As the pupil dilates and constricts, this material along with iris pigment is literally rubbed off the lens and is dispersed in the aqueous (see question 2 for details of the anatomy). Both pigment and this exfoliative material clog the trabecular meshwork leading to a build up of fluid pressure. Not all persons with exfoliative syndrome develop glaucoma or elevated pressure. However, if you have exfoliative syndrome, your chances of developing glaucoma at some point in your life are six times higher than if you don't. It usually begins in one eye long before the other. Therefore, persons with exfoliative syndrome need to be monitored carefully for the development of glaucoma. Fortunately with this type of glaucoma, treatment is highly successful (see question 10).
These types of glaucomas are generally as a result of an insult or injury to the eye. These events can fall into several categories:
It is not an understatement to say that EVERYONE, children to older adults, should be concerned about glaucoma, because early detection and treatment are the only ways to prevent irreversible blindness. See below for risk factors that place certain people at greater risk.
5. ARE THERE RISK FACTORS FOR THE DEVELOPMENT OF GLAUCOMA? There are several conditions that put some people at greater risk:
Other risk factors include:
6. WHAT'S THE DIFFERENCE BETWEEN A GLAUCOMA SUSPECT AND A GLAUCOMA PATIENT? Glaucoma can be extremely difficult to diagnose, particularly in the early stages. An example of a glaucoma suspect would be a person who may have elevated pressures, but a normal optic nerve exam and visual fields. Elevated pressure alone does not mean glaucoma, although it is an important risk factor (see question 5). Such a person would be monitored on an appropriate basis, and even perhaps treated if the pressure were high enough to be a significant risk.
Another confusing scenario would be a patient with suspicious looking optic nerves, but with normal visual fields and pressure. Normal-tension glaucoma in this case may be suspected, but still difficult to diagnose for sure. Being a glaucoma suspect basically means that a potential problem may have been caught in the very early stages and can be watched or treated early to prevent damage. By contrast, a glaucoma patient by definition means that damage has occurred, either in the way of optic nerve damage, or damage to the vision as demonstrated by visual field testing. This means that optic nerve fibers have already undergone irreversible damage, and that treatment will be necessary to prevent any further damage to the nerve or to your vision.
7. HOW CAN I TELL IF I HAVE GLAUCOMA? The vast majority of cases of early glaucoma have no symptoms. Except for acute forms of glaucoma, there generally is no pain or discomfort. Most patients are totally unaware that there is anything threatening their vision. In advanced glaucoma, patients may complain of generally blurred vision or loss of peripheral vision. In acute glaucoma, pain is prominent with other symptoms and signs such as red eye, halos, light sensitivity, and headache. The intensity of pain can vary from a low grade brow ache to intense aching. The best method for diagnosing glaucoma is through a comprehensive examination. This should be done regardless of age, but especially if risk factors (see question 5) are present. Your ophthalmologist has a variety of diagnostic tools available in the investigation for possible glaucoma (see question 9). Remember too that there are many other causes of blurred vision and ocular pain.
Glaucoma is usually a painless disease. Pain is more related to the rate of pressure rise (as seen in the acute forms of glaucoma) and less related to the level of pressure itself. It is well known that high levels of pressure that occur slowly over a period of time have little or no symptoms of discomfort. We've seen patients with intraocular pressures of 50 millimeters of mercury (upper limits of normal - 22) and didn't have a clue that anything was wrong. It is as though the eye acclimates and compensates. With sudden rises in pressure, however, discomfort may occur with pressures far below that level.
Most cases of glaucoma are "silent" meaning that there are no warning signs that specifically point to glaucoma. Except in advanced cases where there may be profound visual loss, glaucoma generally goes undetected. An eye examination is the best method of glaucoma detection (see question 13 for details). During the course of an examination, if your ophthalmologist becomes suspicious of glaucoma, he may perform other tests to clarify or stage the level of disease that a person may have. These tests are listed below:
This method is a highly accurate form of IOPdetermination and is completely painless.
Applanation tonometry is the most common method of IOP determination. There are other less common forms of pressure determination. For example, air puff tonometry reads IOP by blowing a puff of air against the eye. Because nothing touches the eye, numbing drops are not needed. Patients are aware of air being blown into the eye, however.
During this test, you will be seated in front of the visual field machine that your doctor uses. Your head will be positioned before a white screen with your chin comfortably resting on a chin rest. Within this white screen will be a target that the testing eye (other eye will be covered) will fixate on. When the test begins, you will see spots of light of varying intensities flash one by one in different parts of your side vision. You simply press a button each time you happen to see a light stimulus. The computer then takes these responses and uses the information to form an analysis of your visual space. Sophisticated programs can then compare your responses with what is statistically normal for someone your age and level of vision. The test is easy and is of course painless since it is a visual test. Testing programs have become much more refined and do not take near the time or require the concentration that programs in the past did. There are other tests that have become available for early glaucoma diagnosis, which concentrate on detecting early optic nerve disease. These technologies are still being developed and refined. They include the Heidelberg Retinal Tomograph, the GDx, and the Optical Coherence Tomography System. 10. WHAT IS THE TREATMENT FOR GLAUCOMA? Glaucoma is generally treated "medically" (observation in suspect cases, eye drops, and/or rarely pills). Surgery (laser, traditional surgery) is generally reserved for cases that cannot be controlled medically. Some surgeons however are using laser treatment as the first line of treatment in an attempt to avoid daily use of eyedrops. Rarely in this country is a traditional glaucoma operation performed before trying medical or laser treatment. Some countries however do traditional glaucoma surgery as their first line of treatment and claim good results. There are studies that are looking into which is the best initial treatment of glaucoma. Treatment however often includes a combination of methods.
There are many types of eye drops used in glaucoma, and advances in pharmacology (the study of drugs) has greatly revolutionized the way glaucoma is treated. Depending upon the medication, drops may be used from once to four times per day, and may be used in combination with other drops. All eye drops cause a certain level of stinging and burning, which should be very short-lived. Also, just like other medication, eye drops may uncommonly cause other side affects, such as blurred vision, redness, and even problems such as insomnia, irritability, shortness or breath, heart rhythm disorders, and others. Your ophthalmologist should advise you of possible side affects of the drops that you're on. Also, make sure that (s)he knows what other medication you are taking. To minimize absorption into the bloodstream and maximize absorption into the eye, close your eyes for a minute or so and press against your tear ducts located in the nasal corners of your eyes. Your ophthalmologist can demonstrate proper eye drop technique for you.
11. HOW DOES LASER TREATMENT WORK FOR GLAUCOMA? IS THE TREATMENT PAINFUL? When medication does not achieve the desired results, loses their effects, or is intolerable due to side affects, then your ophthalmologist may recommend laser treatment. There are basically two techniques of laser treatment used in the glaucomas. For acute glaucoma (see question 3), laser iridotomy is considered the treatment of choice after stabilization with medication. For open angle glaucoma and most other forms of chronic glaucoma, laser trabeculoplasty is the technique of choice. See below for a description of both techniques.
At Davidson Eye Associates, laser treatment is performed in an office setting. Generally, patients come in an hour before the procedure to have some preparatory eye drops instilled. Just before the treatment begins, numbing drops are instilled which may cause short-lived stinging. During the laser procedure, patients will see bright flashes of light but will experience no pain otherwise. The procedure takes between ten and twenty minutes. After the treatment, we will monitor the eye and its pressure for the first hour or two. Most patients can then resume their normal activities at home, although the vision in the treated eye may be blurred for several hours. There may be some minor discomfort for a few hours after the procedure. Initial follow up visit is then scheduled which can range from one day to one week after the treatment.
In acute glaucoma (see question 3 for details and pictures of a narrow angle), pressure can build up rapidly in the eye causing visually threatening damage to the optic nerve. In doing a laser iridotomy, an opening in the iris allows equalization of pressure in the posterior and anterior chambers. This allows pressure to flow directly into the angle for drainage, and also allows the peripheral iris to "fall back" or
relax, creating a wider angle for better fluid flow. Laser iridotomy is generally curative in preventing attacks of acute glaucoma. For those who have suffered an attack of acute glaucoma, this technique can prevent further attacks but will not restore any vision that may have been lost. For open angle glaucoma and other forms of nonacute glaucoma (see question 3 for details), laser trabeculoplasty can be done to add control. Here, the laser beam heats up the trabecular meshwork causing it to "stretch open," and allowing fluid to drain out more earily. In laser trabeculoplasty, approximately 80% of patients respond well enough to laser treatment to avoid surgery (see question 12). It may take several weeks to see the full effect, however. Although some patients find that the laser treatment allows control of their pressure without the use of eye drops, most find that eye drops at some level are still necessary. Remember, the goal of laser treatment is control of pressure, not the elimination of eye drops. Laser surgery for glaucoma is generally considered a low risk operation, which is why it has become a common form of glaucoma treatment. An uncommon complication is a pressure spike which can usually be managed with medication and rarely necessitates emergency surgery. The risk for visual loss from pressure spike or macular swelling is also rare. Laser surgery for glaucoma does not cause cataracts. Sometimes laser treatment has no affect on the pressure. Even with successful treatment with a good pressure response, glaucoma must be monitored since the treatment can lose its effect over time.
12.WHEN IS SURGERY NECESSARY FOR TREATMENT OF GLAUCOMA? In this country, surgery is considered as a last resort when other treatments such as medication and laser surgery have failed. There are several types of glaucoma operations performed world-wide. The most common performed procedure, however, is called a trabeculectomy. This surgery involves removing a portion of the trabecular meshwork (see question 2 for details) which allows the aqueous to drain out of the eye more easily resulting in lower intraocular pressure (IOP). Glaucoma surgery is generally done as an outpatient procedure under local anesthesia with sedation. Unless there are complications, patients go home an hour or so after their surgery. Patients are seen the next day for a post-surgical evaluation of the eye, vision, and for measurement of the IOP. It can take several weeks for vision to get back to its baseline following the operation. Postoperative medications generally include an antibiotic drop, an anti-inflammatory drop, and a cycloplegic drop (keeps the pupil dilated and helps manage pain). Glaucoma drops may be continued at some level depending upon what your ophthalmologist feels is needed. The postoperative period generally lasts two to three months. The majority of patients do well with surgery, and most find that surgery controls them without the use of medication. There are risks to the procedure, especially in advanced glaucoma. Risks can include visual loss, cataract development from the procedure, or a failed procedure necessitating a re-operation.
13. HOW OFTEN SHOULD I HAVE MY EYES CHECKED FOR GLAUCOMA? Routine eye examinations are a vital part of maintaining ocular health and detecting silent disease. Recommendations for eye examinations vary. For the detection of glaucoma, Davidson Eye Associates recommends the following schedule as a guideline. Precisely how often a patient should be seen will depend upon their circumstances and risk factors. Davidson Eye Associates Recommended Guidelines
Risk Factors -Age -Family History -Elevated IOP -Race -Diabetes -Hypertension -Blunt Injury -Prolonged use of steroid medication
*Note: Recommendation depends upon the type and number of risk factors involved. See question 5 for details. Questions? Please feel free to contact us by phone or e-mail. For related web sites, please click on Links below. Home | Mission Statement | About the Practice | Doctor Information | Links | Site Map | About Your Privacy |
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