Glaucoma as presented by the guild, to be viewed by the public

1. Triad

   1. Health Information Highway
      http://www.stayhealthy.com/hih.htm

      Health Resource Directory
      http://www.stayhealthy.com/hrd.htm

      http://www.stayhealthy.com/hrd/DICOPr_ENDI_EYEANOTH_Glma.htm

      Glaucoma is a group of diseases characterized by the triad of elevated intraocular pressure, optic nerve injury, and visual loss.

   2. VISIONTIMES
      Sacramento Internet and Beta One Systems Corp., 1996
      http://www.visiontimes.com/pub/pugloss.htm http://www.visiontimes.com/pub/puglo_sf.htm

      Glaucoma

      Disease characterized by abnormally increased intraocular pressure, optic atrophy, and loss of visual field.

   3. Molecular Ophthalmology Laboratory, University of Iowa
      http://mol.ophth.uiowa.edu/MOL_WWW/Glau.html

      Glaucoma is a group of diseases characterized by the triad of elevated intraocular pressure, optic nerve injury, and visual loss.

2. Modified Triad

   No examples found.

   Elevated-IOP Theory

   1. Oakland Tribune? (Associated Press) 1993?

      Mesce, Debra

      . . .glaucoma. . .the disease, caused by a buildup of fluid pressure inside the eye. The fluid buildup eventually damages nerve cells in the eye.

   2. THE CANADIAN INSTITUTE FOR THE BLIND
      http://www.cnib.ca/glaucoma.htm

      Introduction

      Glaucoma is a disease affecting 1 of every 100 Canadians over 40 years of age. It is one of the most common causes of blindness. Although associated with increased age, glaucoma may develop at any age from infancy on. The basic cause of glaucoma is unknown, but a number of risk factors have been identified. These include age, heredity, myopia (shortsightedness), general disease such as early heart attack and stroke, and raised intraocular pressure (IOP). Raised IOP is found in most types of glaucoma and is the main target for control of the disease. When there is a balance between fluid (aqueous) pumped into the eye and the amount that escapes from the eye, the IOP is normal. Raised IOP occurs when fluid outflow is obstructed. Visual loss in glaucoma is thought to be caused by raised IOP and other influences on the optic nerve, located at the back of the eye. The gradual loss of nerve function causes loss of peripheral, or side, vision painlessly and without notice.

   3. Glaucoma
      http://www.ttsh.gov.sg/eye/glaucoma.html

      Introduction

      Glaucoma is an important cause of blindness in Singapore. It occurs more commonly in adults over 40, females and tends to run in families. Glaucoma affects both eyes in most people though usually not at the same time. What is glaucoma? Glaucoma is a condition in which there is raised pressure within the eyeball leading to irreversible damage to the optic nerve. The optic nerve is responsible for sending messages from the eye to the brain and so enabling us to see. Glaucoma will therefore lead to blindness if not detected and treated early.

   4. GLAUCOMA RESEARCH FOUNDATION

      Understanding & Living with Glaucoma: A Reference Guide for People with Glaucoma and Their Families
      http://www.glaucoma.org/booklet.html

      Writer: Lynn A. Whitmore
      Library of Congress catalog number 88-207450 ISBN 0-9621579-0-2.
      Funding for Understanding and Living with Glaucoma is provided by a grant from Allergan Inc.

      WHAT IS GLAUCOMA?

      Glaucoma occurs when there is too much fluid pressure in the eye, usually because the plumbing system is not working correctly. The drainage canals may become clogged or covered over, but the ciliary tissues continue to produce fluid. In other words, the faucet is still turned on, but the sinks drain is blocked or its pipes are clogged. In glaucoma, the increased fluid pressure builds up and pushes the optic nerve back into a cupped or concave shape. If the intraocular pressure remains too high for too long, the extra pressure damages parts of the optic nerve. This damage appears as gradual visual changes and then loss of vision. The early visual changes are very slight and do not affect the central vision the center portion of what is seen when looking straight ahead or reading. Parts of the peripheral vision--the top, sides and bottom areas of vision are affected and may not be noticed by the patient at first. Glaucoma usually occurs in both eyes, but extra fluid pressure often begins to build up first in only one eye. NO SYMPTOMS In the most common form of glaucoma, this build-up of fluid pressure happens gradually, usually without discomfort or painful symptoms.

   5. International Glaucoma Association
      Registered Charity No.274681
      http://www.iga.org.uk/iga/PAT_s6.htm

      Section 6: A Parents Guide to Glaucoma in Babies and Children

      General Questions about Glaucoma in Babies and Children

      1. What is Glaucoma/Buphthalmos in small children?

      There are many forms of infantile glaucoma, but in the majority there is an abnormal fluid drainage angle of the eye. For an eye to be healthy, aqueous fluid (aqueous just means watery in Latin) circulates in the eye and then flows out through the eye's drainage angle. The drainage angle consists of a sponge like tissue through which the fluid passes into a pipe (the canal of Schlemm) and this joins with the blood vessels around the eye. If the sponge is covered by a membrane (which acts like a plastic sheet) the fluid cannot pass through to the sponge and pressure builds up causing glaucoma. Other structures, such as the canal (drainpipe), may be abnormally formed in the baby and this can also restrict the flow of the fluid.

      3. Why do you only hear of older people getting glaucoma?

      Glaucoma is much rarer in children. The cause of the glaucoma is completely different in adults - whilst most of the children have an abnormally formed drainage angle, in adults the angle worked very well for many years before becoming less efficient and causing a rise in pressure although mild developmental defects may occasionally predispose to a rise in adult eye pressure.

   6. National Eye Institute
      National Institutes of Health
      Public Health Service
      U.S. Department of Health and Human Services
      http://seamless.seamless.com/alexanderlaw/txt/brochure/sight. shtml
      NIH Publication No. 91-3251
      Don't lose sight of glaucoma: Information for people at risk

      1. What is glaucoma ?

      Glaucoma is an eye disease in which the normal fluid pressure inside the eyes slowly rises, leading to vision loss-or even blindness. This brochure is about open-angle glaucoma, the most common form of the disease.

      2. What causes it?

      At the front of the eye, there is a small space called the anterior chamber. Clear fluid flows in and out of the chamber to bathe and nourish nearby tissues. In glaucoma, for still unknown reasons, the fluid drains too slowly out of the eye. As the fluid builds up, the pressure inside the eye rises. Unless this pressure is controlled, it may cause damage to the optic nerve and other parts of the eye and loss of vision.

   7. Dr. Anthony Origlieri, Ophthalmologist
      Montclair Community Hospital
      http://www.kabmed.com/MCH/eye_care.htm

      Q: What is glaucoma?

      A: Fluid is always flowing through the inside of the eye. If you have glaucoma, this fluid doesn't flow normally. As a result, the pressure inside of your eye rises and damages your sight. If your pressure remains high it can cause blindness.

   8. WASHINGTON ASSOCIATION OF OPTOMETRIC PHYSICIANS
      http://www.eyes.org/information.html

      Information and Definitions

      Glaucoma:

      What is glaucoma?

      Glaucoma is an eye disease in which the internal pressure of your eye rises to a point that the optic nerve is damaged. The pressure that builds up is due to a problem in the flow or drainage of fluid normally produced in your eye. Glaucoma is one of the leading causes of blindness in the U.S.

      What causes glaucoma?

      The exact cause of glaucoma is not known. For some reason, the passages that normally allow fluid within your eye to drain out become clogged or blocked. This results in fluid building up within your eye and ncreasing pressure on the optic nerve. The nerve fibers and blood vessels in the optic nerve can easily be damaged by this pressure. An injury, infection or tumor in or around the eye can also cause the pressure to rise.

   9. U. S. Healthcare & Aetna Health Plans
      http://www.ushc.com/

      Look up health information

      HEALTH WATCH
      http://www.ushc.com/health/5612.html

      GLAUCOMA

      What Is Glaucoma?

      Glaucoma is a disease of the eye characterized by a buildup of fluid within the eye. This fluid, known as aqueous humor, bathes the eye in nutrients and helps the eyeball maintain its shape. In a healthy eye, aqueous humor is continuously drained and replenished. In a person with glaucoma, the fluid does not drain properly. Instead, it builds up and puts pressure on the optic nerve. When the pressure gets too high, it causes damage to the optic nerve, which results in partial or total vision loss.

   10. University of Cincinnati Medical Center
       aging/additionalinfo/Glaucoma.html NetWellness
       Revised: May 30, 1996
       Information for People at Risk

       1 What is glaucoma?

       Glaucoma is an eye disease in which the normal fluid pressure inside the eyes slowly rises, leading to vision loss --or even blindness. This brochure is about open-angle glaucoma, the most common form of the disease.

       2 What causes it? At the front of the eye, there is a small space called the anterior chamber. Clear fluid flows in and out of the chamber to bathe and nourish nearby tissues. In glaucoma, for still unknown reasons, the fluid drains too slowly out of the eye. As the fluid builds up, the pressure inside the eye rises. Unless this pressure is controlled, it may cause damage to the optic nerve and other parts of the eye and loss of vision.

   11. Online Eye Care & Treatment
       http://www.healthtouch.com/

       Healthtouch® Vision Problems &

       Eye Disorders

       Glaucoma
       http://www.healthtouch.com/level1/leaflets/100934/aoa004.htm

       Glaucoma is an eye disease in which the passages that allow fluid in the eye to drain become clogged or blocked. Increased pressure inside the eye then damages the optic nerve and causes vision loss. Glaucoma cannot be prevented but if diagnosed and treated early, it can be controlled. Vision lost to glaucoma, however, cannot be restored. Copyright 1994-1996, American Optometic Association Licensed to Medical Strategies, Inc. (MSI)

   12. EYE CENTERS OF FLORIDA ONLINE PATIENT BROCHURES
       http://www.eyeville.com/fleye/eyeq.html

       Improve Your Eye Q

       What Is Glaucoma? Is There A Cure For This Condition? A common disease of the eye, glaucoma occurs when the pressure of fluid in the eye increases, damaging the optic nerve. In its early stages, glaucoma can be effectively treated with medication. In its later stages, surgery may be necessary to correct the condition and restore vision. If untreated, glaucoma can cause serious vision loss or blindness. While glaucoma can be treated and further vision loss avoided, there is no cure for this disease. Glaucoma patients should have routine exams, to detect and arrest any further progression of the disease.

   13. Vision Trends Magazine
       http://www.direct.ca/excel/vtrends.shtml

       What is Glaucoma? Glaucoma is a disease in which the fluid pressure in the eyeball increases and may damage the optic nerve. This damage can cause severe vision loss and even blindness, if untreated. Excel's Internet Optical, Inc., 1995

   14. Science Sleuths, Elementary Los Angeles County Department of Education
       http://electra.cortland.com/vdyweb/teams/ Videodiscovery

       http://electra.cortland.com/vdyweb/teams/GLOSS.HTM

       glaucoma (glao-ko'-ma) A treatable eye disease in which high pressure builds up inside the eye. If left untreated, glaucoma can cause loss of vision.

   15. All Saints Health Care System
       http://www.tms.tribune.com/rjt_health/

       http://www.tms.tribune.com/rjt_health/glossary.htm

       glaucoma --

       a type of eye disease in which pressure builds within the eye, causing impaired vision

   16. UK Telecommunications whatever
       http://www.tms.tribune.com/rjt_health/

       Glaucoma

       An increase of intraocular pressure sufficient to damage structure or function of the eye.

   17. Kaiser Permanente's Medical
       http://www.tms.tribune.com/rjt_health/

       Glossary: G-H

       Glaucoma

       A condition where abnormally high pressure of the fluid in the eye causes damage.

   18. The EyeCare Connection
       Larry Bickford, O.D.
       PO Box 3896
       Santa Barbara, CA 93130-0043
       http://www.west.net/~eyecare/

       GLOSSARY OF OPHTHALMOLOGIC TERMS
       http://www.west.net/~eyecare/glossary.html

       Glaucoma:

       abnormally increased intraocular pressure resulting in optic nerve damage and loss of visual field

   19. The EyeCare Connection (Redone 1/27/97)
       Larry Bickford, O.D.
       Adult & Pediatric Vision Care
       http://www.west.net/~eyecare

       Glaucoma is the diagnosis given to the ocular condition when there is loss of retinal nerve fibers and a corresponding loss of vision. The visual defect is most often observed as enlargement of the physiological blind spot and other visual field losses. Left untreated, the disorder can ultimately result in serious visual field loss with only limited direct central vision, or worse. Treated, and treated early and properly, vision can often be saved. Early treatment may prevent significant vision loss or at least arrest the process, sometimes completely and other times with varying degrees of loss of parts of the visual field.

       For clinicians, the major issues are early diagnosing and effectively treating the condition. Unfortunately, unlike some other ocular conditions, glaucoma does not often lend itself to simple diagnosis or treatment. Recently, we have come to understand much more about the mechanisms of glaucoma. And within the last few months there have been a few brand new medications which show great promise for more effectively and conveniently managing the disorder.

       What is Glaucoma?

       Glaucoma occurs as a result of increased intraocular fluid pressure (IOP), as measured by an instrument called a tonometer. The eyeball is basically a rigid sphere filled with fluid. As the total amount of fluid increases, pressure increases, similar to over inflating a tire. Sooner or later, something has to give. It is the retinal nerve fibers that become damaged and die, and with them goes the vision. But 25% of the time, glaucoma can occur in apparent absence of elevated pressure. It is also possible to have increased pressure without nerve damage (ocular hypertension). These are examples of some of the many mysteries of glaucoma.

       The Two General Types of Glaucoma

       The two primary causes for increased pressure are increased aqueous fluid production and decreased fluid outflow. In the normal healthy eye, the aqueous fluid is constantly being produced and drained, normally at equal rates. In open angle glaucoma, the tissue producing the fluid becomes over-active. Medications can reduce the fluid production. At other times, the drainage channels can become blocked. This is angle closure glaucoma. There are a number of causes for this anomaly, including anatomical defects, degenerative tissue defects (including possible systemic immune system and connective tissue disease), trauma and internal eye infection. Again, medications can sometimes help open the drainage and increase outflow, and there is a laser surgical procedure to clean out debris, widen the outflow channels or even open a new channel.

       Additionally, certain medications (e.g., topical ocular corticosteroid anti-inflammatory drugs, orally administered steroid medications and vasoconstrictor drugs, as well as other pharmaceuticals) can, as a side effect, raise the intraocular pressure.

       Researchers are also concerned with a third mechanism of action relating to open angle glaucoma. This has to do with restriction of the blood flow to the nerve fibers which may or may not be related to elevated intraocular fluid pressure.

       You can gather from the above that glaucoma has many possible causes, and therefore a variety of treatments. Sometimes the disorder can be completely resolved, sometimes it requires constant medical control with medications and/or surgery---still with very good outcomes as far as saving vision. But sadly, there are times when medical intervention comes too late, or is otherwise ineffective at stemming the course of the disease.

       The Two Theories of Open Angle Glaucoma

       The current understanding of the disease is that there are structures called microtubules within the axons of each of the hundreds of thousands of nerve fibers comprising the optic nerve. These microtubules serve as corridors to remove metabolic waste products and to supply nutrients to maintain the health of the individual nerve fibers. When these tubules are damaged, perhaps crushed by the increased pressure, the nerve fiber becomes functionless---dead. Vision is lost, little by little as the number of damaged nerve fibers increase. By the time we can measure visual field defects, a great deal of damage has already occurred.

       Localized loss of blood supply can also cause the nerve cell to die, and this loss of blood flow may be related to elevated pressure or an ischemic event where the blood supply is otherwise mechanically blocked.

       The mechanical theory, then, explains how the increased pressure crushes the microtubules, depriving the nerve of nutrients. It also helps explain loss of blood flow as the internal eye pressure exceeds that of the blood vessels' pressure. It does not, however, explain low-pressure glaucoma or why some people can have elevated pressure without damage to the nerves (ocular hypertension).

   Modified/Questionable IOP Theory

   1. American Academy of Ophthalmology, 1996
      http://www.eyenet.org/public/faqs/glaucoma_faq.html

      What Is Glaucoma?
      http://www.eyenet.org/public/faqs/glaucoma/glc_what.html

      Glaucoma causes damage to the optic nerve. The optic nerve carries the images we see to the brain. The optic nerve is like an electric cable containing about 1.2 million wires. Glaucoma can damage nerve fibers, causing blind spots to develop. What causes glaucoma? Many people know that glaucoma has something to do with pressure inside the eye - the intraocular pressure (IOP). Pressure builds up in the eye when the clear liquid called the aqueous humor, which normally flows in and out of the eye, is prevented from draining properly. This can happen in different ways, depending on the type of glaucoma. The resulting increase in pressure within the eye can damage the optic nerve. Ophthalmologists used to think that high intraocular pressure was the main cause of optic nerve damage in glaucoma, however we now know that even people with "normal" IOP can experience vision loss from glaucoma - so-called "normal tension glaucoma". Some people with high intraocular pressure never develop the optic nerve damage of glaucoma. (These people need to be followed carefully by an ophthalmologist, because they are considered "glaucoma suspects"). Elevated IOP is still considered a major risk factor for glaucoma, though, because studies have shown that the higher the IOP is, the more likely optic nerve damage is to occur.

   2. THE GLAUCOMA FOUNDATION
      http://www.aegix.com/info/about.htm

      What is glaucoma?

      Glaucoma is actually a group of eye diseases which cause damage to the optic nerve, usually resulting from elevated fluid pressure within the eye. This elevated pressure is caused by a backup of fluid within the eye. Gradually, loss of vision occurs. Through early detection, diagnosis, and treatment, you and your doctor can help to preserve your vision. The disease is called the "silent thief of sight" because it strikes without obvious symptoms. Therefore, the person with glaucoma is usually unaware of it until serious loss of vision has occurred. In fact, half of those suffering damage from glaucoma do not know it. Currently, damage from glaucoma cannot be reversed. Research funded by The Glaucoma Foundation seeks to find a cure. For further details, see also the online edition of Doctor, I Have a Question

   3. Drug Watch Oregon.
      1/21/94
      http://www.lec.org/Drug_Watch/Public/Documents/MJforGlaucoma. html

      GLAUCOMA
      Is Marijuana a Safe and Effective Treatment?

      What is Glaucoma:

      Glaucoma, a leading cause of blindness, in the United States, afflicts nearly 2 million Americans, about 60,000 of whom are legally blind. Open angle closure glaucoma: In the vast majority of cases this type of glaucoma is without symptoms. It is associated with mild elevation of intraocular pressure that produces chronic damage to the optic nerve. Open angle closure glaucoma is treated medically with drugs that reduce aqueous humor formation. Acute angle closure glaucoma: This rare form of the disease, which may include pain, blurring of vision, halos around lights, etc., is treated with laser or surgery. Although elevated intraocular pressure is a common symptom of glaucoma, nearly 20 percent of those who have the disease do not experience elevated pressure. For these the traditional screening tests may miss the diagnosis and, since glaucoma patients "almost never have symptoms," damage will continue to progress in their eyes.

   Multifactor IOP Theory

   1. Gleams (Newsletter of the Glaucoma Research Foundation, San Francisco, CA), 14:3 (Winter 1997) [p. 1, col. 2]

      Until recently, glaucoma was largely defined as "pressure within the eye higher than the statiscal norm of the population." It was long believed that this elevated intraocular pressure (IOP) would cause a certain type of damage to the optic nerve, called glaucoma. This view is too simplistic, since high eye pressure is not always required to cause the optic nerve damage seen in people with glaucoma. Other factors are probably involved. The adequacy of blood flow may play a role, as well as certain factors which may damage the optic nerve, or the interruption of factors which are required to maintain its health.

   2. Eye to Eye (Newsletter of The Glaucoma Foundation, New York, NY), 7:4 (Fall 1996) [p. 4, "New Directions in Glaucoma Treatment"]

      A variety of underlying causes can result in glaucomatous damage to the optic nerve. The most well recognized of these is damage to the trabecular meshwork, the drainage system of the eye. Fluid (aqueous humor) is produced in the eye at a continuous rate, so that blockage of the drainage system results in elevated intraocular pressure (IOP). Therefore, most research and antiglaucoma therapy have been directed at reducing IOP by increasing the rate of drainage or reducing the rate at which the eye produces aqueous humor (turning down the faucet). Elevated IOP is clearly not responsible for all types of glaucoma. About 33% of patients have IOP which is considered to be "normal". Recent advances in high resolution ocular imaging have demonstrated abnormalities in ocular blood flow in some of these patients. We have begun to evaluate the role of anti-hypertensive medications known as calcium channel blockers in patients thought to have arterial spasm. In addition, 24-hour ambulatory blood pressure monitoring devices have revealed abnormal dips in blood pressure during sleep that may contribute to poor ocular circulation.

   3. Usenet: Subject: Glaucoma FAQ 1/2

      From: ritch@inx.inx.net (ritch)

      Date: 1996/03/04

      Message-Id: <4hdgrc$hj2@ixc.ixc.net>
      X-Posted-From: InterNews 1.0.6@pm1-50.inx.net Organization: P.O.P.
      X-Authenticated: ritch on POP host inx.inx.net
      Newsgroups: alt.support.glaucoma,sci.med.vision

      http://www.web-xpress.com/iaoo/glaucoma/glaufaq.html
      http://www.web-xpress.com/athens/glaucoma.html

      FREQUENTLY ASKED QUESTIONS: GLAUCOMA
      Copyright, Robert Ritch, MD (ritch@inx.net)
      Professor and
      Chief, Glaucoma Service the New York Eye and Ear Infirmary
      310 East 14th Street, New York, NY 10003
      and
      Jeffrey Liebmann, MD (liebmann@inx.net)
      Clinical Associate Professor of Ophthalmology
      Associate Director, Glaucoma Services The New York Eye and Ear Infirmary
      Updated March 3, 1996

      This is the THIRD posting of this FAQ sheet. It is still under development and extensive additions will appear over the next few months.

      I. WHAT IS GLAUCOMA?

      A.What glaucoma is NOT

      It is important to note that glaucoma is NOT a DISEASE. A disease has a specific etiology, mode of onset, pathophysiology, and course, or natural history. Intervention can potentially occur at a number of different stages, from prevention, to intervention to limit progression, to cure, and to reversal of damage caused by the disease. Over the last 50 years, what we could call the CENTRAL DOGMA has held sway. This dogma goes as follows: Glaucoma is a disease caused by elevated intraocular pressure (IOP). The elevated IOP damages and destroys the axons of the optic nerve, leading to progressive blindness. Glaucoma can be divided into two broad types - OPEN-ANGLE and ANGLE-CLOSURE. Each of these, in turn, can be divided into primary and secondary forms. This dogma has played a major role in retarding thinking and inhibiting new approaches to understanding and therapy, and should be discarded.

      B. What glaucoma IS

      Glaucoma is an end stage, analogous to congestive heart failure or liver failure. Glaucoma is an optic neuropathy characterized by a specific pattern of optic nerve head and visual field damage, which represents a final common pathway resulting from a number of different conditions which can affect the eye. While elevated IOP is the most important risk factor for the development or progression of glaucomatous damage, it is still only a risk factor and not the disease itself. Some of the entities which lead to glaucoma are becoming well characterized, although most related conditions remain to be discovered or fully elucidated. There are other risk factors which can lead to glaucomatous damage in the face of normal IOP. The hot research topic at the present time is that of blood supply to the eye and its regulation. An insufficient blood supply is believed to be a major risk factor for glaucomatous damage. Other possible risk factors, most of which have been as yet little explored, include autonomic insufficiency, low blood pressure, inherited or acquired abnormalities of the connective tissue of the lamina cribrosa, abnormally low intracranial pressure, autoimmune phenomena, primary ganglion cell degeneration, excitotoxins (aspartate, glutamate), and other as yet unconsidered possibilities.

      C. The problem with terminology

      Terminology is another source of confusion. The way the term "glaucoma" is used creates confusion in the minds of physicians and patients alike. For instance, we use the term primary open-angle glaucoma to refer to a patient with elevated IOP and visual damage, while reserving the term "ocular hypertension" for persons with elevated IOP but no detectable disc or visual field damage. We can also use the term "glaucoma suspect," which then includes ocular hypertensives and persons with large cup/disc ratios who may have normal-tension glaucoma but still have normal visual fields. A patient presenting with acute angle-closure, a markedly elevated IOP, but with a normal disc and field is considered to have "glaucoma," while a patient with appositional closure and peripheral anterior synechiae, but with normal IOP, discs and fields, has "chronic angle-closure glaucoma." In some instances we use the term to describe the disc and field damage, in others the angle damage, and in still others the pressure alone. Within the category of angle-closure, the terminology is inconsistently used. Some use "angle-closure," others "closed-angle," and still others "narrow angle." The latter is particularly misleading, since it can describe a patient with primary open-angle glaucoma and narrow angles or one with actual angle-closure. Open-angle glaucoma and angle-closure glaucoma will be described below. As a general rule, in the open-angle glaucomas, the eye is anatomically normal, but blockage or malfunction of the drain of the eye (the trabecular meshwork) leads to elevated IOP. In low-tension glaucoma, the abnormality is not in the meshwork but at the level of the optic disc. In the angle-closure glaucomas (yes, there are more than one), the trabecular meshwork is normal, but the iris is pushed against the meshwork, blocking the flow of fluid (aqueous humor) from the eye. The analogy to a sink is a useful one. In a normal eye, the faucet is always on and the drain is always open. In open- angle glaucoma, the drain gets clogged. When this happens, aqueous can not leave the eye as fast as it produced, causing the fluid to back up. But since the eye is a closed compartment, the "sink" doesn't overflow; instead the backed up fluid causes increased pressure to build up within the eye. We need to use chemical drain-cleaner (eyedrops) to open the drain or turn down the faucet. If this is insufficient, we can snake the train (laser trabeculoplasty), and if that doesn't work, we need to put in new plumbing (surgery). In angle-closure glaucoma, the drain is normal, but it's covered by a stopper. We need to remove the stopper (laser iridotomy or laser iridoplasty) rather than treat with medications. Open-angle and angle-closure glaucomas are about as alike as a heart attack and a bullet wound to the heart. The disease mechanisms, the basic approach to treatment, and the prognosis all differ. And that is why the terminology is confusing.

   4. Internet VisionCare
      http://www.visioncare.com/faq.htm

      Frequently Asked [VisionCare] Questions

      What is glaucoma? This is a simple question without a simple answer. There are several forms of glaucoma, but the one most people think about, and the most common form, is called Chronic Open Angle Glaucoma (COAG for short). This is the form I will discuss here. Traditionally glaucoma (COAG) was thought to be an eye disease characterized by increased pressure within the eye. Today we have learned that the pressure inside the eye, (IOP for short) is but one factor in determining if any particular patient has glaucoma. Other important factors are the patients age, race, family history, optic nerve condition, and field of vision. It is the last factor, the field of vision, from which the definitive diagnosis of glaucoma is made. In glaucoma, the patient loses, very slowly at first, his or her field of vision. Very small blind spots begin to form, usually far out in the side or peripheral vision. These blind areas eventually coalesce together into larger blind spots, until, finally, the eye is blind. The problem with glaucoma is that the loss of sight occurs so slowly that many, if not most people are unaware of the change until very late in the disease - when treatment is difficult and the outcome often poor. Until sight is gone, there are no signs or symptoms associated with Glaucoma!

   5. GLAUCOMA RESEARCH FOUNDATION

      Glaucoma: No Longer Just a Pressure Problem
      http://www.glaucoma.org/topics.html

      From the early 1800's until the last quarter of the 20th century, glaucoma was defined as "pressure within the eye higher than the statistical normal of the population." It was believed that this elevated intraocular pressure (IOP) would cause a certain type of damage to the optic nerve, which would eventually cause blindness if left untreated. Most experts now agree that glaucoma is a series of conditions, characterized by a particular form of optic nerve damage that is often-- but not always-- associated with elevated IOP. The American Academy of Ophthalmology and the Glaucoma Research Foundation now define glaucoma as "a group of diseases with certain common features including an intraocular pressure that is too high for the continued health of the eye." Although raised IOP is no longer thought to be the only damaging factor in glaucoma, it is still the main treatable aspect in glaucoma therapy. While it is clear that elevated eye pressure is a risk factor for optic nerve damage, the mechanism that causes optic nerve damage is not clear.

   IOP Theory Degenerated / Cause Reversal

   No examples found.

   IOP Only Risk Factor

   No examples found.

   Dyad

   1. DOC IN THE BOX
      http://www.proservices.com/

      Medical Information

      Ophthalmology

      Glaucoma

      Original Question: What is glaucoma?
      Response: Glaucoma is a disease of the optic nerve of the eye. It is one of the leading causes of blindness affecting up to 2% of the population. Light rays are focused onto the retina which is like the film of the eye. The stimulated retina sends nerve impulses through the optic nerve to the brain. The nerve impulses are processed by the brain to form the images that we see. In glaucoma, optic nerve fibers are damaged so that light rays that fall upon the retina are not transmitted to the brain. This causes blind spots to form in the field of vision. These blind spots, or scotomas, usually develop in the peripheral field of vision and can progress to complete blindness.

   Visual-Field Defect Not Explained by Other Disease

   No examples found.

   Optic Neuropathy

   No examples found.

   Collection of Unspecified Number of Signs

   1. Frequently-Asked-Questions for sci.med.vision
      $Date: 1996/03/13 00:40:28 $, $Revision: 1.29 $
      AUTHOR: Grant Sayer, BOptomBSc
      CONTRIBUTORS: Barbara La Scala, Scott Fitz, Ronald Jones, David Nelson M.D, Nathan Schwade PhD, Alex Eulenberg, Darren Berar, W.Lee Wan M.D, Robert Sekuler
      http://www.webcom.com/~optcom/
      http://spectacle.berkeley.edu
      gopher://eyesite.optometry.ohio-state.edu
      email (Ascii) - grants@research.canon.oz.au

      5.6 Glaucoma --------------

      Glaucoma is a symptomatic condition and not a disease "sui generis". It is a collection of physicals signs: raised intra- ocular pressure, visual field loss, enlargement of the blind spot and changes in the appearance of the optic nerve head. There are a variety of clinical classifications of glaucoma.

   Neurotoxin-Caused

   1. New York Times, Mar. 20, 1996: B9 ("Health") (Based on Dreyer's Arch Ophthal article on page of intraprofessional descriptions)

      Hilts, PJ

      The blindness that results from glaucoma, long thought to be a result of too much fluid inside the eye, may be more the result of a neurotoxin, according to a new report that has intrigued, but not completely convinced, other scientists. Glaucoma . . . It is a slow, progressive disorder that ultimately causes irreversible blindness because it kills the nerves that pick up optical signals in the eye and carry them to the brain. It is characterized by selective losses--areas are "punched out" or "drop out" of the visual field--rather than overall dimness.

   As Used to Categorize "Glaucoma" in Clinical Studies

   No examples found.

   As Related to Population Screening

   No examples found.

   Official Recognition of Reality's Sneak-Theft of the Elevated-IOP Theory

   No examples found.

   Definition Advertised but Not Produced

   1. THE VIRTUAL EYE CENTER
      http://icaro.zia.ms.it/oculistica/eye/indexgb.html

      Institute of Ophthalmology University of Pisa, Pisa, Italy
      e-mail: benelli@clioc.med.inipi.it

      Public utility services

      Glaucoma
      http://icaro.zia.ms.it/oculistica/eye/glaucogb.html

      What is glaucoma? If you are near or past the age of 35, you have a direct interest in knowing how to prevent blindness from glaucoma. Glaucoma is a leading cause of blindness among adults in the United States. It is estimated that one out of every seven blind persons is a victim of glaucoma. Practically all of them had normal sight most of their lives. But sometime during their 40s, 50s or 60s, they went blind, for glaucoma rarely strikes until after the age of 35. Their sight can never be restored. There are two principal types of glaucoma, acute and chronic. The acute type strikes suddenly, inflicting cloudy vision, sometimes with severe pain in and around the eyes. The chronic type--which is more common--progresses slowly and painlessly. The victim is only vaguely disturbed by the symptoms which come and go; as a result, he postpones visiting an eye doctor. This brochure is mainly about the most common kind of glaucoma, which is called open-angle glaucoma. Other kinds of glaucoma are described briefly.

   2. Excimer Laser Filtration Surgery
      http://137.142.42.104/StudentArea/bernstein/SeminarSlides/int ro.html
      Authors: Anne Brooks, Martin Samuel, F.R.A.C.O., Nannette Carroll, Nicholas Downie, F.R.A.C.O., and Hugh Taylor
      Presentation: Marrick A. Bernstein
      May 8, 1996

      Background on Glaucoma

      Two Most Common Types of Glaucoma

      1.(Chronic) Open Angle Glaucoma

      2.(Acute) Angle Closure Glaucoma

      3.Normal Aqueous Flow (Chronic) Open Angle Glaucoma

   3. A Service of Computers In Eyecare, Inc. and Eyecare Technology Magazine
      ®. 804 Reading Street, Suite B, Folsom, CA 95630. (916) 985-7300.
      http://dns.logonit.net/etonline/all.htm

      Patient Education Vision & Your Health

      Glaucoma & Your Eyes·

      WHAT IS GLAUCOMA?
      (Courtesy of the American Academy of Ophthalmology.)

      [missing]

   4. SUNY Plattsburgh
      Department of Biological Sciences
      Marrick A. Bernstein, Student
      http://137.142.42.104/StudentArea/bernstein/SeminarSlides/OPEN.HTML
      May 8, 1996

      Excimer Laser Filtration Surgery

      3.What is Glaucoma?
      Two Most Common Types of Glaucoma

      1.(Chronic) Open Angle Glaucoma

      2.Symptoms

      Development is very gradual
      Unnoticed
      Loss of peripheral vision
      Opposite eye compensates
      Pain is not a characteristic

      3.Causes

      Unknown

      2.(Acute) Angle Closure Glaucoma

      2. Symptoms

      Usually monocular
      Eye is red and painful
      Vomiting and Nausea
      Frequent attacks of pain and blurred vision

      3.Causes

      Believed to be hereditary

Return to Physicians

Go to the CapitolHill GeoPage