• What is glaucoma?



• How is glaucoma treated?



• Is one segment of the population more at risk for developing glaucoma?



• Are there different forms of glaucoma?



• How is glaucoma diagnosed?



• How do eye doctors document optic nerve damage?



• What new research is being done to find a cure for glaucoma?



• Can you have glaucoma without having increased pressure inside the eye?



• Can glaucoma be cured by laser techniques?

For more questions and answers about research and science issues concerning glaucoma, please visit the Real Life Questions section of our website.

What is glaucoma?

Glaucoma is actually a group of eye diseases that lead to damage of the optic nerve (the bundle of nerve fibers that carries information from the eye to the brain), which can then lead to vision loss and the possibility of blindness. Optic nerve damage usually occurs in the presence of high intraocular pressure; however, it can occur with normal or even below-normal eye pressure. Glaucoma is estimated to affect approximately three million Americans, and up to half of these individuals may be unaware that they have it.

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How is glaucoma treated?

Treatments vary depending on the specific glaucoma diagnosis:

• Open-angle glaucoma treatment usually begins with medications (eye drops, for example) that help the eye either drain fluid more effectively or produce less fluid. Several forms of laser surgery can also help fluid drain from the eye; these include trabeculoplasty, cyclophotocoagulation, and SLT (Selective Laser Trabeculoplasty). Conventional surgery (trabeculectomy or aqueous shunt procedure) to create a new opening for fluid to drain is usually performed after other treatment options have failed.

• Acute closed-angle glaucoma (a medical emergency) is treated with medications, laser peripheral iridotomy or iridectomy.

• Chronic closed-angle glaucoma is treated with laser peripheral iridotomy and medications.

• Normal-tension glaucoma is currently treated in the same fashion as open-angle glaucoma. When this form of the disease is better understood, then treatment strategies will be modified.

• Congenital glaucoma is usually treated with medications and either goniotomy or trabeculotomy, two forms of eye surgery.

• Juvenile glaucoma is treated using medications, laser surgery and filtering surgery.

• Secondary glaucoma treatment depends on whether the condition is acute or chronic. The underlying condition causing the increase in eye pressure will need to be addressed and this, of course, will vary depending on the cause.
  
  
  • Pigmentary glaucoma is treated using medications, laser surgery and filtering surgery.
  
  
  
  • Pseudoexfoliation syndrome is treated using medications, laser surgery and filtering surgery. Surgical techniques may be used earlier than in open-angle glaucoma.
  
  
  
  • Irido-corneal-endothelial syndrome (ICE) is not well understood and it is not known how to keep the condition from progressing. Medications are often used to help manage the glaucoma and corneal transplants are sometimes needed to treat swelling of the cornea.
  
  
  
  • Neovascular glaucoma may be managed with medications and if abnormal blood vessel growth is occurring in the back of the eye (diabetic retinopathy, for example), a laser procedure called scatter panretinal photocoagulation can be helpful. When the abnormal growth of blood vessels in the retina are treated, the abnormal blood vessel growth that is blocking fluid drainage near the front of the eye may begin to improve also. Trabeculectomy and surgery to destroy parts of the ciliary body (the part of the eye that produces eye fluid - the aqueous humor) may also be used in an effort to decrease eye pressure.

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Is one segment of the population more at risk for developing glaucoma?

Glaucoma is a leading cause of blindness among African Americans and Hispanics in the United States. African Americans experience glaucoma at a rate of three times that of Caucasians and experience blindness four times more frequently. Between the ages of 45 and 64, glaucoma is fifteen times more likely to cause blindness in African Americans than in Caucasians. Also, the elderly are more susceptible to developing glaucoma. If you are over 60, there is a greater risk of developing glaucoma. It has also been suggested that individuals with Japanese ancestry may be at greater risk for normal-tension glaucoma and that Asian or Eskimo descent may pose a greater risk for closed-angle glaucoma.

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Are there different forms of glaucoma?

There are two main forms of glaucoma: open-angle (which is the most common form and affects approximately 95% of individuals) and closed-angle. There are also several other varieties of glaucoma, including normal-tension, congenital, juvenile and secondary.

• Open-angle glaucoma, the most common form of the disease, has no symptoms at first. It is a progressive disease characterized by optic nerve damage. High eye pressure is the most significant recognized risk factor for the development and progression of the disease. The pressure in the eye builds up gradually. At some point, side vision (peripheral vision) is lost and without treatment, total blindness will occur.

• Closed-angle glaucoma comes in two forms: chronic or acute. Acute closed-angle glaucoma is a medical emergency that must be treated immediately or blindness can result in one or two days. This happens when the normal flow of aqueous humor between the iris and the lens suddenly becomes blocked. Symptoms may include severe pain, nausea, vomiting, and blurred vision. When the patient looks at a light source they may also see colored halos around the lights. Chronic closed-angle glaucoma progresses slowly and can produce damage without symptoms, similar to open-angle glaucoma.

• Low-tension or normal-tension glaucoma occurs in people with normal eye pressure who have optic nerve damage and experience narrowed side vision. Lowering eye pressure at least 30 percent through medicines slows the disease in some people. Glaucoma may worsen in others despite low pressures. A comprehensive medical history is important in identifying other potential risk factors, such as low blood pressure, that contribute to low-tension glaucoma. If no risk factors are identified, the treatment options for low-tension glaucoma are the same as for open-angle glaucoma.

• Congenital glaucoma is a condition where babies are born with defects that prevent the normal drainage of fluid from the eye.

• Juvenile glaucoma has been used to describe open-angle glaucoma in children, adolescents and young adults.

• Secondary glaucoma occurs as the result of some other recognizable medical condition in the eye or the body, and can be of the open-angle or closed-angle variety. The following are examples of secondary glaucoma:

• Pigmentary glaucoma is a rare form of the disease where pigment granules from the iris flake off into the aqueous humor (eye fluid) and then clog the eye's drainage system (trabecular meshwork).
  
  
• Pseudoexfoliation syndrome occurs when outer layers of the lens flake off and block normal flow of the aqueous humor.
  
  
• Iridocorneal Endothelial Syndrome (ICE) consists of a number of features, including the loss of cells from the cornea, which break off and block the drainage channels in the eye, resulting in increased eye pressure. There also may be scarring that connects the iris to the cornea.
  
  
• Neovascular glaucoma results from abnormal blood vessel growth that blocks the fluid drainage channels of the eye, resulting in increased eye pressure. Low blood supply to the eye as a result of diabetes, insufficient flow of blood to the head due to blocked arteries in the neck, or blockage of blood vessels in the back of the eye can cause the abnormal blood vessel growth.

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How is glaucoma diagnosed?

Several tests can help your eye doctor detect glaucoma. Individuals at high risk for glaucoma should have a dilated pupil eye examination at least every two years. Tests involved in the diagnosis of glaucoma include:

• Tonometry measures the pressure inside the eye. The following are examples of tonometers:
  
  One is the air puff, or noncontact tonometer, that emits a puff of air. The eye’s resistance to the air indicates the eye pressure. Another is the applanation tonometer which actually touches the eye’s surface after your doctor has placed drops in both your eyes to numb them. The applanation tonometer measures the amount of pressure necessary to flatten the cornea. The applanation tonometer is the most sensitive. But, the patient must have a clear, regularly-shaped, cornea in order for the applanation tonometer to function properly. Finally, the electronic indentation method uses a digital pen-like instrument to measure pressure. This also requires that the instrument make contact with the cornea after anesthetic drops have been applied to the eyes.



• Pupil dilation involves the use of special drops that temporarily enlarge the pupil so that the eye doctor can obtain a better view of the inside of the eye.



• Visual field testing measures the entire area that can be seen when the eye is looking forward. This documents straight-ahead (central) and/or side (peripheral) vision. This test measures the dimmest light that can be seen at each spot tested. The test requires the patient to respond to the appearance of light by pressing a button every time a flash of light is perceived.



• Visual acuity measures how well you see at various distances. While seated 20 feet away from an eye chart, the patient is asked to read standardized visual charts with each eye. The test will be performed with and without corrective lenses.



• Pachymetry involves using an ultrasonic wave instrument to help determine the thickness of the cornea. This test can help your doctor better evaluate your eye pressure readings.



• Ophthalmoscopy allows the eye doctor to examine the interior of the eye by looking through the pupil with a special instrument. It is helpful in detecting damage to the optic nerve that is due to the effects of glaucoma.



• Gonioscopy allows the doctor to view the front part of the eye (anterior chamber) to determine if the iris is closer to the back of the cornea than usual. This test can help diagnose closed-angle glaucoma.



• Optic nerve imaging helps the eye doctor document how the optic nerve changes over time. Scanning laser polarimetry (GDx), confocal scanning laser ophthalmoscopy (Heidelberg Retinal Tomograph or HRT II), and optical coherence tomography (OCT) are all examples of optic nerve imaging techniques. All three imaging techniques are painless and non-invasive. The patient’s eye doctor will make the determination as to which method(s) to use.

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When a patient has glaucoma or is at high risk for developing the disease, physicians may document how the optic nerve changes over time by making drawings, taking photographs, or using a new technique called optic nerve imaging. Scanning laser polarimetry (GDx), confocal scanning laser ophthalmoscopy (Heidelberg Retinal Tomograph or HRT II), and optical coherence tomography (OCT) are all examples of optic nerve imaging techniques. The patient’s eye care professional will make the determination as to which method(s) to use.

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What new research is being done to find a cure for glaucoma?

New research is focusing not only on lowering pressure inside the eye, but is also exploring medications that will protect and preserve the optic nerve from the damage that causes vision loss as well as the role of genetic factors. There has been progress in understanding the genetics of glaucoma in the last few years. Genes have been found that are associated with congenital glaucoma, juvenile glaucoma, normal-tension glaucoma, adult-onset open-angle glaucoma, pigmentary glaucoma, and other conditions that are associated with secondary glaucoma.

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Can you have glaucoma without having increased pressure inside the eye?

Glaucoma is actually a group of eye diseases that damage the optic nerve, which can then lead to vision loss and possibly blindness. In many people, fluid pressure increases inside the eye and damages the optic nerve (the bundle of nerve fibers that carries information from the eye to the brain). Elevated eye pressure does increase the risk of developing glaucoma, however, the disease can occur in people with normal or even lower than normal eye pressure. In addition, there are individuals who have higher than normal eye pressure who do not develop the symptoms of glaucoma. "Normal Tension Glaucoma" (NTG) can be diagnosed by observing the optic nerve for any signs of damage. This information can be obtained by using an ophthalmoscope (a hand-held instrument that has its own light source and enables the physician to look through the pupil and observe the back of the eye) to observe the shape and color of the optic nerve. In addition, a visual field test can help determine if there is any current loss of peripheral vision. Sometimes patients are not aware that there is a loss of sight in certain parts of the visual field. The risk factors for developing NTG include a family history of glaucoma, cardiovascular disease and possibly Japanese ancestry. Research is ongoing to determine all of the factors that contribute to the optic nerve damage and why certain individuals are more susceptible. In addition to lowering pressure inside the eye, the role of genetic factors and medications that will protect and preserve the optic nerve from damage are two areas that researchers are exploring. Currently, there is no "cure" for NTG; however, early diagnosis and treatment can control glaucoma before vision loss or blindness occurs.

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Can glaucoma be cured by laser techniques?

Laser surgery can help control the symptoms of glaucoma; however, no treatments are currently available that will cure the disease. Several forms of laser surgery can help fluid drain from the eye or decrease the amount of fluid produced; these include trabeculoplasty, iridotomy, and cyclophotocoagulaton and SLT (Selective Laser Trabeculoplasty). These techniques help maintain a normal eye pressure and minimize the risk of further damage to the optic nerve.

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Glossary of glaucoma treatments

• Aqueous shunt procedure - a tiny tube is inserted into the anterior chamber of the eye (the region of the eye between the cornea and the lens), which facilitates the drainage of fluid. This technique is usually used for patients that have not responded to trabeculectomy or are not candidates for this procedure.



• Cyclophotocoagulaton - a procedure most often used to treat more aggressive or advanced forms of glaucoma. The laser is directed towards the ciliary body. This helps to decrease the production of aqueous humor.



• Goniotomy - a tiny blade is inserted through the cornea, which then cuts the trabecular meshwork (eye fluid drains out of the eye through this spongy tissue located near the cornea), allowing the eye fluid to flow out of the eye in a normal fashion.



• Incisional surgery - a new opening is created for fluid to drain through and is usually performed after other treatment options have failed. This is usually performed in a hospital, with local anesthesia and possibly sedation. A very tiny piece of the sclera (the tough outer coat that protects the entire eyeball) is removed, allowing for fluid to drain through it, resulting in a decrease in eye pressure.



• Iridectomy - a procedure in which a small section of peripheral iris is removed by the laser, which allows fluid to drain more easily from the eye.



• Laser peripheral iridotomy - a small opening is made in the iris (the colored ring of tissue behind the cornea that regulates the amount of light entering the eye by adjusting the size of the pupil) so that the fluid in the eye can drain.



• Scatter panretinal photocoagulation - a laser procedure that destroys abnormal blood vessels in the retina, which may occur with neovascular glaucoma.



• SLT (Selective Laser Trabeculoplasty) - a low energy laser procedure that potentially can be repeated without causing tissue damage. It can have an impact on specific cells in the trabecular meshwork (the mesh-like canals that help drain fluid from the eye) without causing collateral tissue damage.



• Trabeculectomy - a small section of the trabecular meshwork (eye fluid drains out of the eye through this spongy tissue located near the cornea) is removed. This allows the aqueous humor to drain more easily. A small channel is made through the white part of the eye under your upper eyelid. This channel will allow the fluid made naturally in the eye to drain away more easily.



• Trabeculoplasty - a high-energy beam of light (laser) is aimed at a lens and reflected onto the trabecular meshwork (eye fluid drains out of the eye through this spongy tissue located near the cornea). The laser makes burns in the trabecular meshwork and stretches the drainage holes that are found there. This helps fluid drain more easily out of the eye and helps brings eye pressure back into a normal range.



• Trabeculotomy - An incision is made in the outer portion of the eye. A tiny probe is inserted into the canal that drains fluid from the eye and then it becomes twisted, so that it breaks through the trabecular meshwork. Eye fluid then is able to drain out of the eye through this spongy tissue located near the cornea. This allows the eye fluid pressure to remain in a more normal range.

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Some of the information in this section of our website was obtained from the National Eye Institute and the the National Library of Medicine.

Reviewed on 2/14/2008