What is glaucoma? [ 04/29/13 ]
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 possibly blindness. Optic nerve damage usually occurs in the presence of high eye (intraocular) pressure; however, it can occur with normal or even less than normal eye pressure. More than three million Americans are living with glaucoma, 2.7 million of whom—aged 40 and older—are affected by its most common form, open-angle glaucoma. Some studies have shown that perhaps half of people living with glaucoma aren't even aware they have the disease. Worldwide, an estimated 66.8 million people are visually impaired due to glaucoma, and an estimated 6.7 million are blind.
Are there different forms of glaucoma? [ 04/29/13 ]
There are two main forms of glaucoma: open-angle (the most common form, affecting approximately 70-95% of individuals); and angle-closure. There are also several other forms of glaucoma, including normal-tension, congenital, juvenile, and secondary.
Open-angle glaucoma, the most common form of the disease, is progressive and characterized by optic nerve damage. The most significant risk factor for the development and advancement of this form is high eye pressure. Initially, there are usually no symptoms, but as eye pressure gradually builds, at some point the optic nerve is impaired and peripheral vision is lost. Without treatment, an individual can become totally blind.
Angle-closure glaucoma may be acute or chronic. In acute angle-closure glaucoma, the normal flow of eye fluid (aqueous humor) between the iris and the lens is suddenly blocked. Symptoms may include severe pain, nausea, vomiting, blurred vision, and seeing a rainbow halo around lights. Acute angle-closure glaucoma is a medical emergency and must be treated immediately, or blindness could result in one or two days. Chronic angle-closure glaucoma progresses more slowly and can damage the eye without symptoms, similar to open-angle glaucoma.
Normal-tension glaucoma occurs when eye pressure is normal, yet the optic nerve is damaged and peripheral vision is lost. Lowering eye pressure through medication sometimes slows the progress of the disease, but this type of glaucoma may worsen despite low pressure. The treatment is generally the same as for open-angle glaucoma.
Congenital glaucoma affects infants born with defects that prevent the normal drainage of fluid from the eye.
Juvenile glaucoma is open-angle glaucoma that affects children, adolescents and young adults.
Secondary glaucoma can be open-angle or closed-angle and is the result of some other medical condition in the eye or the body.
Are some people at greater risk of developing glaucoma? [ 04/29/13 ]
Glaucoma is a leading cause of blindness among African Americans and Hispanics in the U.S. Three times as many African Americans have glaucoma than Caucasians, and four times as many are blind. Between the ages of 45 and 64, glaucoma is fifteen times more likely to cause blindness in African Americans than in Caucasians. All people older than 60 are at a greater risk of developing glaucoma than people who are younger.
How is glaucoma diagnosed? [ 04/29/13 ]
Individuals at high risk for glaucoma should have a dilated-pupil eye examination at least every two years. Eye doctors use several tests to detect glaucoma:
Tonometry measures the pressure inside the eye. Examples of tonometers include:
- The air-puff (noncontact) tonometer, which emits a puff of air. Eye pressure is measured by the eye's resistance to the air.
- The applanation tonometer, which touches the eye's surface after the eye has been numbed and measures the amount of pressure necessary to flatten the cornea. This is the most sensitive tonometer, but a clear, regularly-shaped cornea is needed for it to function properly.
- The electronic indentation method, which measures pressure by directly contacting anesthetized eyes with a digital pen-like instrument.
In pupil dilation, special drops temporarily enlarge the pupil so the doctor can better view the inside of the eye. Various instruments allow the doctor to determine the thickness of the cornea, to view the front and/or the interior of the eye, and to monitor optic nerve changes over time.
Visual field testing measures the entire area seen by the forward-looking eye to document straight-ahead (central) and/or side (peripheral) vision.
A visual acuity test uses an eye chart to measure sight at various distances.
How do eye doctors document optic nerve damage? [ 04/29/13 ]
When a patient has glaucoma or is at high risk for developing the disease, physicians may document changes over time in the optic nerve through imaging techniques including stereo optic nerve photographs, scanning laser polarimetry (GDx), confocal scanning laser ophthalmoscopy (Heidelberg Retinal Tomograph or HRT II) and optical coherence tomography (OCT). An eye care professional will determine which method(s) to use.
Is there a cure for glaucoma [ 04/29/13 ]
No, but there are sight-saving treatments. So the sooner a person is diagnosed, the more vision can be preserved.
The most common treatments for glaucoma are eye drops and, rarely, pills. There are a number of different categories of eye drops, but all are used to either decrease the amount of fluid (aqueous humor) in the eye or improve its outward flow. Sometimes doctors will prescribe a combination of eye drops. People using these medications should be aware of their purpose and potential side effects, which should be explained by a medical professional. A doctor can decide which medications are best suited for a patient based on the individual case of glaucoma, medical history, and current medication regimen.
Treatments vary depending on the type of glaucoma. The most common include:
Open-angle glaucoma treatment normally begins with medications, usually eye drops or, rarely, pills that either help eye fluid drain more effectively or cause the eye to produce less fluid. Several forms of laser surgery can also help fluid drain from the eye. Conventional filtration surgeries such as the glaucoma drainage implant are sometimes used to create a new opening for fluid drainage.
Acute angle-closure glaucoma (a medical emergency) is treated with medications and/or laser procedures.
Chronic angle-closure glaucoma is treated with a laser procedure, often in an office or clinic under local anesthesia, and with medications.
Normal-tension glaucoma is currently treated in the same ways as open-angle glaucoma. When this form of the disease is better understood, treatment strategies may be modified.
Congenital glaucoma is usually treated with medications and one of two forms of eye surgery.
Juvenile glaucoma is treated using medications, laser surgery and conventional filtration surgery.
Secondary glaucoma can be open-angle or angle-closure, and acute or chronic. Treatment depends on these factors and whether the underlying condition causing increased eye pressure needs to be addressed.
Where can I find more information about glaucoma? [ 04/29/13 ]
The BrightFocus National Glaucoma Research website goes into greater depth on many topics and covers additional areas of concern, both medical and social. You can learn where to get help and access to resources, as well as download free publications. And explore our Ask an Expert section where you can read or post queries to doctors. For more information dealing with the topics below, please visit the helpful organizations section of our website.
- Clinical Trials
- Organizations of Eye-care Professionals
- Federal Government Programs and Services
- General Information, Resources and Referrals
- Legal Assistance
- Low Vision Aid Resources
- Low Vision Organizations
- Print and Audio Materials for the Visually Impaired
- Senior Housing
- State and Local Resources
Can you have glaucoma without having increased pressure inside the eye? [ 04/29/13 ]
Elevated eye pressure increases the risk of developing glaucoma; however, the disease can occur in people with normal or even lower-than-normal eye pressure. It is optic nerve damage that can lead to vision loss and possible 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). In addition, individuals with higher-than-normal eye pressure do not always develop the symptoms of glaucoma.
Since normal-tension glaucoma does not involve high eye pressure, it is diagnosed by observing the optic nerve for any signs of damage. The eye doctor will use an ophthalmoscope to look through the pupil at the shape and color of the optic nerve. In addition, a visual field test can help determine if there is any loss of peripheral vision. The risk factors for developing normal-tension glaucoma include a family history of glaucoma, low eye pressure, and cardiovascular disease. Ongoing research is aimed at determining all of the factors that contribute to the optic nerve damage. For example, scientists believe the optic nerve may be affected by blood flow in the eye. Researchers are also investigating susceptibility and genetic factors.