In simple terms, glaucoma is a buildup of fluid inside the eye. It's the leading cause of blindness among adults in the United States, and estimates are that one of every seven persons is a victim. Your eyes are essentially hollow globes filled with a constantly circulating fluid that must drain out of the eye as more fluid is pumped in. When the passages that allow fluid to drain become clogged or blocked, the fluid pressure can build and eventually cause damage to the optic nerve. That buildup of pressure is called glaucoma. Of the two types of glaucoma, open-angle and acute-(or closed) angle. The latter is far more serious and represents only about 10 percent of total glaucoma cases.
The Risks of Glaucoma
Because open-angle glaucoma, the more common version of the disorder, usually develops gradually and without symptoms, regular eye exams are important in detecting the disease before it damages your eyesight. If detected at an early stage and treated promptly, glaucoma can be controlled with little or no further vision loss. People of all ages can develop glaucoma, but it most frequently occurs in those who are more than 40 years of age. People of African-American heritage are also at greater risk, as are those with a family history of glaucoma, those who are very nearsighted and those who have diabetes.
Acute or closed-angle glaucoma can develop more quickly and may be accompanied by symptoms such as blurred vision, a loss of side vision, appearance of colored rings around the eyes, and pain or redness in the eyes. A combination of any of these symptoms necessitates an immediate eye examination.
Preparation for the Examination
Before the examination, patients will be asked to supply their address and telephone numbers, insurance information, names of other doctors, list of medications being taken, and past medical records if available. Some doctors ask patients to bring to the exam all medications currently being used. Because a glaucoma exam includes dilating the eyes, it's a good idea to bring sunglasses to wear during the trip home.
The exam usually begins with a visual acuity test and refraction to determine how well you can see with and without eyeglasses or contact lenses. Then, it moves on to more specialized procedures, which allow the doctor to determine whether the disease has already caused damage to the eye.
Introacular Pressure Test
Visual Field Test
There are two kinds of tests. In a moving target test, the targets are moved from the side, where they are not visible, towards the center of vision until the patient sees them. This test can be done with either a black screen on the wall or with a large bowl-shaped instrument.
The other is fixed target test, called computerized static perimetry. It uses small points of light that appear bright or dim but do not move. During this test, a patient sits in a chair facing either a bowl-shaped instrument or a computer screen.
The visual field examination is important in detecting many disorders of the eye, optic nerve and brain. One of the early symptoms of glaucoma, for instance, is the appearance of "blind spots" that can be detected by a visual field test.
When all the tests are complete and outcomes analyzed, the eye doctor will discuss the results and recommend an appropriate course of treatment if needed. The first line of treatment is often the use of eye drops administered three times per day or oral medication to help drain the fluid and lower pressure. Sometimes the use of eye drops or pills is all that is needed to lower pressure. Following the eye drops and oral medication directions closely is extremely important for control of the disease.
When pressure can not be lowered adequately with eye drops or oral medication, or side effects are too severe, the eye doctor may turn to laser treatment. Laser surgery uses focused light to reopen the drainage area to alleviate the buildup of fluid.
Regardless of whether surgery is needed, glaucoma requires careful monitoring, including regular return visits to the doctor to be sure the disease is not progressing.
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