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A tonometry test, more commonly known as an eye pressure test, is a simple medical procedure that measures intraocular pressure. Usually performed at an optometrist's office by a doctor or medical technician, the test takes only seconds. A patient experiences minimal discomfort as a sensor comes into contact with the eye. The test is accurate in diagnosing and measuring the progression of glaucoma, a condition that causes increased intraocular pressure.
Though medical device companies have created a variety of machines to perform an eye pressure test, a patient will generally experience one of two examples. The most common type of eye pressure test is one taken by a Goldmann tonometer. After receiving numbing eye drops, a patient sits forward and positions his or her head on a stable shelf in order to remain still during the test. A doctor positions the tonometer in front of the eye and makes contact with the cornea. Measuring the eye's resistance gives an accurate reading of intraocular pressure.
The second type of test, given by both doctors and medical technicians, involves a hand-held device resembling a large pen. These devices are separated into two groups: those that measure intraocular pressure through contact with the cornea and those that measure through the half-closed eyelid. A patient, after receiving numbing eye drops, either lies down or put his or her head back while sitting. The device's weight puts pressure on the eye, and the doctor/medical technician holds it in place until the device produces a digital readout.
The primary purpose of the eye pressure test is to diagnose glaucoma. As glaucoma does not have acute, painful symptoms, the test is necessary to catch this degenerative disease. After a diagnosis, when a patient has started medication or undergone surgery, future eye pressure tests can tell a doctor if intraocular pressure is rising again. By giving patients and doctors an early warning, the eye pressure test raises the chances that the patient will experience more years of good sight.
Outside of glaucoma, the eye pressure test is a valuable tool for diagnosing other conditions. For example, raised intraocular pressure is a common symptom of diabetes. Also, a patient with previous eye trauma requires regular tests to make sure the effected eye has adequate intraocular pressure. Low pressure, known as hypotony, can lead to cataracts and more serious conditions as eye pressure falls lower.