This audio article is from VisualFieldTest.com.
Read the full article here: https://visualfieldtest.com/en/how-to-test-for-glaucoma
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Excerpt:
Introduction Glaucoma is a complex eye disease in which no single test can provide a definitive answer. Instead, a battery of tests is needed to build a full picture of your eyes: measuring pressure, examining the drainage angle, evaluating the optic nerve head, and mapping your visual field. Each test provides one piece of the puzzle. When you understand what each test does and what the numbers mean, you become an active partner in your care – not just a passive patient sitting in the dark. This guide will explain why multiple tests are necessary and how each one contributes unique information about your eye pressure, anatomy, nerve health, and vision, with clear explanations of the results you’ll receive. Why Multiple Tests Matter Glaucoma is defined by damage to the optic nerve, often associated with high eye pressure (intraocular pressure or IOP), but it can occur even with “normal” pressure. For example, many glaucoma patients actually have relatively low measured IOP because they have thin corneas, which can make pressure readings appear falsely low (). Conversely, a very thick cornea can make IOP look higher than it really is. On the other hand, some eyes with higher pressure never develop glaucoma. Therefore, doctors must look at eye anatomy and function in addition to pressure. This means examining the drainage angle (to see if fluid can escape properly), inspecting the optic nerve for damage, and testing your peripheral vision. In practice, this requires a comprehensive evaluation with complementary tests (). One review of international guidelines notes that general screening is of “limited clinical utility,” and no single test has both the sensitivity and specificity needed (). The takeaway is that a combination of pressure measurement, imaging, and visual field testing is used to confirm or rule out glaucoma. Empowering you as a patient means explaining each test and result. When you walk out of the exam room, you should know, for example, “The average IOP measured 18 mmHg and the pachymetry showed my cornea is thin, which means my true IOP is probably higher,” or “My OCT shows red areas where my nerve fiber layer is thinner than normal.” Armed with this knowledge and the actual printouts of your tests, you can track trends over time and ask informed questions. Measuring Intraocular Pressure (Tonometry and Pachymetry) The only modifiable risk factor for glaucoma is high eye pressure. Measuring IOP is therefore a crucial first step, but even this has nuances. Goldmann Applanation Tonometry (GAT) is the gold standard for IOP measurement. () In this test, a tiny probe gently flattens (“applanates”) the cornea, using a slit-lamp microscope. GAT has been used for decades and is very well validated. () It requires anesthetic eye drops and careful technique. Most clinical trials and glaucoma treatment thresholds are based on Goldmann IOP values. Because GAT relies on flattening the cornea, its reading is accurate for an “average” cornea (about 520 microns thick ()). But if your cornea is much thinner or thicker, the reading can be off (more on that below). Non-Contact (Air-Puff) Tonometry is the familiar–and more comfortable–test that blows a brief puff of air onto your eye. It also measures pressure by analyzing how the cornea flattens under the air impulse. Modern air-puff devices have shown very s
