Tutorial Glaucoma #8 Exames para o diagnóstico do glaucoma


Are you aware of the necessary tests for diagnosing Glaucoma? We already know that Glaucoma is a silent disease When symptoms do occur, it is too late to prevent vision loss. The most effective way to prevent vision loss is by annually visiting the ophthalmologist Speaking of which, I highly suggest you watch Tutorial 3 for other ways of preventing Glaucoma You will find the link down below this video. During the ophthalmic test, we look for optic nerve changes or high eye pressure as well as changes in the front part of the eye that may cause problems in the future. Since this is an extremely difficult disease to diagnose mainly in early stages we usually make use of complementary tests to confirm the diagnosis and also to identify in which stage the disease is. A correct diagnosis will directly lead to treatment. It is important to mention that normal test results do not necessarily indicate the absence of the disease; it may still be in its early stage so that is why the patient may not have been tested positive yet. For example, the visual field. It measures the central visual field within 30 degrees, that is, peripheral losses such as the ones that occur in the early stages of Glaucoma are not detected However, being tested positive may have another cause. In my point of view, a test that has led to a cost-effectiveness optimization of the diagnosis is the Optical Coherence Tomography (OCT). This exam is over 90% sensitive; I said 90%! On the contrary, the sensitivity of the visual field only occurs for diagnosing Glaucoma when the disease has already damaged at least 40% of the optic nerve fibers. The OCT for Glaucoma diagnosis may include the evaluation of the Anterior Chamber Angle, the evaluation of the Nerve Fiber Layer around the optic nerve, as well as the so-called retinal ganglion cells. The damages related to the disease occur in one of these three locations. The evaluation of the Anterior Chamber Angle is extremely important so as to determine the type of Glaucoma, as shown in the Glaucoma Tutorial 4. Besides OCT, there is a classic test for this purpose: Gonioscopy. Pressure measurements are essential to indicate the main risk factor for developing Glaucoma: the ocular hypertension. We may make simple measurements, a pressure curve – it may be carried out all day (DIURNAL TENSION CURVE) or through provocative tests, being the water-drinking test the most important one. In order to measure intraocular pressure, we use a device called Tonometer. Corneal surface thickness has an influence, being that thicker surfaces are more resistant and lead to falsely high IOP readings and vice-versa. Fundus Photography, including the nerves, is also frequently used. It can register and sometimes show some signs of the disease. There are other tests that are less often used, in more specific cases. Repetition of tests in programmed intervals aims to provide details of the evolution or the occurrence of a lesion. The choice of a test or even the combination of tests varies from doctor to doctor. Most of the time, we achieve the same results through different ways. In my opinion, the most important thing is the clinical reasoning from a detailed test and, when it is complemented by a high sensitivity test for diagnosing Glaucoma and in carefully determined intervals, we are going to have a highly reliable diagnosis of the disease. Vision is the most important human sense. Thank you for watching. See you soon!

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