Glaucoma Diagnosis
How to know if I suffer from primary glaucoma?
As time goes by we have observed that the most frequent type of glaucoma is that of “open-angle”, which generally the patient does not notice until he or she has lost vision at the central part of the eye (i.e.: when staring at someone else’s eyes).
We have repeatedly perceived that this disorder goes unnoticed because the eye which is less affected often “helps” the other. What’s more, people usually pay more attention to the central part of the sight, which remains unaffected until the disorder is quite advanced.
Furthermore, people also assume that the loss of sight at the edges of the peripheral visual field is a normal symptom of advanced age, which is not true at all. That is why we recommend that everyone over 40 years old examines their eyes every two years. As we will see, some examinations are crucial in order to detect glaucoma.
How does the Instituto Oftalmológico Amigó detect and control glaucoma?
At IOA (Instituto Oftalmológico Amigó) we examine three fundamental conditions so as to diagnose glaucoma:
1. Determine the intraocular pressure
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Firstly, we determine if intraocular pressure is at a high level, which would be associated to an early stage of the disorder. In addition, it is known that the possibilities of preserving the sight are related to a significant decrease of intraocular pressure.
Measurements of intraocular pressure or tonometry are usually performed with the commonly named “blue-light test” (Goldmann tonometer), which consists of a prism placed against the cornea. Even though this painless method is virtually accurate, it is a matter of fact that in some patients it could be erroneous. This occurs because the test does not consider the thickness of the cornea (the transparent lens at the surface of the eye). Its thickness directly influences the results of intraocular pressure measurement tests. Due to the above, our centre makes use of the ORA (OCULAR REICHELT ANALYZER) in patients above 40 years old since 2008. ORA is a sophisticated test that provides an accurate measure of the intraocular pressure taking into account the thickness of each cornea. It also indicates the state of the eye tissue, along with the patient’s possibilities of suffering from glaucoma. ORA is different from the non-contact tonometry that uses a puff of warm air, another method to measure the intraocular measure frequently used in optical stores. These use an instrument that releases air against the eye and measures the pressure painlessly. Although considered less accurate than applanation tonometry, it is used for the screening of glaucoma. |
 Classic method of intraocular pressure measurement
 ORA is probably the newest and most accurate method currently used for the measurement of intraocular pressure.
 Diagram showing the intraocular pressure measurements provided by ORA in a glaucoma case. Real ocular pressure is of 31.4, higher than 29.1, which would be the result provided by a classical method. |
2. Determine nerve damage
The optic nerve transmits visual information from the retina to the brain, and primary glaucoma is characterized by the gradual damage of it. Thus, the next test to be carried out at the IOA determines if the nerve has been already damaged by glaucoma or not.
The most accurate method to detect early damage in the optic nerve is the OCT (Optical Coherence Tomography), which we use at the IOA. This scanner allows us to know whether your optic nerve behaves according to your age or not, the level of damage if existent, and at which rate it would progress.
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The first picture on the right (») shows how the scanner examines the optic nerve, which permits us to detect and treat glaucoma from its early stage of development; an impossible task with other methods.
It is a painless and easy method that uses a sophisticated beam of light allowing our experts to study the state of the optic nerve in a few minutes. The great advantage of this new method, the OCT, is that it anticipates other methods at use, such as the classic visual campimetry. At IOA we control the glaucoma before the damage of the sight is advanced and even before it starts to develop. The second image at the left (») shows the green circle next to the right optic nerve (upper arrow), indicating total absence of damage. On the contrary, the partially red colored circle below, measuring the left optic nerve, indicates that glaucoma has already affected several parts of the nerve. |
 Performing of the OCT (Optical Coherence Tomography) at the IOA. |
 Measurements results provided by the OCT. |
3. Visual field measuring
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Once detected the damage at the optic nerve level by means of the OCT, the following test measures each eye’s visual field, also known as campimetry or computerized perimetry.
Visual field or campimetry confirms to us the presence of damage in the optic nerve. Unfortunately, it only does so when the damage is at a quite advanced stage, which is why the OCT is not of great importance at an early stage. However, once the damage is diagnosed in the visual field, this method is highly useful. Utilizing sophisticated statistics and computerized software, it is determined if the disorder is being detained with the treatment, if on the contrary it keeps progressing or if the treatment must be modified. Due to this reason it is crucial that campimetries be often performed on the patients with glaucoma or likely to suffer from it. The decrease in the visual field observed in the picture at the right is one of the three main signs of advanced glaucoma as a result of gradual optic nerve damage. Once damaged, the lost sight will not ever be recovered. |
 Computerized perimetry in glaucoma tests
 Sight of a patient with glaucoma. |
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