What is glaucoma?
We define glaucoma as a set of diseases that produce a progressive decrease of the layer of nerve fibres of the optic nerve, which then produce a progressive loss of the sensitivity to contrast and a decrease of the peripheral visual field.
In most cases, this disease is related to a high intraocular pressure (IOP), although it can also appear in the context of a normal IOP (normotensive glaucoma).
There are different types of glaucoma:
- Depending on the iridocorneal angle (anatomical area where the aqueous humor drainage takes place):
- Open angle Glaucoma The angle is normal
- Closed angle Glaucoma The angle is lower than normal, and therefore there is an increase of the resistance to the passing of the aqueous humor at this level.
- According to its origin:
- Primary Glaucoma: No known pathologies associated
- Secondary glaucoma: A pathology is associated, such as a neovascular glaucoma (vascular pathology such as diabetes, venous thrombosis, etc.), inflammatory glaucoma, uveitic glaucoma, pseudoexfoliative glaucoma, etc.
- Depending on when it appears:
- Congenital glaucoma: from birth.
- Youth glaucoma and adult glaucoma (the most frequent).
Which are the risk factors?
Intraocular pressure is considered the main risk factor in this pathology, as most patient with this disease have increased IOP. And yet, it is not a determinant factor in all cases, as we also have patients with high pressures without glaucomatous damage, which we call ocular hypertensive patients, and patients with IOP within the normal values with glaucoma, which we call normotensive glaucomatous patients.
Other known risk factors are the following: Myopia, family history, age, female gender or vascular deregulation.
Glaucoma protocol- study
Glaucoma is also known as the silent thief of sight, as it reduces the peripheral visual field slowly, insidiously and progressively, of which the patient is not aware until highly advanced stages of the disease. That is why it is very important to conduct a complete ophthalmologic study every year as from the age of 40, especially is there is a risk factor.
The complete glaucoma protocol or study must include a set of tests to try and find indications or very initial stages of the disease, with the aim of trying to prevent it, or at least slow it down as much as possible with the different treatments.
This protocol must include the following tests:
- Complete ophthalmologic study, that includes a good anamnesis of the personal and family history, allergies, the patient's past illnesses. eye and general treatments, etc. It also includes:
- Intraocular pressure test: Carried out with the Goldman Applanation Tonometer. The normal IOP range is of between 11 and 21 mm of Hg (millimetres of mercury).
- Biomicroscopic study: The anterior part of the eye is examined to rule out the presence of pseudoexfoliation, retro corneal pigment, cataracts, synechiae and other pathologies that may suggest the presence of secondary glaucoma. In this study, special emphasis is placed on the irodocorneal angle by conducting a study with gonioscopy, that classifies the angle opening degree into four degrees: Degree 4 is the most open, and degree 0 is completely closed.
- Ocular fundus study: Is the key study, because it provides a direct view of the optic nerve and it is here where the most significant and almost pathognomonic signs of glaucoma are seen: We place special interest in describing the colour, size and shape, the excavation, vascular angle and surrounding atrophy.
When this complete ophthalmologic study has concluded, a set of additional studies are carried out aimed at evaluating both the function and the structure of the optic nerve.
- Study with Pentacam Topography, test with which we collect the following information:
- Corneal pachymetry: Thickness of the cornea, essential to correct deviation of the intraocular pressure taking due to extremely fine or thick corneas.
- Depth of the anterior chamber.
- Objective measure of the iridocorneal angle, that complements the results obtained with the gonioscopy.
- Campimetry. It is one of the gold standard tests in the study of glaucoma. It provides functional information on how the patient perceives the vision around a fixed vision point, and therefore describes in a subjective way how and when we see our field of vision.
- Optical coherence tomography of the optic nerve and ganglion cells. This state-of-the-art test enables analysing the thickness of the layer of optic nerve fibres in an easy and objective way and to compare it with analysis of the same patient of another date, as well as a database of the device its self, that is, compares the patient's data with the data of other patients of his/her same age and sex to know where his/her range would be in a normal series (inside the range, on the limit, or outside the normal range). It provides structural information.
The study of the ganglion cells has significance for the early analysis of the glaucomatous pathology, providing useful information on the probability that a structural damage has a connection with a peripheral functional damage and thereby helps us to treat very initial stages of glaucoma and even pre-perimeter ones.
- Retinography: Taking serial photographs of the optic nerve enables analysing the structural changes that have taken place over the years and take measures to prevent their progression.
“The art of managing glaucoma correctly consist in sorting by importance all the data and information we have and that sometimes is contradictory, other times it is premonitory and most times is sufficient to take decisions on who to treat this disease”.
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Treatments to correct glaucoma
In mild cases, it is likely the disease is kept under control with medical treatment, by using antihypertensive eye drops.Medical
There are mainly two laser treatments for glaucoma, iridotomy and trabeculoplasty; and two types of laser: Aragon Laser Trabeculoplasty (ALT laser) and Selective Laser Trabeculopasty ( SLT laser)Laser
Surgical treatment of glaucoma may be perforating (trabeculectomy, trabeculectomy with express implant, MIGS or valves) or non-perforating.Surgical