5 Keys to Understanding Glaucoma, the Leading Cause of Blindness

The week of March 12 is the “WORLD GLAUCOMA WEEK” organized by the World Glaucoma Association to raise awareness of this disease that affects more than 80 million people worldwide, and approximately 11 million suffer bilateral blindness.

We interviewed the ophthalmologist, José Arrieta, a specialist in Glaucoma and Refractive Surgery to tell us about this disease and how we can prevent glaucoma blindness.

- What is glaucoma?

It is called “The Silent Thief of Vision” because it does not give any symptoms until it is too late. It is the most common cause of irreversible blindness in the world, caused by elevated Intraocular Pressure (IOP) which causes damage to the optic nerve with consequent deterioration of the visual field, (although there are some rare cases where IOP may be within normal parameters for the population, i.e. 8 to 20 mmHg, and even so be older than that which optic nerve can withstand and I can deteriorate it over the years, which is called “Low tension Glaucoma” or Low Pressure Glaucoma)

- What is intraocular pressure?

Inside the eye, a liquid is forming all the time called aqueous humor, which is responsible for nourishing the internal structures of the eye, forms in the ciliary bodies behind the iris, passes through the pupil, and seeps into the trabeculate, which is a kind of “mesh” through which it drains into the general circulation, when that trabeculate does not manages to filter all the aqueous humor, part of it is retained and the IOP increases caused damage to the optic nerve.

- How is high intraocular pressure detected?

The big problem with this type of glaucoma is that it is asymptomatic, that is, a person can be with 30 mmHg of IOP, and not realize it because in general it hurts from 40 mmhg when it is twice as normal. But as time progresses, and the IOP remains elevated, the optic nerve is damaged and loss of fibers occurs nervous, thus causing irreversible loss of peripheral vision until total blindness is reached.

There is another type of glaucoma called Acute Angle-Closure Glaucoma, which, as the name implies, occurs in acute form and is a medical emergency, IOP rises suddenly and can reach more than 60 mm Hg, causes very intense eye pain, which some women say is worse than labor pains, and must be treated within the first 6 hours, because if more than 6 hours pass with this level of IOP, the optic nerve begins to be irreversibly damaged and is the most common cause of irreversible blindness in the world.

There are other causes of glaucoma, such as eye injuries, systemic diseases, the use of some medications such as corticosteroids, or medication to treat parkinson's, epilepsy, depression, prostate diseases, among others.

- How is glaucoma detected when there are no symptoms?

In most patients who do not have a hereditary history, glaucoma is detected through routine studies such as simple taking of the IOP in the office, or through the examination of the optic nerve through an eye fundus, these give us indications that there may be an alteration in the management of IOP, which leads us to perform studies of greater complexity such as Pachymetry, Computed Visual Field (CVC), HRT, or Optical Coherence Tomography (OCT) and gonioscopies, which provide us with greater data on ocular ultrastructure and the damage that could occur. Although the Computed Visual Field remains the study of choice when determining the functional damage suffered by the patient, since it evaluates peripheral vision, which is the one that is first altered in patients with glaucoma.

We currently have state-of-the-art technology that allows the patient to take the pressure at home by means of a portable tonometer (ICARE), using a portable tonometer (ICARE), during the 24 hours to determine the daily IOP curve and then, using software, monitor how the intraocular pressure was during the day to see the fluctuations of it at different times.

- Is there any age to start controlling IOP?

Glaucoma is more common after the age of 40, (although glaucoma exists since birth), so ideally everyone should have a routine IOP intake once a year and should be part of any ophthalmological check-up regardless of the patient's age. The usual thing is that patients consult to change glasses, and by taking pressure routinely, we can see if it is altered, and by carrying out the relevant studies, which take only a few minutes, without any pain and non-invasively it is determined whether or not she suffers from glaucoma. If you have a family history of glaucoma, these studies should be done at a younger age because there are cases of congenital glaucoma, which are very aggressive and can cause blindness at a very young age. Before, in order to take the IOP of a baby we had to sedate him, but now thanks to modern Icare tonometers, you don't even need the placement of anesthesia drops for taking it, we can take the IOP of a baby in the maternal arms, in just a few seconds and without any pain we can determine the value of his IOP.

- How is glaucoma treated?

The first step is to determine what type and degree of glaucoma the patients have. Before, the initial therapy was to use drops for glaucoma, but currently the trend is to use the SLT laser “Selective Laser Trabeculoplasty” to lower the IOP and avoid the side effects of the drops and the use of antiglaucomatous eye drops is reserved only for patients. patients who do not respond to SLT and when we do not reach the IOP target or goal. There are also surgeries for glaucoma but are reserved for more advanced cases in which IOP cannot be controlled in Target values.

In cases where the patient has to be operated on, there are now much more modern surgeries than conventional trabeculectomies such as EPNP or stents to lower IOP more harmlessly for the patient and with better visual results than with traditional techniques.

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