22 June, 2022
GLAUCOMA: The importance of performing a tonometry
Glaucoma is an eye disease that causes gradual vision loss. This vision loss occurs when the fibres of the optic nerve, that transmit visual information from the eye to the brain, are damaged, usually due to a higher than normal intraocular pressure.
It is one of the main causes of blindness in people over 60 years of age. Less frequently, it can also appear in young people and even congenitally.
In many cases, the patient does not notice any symptoms until a very advanced stage of the disease. For this reason, and given that the vision lost due to glaucoma cannot be recovered, it is of great importance to carry out regular eye check-ups that must include the measurement of intraocular pressure. If glaucoma is diagnosed in the early stages, it can be treated to slow or prevent its progression and prevent vision loss.
Types of glaucoma:
There are many types of glaucoma, but we can differentiate two main categories:
- Chronic open-angle glaucoma: This is the most common type and occurs gradually. It appears when the aqueous humour is not drained properly, leading to increased pressure inside the eye that begins to damage the optic nerve. This type of glaucoma is painless and visual changes do not appear until very advanced stages.
- Acute angle-closure or narrow-angle glaucoma: it occurs when the iris blocks the drainage angle, causing a sudden increase of the intraocular pressure. This is known as an acute angle-closure glaucoma attack, when it occurs you should see an ophthalmologist immediately, since it can cause blindness if it is not treated on time.
Acute angle-closure glaucoma attacks do present symptoms and it is convenient to know them in order to act in time:
- Severe eye pain
- Sudden vision loss (blurred vision)
- Nausea or upset stomach
- Seeing halos around lights
Causes of glaucoma
The risk factors for glaucoma are diverse; some of the most important are the following:
- Family history: it increases up to 10 times the risk of suffering from it.
- Age: people over the age of 60 have a higher risk of suffering from it.
- Race: in African American or Latin-American people the risk increases at the age of 40.
- Arterial hypertension.
- Eye trauma.
- High myopia.
Likewise, there are other risk factors such as smoking, prolonged treatment with corticosteroids, hyperopia, having a thin cornea, etc.
Like we said previously, early diagnosis of glaucoma is essential to avoid significant vision loss. To diagnose it, it is necessary to carry out three fundamental tests:
- Tonometry: is the measurement of intraocular pressure. Intraocular pressure is considered normal when it is between 12 and 22 mm HG (millimetres of mercury).
- Perimetry or campimetry: used to assess the visual field, so that we can know if glaucoma has started to affect vision.
- OCT (Optical Coherence Tomography): allows obtaining scanner-type images of the retina and the optic nerve. In case of glaucoma, it allows to know if the fibres of the optic nerve have been damaged.
There are different treatment options for glaucoma depending on the evolution and severity of each case. These are some of them:
- Medication: there are several types of medication that can be used, but all of them are aimed to reduce intraocular pressure. Usually, they are applied in the form of eye drops, although there are also some in the form of pills.
- Laser: depending on the type of glaucoma, it can be used to make the drainage angle work better (trabeculoplasty) or to create a small hole in the iris through which aqueous humour can flow (iridotomy).
- Surgery: the goal is to create a new drainage path for the aqueous humour and can be performed using two techniques:
- Filtering surgery or trabeculectomy: consists of creating an opening in the sclera and removing part of the trabecular meshwork.
- Drainage tubes: consists of inserting a small device that allows excess fluid to drain and consequently reduce intraocular pressure.
In conclusion, we can say that glaucoma is a disease in which early diagnosis is crucial. Therefore, regular visual examinations are essential especially in people with risk factors.
At L’Atelier Óptica we are aware of the importance of our role in primary care and we include the measurement of intraocular pressure in our eye check-up protocol. For this, we have a tonometer that does not require the use of an anaesthetic. We also offer an intraocular pressure measurement service for those patients who need it both occasionally and for those who want to follow up.