Many people see less well with age. In addition, eye diseases frequently occur that make it more difficult to see and may even result in blindness. These eye diseases also include glaucoma.
The term “glaucoma” refers to various eye diseases in which the optic nerve is damaged. As a result, larger and larger gaps emerge in the visual field (the range of what can be seen without moving the eyes). These usually go unnoticed to begin with. In the advanced stages of glaucoma, visual acuity also decreases.
The range of what people with glaucoma can see becomes totally or partially imperceptible in places. “Blind spots” occur, usually next to the point of sharpest vision (the “macula,” an area in the middle of the retina where photoreceptors are particularly dense; macula comes from the Latin term “macula lutea” or “yellow spot”) and up to the edges of the visual field. As central vision is not impaired at first, those affected often do not immediately notice the limitations of their visual field.
Over time, however, these “blind spots” can make it increasingly difficult for those affected to find their bearings in everyday life. Looking straight ahead, things can still be clearly seen right in front of you – but everything that happens to the left and right is only blurred. And the adjustment of the eyes to different light conditions can also be impaired, so that people suddenly have visual problems when stepping from lighter to darker conditions. It is also a challenge to correctly assess obstacles such as steps or kerbs, which often leads to considerable uncertainty and an increased risk of falling for those affected.
What is known as narrow-angle glaucoma can also lead to a glaucoma episode. This results in a rapid and big increase in intraocular pressure, which can lead to symptoms such as acute visual disturbances, reddening of the eyes, severe headaches and eye pain or nausea.
The most common cause of glaucoma is excessive intraocular pressure. Intraocular pressure is generated in the chambers of the eye between the cornea and the lens. The chambers of the eye contain a fluid, known as the aqueous humour, which is formed in the eye itself. It flows continuously from the posterior to the anterior chamber of the eye and from there out again through a very fine channel. This circulation ensures a constant pressure in the healthy eye.
If the aqueous humour is no longer able to drain properly, it builds up, resulting in an increase in intraocular pressure. This process strains the optic nerve and there is a risk of nerve cells dying off. The resilience of the optic nerve determines whether the increase in intraocular pressure leads to damage or not.
Fortunately, the optic nerve is only susceptible enough to actually become damaged in some of those experiencing increased intraocular pressure. However, if the aqueous humour no longer flows at all, the intraocular pressure suddenly increases excessively; the reason for this is that drainage of the aqueous humour is completely blocked in such cases (known as narrow-angle glaucoma).
The intraocular pressure is measured in mmHg (millimetres of mercury) – this is the same unit that is used for measuring blood pressure. “Healthy” intraocular pressure is between 10 and 21 mmHg. However, intraocular pressure in glaucoma is not always above normal levels. In almost half of all people suffering from glaucoma, damage to the optic nerve can be detected, but no increased intraocular pressure can be observed. In the medical profession, this form of glaucoma is known as “normal tension glaucoma”, because it is assumed that normal intraocular pressure is already too high for those affected.
Inadequate blood supply to the optic nerve can also be the cause of glaucoma. In this case, the nerve cells are not adequately supplied with oxygen and nutrients. Glaucoma can also occur as a consequence of inflammation, injuries and vascular diseases. Experts refer to this as secondary glaucoma. And there are even rare cases where glaucoma is congenital.
In addition, old age, family history, severe short-sightedness and diabetes increase the risk of glaucoma.
Increased intraocular pressure is observed in approximately four out of 100 people over the age of 40. Around ten in 100 people with increased intraocular pressure experience loss of vision within five years, which means that only a few of these people actually develop glaucoma. The risk of developing glaucoma depends on factors such as the thickness of the cornea and the level of intraocular pressure. To put it another way, people with very high intraocular pressure have a significantly higher risk of developing glaucoma than people with slightly increased intraocular pressure.
It is important to know that ophthalmologists can now diagnose glaucoma even though no symptoms have yet occurred. For you as a patient, this means that you should have your intraocular pressure measured at regular intervals – it is recommended that people over the age of 40 undergo early glaucoma screening every two years and people over the age of 60 should do this every one to two years.
As part of the medical check-up, the ophthalmologist first asks whether there are any possible symptoms and examines the eye. Using a special instrument, known as an ophthalmoscope, the specialist can examine the inside of the eye and identify possible damage to the optic nerve. In addition, intraocular pressure is measured, usually by means of what is known as applanation tonometry. This examination involves anaesthetising the eye with a drop of fluid and then placing a small volumetric flask on the cornea.
If glaucoma is suspected, the ophthalmologist also measures the visual field. This makes it possible to determine whether certain parts of the range of vision have been restricted and whether blind spots have already occurred.
Long-term reduction of intraocular pressure can help to delay or stop the gradual loss of vision. However, glaucoma cannot be completely cured, as damage to the optic nerve is irreversible. In the case of glaucoma, intraocular pressure is usually treated with eye drops. Depending on the preparation, it can be used once or several times a day.
Regular check-ups by an ophthalmologist are also important. These are offered one to three times a year (depending on how far glaucoma has already progressed).
If the prescribed medication is no longer sufficient or poorly tolerated, a procedure using laser technology or surgery (known as minimally invasive glaucoma surgery) may be considered.
If you need glaucoma surgery, your ophthalmologist will suggest the surgical method they believe is most appropriate to maintain your vision for as long as possible and to best reflect the current situation. Surgery for glaucoma can neither eliminate it nor improve vision. The aim of minimally invasive glaucoma surgery is to reduce intraocular pressure by creating an alternative drainage channel to slow down or even stop the progression of the disease.
Filtration surgery involves placing a drain between the anterior chamber of the eye and the scleral (from sclera; this encases the eyeball up to the edge of the cornea) or subconjunctival space, i.e. below the conjunctiva. In certain cases, it may be necessary to use mechanical devices, i.e. implants, or chemical agents to facilitate filtration. As regards filtration surgery, the surgeon again has two procedures at their disposal to reduce intraocular pressure: With the procedure known as trabeculectomy, a recess is cut into the trabecular meshwork (part of the anterior chamber angle and the main drain for the aqueous humour in the eye; it consists of loose tissue that looks like a sponge when viewed under a microscope), which requires the eye to be opened during the procedure. With the procedure known as sclerectomy, on the other hand, the outer wall of the eye is thinned out in a defined “window area” – not at the surface, but deep inside the eye – so the aqueous humour can flow out of the eye more easily via the now wafer-thin membrane.
Please note: A glaucoma episode must be treated quickly to avoid damage to the optic nerve. This is why it is important to go to a doctor’s surgery or eye hospital immediately if symptoms such as acute visual disturbances and eye pain occur.
Even if you have an outpatient operation, you will remain under observation for some time after – until you feel fit enough for the journey home. You are not allowed to drive on the day of the procedure, nor should you make your way home unaccompanied by public transport. Have family or friends pick you up or take a taxi home.
Your doctor will prescribe drops and ointments for the initial period after the procedure, which you should use exactly as prescribed. They may also prescribe you a painkiller for the first few days after the operation. They will also talk to you about how often you might need to attend for follow-up appointments.
The term “glaucoma” refers to various eye diseases in which the optic nerve is damaged. As a result, larger and larger gaps emerge in the visual field (i.e. the range of what can be seen without moving the eyes). These usually go unnoticed to begin with. In the advanced stages of glaucoma, visual acuity also decreases.
Increased intraocular pressure is the most common risk for the development of glaucoma. As glaucoma can have serious consequences for a person’s eyesight, the early detection of glaucoma by regularly measuring intraocular pressure is an important measure for preventing blindness.
Unfortunately, glaucoma often causes unnoticed damage to the optic nerve and thus also the retina, causing vision to deteriorate in the long term – even leading to blindness. The loss of vision in glaucoma develops gradually and usually over several years.
Initially, people suffering from glaucoma usually have no symptoms. In the advanced stage, the disease manifests itself in visual field loss, eye pain and / or headache. Acute glaucoma (i.e. a glaucoma episode) causes symptoms such as sudden visual disturbances, a very hard eyeball, severe headache and eye pain and nausea.