Eye diseases like glaucoma can occur as we get older. The disease is also known as green star. Potential sight loss can be stopped if glaucoma is identified and treated early. According to estimates, around 2 in 100 people aged over 40 in industrialized countries develop glaucoma.

At a glance

  • Potential sight loss can be stopped if glaucomais identified and treated early.
  • Around 2 in 100 people aged over 40 in industrialized countries have glaucoma.
  • The term glaucoma refers to a variety of eye diseases that damage the optic nerve.
  • The field of vision has missing areas that become bigger and bigger – this usually remains unnoticed at first.
  • The most common form of glaucoma, over 90 percent of cases, is wide-angle glaucoma (open-angle glaucoma).
  • Wide-angle glaucoma progresses slowly: damage to the optic nerve only leads to impaired vision after many years.

Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.

Glaukom: Eine Ärztin schaut durch ein Skiaskop in das Auge einer Patientin.

What is glaucoma?

In many people, vision deteriorates with age. This development is normal. However, eye diseases may occur which impair sight and even lead to blindness. A common eye disease is glaucoma (green star). According to estimates, around 2 in 100 people aged over 40 in industrialized countries develop glaucoma.

The term glaucoma refers to a variety of eye diseases that damage the optic nerve. Glaucomas cause the field of vision to have missing areas that become bigger and bigger – this usually remains unnoticed at first. Field of vision refers to the sight range that is perceived without moving the eyes. In advanced states, sight also becomes less acute.

The most common form of glaucoma, over 90 percent of cases, is wide-angle glaucoma (open-angle glaucoma). It progresses slowly. Damage to the optic nerve only leads to impaired vision after many years. It is usually treated with eye drops or a surgical procedure.

What are the signs of glaucoma?

A person with glaucoma can no longer see certain areas or can only see them to a limited degree. The “blind spots” usually occur next to the point of most acute vision (macula) and up to the edges of one's field of vision. Because one's central vision is not initially affected, the sufferer often fails to immediately notice these limitations. 

However, as years go by, these blind spots can make everyday orientation increasingly difficult. People with green star can, for example, see straight ahead when driving, and clearly discern the road ahead, but not people and things on the sidewalk to the right and left. Adaptation to different light conditions may also be difficult – for example, when entering a dark hallway from outside. The sufferer also often finds it more difficult to judge obstacles like steps and curbstones. This can lead to a greater risk of falling.

With narrow-angle glaucoma, so-called acute angle-closure glaucoma attacks may occur. In these, there is a sudden, marked increase in intraocular pressure. Typical complaints are acutely impaired vision, reddening of the eyes, headaches and eye pain, and nausea.

What are the causes of glaucoma?

Glaucoma is often caused by elevated intraocular pressure. Intraocular pressure occurs in the chambers of the eye between the cornea and the lens. The chambers of the eye contain the so-called aqueous humor – a fluid that forms in the eye. This continuously flows from the posterior to the anterior chamber and, from there, out again through a very fine vessel (Schlemm's canal). In a healthy eye this cycle produces a constant pressure. The aqueous humor also supplies the cornea, iris and lens with nutrients.

If the aqueous humor is unable to flow away properly, there is a blockage that increases the intraocular pressure. This puts pressure on the optic nerve. There is then a danger of nerve cells dying off.

Intraocular pressure is measured in mmHg (millimeters of mercury), the same unit used to measure blood pressure. Values between 10 and 21 mmHg are the norm. With glaucoma, however, the intraocular pressure is not always higher than the norm. Almost half of all sufferers have damage to their optic nerve, but do not have high intraocular pressure.

Poor blood flow in the optic nerve is also debated as a cause of glaucoma. In this case, the nerve cells receive an insufficient supply of oxygen and nutrients. Green star may also be the result of inflammations, injuries and vascular disease. It is then referred to as secondary glaucoma.

What are the risk factors for glaucoma?

Apart from the thickness of the cornea, the risk of glaucoma also depends on the intraocular pressure: very high values cause glaucoma more frequently than only slightly higher values.

Risk factors for glaucoma are high intraocular pressure, older age and family predisposition.

Other risk factors include advanced age, family predispositions, extreme short-sightedness and diabetes. People with black skin color also suffer more frequently from green star.

How common is glaucoma?

Approximately 2% of people over 40 develop glaucoma.

According to estimates, around 2 in 100 people aged over 40 in industrialized countries develop glaucoma. But around 4 people in 100 aged over 40 have elevated intraocular pressure.

How does glaucoma develop?

Open-angle glaucoma usually develops slowly. It often goes unnoticed at first. As it progresses, the blind spots can get bigger until the sufferer can only see in the very central range. But this development often takes many years, or even decades. So many people with glaucoma can still see well enough even 20 years after the diagnosis, for example – particularly if the green star is treated well.

Only a few people go completely blind through glaucoma – this applies to every type. In Germany estimates range from around 1,100 such cases per year.

Acute angle-closure glaucoma can also go unnoticed for a long time. However, a glaucoma attack will occur very suddenly and it can lead to lasting impaired vision within hours or days. It has to be treated as an emergency.

How can glaucoma be identified early?

Many eye specialists offer screening tests that have to be paid for privately. In such a test, the specialist examines the optic nerve, appraises the eye with a slit lamp microscope, and measures the intraocular pressure. Statutory health insurance providers only pay for these tests when there is reason to suspect glaucoma or when there are specific risks, for example when diabetes has caused eye damage.

Important: The issue of whether general screenings could be useful after a certain age or for some at-risk groups has not yet been fully studied.

How is glaucoma diagnosed?

Eye specialists can identify glaucoma before the first symptoms are noticed. To produce their diagnosis, they first ask about symptoms and then examine the eye with a special instrument, the ophthalmoscope. They use this to examine the inner eye and detect any possible damage to the optic nerve. They also measure the intraocular pressure, usually using applanation tonometry. This involves first anesthetizing the eye with a drop of liquid and then placing a small cone on the cornea.

If glaucoma is suspected, the field of vision is measured, too. This enables the specialist to check whether vision is already impaired and there are blind spots.

How is glaucoma treated?

Glaucoma cannot be cured, as optic nerve damage cannot be reversed. But reducing the intraocular pressure can help to slow down or stop the deterioration of the glaucoma. Intraocular pressure is reduced using eye drops. Depending on the medication, they are used once or more per day. Regular checkups at the ophthalmologist's are also important. Depending on how advanced the disease is, these checkups are offered one to three times per year.

If medication is insufficient, or becomes insufficient, or if the sufferer does not tolerate it well, a laser procedure or operation is possible.

Important: A glaucoma attack must be treated quickly to prevent the optic nerve from being damaged. Important: in the case of typical complaints such as acutely impaired vision and eye pain, sufferers need to consult a medical practice or hospital immediately. There, laser treatment, for example, can get the blocked aqueous humor flowing again.

For more detailed information on glaucoma, for example how it is treated, go to

How does one live with glaucoma?

Some people find it unsettling when they are diagnosed as having high intraocular pressure, even if they can see quite normally. The idea that high intraocular pressure can increase the risk of glaucoma can trigger anxiety when they have even minor sight issues, even if the problems may have very different causes.

Glaucoma patients often worry enormously that they could go blind at some point, so many of them want to quickly get detailed information about the treatment options and the potential consequences of the disease.

If glaucoma does actually cause loss of sight, the sufferer should adapt their everyday life to the circumstances. For example, their home can be rearranged so that they can find their way around more easily. Additional light sources may be helpful in such cases. Tripping hazards should also be removed to prevent falls. 

Important: Sufferers sometimes find it hard to know when they should stop driving because of their glaucoma. They often first change their driving habits and, for example, avoid driving at night or unfamiliar routes. So every glaucoma sufferer must think hard about when their limitations are becoming too major and dangerous, also because driving is no longer legal when a person's field of vision is badly restricted. Detailed information and advice on this subject is available from eye specialists.

Many sufferers find it difficult to come to terms with degenerating sight. One reason is that they become badly dependent on other people's help. But it is important for sufferers to learn to relinquish control in some areas. The people around them can help them to keep their activities going and maintain social contacts.

Talking to family members and friends about needs and anxieties can also unburden the sufferer, and strategies can be developed together to deal with the advancing condition.

The website has reports from people with experience of glaucoma.

In cooperation with the Institute for Quality and Efficiency in Health Care (Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen) (IQWiG).

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