Introduction

Photo of an older man at the library (lisafx / iStock / Thinkstock)

Vision often worsens with age. In addition to this normal aging effect, people may also develop eye conditions that further impair their eyesight or even lead to blindness. Glaucoma is one of the more common eye diseases.

The term "glaucoma" is used to describe a number of different eye conditions, all of which involve damage to the optic nerve. This leads to ever larger gaps in the field of vision, which often remain unnoticed at first. Your field of vision is what you can see when you look straight ahead, without moving your eyes. In advanced stages, your ability to see things sharply (visual acuity) also gets worse.

The following information mainly covers the most common form of glaucoma, called primary open-angle glaucoma (POAG). It progresses slowly, and damage to the optic nerve will not cause vision problems for many years. Eye drops and surgery are the most common treatment options.

Symptoms

People with glaucoma can no longer see certain areas within their field of vision, or can only see them to a limited degree. Blind spots appear, usually near the point of sharpest vision (macula) and up to the edges of the field of vision. Because central vision is not affected at first, these problems are often not noticeable at the beginning.

But the blind spots can make it increasingly difficult to get around in everyday life. When looking straight ahead, for example while driving, you can see the street ahead of you clearly, but not the people and objects on the sidewalks to the right and left. It can also be difficult to adjust to changes in light, like when you enter a dark room from outdoors. And it can become increasingly harder to see obstacles like steps or the curb.

Acute glaucoma attacks, also referred to as acute angle-closure glaucoma, are rare. They happen when there is a sudden and great increase in intraocular pressure (the pressure inside of the eyeball). Typical symptoms include acute vision problems, reddening of the eye, intense pain in the head and eye, and nausea. Angle-closure glaucoma must be treated quickly to avoid any damage to the optic nerve.

Causes

Glaucoma is often caused by increased intraocular pressure. Intraocular pressure arises in the chambers of the eye between the cornea and the lens. The chambers contain a fluid called aqueous humor that is produced by the eye itself. It flows continuously from the back (posterior) chamber to the front (anterior) chamber and then drains out through a very thin tube (Schlemm's canal). This cycle helps to maintain a constant healthy pressure in the eye. The aqueous humor also provides nutrients to the cornea, the iris and the lens. 

Illustration: GlaucomaGlaucoma

If the aqueous humor is prevented from draining properly, it starts to build up and the pressure within the eye increases. The optic nerve is squashed and nerve cells might die as a result. Whether high intraocular pressure causes damage will depend on various factors, including how strong the optic nerve is: only some people will be susceptible to nerve damage. Intraocular pressure is measured in mmHg (millimeters of mercury), the same unit used for blood pressure. Readings between 10 and 21 mmHg are considered normal.

But glaucoma isn't always caused by high intraocular pressure. About half of all people who develop glaucoma have optic nerve damage without having high intraocular pressure. It is thought that normal pressure might already cause damage in these people. Glaucoma of this type is also called "normal-tension glaucoma" (NTG) for that reason.

Another possible cause might be poor blood circulation to the optic nerve. In this case, not enough oxygen and nutrients reach the nerve cells. Glaucoma may also result from inflammations, injury or vascular disease. It is then called secondary glaucoma. Only very rarely do people have glaucoma from birth.

It is not always possible to determine what the trigger is because not all causes of glaucoma are known. The various factors probably interact too.

Risk factors

About 4 out of 100 people over the age of 40 have high intraocular pressure. But only few of them will develop glaucoma: It is estimated that about 10 out of 100 people with high intraocular pressure will experience loss of vision within five years. The risk is determined by various factors, including corneal thickness and the level of your intraocular pressure. People with very high intraocular pressure are quite a lot more likely to get glaucoma than people whose intraocular pressure is only slightly elevated.

But other factors like age (people over 50 are more likely to develop it), family history, severe nearsightedness and diabetes can increase the risk too. And people with dark skin are also more likely to develop glaucoma.

Outlook

Glaucoma usually develops gradually and remains unnoticed at first, but sometimes arises very rapidly. The blind spots may continue to spread over time, until it is only possible to see the very center of the field of vision. Some people go completely blind - it is estimated that about 1,100 people go blind due to glaucoma (all forms) in Germany every year.Illustration of possible limitations to field of visionVision problems caused by glaucoma

Diagnosis

Eye doctors can diagnose glaucoma even before the first symptoms become noticeable. They will first ask about any existing symptoms and then examine your eye. A special instrument called an ophthalmoscope is used to look at the inside of the eye and see if the optic nerve is damaged. Intraocular pressure is also measured, usually with a technique called applanation tonometry. This involves numbing the eye using a drop of liquid, and then placing the small tip of a measuring device against the cornea.

If glaucoma is suspected, your eye doctor will also measure your field of vision. This is done to see if parts of the field of vision are affected and whether blind spots have already developed.

Screening

Many eye doctors offer screening tests to detect high intraocular pressure and glaucoma. People who would like to be tested for glaucoma have to pay for it themselves. The tests involve checking the optic nerve, measuring the intraocular pressure and examining the eye with a slit lamp. In Germany, statutory health insurers will only cover the costs if doctors suspect that you have glaucoma or if you have certain risk factors.

Not enough research has been done to tell whether generally screening for glaucoma is a good idea in particular age groups or high-risk groups.

Research summaries

Treatment

Lowering high intraocular pressure can help to delay or stop the gradual progression of vision loss. Glaucoma can't be cured, though, because existing damage to the optic nerve can't be reversed. If someone has glaucoma and high intraocular pressure, it is usually treated using eye drops. Depending on the specific product, the eye drops are applied either once or several times a day.

Surgery or laser therapy may be considered if the medication doesn't work, stops working after a while, or is not well tolerated.

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Everyday life

Many people who are found to have high intraocular pressure will feel quite nervous about it, even though their vision is still perfectly fine. Just knowing that you have high intraocular pressure, and therefore a higher risk of developing glaucoma, may cause you to worry about even the slightest trouble with your vision, although it probably has nothing to do with glaucoma.

People with glaucoma are often very scared of going blind. Especially at the start, many people want to find out all about the treatment and how the diagnosis might affect their life.

Sooner or later the loss of vision will mean that changes will have to be made to adapt to the new situation. You may have to re-design your home environment to make it easier to find your way around. The new circumstances may also affect your job or everyday activities such as sports, shopping or reading. Seeking support and finding out about things that could help you - for instance, by asking your doctor or health insurer - can make everyday life easier. People who have glaucoma also say that it helps to have detailed information about the condition and ways of coping with it, or to talk with others who also have glaucoma, for example in a self-help group or an internet forum.

It is often difficult to recognize the point at which glaucoma makes it impossible to drive a car safely. At first, people with glaucoma often start making changes to their driving habits, for instance by no longer driving at night or only sticking to familiar streets. It is important for family and friends to be aware of this so they can help determine when the person's vision becomes too much of a problem and they start being a danger to themselves and others. Once a certain amount of eyesight has been lost, driving is illegal. Your eye doctor can give you more specific information and advice.

It is often not easy to deal with becoming more dependent on help from others due to problems with your vision. But you may need to give up the control over some things to people you trust.

Talking about your worries and fears with family and friends early on can be a great relief. Together you can develop strategies for dealing with worsening eyesight. Having people who are there for you and who understand and support you can really make things easier in life - particularly if you are dealing with a difficult health condition and want to continue to stay as active as you can.

Further information

In Germany, there are numerous sources of support for people with glaucoma, including self-help groups and information centers. Support services may be organized quite differently from region to region, though, and they are not always easy to find. Our list may help you find and make use of local services.

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Please note that we do not provide individual advice on matters of health. You can read about where to find help and support in Germany in our information “How can I find self-help groups and information centers?”

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