Our eyesight often gets worse with age. In addition to this normal aging effect, people may also develop eye diseases that impair their vision, or even lead to blindness. Glaucoma is one of the more common eye diseases. It's estimated that, in the industrialized world, about 2 out of 100 people over the age of 40 years have glaucoma.
The term "glaucoma" is used to describe a number of different eye conditions, all of which involve damage to the optic nerve. This damage leads to ever larger gaps in the field of vision, which usually go 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.
Over 90 percent of people who have glaucoma have a form called open-angle glaucoma. This form progresses slowly, and damage to the optic nerve doesn't cause vision problems for many years. Eye drops and surgery are the most commonly used treatments. Angle-closure glaucoma is less common: This type can go unnoticed for a long time, but then very suddenly cause severe vision loss and other problems.
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 isn’t 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 hallway from outdoors. And it can become increasingly harder to see obstacles like steps or the curb. This increases the risk of falls.
Angle-closure glaucoma may lead to an acute attack of glaucoma. This happens when there’s a sudden and great increase in intraocular pressure (the pressure inside the eye). Typical symptoms include acute vision problems, reddening of the eye, intense headache and eye pain, and nausea.
Glaucoma is often caused by increased intraocular pressure (pressure in the eye). 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.
If the aqueous humor can’t drain 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 optic nerve damage. In angle-closure glaucoma, the drainage of aqueous humor may be blocked completely. If that happens, no aqueous humor at all can leave the eye, and the eye starts to swell up quickly.
Intraocular pressure is measured in mmHg (millimeters of mercury), the same unit used for blood pressure. Readings between 10 and 21 mmHg are considered to be 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 supply 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’s not always possible to determine what has caused the optic nerve damage because not all causes of glaucoma are known. It’s probably caused by a combination of factors coming together too, which makes it harder to pinpoint a single cause.
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 the thickness of your cornea and the level of pressure inside your eye. People with very high intraocular pressure are quite a lot more likely to get glaucoma than people whose intraocular pressure is only slightly higher than normal.
Open-angle glaucoma usually develops gradually and goes unnoticed at first. The blind spots may continue to get bigger over time, until it's only possible to see the very center of the field of vision. Many years or decades often pass until that happens. This means that many people can still see well enough even 20 years after being diagnosed – especially if they receive effective treatment. The damage that has already been done to a person's vision can't be undone by treatment, though.
Only a small number of people who have glaucoma (either form) go completely blind over the years. It's estimated that this happens to about 1,100 people in Germany each year.
Angle-closure glaucoma can also go undetected for a long time. But an acute attack of glaucoma can occur quite suddenly. This should be treated as a medical emergency because it can lead to lasting loss of vision within a few hours or days.
Vision problems caused by glaucoma
Eye doctors can diagnose glaucoma even before the first symptoms become noticeable. They will first ask about any 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 tip of a small measuring device against the cornea.
If it is thought you might have glaucoma, 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.
Many eye doctors offer screening tests to detect high intraocular pressure or glaucoma. People who would like to have these screening tests have to pay for them 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, such as eye damage caused by diabetes.
Lowering intraocular pressure can help to delay or stop the gradual loss of vision. Glaucoma can't be cured, though, because the damage already done to the optic nerve can't be reversed. If someone has glaucoma and high intraocular pressure, it’s usually treated using eye drops. Depending on the specific product, the eye drops are applied either once or several times a day. Regular check-ups at the eye doctor are also important here. The check-ups are offered one to three times a year, depending on how advanced the glaucoma is.
Surgery or laser treatment may be considered if the medication doesn't work, stops working after a while, or isn’t well tolerated.
Acute attacks of glaucoma must be treated quickly to avoid any damage to the optic nerve. So it's important to go to a doctor or hospital immediately if you have any of the typical symptoms, such as acute vision problems or pain in your eye. There they may use laser treatment to drain the fluid that has built up.
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 may have nothing to do with glaucoma.
If glaucoma leads to major vision loss, everyday life needs to be adjusted to the new situation. Things at home can be set up to make it easier to find your way around – for instance, by adding additional sources of light. Removing tripping hazards is important too, in order to prevent falls. It's also usually possible to make changes at work or in 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. Many people who have glaucoma also find it helpful to find out more about the condition and ways to cope with its effects, or to talk with other people who have glaucoma – for instance, in a support group or on an internet forum.
It's 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's important to try to be aware of when your vision becomes too much of a problem and you start putting yourself and others at risk. Once a certain amount of eyesight has been lost, driving is illegal. Your eye doctor can give you more specific information and advice.
It's not easy to deal with worsening vision and being increasingly dependent on other people. But you may eventually have to give up control in some areas of your life. Other people can then help you to keep up your usual activities as much as possible and to maintain social contacts.
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’re dealing with a difficult health problem and want to stay as active as you can.
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