Glaucoma: How can screening tests help?

Photo of a woman having her eyes examined
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Many eye doctors offer tests for . But statutory health insurers (in Germany) only cover the costs if you have risk factors or if the doctor suspects you may have . There's no good-quality research on whether or not programs for the general population are beneficial.

Glaucoma is an eye disease that causes vision to become worse over time. It progresses slowly, and doesn't cause any immediate vision problems. By the time you notice that you have , damage to the eye is usually already at an advanced stage and can't be reversed. So it's generally important to diagnose and treat the disease as early as possible. But it's not clear whether for the general population is the best way to do this.

What does glaucoma screening involve?

Doctors screen for using a combination of tests that are also used to diagnose eye problems:

  • In a test known as ophthalmoscopy, the eye doctor uses a special instrument called an ophthalmoscope to look into your eye. This makes it possible to detect optic nerve damage.
  • Intraocular pressure (the pressure in your eye) is measured using a technique called tonometry. Here the eye is first numbed with a drop of liquid. The doctor then presses a small probe against the to measure the pressure inside the eye.
  • A slit lamp is used to examine the front part of the eye. This is done to see whether the fluid in the eye (called aqueous humor) can drain out of the eye freely.

These tests don't take very long, and they carry little risk and aren't painful. If your doctor believes you have , he or she can also measure your field of vision. This is done to see whether there are any gaps in your field of vision and whether blind spots have already developed.

When are the costs of glaucoma screening covered?

In Germany, statutory health insurers only pay for these tests if:

  • you regularly use steroids (such as corticosteroids) to treat another medical condition,
  • a problem in the front part of your eye is preventing aqueous humor from draining out,
  • you have typical symptoms, such as gaps in your field of vision or trouble seeing,
  • diabetes has caused eye damage,
  • you have eye injuries that make it necessary to rule out ,
  • you have planned eye surgery, and need to rule out the possibility of before or after the procedure,
  • the back of your eye has changed and/or your is too high.

If none of these apply to you, will usually be classified as an individual healthcare service in Germany (individuelle Gesundheitsleistung, or IGeL for short) and you will have to pay for it yourself. Eye doctors usually offer this test for about 15 to 40 euros.

Pros and cons of the screening test

Over the last few years, different groups of researchers have looked into the question of whether offering screening to everyone over a certain age has any benefits. They did a search for studies on whether prevents loss of vision. They also wanted to find out how reliably the eye tests can tell whether someone has or not.

But the searches for studies didn't turn up much: There's hardly any research on the benefits of for in the general population. This means that it's not possible to say whether for will have any advantages or disadvantages for people who don't have any symptoms or aren't at greater risk of developing . And many questions remain unanswered:

  • Who benefits from ?
  • For what age groups does it make sense?
  • Does result in unnecessary treatment?
  • Which tests are best suited for purposes?
  • How often should be done?

Despite these unresolved issues, in Germany, has become one of the most common individual healthcare services that doctors offer.

Screening will generally always have advantages and disadvantages, regardless of what is being screened for. A test may deliver the wrong results – for example, if someone is diagnosed with after the test, although their eyes are actually healthy. This is called a "false positive" result. If people are wrongly diagnosed with a disease, they may take medication they don't need and the might cause unnecessary distress. But it's difficult to draw any conclusions about the disadvantages of for because there are no good studies in this area.

What should you know about glaucoma screening?

Some eye doctors only measure the pressure inside your eye when for , but it's not advisable to have that done. Testing isn't enough on its own to diagnose or determine whether you have a higher risk of developing . Some people have even though they don't have high . And others may have high , but don't develop .

In order to get an idea of whether you have or a higher risk of developing it, other tests would have to be done too. These tests involve examining the optic nerve and the nerve fibers of the , as well as testing your field of vision. You may need more tests if your doctor thinks you might have . A thorough examination would also include your doctor asking about your medical history, your life circumstances and symptoms.

Not clear whether the advantages outweigh the disadvantages

Why is not covered by statutory health insurers in Germany if can be treated when caught in time? The answer is: Just because a disease can be treated, it doesn't automatically mean that it's a good idea to have everyone tested. To decide whether makes sense, you need to know whether it actually has the advantages it is thought to have. And you have to know about the possible disadvantages too.

Experiences with other programs have shown that misdiagnosis is inevitable. This can make patients out of people who don't actually have the disease. They are then given further examinations that may be unnecessary or unpleasant. Or they may be given treatment even though they won't benefit from it and it could have side effects. So there's a risk of overdiagnosis and overtreatment.

These fundamental concerns might not apply to . But that's precisely the problem: The actual advantages and disadvantages of can't yet be assessed with any certainty, simply because no good-quality research is available.

Ervin AM, Boland MV, Myrowitz EH, Prince J, Hawkins B, Vollenweider D et al. Screening for Glaucoma: Comparative Effectiveness. April 2012. (AHRQ Comparative Effectiveness Reviews; Volume 59).

Hatt S, Wormald R, Burr J. Screening for prevention of optic nerve damage due to chronic open angle glaucoma. Cochrane Database Syst Rev 2006; (4): CD006129.

Schnell-Inderst P, Hunger T, Hintringer K, Schwarzer R. Individuelle Gesundheitsleistungen. 2011. (DAHTA Schriftenreihe Health Technology Assessment; Band 113).

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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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?

Updated on August 1, 2019
Next planned update: 2022

Authors/Publishers:

Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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