Introduction

Photo of an older couple taking a walk on the beach (PantherMedia / Nils Weymann)

It’s normal for our vision to gradually get worse with age. Some people also have medical conditions that further affect their vision or may even lead to blindness. One possible cause of worsening vision is age-related macular degeneration (AMD).

AMD is a chronic condition that usually affects both eyes and is brought about by a metabolic disorder. It develops in the macula, the part of the eye that is especially important for seeing sharp images. But vision loss usually only occurs in more advanced stages of AMD. There are two types of AMD: “dry” and “wet.” Wet AMD causes vision loss more quickly. Neither can be cured. But treatment for wet AMD can help to keep and sometimes even improve vision, or at least slow down the progression of the disease.

Symptoms

Macular degeneration causes the gradual loss of vision in the part of the eye where we see things in sharpest detail. This area is at the center of the retina and takes its full Latin name from its yellowish color (“macula lutea,” meaning “yellow spot”). We need this “central vision” to do things like read, drive a car or recognize faces.

Central vision loss makes objects appear blurry and distorted, particularly when you look at them directly. In advanced AMD, people can no longer see them at all. Although objects towards the edge of your field of vision usually remain visible, it is difficult to see what they are.

Illustration: Typical loss of vision caused by AMD; Things that you focus your vision on appear blurry, left: Page of a book, right: FaceTypical loss of vision caused by AMD

Causes and risk factors

The causes of age-related macular degeneration aren’t fully understood. AMD is believed to result from a problem with the very intensive metabolic processes that take place in the sensory cells of the retina. These processes release by-products that are usually broken down by the body. But if the body can’t break these substances down, small deposits called drusen start to form. These deposits prevent enough oxygen and nutrients from reaching the retina. In the dry form of AMD, this causes the light-sensitive cells in the retina to die off. The pigments underneath the retina may also change.

In wet macular degeneration, new blood vessels start growing underneath the retina as a reaction to the deposits. They grow into the retina and may lift it up. The new blood vessels may become “leaky,” allowing blood and fluid to seep into the retina, damaging the cells there.Illustration: Structure of the eye and growth of new blood vessels – as described in the articleLeft: Structure of the eye, Right: Growth of new blood vessels

Your individual risk is somewhat greater if close relatives already have AMD. It is also known that AMD is more common in people who smoke, and they tend to get it at younger ages than non-smokers. Frequent exposure to the sun may also possibly increase the risk, but this is not certain.

Prevalence

The condition becomes increasingly common in older age: About 1 out of 100 people between the ages of 65 and 75 have age-related macular degeneration, and as many as 10 to 20 out of 100 people over the age of 85 are affected. In industrialized countries, macular degeneration is the most common cause of severe vision loss in older people.

Outlook

The course of AMD is different in different people. There are three stages:

  • Early-stage AMD: Medium-sized drusen deposits and no pigment changes, no loss of vision.
  • Intermediate AMD: Large drusen and/or pigment changes. There may be mild vision loss, but most people don’t experience any problems.
  • Late-stage AMD: Dry or wet macular degeneration that causes vision loss.

Dry AMD progresses much more gradually than wet AMD, and it is also less likely to cause vision loss or other vision problems. Most people with advanced AMD have the wet form of the condition.

The time it takes for the disease to progress to late-stage AMD with vision loss depends on various factors, including the size of the deposits that have formed in the retina. About 1 to 3 out of 100 people with small drusen experience vision problems within five years, and about 50 out of 100 people with larger drusen have late-stage AMD and vision loss within five years. Dry AMD can also turn into wet AMD, which quickly worsens if left untreated but can be stopped or slowed down by various treatments.

People with late-stage AMD may lose the ability to read or recognize faces. AMD doesn’t usually lead to complete blindness. Even at a very advanced stage of AMD in both eyes, it is usually still possible to find your way around. But the overall vision loss can be so severe that it meets the legal definition of “blindness,” for which the German health care system provides monthly disability benefits.

Diagnosis

The eye doctor will first ask about the symptoms and any other medical conditions. Then your eyes will be closely examined using a microscope with a light on it, called a slit lamp, to look at the front and middle sections of your eye. The fundus (the inside of your eye opposite the lens) is also checked. Before the examination, eye drops are used to dilate (open) your pupils. Different types of tests can help get an idea of how much your central vision has been affected.

Other tests can confirm the diagnosis and help to plan treatment. If the doctor thinks you have wet AMD, an examination called fluorescein angiography of the retina can be used to check whether that is true. This involves injecting a dye solution into a vein in your arm. The solution is carried to the blood vessels in the retina. A special camera can then be used to detect changes in these vessels.

Another test that may be done is known as optical coherence tomography (OCT). OCT uses a laser to measure things like the thickness of the retina, as well as to detect any fluid-filled pockets. In Germany, this test is offered as an individual health care service (IGeL). The costs aren’t covered by statutory health insurers because it doesn’t have a proven benefit.

Prevention

People who don’t smoke are less likely to develop macular degeneration.

Dietary supplements are sometimes recommended for the prevention of AMD. The recommended supplements include beta-carotene, vitamins, zinc, omega-3 fatty acids and Ginkgo biloba.

Research has shown that people who have healthy eyes can't prevent macular degeneration by taking vitamin E or beta-carotene supplements. The other supplements haven’t been tested in suitable studies.

Treatment

There is currently no effective treatment for dry macular degeneration.

Wet AMD is typically treated with medicine that is injected into the eye to prevent blood vessel growth. This medicine is known as anti-vascular endothelial growth factor (anti-VEGF). Although this treatment can’t cure AMD, it can stop or at least slow down the progression. Sometimes vision even improves again during treatment.

Photodynamic therapy is less effective, and therefore no longer that common. Laser therapy is also only rarely used nowadays. This treatment involves heating and destroying abnormal blood vessels with laser beams. Photodynamic therapy applies a combination of medication and laser beams. Both of these therapies are only very rarely suitable for treating wet AMD. They also have more side effects than anti-VEGF therapy.

In some exceptional cases – and if no other treatment has helped – abnormal blood vessels may be removed surgically.

Dietary supplements containing a combination of certain ingredients (vitamin C, vitamin E, zinc, copper, and lutein with zeaxanthin or beta-carotene) may be able to slow the progression of the disease in people who are at greater risk of developing late-stage AMD.

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Labels: Age-related macular degeneration, Aging and geriatric care, AMD, H35, H36, H54, Head and nerves, Macular degeneration