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15 October 2010

Getting to grips with macular degeneration

While age-related macular degeneration is not widely known about it is an important eye condition and the leading cause of visual impairment in senior citizens of European decent.

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Advances being made against this eye disease of the elderly

While age-related macular degeneration (AMD) is not widely known about it is an important eye condition and the leading cause of visual impairment in senior citizens of European decent.

This is according to Dr Enslin Uys who is in full time practice at Netcare St Anne’s Hospital in Pietermaritzburg. Dr Uys noted that an estimated fifteen million people in the United States have the condition, and approximately two million new cases are diagnosed annually.

Speaking on World Sight Day, Dr Uys said that the fact that AMD caused so many elderly people visual impairment made it an important disease for the public to be aware of. While dry macular degeneration, the most common form of the disease, cannot be cured, there are ways to slow its progression and to deal with its effects.

Age-related macular degeneration (AMD) is a progressive disease of the retina whereby the light-sensing cells in the central area of vision (the macula) stop working and eventually die. The disease is thought to be caused by a combination of genetic and environmental factors, and it is most common in people who are age sixty and over.

There are two forms of the AMD: dry macular degeneration and wet macular degeneration. The former makes up around 90% of cases and the latter between 10 and 15% of cases.

Dry macular degeneration

Dry macular degeneration is distinguished by yellowish deposits of debris in the retina called "drusen". The material comprising these deposits is usually carried away by the same blood vessels that bring nutrients to the retina. For reasons as yet unknown, this process is diminished in macular degeneration. Some of the potential causes being studied are inflammation, inadequate blood circulation in the retina, and premature aging of the sight cells due to genetic deficiencies. In addition, environmental, behavioural (e.g. smoking) and dietary factors are thought to contribute to the progress of the disease in those who are susceptible to it.

Treatments and cures for dry AMD and the juvenile forms of MD will likely come from the fields of genetic replacement therapy and stem cell transplantation. A good amount of research is being done in these areas, and we can reasonably expect a cure to be found within a decade or two.

There is as yet no way to actually prevent the dry form of macular degeneration, but studies have shown that a person can take certain steps to help slow its progress:

               Eat a diet rich in leafy green vegetables;

               Take daily doses of antioxidants and zinc as recommended by the Age-Related Eye Disease Study (AREDS),

               Supplement this healthy diet with lutein and zeaxanthin;

               Avoid excessively bright sunlight by wearing a wide-brimmed hat and wrap-around sunglasses that are protective against both ultraviolet (UV) rays and blue light;

               Do not smoke or give up smoking; and

               Contact a low vision specialist such as a Ophthalmologist if vision worsens.

Wet macular degeneration

About 10 to 15% of macular degeneration cases are the "wet" or "exudative" form, in which newly formed, immature blood vessels grow and leak into the spaces above and below the photoreceptor cells of the eye.

Laser treatments and surgery are sometimes used in the treatment of some forms of wet macular degeneration. Pharmaceutical treatments are also showing themselves to be amazingly successful in the condition’s treatment.

What to expect

To distinguish between the dry form and the wet form the eye specialist (Ophthalmologist) often has to do further examinations or tests. The most commonly used examination is a dilated examination of the back of the eye, a fluorescein angiogram (FA) and ocular coherence tomography (OCT).

At its worst, macular degeneration will damage only central vision, which arises from the macular area, comprising less than 5% of the total retina, but responsible for about 35% of the visual field. This means that an affected person will find it difficult or impossible to read, drive, or recognize faces. The peripheral vision, however, is left untouched, so macular degeneration does not, by itself, lead to total blindness. Many affected people move about with no assistance at all and lead independent, productive lives. The most successful of them have also learned to use a wide variety of visual aids such as magnifiers, closed circuit TV readers or special bioptic glasses.

The risk of developing macular degeneration depends upon a person's age and whether soft drusen and/or changes in retinal pigment (colour) are present.

Understanding and treatment of macular degeneration in all of its forms is progressing steadily. Meanwhile, education helps people to become discriminating consumers of therapies and services. It also keeps them aware of progress in the continuing battle to slow macular degeneration and improve the quality of life of those who have it. (Netcare St Anne’s Hospital/ October 2010)

 
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