What is age-related Macular Degeneration?
Age-related Macular Degeneration (ARMD), also known as senile macular degeneration, is damage or breakdown
of the macula. The macula is a very small part of the retina, the light-sensitive
tissue of the eye, which is responsible for central vision. This is the part of
the retina which produces the finest detailed vision.
How does Macular Degeneration affect vision?
As Macular Degeneration damages the part of the retina responsible for central vision and for seeing
fine detail, it becomes difficult to see small details of objects. Vision to the
sides is not affected. If both eyes are affected, reading and other tasks requiring
fine vision may become very difficult. Macular Degeneration does not cause blindness. Because some
side vision remains, usually people can still take care of themselves.
What causes Macular Degeneration?
Macular Degeneration is the result of ageing processes in the eye. Some of the layers of the retina
thicken and waste material which is usually removed from the retina forms deposits,
distorting the retina. This distortion can cause damage to the other layers of
the retina. In about 10 per cent of cases, new blood vessels grow into the macula
from beneath. These newly-formed vessels are fragile and often leak blood into
the retina where the blood causes scar tissue to form. The scarring blocks out
central vision to a severe degree. There are also some other forms of macular
degeneration which are inherited and not associated with ageing.
How common is Macular Degeneration?
Macular Degeneration mainly affects older people: about four per cent of those more than 40 years old,
nine per cent of those over 50 years, 23 per cent of those over 65 years and 31
per cent of those aged 80 years or more. Men and women are equally affected. Macular Degeneration
accounts for up to 45 per cent of legal blindness and up to 70 per cent of seriously
impaired vision in people over the age of 70 years.
How is Macular Degeneration detected and diagnosed?
People with Macular Degeneration may notice that their vision has deteriorated. Many patients do not realise
that they have a problem until their vision becomes blurred. Optometrists perform
a number of tests in an examination which enables them to detect the presence
of Macular Degeneration in the early stages.
The optometrist examines the macula carefully with an instrument called an ophthalmoscope
which allows examination of the interior of the eye. Sometimes the optometrist
may place a drop in the eye to dilate the pupil to get a better view of the internal
structures. Through the ophthalmoscope the optometrist will look for changes in
the structure of the macula such as accumulations of waste material or new blood
vessels.
Another test which may be used is a grid pattern known as an Amsler chart. This is a regular
grid which looks like a piece of graph paper. Patients with Macular Degeneration often report that
sections of the grid appear to be distorted or missing.
Optometrists will usually refer patients whom they suspect have Macular Degeneration to an ophthalmologist (eye
surgeon) for confirmation of the diagnosis. The ophthalmologist may perform a
test called fluorescein angiography. In this test a fluorescent dye is injected
into the patient's bloodstream and the ophthalmologist observes the progress of
the dye through the blood vessels in the retina. This reveals any leaking blood
vessels.
Can Macular Degeneration be treated?
When most body tissues such as a muscle, skin or bone are damaged, the tissues' cells
have the capacity to regrow and repair the damage. Because nerve cells cannot
regenerate, damage to nerve tissue, such as the retina, is usually permanent and
irreversible. This is why the vision loss in Macular Degeneration is so difficult to treat, compared
with other vision disorders. For example, it is possible to remove and replace
the eye's lens in a person with cataract but it is not possible to replace or
even repair the retina of a person with Macular Degeneration.
Where new blood vessels have appeared in the macula area, laser surgery may be used.
In this treatment a focused, intense beam of laser light is used to seal off leaking
blood vessels and to prevent new vessels growing. This treatment is most effective
when it is applied in the very early stages of the disease, before extensive damage
has been done.
While there is little which can be done to prevent or cure Macular Degeneration, people with the disease
can be helped to continue functioning normally. Many patients with Macular Degeneration will eventually
come under the classification of being a low vision patient. Special help in the
form of low vision devices is available from optometrists and specialist low vision
clinics. Low vision devices enable patients to make the most of their vision and
include items such as miniature telescopes, high-powered reading spectacles, hand-held
and stand magnifiers, closed circuit televisions and other simpler aids such as
large-print books.
What should you do about Macular Degeneration?
For treatment of Macular Degeneration to be effective, it must be diagnosed as early as possible. Regular
eye examinations are the key to early detection of retinal changes and other signs
of disease. If you notice any change in the quality of your vision, have your
eyes examined immediately. Regular examinations are particularly important for
people over the age of 50 years and people whose families have a history of eye
problems. |
