Age-Related Macular Degeneration
Eye Diseases and Disorders Series
LPR staff project - July 17, 2001
(This article is for information purposes only. Always consult your doctor for medical advice.)
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The following article is provided courtesy of the National Eye Institute. Printed copies of this article, as well as a complete list of free publications offered by the NEI can be found on their NEI Publications Catalog.
Age-Related Macular Degeneration
Information for Patients
By the National Eye Institute
This pamphlet is designed to help
people with age-related macular
degeneration and their families better
understand the disease. It describes the
causes, symptoms, diagnosis, and
treatment of age-related macular
degeneration.
Age-related macular degeneration
(AMD) is a disease that affects your
central vision. It is a common cause of
vision loss among people over age of
60. Because only the center of your
vision is usually affected, people rarely
go blind from the disease. However,
AMD can sometimes make it difficult to
read, drive, or perform other daily
activities that require fine, central vision.
What is the macula?
The macula is in the center of the
retina, the light-sensitive layer of tissue
at the back of the eye. As you read,
light is focused onto your macula.
There, millions of cells change the light
into nerve signals that tell the brain
what you are seeing. This is called your
central vision. With it, you are able to
read, drive, and perform other activities
that require fine, sharp, straight-ahead
vision.
How does AMD damage
vision?
AMD occurs in two forms:
Dry AMD affects about 90 percent
of those with the disease. Its cause
is unknown. Slowly, the light
sensitive cells in the macula break
down. With less of the macula
working, you may start to lose
central vision in the affected eye as
the years go by. Dry AMD often
occurs in just one eye at first. You
may get the disease later in the other
eye. Doctors have no way of knowing
if or when both eyes may be
affected.
Wet AMD --Although only 10 percent
of all people with AMD have this
type, it accounts for 90 percent of all
severe vision loss from the disease.
It occurs when new blood vessels
behind the retina start to grow
toward the macula. Because these
new blood vessels tend to be very
fragile, they will often leak blood and
fluid under the macula. This causes
rapid damage to the macula that can
lead to the loss of central vision in a
short period of time.
Who is at risk for AMD?
Although AMD can occur during middle
age, the risk increases as a person gets
older. Results of a large study show that
people in their 50s have about a two
percent chance of getting AMD. This risk
rises to nearly 30 percent in those over
age 75. Besides age, other AMD risk
factors include:
- Gender--Women may be at greater risk
than men, according to some studies.
- Smoking--Smoking may increase the
risk of AMD.
- Family History--People with a family
history of AMD may be at higher risk of
getting the disease.
- Cholesterol--People with elevated
levels of blood cholesterol may be at
higher risk for wet AMD.
What are the symptoms
of AMD?
Neither dry nor wet AMD causes any
pain. The most common symptom of dry
AMD is slightly blurred vision. You may
need more light for reading and other
tasks. Also, you may find it hard to
recognize faces until you are very close
to them.
As dry AMD gets worse, you may see a
blurred spot in the center of your vision.
This spot occurs because a group of
cells in the macula have stopped
working properly. Over time, the blurred
spot may get bigger and darker, taking
more of your central vision.
People with dry AMD in one eye often
do not notice any changes in their
vision. With one eye seeing clearly, they
can still drive, read, and see fine details.
Some people may notice changes in
their vision only if AMD affects both of
their eyes.
An early symptom of wet AMD is that
straight lines appear wavy. This
happens because the newly formed
blood vessels leak fluid under the
macula. The fluid raises the macula from
its normal place at the back of the eye
and distorts your vision. Another sign
that you may have wet AMD is rapid
loss of your central vision. This is
different from dry AMD in which loss of
central vision occurs slowly. As in dry
AMD, you may also notice a blind spot.
If you notice any of these changes in
your vision, contact your eye care
professional at once for an eye exam.
How is AMD detected?
Eye care professionals detect AMD
during an eye examination that includes:
Visual acuity test: This eye chart test
measures how well you see at various
distances.
Pupil dilation: This examination
enables your eye care professional to
see more of the retina and look for signs
of AMD. To do this, drops are placed
into the eye to dilate (widen) the pupil.
After the examination, your vision may
remain blurred for several hours.
One of the most common early signs of
AMD is the presence of drusen. Drusen
are tiny yellow deposits in the retina.
Your eye care professional can see them
during an eye examination. The
presence of drusen alone does not
indicate a disease, but it might mean
that the eye is at risk for developing
more severe AMD.
While conducting the examination, your
eye care professional may ask you to
look at an Amsler grid. This grid is a
pattern that resembles a checkerboard.
You will be asked to cover one eye and
stare at a black dot in the center of the
grid. While staring at the dot, you may
notice that the straight lines in the
pattern appear wavy to you. You may
notice that some of the lines are
missing. These may be signs of wet
AMD.
If your eye care professional suspects
you have wet AMD, you may need to
have a test called fluorescein
angiography. In this test, a special
dye is injected into a vein in your arm.
Pictures are then taken as the dye
passes through the blood vessels in the
retina. The photos help your eye care
professional evaluate leaking blood
vessels to determine whether they can
be treated.
How is AMD treated?
Dry AMD currently cannot be treated.
But this does not mean that you will
lose your sight. Fortunately, dry AMD
develops very slowly. You may lose
some of your central vision over the
years. However, most people are able to
lead normal, active lives--especially if
AMD affects only one eye.
Some cases of wet AMD can be treated
with laser surgery. The treatment
involves aiming a high energy beam of
light directly onto the leaking blood
vessels. Laser treatment is more
effective if the leaky blood vessels have
developed away from the fovea--the
central part of the macula. But even if
the blood vessels are growing right
behind the fovea, the treatment can be
of some value in stopping further vision
loss.
How is laser surgery
preformed?
Laser surgery is performed in your eye
care professional's office or eye clinic.
Before the surgery, he or she will:
(1)
dilate your pupil and
(2) apply drops to
numb the eye. In some cases, he or she
also may numb the area behind the eye
to prevent any discomfort.
The lights in the office will be dim. As
you sit facing the laser machine, your
eye care professional will hold a special
lens to your eye. You may see flashes of
light.
You can leave the office once the
treatment is done, but you will need
someone to drive you home. Because
your pupils will stay dilated for a few
hours, you also should bring a pair of
sunglasses.
For the rest of the day, your vision may
be a little blurry. Your eye may also hurt
a bit. This is easily controlled with drugs
that your eye care professional can
suggest.
You will need to make frequent
follow-up visits. During each exam, you
may have fluorescein angiography to
make sure that the blood vessels are not
still leaking, or that new blood vessels
have not developed. If the vessels
continue to leak, you might need some
more laser surgery. It is important to
realize that laser surgery is not a cure
for AMD. It is only a treatment to help
stop further vision loss. The risk of new
blood vessels growing back after laser
treatment is relatively high.
What research is being
done?
The National Eye Institute (NEI) is the
Federal government's lead agency for
vision research. The NEI is supporting a
number of research studies both in the
laboratory and with patients to learn
more about the cause of AMD. This
research should provide better ways to
detect, treat, and prevent vision loss in
people with the disease.
There is some suggestion that certain
vitamins and minerals may play a role in
the treatment of AMD. This treatment
needs much more research before
scientists can know for sure if it is
helpful. The NEI is currently sponsoring
the Age-Related Eye Disease Study to
provide clear information on whether
vitamin or mineral supplements are of
any benefit.
Scientists have begun to study the
possibility of transplanting healthy cells
into a diseased retina. Although this
work is at a very early stage and still
experimental, someday it may help
people keep their vision or restore some
lost vision.
What can you do to
protect your vision?
Dry AMD. If you have dry AMD, you
should have your eyes examined
through dilated pupils at least once a
year. This will allow your eye care
professional to monitor your
condition and check for other eye
diseases as well.
You should also obtain an Amsler
grid from an eye care professional to
use at home. This will provide you
with a quick and inexpensive test to
evaluate your vision each day for
signs of wet AMD. It works best for
people who still have good central
vision. You should check each eye
separately--cover one eye and look
at the grid, then cover your other eye
and look at the grid. You also may
want to check your vision by reading
the newspaper, watching television,
and just looking at people's faces. If
you detect any changes, you should
have an eye exam.
Wet AMD. If you have wet AMD, it
is important not to delay laser
surgery if your eye care professional
advises you to have it. After surgery,
you will need to have frequent eye
examinations to detect any
recurrence of leaking blood vessels.
Studies show that people who smoke
have a greater risk of recurrence than
those who don't.
In addition, you should continue to
check your vision (at home with the
Amsler grid or other methods) as
described under dry AMD and
schedule an eye exam immediately if
you detect any changes.
What can you do if you
have already lost vision to
AMD?
Normal use of your eyes will not cause
further damage to your vision. Even if
you have lost sight to AMD, you should
not be afraid to use your eyes for
reading, watching TV, and other usual
activities.
Low vision aids are available to help you
make the most of your remaining vision.
Low vision aids are special lenses or
electronic systems that make images
appear larger. If you need low vision
aids, your eye care professional can
often prescribe them or refer you to a
low vision specialist. In addition, groups
and agencies that offer information
about counseling, training, and other
special services are available. You may
also want to contact a nearby school of
medicine or optometry as well as a local
agency devoted to helping the visually
impaired.
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