Dr. MJ Bazos MD,
This essay 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% 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% of
all people with AMD have this type, it accounts for 90% of all blindness 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
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 2% chance of getting AMD. This risk rises
to nearly 30% in those over age 75.
- Besides Age, other AMD risk factors
- 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
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. Over time, the blurred spot
may get bigger and denser, 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
If you notice any of these
changes in your vision, contact your eye care professional at once for an eye
How Is AMD Detected?
Eye care professionals detect AMD
during an eye examination that includes the following:
•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.
•Tonometry. This is a standard test that
determines the fluid pressure inside the eye. Increased pressure is a possible
sign of glaucoma, another common eye problem in people over age 60.
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. This may
be a sign 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 to seal them. Laser
treatment is best applied soon after the new blood vessels develop, before they
have reached and damaged 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 Performed?
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 bright green or red 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. If the vessels continue to
leak, you might need more laser surgery.
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.
Foundation for the Blind: http://www.afb.orgLighthouse
Federation of the Blind: http://www.nfb.orgAmerican
Academy of Ophthalmology: http://www.eyenet.orgAmerican
Optometric Association: http://www.aoanet.orgThe
Foundation Fighting Blindness: http://www.blindness.orgPrevent
Blindness America: http://www.prevent-blindness.org