| Why
is the Macula Important?
Unlike
a photograph in which the entire picture is in focus, our
eyes can only focus on the object at which we are looking
directly. (Try reading the first word of this sentence while
staring at the period at the end of the sentence).
The macula is responsible for our clear central vision.
The remainder of the retina is used for side or peripheral
vision. Damage to the macula causes blurring of our central
vision which may make it difficult to read, drive, watch
television, and recognize familiar faces.
What
is Age-Related Macular Degeneration?
Macular degeneration is the
leading cause of poor vision in the United States. Each
year, approximately 170,000 new cases of age-related macular
degeneration (AMD) are discovered. Macular degeneration
occurs whenever a previously normal macula begins to deteriorate.
Juvenile macular degeneration begins at a young age and
is quite rare. AMD is very common and occurs in older people,
although getting older does not always result in visual
problems.
As AMD progresses, the central vision begins to blur, but
the peripheral vision remains normal. Please remember that
macular degeneration does not cause total blindness. Even
at its worst, AMD spares peripheral vision and allows patients
to care for themselves. Macular degeneration often affects
both eyes, although the second eye may not become involved
for many years.
There are two main types of AMD, dry macular degeneration
and wet macular degeneration.
Ninety percent of macular degeneration patients have the
dry form. The cells in the macula slowly wear out. The loss
of central vision is often mild. Some patients may have
progressive deterioration, usually over a long period of
time, resulting in severe loss of central vision. Only 10
percent of severe loss of central vision is due to dry AMD.
The more severe wet (exudative form) affects 10 percent
of macular degeneration patients. In this type, fluid may
collect or abnormal blood vessels may grow underneath the
retina. They often cause severe damage to the vision from
bleeding and scarring under the macula. The wet form accounts
for 90 percent of the patients with severe loss of central
vision.
What
Causes Age-Related Macular Degeneration?
Aside
from aging, no specific cause of macular degeneration has
been identified. Heredity plays a role in many patients.
The disorder is limited to the eye and is not associated
with problems elsewhere in the body. Tumors and infections
are not associated with macular degeneration. Extensive
use of the eyes, reading or watching television does not
cause macular degeneration or result in further damage.
There is nothing a person can do that will accelerate or
retard the progress of AMD.
How
do I Know if I Have Macular Degeneration?
Most people with macular degeneration
have either blurred or distorted vision in one or both eyes.
Distorted or wavy vision is a very important symptom and
should be reported promptly to your doctor. This is especially
true when straight lines (doorways, telephone poles, etc.)
appear wavy. Many people with visual loss in one eye may
not realize they have a problem because the good eye takes
over for both eyes.
You will be given a special Amsler grid test to be used
at home to help you recognize early changes in your vision
or identify new areas of distortion This grid test should
be used on a daily basis. It is very important to check
each eye separately.
What
Tests Can I Expect?
The doctor will examine your
eyes on each visit. If necessary, he may order a fluorescein
angiogram. In this test, a dye is injected into an arm vein,
and pictures are taken of the macula as the dye circulates
through the blood vessels. In some cases, another type of
angiogram, called High Speed-ICG, is used to take a movie
of the deepest layers of the eye using a different dye and
a special infrared camera.
Because the vessels of the eye can be photographed directly,
no X-rays are involved and the tests are safe for patients
who are allergic to X-ray dyes. Patients allergic to Iodine
should only have High Speed-ICG with special precautions.
The angiogram provides a detailed picture of the retinal
blood vessels and will detect any abnormal vessels that
might be present. The doctor uses this information to determine
whether treatment might be helpful. The dye is excreted
in your urine for up to 24 hours following the injection.
The whites of your eyes and your skin might turn slightly
yellow for a day. Hospitalization is not required for this
test, and you are free to go home when it is finished.
What
Treatment is Available for Macular Degeneration?
Until recently, the only proven
treatment was laser photocoagulation. However, a break-through
drug called Macugen® was approved by the FDA in December
of 2004. Sabates Eye Centers as the Department of Ophthalmology,
University of Missouri – Kansas City at the Eye Foundation
of Truman Medical Center, was a major study site of Macugen®.
Test results have been very positive. During the three-year
test program, Dr.
Nelson Sabates and the retinal specialists at SEC administered
the drug to volunteer patients every six weeks. In several
cases, the disease was arrested, and in certain instances,
a portion of the patient’s lost vision was restored.
Conventional laser treatment only benefits a small percentage
of macular degeneration patients who have certain types
of the wet form. However, laser can stabilize vision and
prevent further deterioration and in some cases, improve
vision to some degree.
Macugen®
Macugen® is approved to treat all types of wet age-related
macular degeneration. Macugen® works by blocking an essential
signal that causes abnormal blood vessels to grow and leak.
Macugen® is injected into the eye every 6 weeks. The
length of treatment will be determined by your doctor. It's
important to follow the treatment plan your doctors outlines.
This includes all follow-up appointments and scheduled Macugen®
injections.
Conventional Laser Treatment
Conventional laser consists of a strong beam of light, which
enables the physician to seal (cauterize) the abnormal blood
vessels, which may grow in the wet form of macular degeneration.
In very rare cases, before the laser procedure, an anesthetic
injection may be used. The injection often causes the vision
in the treated eye to be blurred for several hours. You
will be in a sitting position for the treatment. The actual
laser treatment, which is not painful, usually takes less
than 5 minutes. You will be able to return home immediately
and resume your normal activities within 24 hours.
Unfortunately, only some types of wet AMD respond to conventional
laser. Laser treatment does not cure macular degeneration,
and it does not necessarily prevent abnormal blood vessels
from returning in the future. It is important for you to
continue to test your vision with the Amsler grid chart.
If further changes are noted, they should be reported promptly
to your doctor. If the abnormal blood vessels do return,
it may be possible to treat them with laser again.
Newer Laser Techniques
Abnormal new blood vessels may grow into the very center
of the macula in some cases of macular degeneration. Such
cases represent the worst type of macular degeneration,
requiring many visits and extreme efforts from both the
patients and the doctor to control the disease and limit
vision loss. Abnormal vessels may grow in a variety of patterns.
Depending on the pattern of leakage, one of the new laser
treatment techniques may be appropriate for an individual
case. If the vessels are very well defined, photodynamic
therapy (PDT) may be a reasonable treatment recommendation.
This involves injection of a medicine called Visudyne, which
is selectively absorbed by abnormal, growing blood vessels.
The medicine is allowed to adsorb for 15 minutes after beginning
infusion through an intravenous line. Nonburning, red laser
light is then shown into the eye, which activates the medicine.
This chemically cauterizes the abnormal blood vessels, with
relatively little effect on the surrounding normal tissue.
This results in visual improvement in only about 15 to 20
percent of cases, but prevents further vision loss in another
50 to 60 percent. This is not the cure, but an effective
way to prevent further vision loss in many patients.
If vessels grow in the center of the macula, resulting in
a diffuse pattern of fluid leakage, photodynamic therapy
has been shown not to be helpful. In these cases, transpupillary
thermal therapy (TTT), another new treatment technique may
be useful. Instead of applying a hot laser, which burns
the tissue that it touches, transpupillary thermal therapy
involves gently heating this area with much cooler laser
settings. This results in very mild photocoagulation of
the abnormal tissue, with less damage to surrounding normal
tissue. This has been shown to stabilize or improve vision
in 50 to 70 percent of patients with this pattern of leakage.
All of these treatments seek to treat the area of leakage
directly. These leaky blood vessels grow in a pattern like
a small flat tree or bush underneath the retina. In many
cases, it would be just as effective to treat the underlying
trunk blood vessel, which feeds this tree. In the past,
available cameras have not been able to visualize the feeder
vessel. There is a new kind of camera now available which
can, in many cases, visualize this feeder vessel. Feeder
Vessel Therapy (FVT) has been shown to be useful in some
cases not treatable by other means.
Vitamins
Research suggests that certain dietary supplements may help.
Vitamins and minerals such as zinc, vitamin E and selenium
are advocated by some researchers for the purpose of trying
to prevent further visual loss from dry macular degeneration.
Other substances that have received much attention include
Bilberry and Lutein. Current studies now show that antioxidant
vitamins and zinc do seem to help, at least with more advanced
disease. Taking one of the "eye vitamin" supplements
as directed provides approximately what was recommended
in the Age Related Eye Disease Study (AREDS). Your doctor
will discuss them with you if he or she feels they might
be appropriate for you.
Dietary Measures
In addition to the vitamins listed above, some people do
believe that certain foods, which contain these vitamins,
or other factors may help control the progression of macular
degeneration. Such foods include dark green leafy vegetables,
red wine (particularly the Cabernet and Petit Syrah grapes)
and other foods rich in antioxidant vitamins.
Surgery
Very few patients with AMD will need surgery. Surgery may
be considered when abnormal new vessels grow in the center
of the macula or when a very large hemorrhage occurs. These
are instances in which the eye is threatened with severe
visual loss. Your doctor will discuss this further if it
is appropriate.
What
to Do if You Have Macular Degeneration?
Have a regular eye examination
at least once yearly. If you are seeing a retinal specialist
as well as your general eye doctor, you may be able to alternate
visits to maximize convenience and reduce cost.
Use an Amsler grid at home to monitor your vision. Look
at the chart from reading distance using any bifocals or
reading glasses you normally use. All you have to do is
take a quick glance. If you stare at it for too long, the
image will fluctuate and become confusing.
Quit smoking and control your blood pressure as well as
you can. Both of these measures may help.
At least consider using antioxidant vitamin supplements.
There is some evidence that these may help stabilize the
wear and tear process. There are three reasonable options:
Use a multivitamin such as Centrum Silver or an equivalent,
Use an “eye vitamin” such as Ocuvite or I-caps,
Go “ala carte” using single preparations including
Vitamin A, D, E, C, B complex, zinc, and selenium. Other
supplements that may help include Lutein, zeaxanthine, Billberry,
and Ginko biloba.
The most convenient choice is to use an
eye vitamin, which contains Lutein either with or without
a multivitamin. It is also reasonable for your younger family
members to consider using these, since the disease has a
hereditary component, and the vitamins may have a preventative
effect.
Eat well and consider including food types that are suggested
to have beneficial effects. These would include dark, green
leafy vegetables such as spinach, other sources of the vitamins
listed above, and red wine (especially from the Cabernet
and Syrah grapes).
Back
to the Retina Center
View
the Macular Degeneration Presentation
Related Links:
Macular Degeneration Foundation
www.eyesight.org
Macugen
http://www.macugen.com/
Macular Degeneration
Network
www.macular-degeneration.org
AMD Alliance International
www.amdalliiance.org
Association for Macular
Disease, Inc
www.macula.org
Foundation Fighting
Blindness
www.blindness.org
Lighthouse International
www.lighthouse.org
The Macula Foundation,
Inc
www.macula.org/foundation/contact.html
National Eye Institute
www.nei.nih.gov
Prevent Blindness America
www.preventblindness.org
AMDhelp
www.amdhelp.com
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