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Age
Related Macular Degeneration
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What is age-related macular
degeneration? |
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Age-related macular
degeneration ("AMD") is a
disease associated with
aging that gradually
destroys sharp, central
vision. Central vision is
needed for seeing objects
clearly and for common daily
tasks such as reading and
driving.
AMD affects
the macula, the part of the
eye that allows you to see
fine detail. AMD causes no
pain.
In some
cases, AMD advances so
slowly that people notice
little change in their
vision. In others, the
disease progresses faster
and may lead to a loss of
vision in both eyes. AMD is
a leading cause of vision
loss in Americans 60 years
of age and older.
AMD occurs in
two forms: wet and dry.
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Where is the macula? |
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The
macula is located in the
center of the retina,
the light-sensitive
tissue at the back of
the eye. The retina
instantly converts
light, or an image, into
electrical impulses. The
retina then sends these
impulses, or nerve
signals, to the brain. |
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What
is wet AMD? |
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Wet AMD
occurs when abnormal blood
vessels behind the retina
start to grow under the
macula. These new blood
vessels tend to be very
fragile and often leak blood
and fluid. The blood and
fluid raise the macula from
its normal place at the back
of the eye. Damage to the
macula occurs rapidly.
With wet AMD,
loss of central vision can
occur quickly. Wet AMD is
also known as advanced AMD.
It does not have stages like
dry AMD.
An early
symptom of wet AMD is that
straight lines appear wavy.
If you notice this condition
or other changes to your
vision, contact your eye
care professional at once.
You need a comprehensive
dilated eye exam.
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What is dry AMD? |
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Dry AMD
occurs when the
light-sensitive cells in the
macula slowly break down,
gradually blurring central
vision in the affected eye.
As dry AMD gets worse, you
may see a blurred spot in
the center of your vision.
Over time, as less of the
macula functions, central
vision is gradually lost in
the affected eye.
The most
common symptom of dry AMD is
slightly blurred vision. You
may have difficulty
recognizing faces. You may
need more light for reading
and other tasks. Dry AMD
generally affects both eyes,
but vision can be lost in
one eye while the other eye
seems unaffected.
One of the
most common early signs of
dry AMD is drusen. |
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What
are drusen? |
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Drusen are
yellow deposits under the
retina. They often are found
in people over age 60. Your
eye care professional can
detect drusen during a
comprehensive dilated eye
exam.
Drusen alone
do not usually cause vision
loss. In fact, scientists
are unclear about the
connection between drusen
and AMD. They do know that
an increase in the size or
number of drusen raises a
person's risk of developing
either advanced dry AMD or
wet AMD. These changes can
cause serious vision loss.
Dry AMD has three
stages, all of which may
occur in one or both eyes:
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Early AMD.
People with early AMD have
either several small drusen
or a few medium-sized drusen.
At this stage, there are no
symptoms and no vision loss. |
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Intermediate AMD.
People with intermediate AMD
have either many
medium-sized drusen or one
or more large drusen. Some
people see a blurred spot in
the center of their vision.
More light may be needed for
reading and other tasks.
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Advanced Dry AMD.
In addition to drusen,
people with advanced dry AMD
have a breakdown of
light-sensitive cells and
supporting tissue in the
central retinal area. This
breakdown can cause a
blurred spot in the center
of your vision. Over time,
the blurred spot may get
bigger and darker, taking
more of your central vision.
You may have difficulty
reading or recognizing faces
until they are very close to
you. |
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Normal vision |
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The same scene as
viewed by a person
with age-related
macular degeneration |
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If you have vision loss
from dry AMD in one eye
only, you may not notice any
changes in your overall
vision. With the other eye
seeing clearly, you still
can drive, read, and see
fine details. You may notice
changes in your vision only
if AMD affects both eyes. If
blurriness occurs in your
vision, see an eye care
professional for a
comprehensive dilated eye
exam.
Ninety percent of all
people with AMD have this
type. Scientists are still
not sure what causes dry
AMD.
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How is AMD detected? |
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Your eye care
professional may suspect AMD
if you are over age 60 and
have had recent changes in
your central vision. To look
for signs of the disease, he
or she will use eye drops to
dilate, or enlarge, your
pupils. Dilating the pupils
allows your eye care
professional to view the
back of the eye better.
AMD is
detected during a
comprehensive VisDRTM
eye exam
that includes:
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Visual acuity
test.
This eye chart test
measures how well
you see at various
distances. |
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Dilated eye exam.
Drops are placed in
your eyes to
widen, or dilate,
the pupils.
VisDRTM
uses 45 degree colour images
of each eye to
detect signs of
damage and other eye
problems.
After the exam, your
close-up vision may
remain blurred for
several hours. |
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Tonometry
(optional). An
instrument measures
the pressure inside
the eye. Numbing
drops may be applied
to your eye for this
test. |
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All of the above tests are
non-invasive. |
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Your eye care
professional also may do
other tests to learn more
about the structure and
health of your eye. |
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Credits: Some of
above contents are extracted
from The National Eye
Institute ("NEI")
publications. The NEI is the US
Federal government's
lead agency for
vision research
under the National
Institutes of Health ("NIH") . |
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