In the United States, Macular Degeneration affects over ten million people.
It is an incurable disease of the eye and is also the leading cause of blindness
in people over the age of 55.
Macular Degeneration is the result of deterioration of the central portion of the retina. In our eye, the very back layer records the images that we see
then sends them through the optic nerve of the eye into our brain. The
macula, which is the retina's central portion, is what focuses the central
vision in the eye that controls our ability to read, recognize colors, drive a
car, and see small details in objects.
As we age, our chances increase dramatically for getting Macular
Degeneration. Research on this disease is limited due to the lack
of funds. Therefore, the exact factors that cause Macular Degeneration are
not known since there is no conclusive evidence.
There are several forms of Macular Degeneration. These include:
- Age-related Macular Degeneration (most common) - There are two forms of
this; wet and dry. The wet form is when new blood vessels form under the
retina and leak causing visual distortion and scar tissue. The dry form
progresses slower than the wet and has less severe vision loss. The
macula deteriorates over time as part of the aging process.
- Cystoid Macular Degeneration - This form results in a loss of vision due
to cysts on or near the macula.
- Diabetic Macular Degeneration - This form is the result of the macula
deteriorating due to diabetes.
- Senile Disciform Degeneration - This is a form of the wet Age-related
Macular Degeneration where the blood vessels hemorrhage severely.
If a family member suffers from Age-related Macular Degeneration, chances
are, through heredity, you may end up with it, also. Women, Caucasians,
and Asians are the most susceptible to developing this disease.
It is believed that the Age-related form may be caused by arteriosclerosis in
the blood vessels that supply blood to the retina. The common theory here
is that what is bad for the heart is bad for your eyes. Items such as
smoking, and a diet that includes a large amount of saturated fat are said to be
two of the worst things contributing to Macular Degeneration. It is also
believed that a diet rich in vitamin A and drinking moderate amounts of red wine
decreases your risk for Macular Degeneration.
The primary symptom in this disease is when we notice a change in our central vision. You may notice a blank or dark spot or blurred vision when looking
straight ahead, even though your peripheral vision will not be affected.
Things may appear smaller than before, you may notice a change in your
perception of color, and you may become sensitive to bright light. This
may happen suddenly or could progressively become more apparent. If you
notice a sudden onset of distortion in your vision, you should immediately see
an ophthalmologist.
The ophthalmologist will examine your eyes after dilation of the pupils.
They look at the retina, examining it for the presence of small yellow bumps
called drusen (Small bright structures seen in the retina and in the optic disc) and also look to see if the macula is thinner than normal.
They may also conduct a visual field test in which they ask if you see blank
spots in your central vision while looking at a white screen. You may also
be subjected to a fluorescein angiography, which is where fluorescent dye is
injected into your vein, then the ophthalmologist will photograph the back of
your eye. This helps them determine if the blood vessels in the back of
your eye are leaking slightly or severely hemorrhaging.
Most patients suspected of having Age-related Macular Degeneration will
undergo a visual test called the Amsler Grid. This is a grid on a sheet of
paper where the patient is asked to look at a dot located in the center of the
page and they are instructed to contact the ophthalmologist if the graph lines
are perceived as being wavy, bent, broken, or missing altogether.
The early detection of this disease is extremely important for two reasons.
The first reason is the loss of vision cannot be reversed, and the second is
there are treatments that may slow or even halt the progression of the wet form
of this disease. In selected cases of wet Macular Degeneration, laser
photocoagulation is effective for sealing leaking or bleeding vessels.
Unfortunately, laser photocoagulation usually does not restore lost vision, but
it may prevent further loss. Yet another form of treatment is radiation therapy using either x-rays or a proton beam. In the blood vessels that
are growing, this form of treatment uses a low dose of radiation since these
vessels are extremely sensitive to treatment. The nerve cells surrounding
the retina are not sensitive to the treatment since they are not growing, and
thus, are not harmed. There is no known treatment for the dry form.
However, there are cell transplantation studies being conducted.
The dry form of this disease will eventually stabilize even though the loss
of vision will not be regained. The wet form may stabilize or even improve
without any treatment. However, this is only temporary.
Although patients suffering with this disease often become legally blind,
they rarely have a total loss of vision. They will retain their peripheral
vision and can usually compensate for the loss of their central vision through
training designed to help them use their peripheral vision. There are
special aids such as magnifiers that allow the patient to read and telescopic aids allowing them to see further away. Through using these aids with
their peripheral vision, most people with this disease can remain independent.
Sources:
http://www.stlukeseye.com
http://www.allaboutvision.com
http://www.macula.org
http://www.mdsupport.org
http://www.blindness.org
http://cancerweb.ncl.ac.uk