What is the
retina?
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The retina is a thin layer of light sensitive tissue which lines
the back of the eye. When light enters the eye, it is focused
by the cornea and the lens onto the retina. The retina then transforms
the light images into electrical impulses which are sent to the
brain through the optic nerve. |
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The retina transforms light images into electrical impulses
which are sent to the brain via the optic nerve. |
What is the
macula?
- The macula is a very small area of the retina which is responsible
for central vision and color vision. The macula allows us to
read, drive, and perform detailed work. Surrounding the macula
is the peripheral retina which is responsible for side vision
and night vision.
What causes
macular degeneration?
- Macular degeneration is most commonly a natural result of
the aging process. With time, the retinal tissues break down
and become thin. This deterioration causes a loss of function
of the macula.
In about 10% of cases of macular degeneration, aging of the
retina is compounded by leakage of the tiny blood vessels which
nourish the retina. Growth of new, abnormal blood vessels in
the scar tissue that forms from the leaking blood vessels is
also common. Blood and leaking fluid destroy the macula, causing
vision to become distorted and blurred. The formation of dense
scar tissue blocks out central vision to a severe degree.
Occasionally, macular degeneration is caused by injury, infection,
or inflammation. The disease may also be hereditary.
What are the
symptoms of macular degeneration?
- The most notable symptom of macular degeneration is blurry
or distorted central vision. Difficulty in reading, doing close
work, or driving may also be noticed. A person with macular degeneration
may experience blurry words on a page, distortion of the center
of a scene, a dark or empty area in the center of vision, or
the distortion of lines.
Macular degeneration may cause words in the
center of a page to appear blurry.
Macular degeneration may also cause a dimming of color vision.
Fortunately, the disease does not cause total blindness, as side
vision is not affected. Macular degeneration only affects central
and color vision. However, if macular degeneration occurs in
only one eye, the symptoms of the disease may not be noticed,
as the "good" eye compensates for the "bad"
eye.
How is macular
degeneration diagnosed?
- A lighted instrument called an ophthalmoscope is used to
examine the retina. In addition, some special tests may be administered.
The Amsler grid test, in which the patient looks at a page similar
to graph paper, is used to detect blind spots or distortion of
central vision. A color vision test will indicate damage to the
macula if the patient cannot detect symbols or letters camouflaged
in colored patterns.
If macular degeneration is detected, a procedure called fluorescein
angiography may be done to check for blood vessel leakage. A
dye, which quickly travels to the eye, is injected into the patient's
arm. Photographs of the blood vessels in the retina are then
taken to determine the extent of damage.
How is macular
degeneration treated?
- Unfortunately, there is no cure for macular degeneration.
However, laser treatment may be used to slow the progression
of the disease. Laser treatment can also be effective in sealing
leaky blood vessels and destroying abnormal vessels so that hemorrhaging
and scarring will not decrease central vision.
Low vision aids
- People who suffer from macular degeneration are able to compensate
for much of their vision loss through the use of low vision aids.
Many magnifying devices, such as spectacles and hand or stand
magnifiers, are available. Bright illumination for reading and
other close work can also be helpful. Books, newspapers, and
other materials are available in large print.
Prevention is the best medicine
- Regular eye examinations are the only means of detecting
macular degeneration, as the symptoms of the disease often go
unnoticed. Early detection of macular degeneration may prevent
further vision loss, since treatment is only effective when started
early. Regular examinations are especially important for older
adults and persons who have family members with a history of
retinal problems.
- If you are experiencing difficulty with central or color
vision or have other- vision problems, you should obtain a complete
eye examination.
