blurred central vision.
grayness, or blank spots in the central field of vision.
distortion: Straight lines appear bent; objects may appear
smaller than in actuality.
reading or doing close work.
When To Call Your Doctor
an ophthalmologist if you have blurred or distorted vision.
simple home test (the Amsler grid) can help monitor visual
changes. Any worsening of vision warrants an immediate visit
to an ophthalmologist.
What Is It?
The macula is the central and most sensitive portion
of the retina, the layer of tissue in the back of the eye that
contains the light-receptive nerve cells essential for sight.
For some people in their 50s, the macula begins to break down
to some extent, resulting in the condition known as age-related
macular degeneration (AMD). In AMD, central vision and the ability
to distinguish fine detail become increasingly impaired, but
peripheral vision remains unaffected. If macular function is
lost completely, activities such as reading become impossible.
There are two forms of AMD: non-neovascular (also
known as nonexudative, atrophic, or dry) and neovascular (exudative
or wet). About 90 percent of those with AMD have the non-neovascular
form, whichalthough irreversible and essentially untreatabletends
to progress slowly and may stabilize so that most patients experience
no serious vision loss. In neovascular AMD, however, fine blood
vessels at the back of the eye proliferate and begin to leak
or exude fluid, possibly scarring the macula and resulting in
permanent central vision loss within days or weeks. Neovascular
AMD may develop suddenly in patients with non-neovascular AMD.
Both forms are painless and most often affect one eye at a time.
AMD is the leading cause of severe and irreversible vision loss
in older Americans.
What Causes It?
The cause is
unknown, although aging is clearly a risk factor. Some evidence
of AMD can be detected in approximately one quarter of all people
over the age of 65 and in one third of those over age 80.
factors include hyperopia (farsightedness), cigarette smoking,
light-colored eyes, and a family history of AMD. High blood pressure,
lifetime sunlight exposure, dietary factors, and genetic susceptibility
may increase the risk of neovascular AMD.
There is no
known way to prevent AMD. Presumably, avoidance of smoking, treatment
of hypertension, and minimal sun exposure (wearing sunglasses
and a hat with a wide brim) might help.
by an ophthalmologist is needed.
AMD is confirmed with fluorescein angiography (injection of a
special dye into the bloodstream to allow clear photographic
images of the blood vessels in the eye to be taken).
How To Treat It
There are no
ways to arrest or reverse the course of non-neovascular AMD.
A research study is testing the use of vitamin and mineral supplements
as a treatment. Retinal cell transplants do not yet work, but
are being tested.
non-neovascular AMD should be monitored for the onset of neovascular
AMD. In the meantime, low-vision optical aids may be useful,
including: high-power reading glasses; a small telescope mounted
on one lens of your eyeglasses; a pocket telescope for reading
street signs; and a closed-circuit television hookup that can
magnify a written page as much as 60 times and display the image
on a television screen.
early enough, neovascular AMD can often be treated with laser
surgery to destroy the new leaking blood vessels. Such surgery
should be performed only by an ophthalmologist with special training
and experience in the procedure.
being tested include new lasers, surgery to remove or move abnormal
vessels, and new drugs that may control new vessel growth.
is essential for all AMD patients.
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