An excerpt from the book Taking
Care of Your Eyes.
macular degeneration (AMD) is the leading cause of poor vision
in people over 60. (It is sometimes found at younger ages,
but that is rare.) When the macula is damaged (or degenerates,
as from AMD), central vision is interfered with, so that when
you look at an object straight on, part of it may seem distorted,
blotted out, or shrouded in a dark haze.
macula is a key part of the retina, the light-sensitive nerve
tissue at the back of the eye that forms the "screen" upon
which images are focused. Though the macular area is tiny,
no larger than a pinhead, it contains all the cells needed
for central vision - seeing straight ahead, seeing fine detail,
and crisp color vision - in other words, the sharpest, most
useful part of vision. AMD usually involves both eyes, though
it may start in one eye and not affect the other eye until
people with even advanced AMD do not lose all of their vision.
No matter how poor central vision gets, your peripheral vision
- the outer edge of your visual field, which does not depend
on the macula - should stay useful. You should continue to
be able to see off to the sides.
are two major forms of AMD, called "dry" and "wet." Most patients
have the dry form, which tends to develop slowly as the tissue
(pigment epithelium and visual cells) beneath the macula gradually
deteriorates. With wet AMD, tissue deterioration is accompanied
by tiny abnormal blood vessels called "subretinal neovascular
membranes." These form under the retina and start to leak
fluid or bleed. If the fluid or blood reaches the macula and
lifts it out of position, vision becomes distorted and visual
sharpness can be lost.
typical first symptom (in either form) is blurring of vision.
When the blurring is gradual, you may think you need new eyeglasses.
But a new prescription is not likely to improve your vision
because the problem is not with the optical parts of the eye.
As time goes on, you may notice a hazy or dark zone in the
center of objects you look at directly. Colors may begin to
look different or lose richness. With wet AMD especially,
straight lines, such as the edges of doorways, may start to
look bent or crooked as vision becomes distorted and wavy.
may may be gradual or sudden (suddenness is more likely with
wet AMD). When the loss of vision is in one eye only, you
can't always tell how long it has existed, since it is "hidden"
when both eyes are used together. It may only become apparent
when the good eye is covered.
vision will be checked and you will have a refraction (test
for glasses) along with a complete eye exam. Your pupils will
be dilated (enlarged) with eyedrops so that the insides of
your eyes can be evaluated with an ophthalmoscope. A special
type of contact lens may be used for examining both retinas
and maculas under the high magnification of a slit lamp microscope.
may be taken of the retina, to determine the extent of the
problem and evaluate its progression. You may also have a
retinal "angiogram," retinal photographs that help identify
the position and extent of any abnormal blood vessels or leakages.
For this test, called fluorescein angiography (FA), an orange-colored
dye (fluorescein) is injected into a vein in your arm and
then a series of photographs is taken as the dye travels through
the eye's blood vessels. If more information is needed, a
dye called indocyanine green (ICG) may be used to make another
type of angiogram. Angiograms provide important guidance for
far, there are no medications that have proven to be effective.
But wet AMD -- in the early stages only -- can sometimes benefit
from treatment with a surgical laser, to seal the leaks or
destroy the abnormal blood vessels under the macula. (The
laser cannot help the dry type of AMD, or even most stages
of the wet type.) The goal of laser treatment is to prevent
further leadage and stabilize vision. Only occasionally does
vision improve. Please don't expect miracles; the laser treatment
may not help at all and vision may even get worse.
usually develops gradually or in small spurts over many months,
then slows down or stops. Both eyes will probably be affected,
though one eye may precede the other by a long time, even
years. Wet changes occur unpredictably; they may even develop
in AMD that started as the dry type, or they may recur in
previously treated wet AMD.
is possible, even with no laser treatment, for the degenerative
process to stop before very much vision has been lost. But
it is more likely that central vision will continue decreasing,
probably to the point that reading is hampered and driving
a car is no longer safe.
You Can Do
addition to having regular eye exams, there is an easy and
important test you can do yourself. Take a few seconds every
day to check your vision with an Amsler grid, a card printed
with a pattern of crossing lines that form small squares.
each eye separately, with the other eye covered. The lines
should look straight and solid. If any lines suddenly start
looking wavy or having missing segments, that could indicate
the beginning of wet changes that might be treatable, and
you should make an appointment to have your eyes checked right
keep in mind that using your eyes will never harm them. You
can continue any of your usual activities as long as you feel
comfortable doing them. Even with reduced vision, your life
can be surprisingly normal and fulfilling.