Macular Degeneration
What
is macular degeneration?
Macular degeneration is the physical disturbance of the center
of the retina called the macula. The macula, which is about
the size of the capital letter "O" in this sentence,
is the part of the retina which is capable of our most acute
and detailed vision. We use the macula for reading, driving,
recognizing faces, watching television, and fine work. Macular
degeneration is the leading cause of legal blindness in people
over age 55. (Legal blindness means that a person can see 6/60
or less with glasses.) Even with a loss of central vision, however,
color vision and peripheral vision may remain clear. Vision
loss usually occurs gradually and typically affects both eyes
at different rates.
What
causes macular degeneration?
The root causes of macular degeneration are still unknown. There
are two forms of age-related macular degeneration, "wet"
and "dry". Seventy percent of patients have the "dry"
form, which involves thinning of the macular tissues and disturbances
in its pigmentation. Thirty percent have the "wet"
form, which can involve bleeding within and beneath the retina,
opaque deposits, and eventually scar tissue. The "wet"
form accounts for ninety percent of all cases of legal blindness
in macular degeneration patients.
Different forms of macular degeneration may occur in younger
patients. These non-age related cases may be linked to heredity,
diabetes, nutritional deficits, head injury, infection, or other
factors.
How
is macular degeneration detected?
Declining vision noticed by the patient or by an ophthalmologist
during a routine eye exam may be the first indicator of macular
degeneration. The formation of deposits of waste material in
the macula, known as "drusen," is often the first physical sign
that macular degeneration may develop. Later, patches of noticeably
thin retina or abnormal blood vessels with bleeding and leakage
beneath the macula may occur. In addition, the following signs
may be indicative of macular problems. Anyone experiencing these
symptoms should consult an ophthalmologist immediately:
a. Straight lines appear distorted and, in some cases, the center
of vision appears more distorted than the rest of the scene.
b. A dark, blurry area or "white-out" appears in the
center of vision.
c. Color perception changes or diminishes.
Is early detection important?
Early detection is important because a patient destined to develop
macular degeneration can sometimes be treated before symptoms
appear, and this may delay or reduce the severity of the disease.
Furthermore, as we develop better treatments for macular degeneration,
whether they are medicinal, surgical, or low vision aids, those
patients diagnosed with macular degeneration can sooner benefit
from them.
If
I have macular degeneration in one eye, will it develop in the
other?
Yes, this is usually the case. In the early stages, only one
eye may be affected, but as the disease progresses, both eyes
are usually affected.
Is
there a cure for Macular Degeneration?
At this time there is no known cure for macular degeneration.
However, there are ways to arrest macular degeneration, depending
on the type and the degree of the condition. These range from
nutritional intervention to lessen the risk of progression to
treatment with special drugs such as Avastin
or Lucentis or with photodynamic
therapy to close the leaking vessels. There are also low
vision aids and techniques for maximizing the use of peripheral
vision to help patients adapt better to their loss of central
vision.
Can nutrition help treat macular degeneration?
Some scientists have suggested an association between macular
degeneration and high saturated fat, low carotenoid pigments,
and other substances in the diet. There is evidence that eating
fresh fruits and dark green, leafy vegetables (such as spinach
and collard greens) may delay or reduce the severity of age-related
macular degeneration. The Age Related Eye Disease Study found
a beneficial effect from high dose supplementation with vitamins
C, E and Beta carotene, along with zinc. They found a reduction
in risk of visual loss of 28% in those with at least moderate
age-related macular degeneration.
Is
macular degeneration hereditary?
Macular degeneration appears to be hereditary in some families
but not in others. Since macular degeneration affects most patients
later in life, it is difficult to study successive generations
in a family. Recent studies of twins indicate that both genetic
and non-genetic factors play important roles in age-related
macular degeneration. Research to determine the genes associated
with hereditary macular degeneration will help lead to early
detection, early intervention, and possible cures.
Does
sunlight affect macular degeneration?
Yes. It has been demonstrated that the blue rays of the spectrum
seem to accelerate macular degeneration more than other rays
of the spectrum. This means that very bright light, such as
sunlight or its reflection in the ocean and desert, may worsen
macular degeneration. Sunglasses that block out the blue end
of the spectrum may decrease the progress of the disease. Again,
more research is needed in this area.
Does
hypertension (or medication for hypertension) affect macular
degeneration?
Yes. Hypertension tends to make some forms of macular degeneration
worse, especially in the "wet" form where the retinal
tissues are invaded by new blood vessels. The medications used
to treat hypertension have not been shown to have any direct
effect on macular degeneration, but they may slow progression
of the disease by reducing hypertension.
Does
smoking or second hand smoke contribute to macular degeneration?
Yes. Any type of smoking or exposure to tobacco smoke can accelerate
the development of the "wet" type of macular degeneration.
