Age-Related Macular Degeneration
Age-Related Macular Degeneration
Overview
Age-related macular degeneration (AMD) is a disease that affects an individual's central
vision. AMD is the most common cause of severe vision loss among people over 60. Because
only the center of vision is affected, people rarely go blind from this disease. However,
AMD can make it difficult of read, drive, or perform other daily activities that require
fine, central vision.
AMD occurs when the macula, which is located in the center of the retina and provides
us with sight in the center of our field of vision, begins to degenerate. With less
of the macula working, central vision -- which is necessary for driving, reading,
recognizing faces, and performing close-up work -- begins to deteriorate.
There are two primary types of AMD:
- dry AMD - This type of AMD is responsible for 90 percent of disease cases. While its cause
is unknown, it occurs as the light sensitive cells in the macula slowly deteriorate,
generally occurring in one eye at a time.
- wet AMD - This type of AMD is responsible for 10 percent of disease cases, but accounts for
90 percent of all severe vision loss caused by either type of AMD. Wet AMD occurs
when new blood vessels behind the retina start to grow beneath the retina where they
leak fluid and blood and can create a large blind spot in the center of the visual
field. If this happens, there is a marked disturbance of vision in a short period
of time.
Symptoms
The following are the most common symptoms of AMD. However, each individual may experience
symptoms differently. Symptoms may include:
- blurry or fuzzy vision
- difficulty recognizing familiar faces
- straight lines, such as sentences on a page, telephone poles, and the sides of buildings,
appear wavy
- a dark or empty area (blind spot) appears in the center of vision
- rapid loss of central vision - vision necessary for driving, reading, recognizing
faces, and performing close-up work
The presence of drusen, tiny yellow deposits in the retina, is one of the most common
early signs of AMD. These will be visible to your physician during an eye examination.
While the presence of drusen alone does not indicate the disease, it may mean the
eye is at risk for developing more severe AMD.
The symptoms of AMD may resemble other eye conditions. Consult a physician for diagnosis.
Diagnosis
In addition to a complete medical history and eye examination, your eye care professional
may perform the following tests to diagnose AMD:
- visual acuity test - the common eye chart test, which measures vision ability at various
distances.
- pupil dilation - the pupil is widened with eyedrops to allow a close-up examination
of the eye's retina.
- Amsler grid - used to detect wet AMD, this diagnostic test uses a checkerboard-like
grid to determine if the straight lines in the pattern appear wavy or missing to the
patient -- both indications may signal the possibility of AMD.
- fluorescein angiography - used to detect wet AMD, this diagnostic test involves a
special dye injected into a vein in the arm. Pictures are then taken as the dye passes
through the blood vessels in the retina, helping the physician evaluate if the blood
vessels are leaking and whether or not the leaking can be treated.
Risk Factors
A risk factor is anything that may increase a person's chance of developing a disease.
It may be an activity, such as smoking, diet, family history, or many other things.
Different diseases, including cancers, have different risk factors.
Although these factors can increase a person's risk, they do not necessarily cause
the disease. Some people with one or more risk factors never develop the disease,
while others develop disease and have no known risk factors.
But, knowing your risk factors to any disease can help to guide you into the appropriate
actions, including changing behaviors and being clinically monitored for the disease.
Possible risk factors for AMD include:
- gender
- according to some studies, women are at greater risk than men.
- age
- although AMD can occur during middle age, the risk for developing the disease increases
as a person ages. Studies have shown that while
- persons in their 50s have only a two percent risk of developing AMD, that rises to
nearly 30 percent in persons over 75.
- smoking may increase risk of AMD.
- family history
- persons with a family history of AMD may have a higher risk of developing AMD.
- high blood cholesterol levels
- Persons with elevated blood cholesterol levels may be at higher risk for wet AMD.
Treatment
Specific treatment for AMD will be determined by your physician based on:
- your age, overall health, and medical history
- extent of the disease
- your tolerance for specific medications, procedures, or therapies
- expectations for the course of the disease
- your opinion or preference
Treatment for wet AMD may include laser surgery, in which a high energy beam of light
is aimed directly onto the leaking blood vessels to deter further leaking.
Currently, there is no treatment for dry AMD. This does not, however, indicate that
sight will automatically be lost, particularly if the AMD affects only one eye. Central
vision may eventually be lost or diminished, but generally the rate of loss is slow.
