|What is age-related macular degeneration?
degeneration (AMD) is a disease associated with aging that gradually
destroys sharp, central vision. Central vision is needed for seeing
objects clearly and for common daily tasks such as reading and driving.
AMD affects the macula, the part of the eye that allows you to see fine detail. AMD causes no pain.
In some cases, AMD advances so slowly that people notice little
change in their vision. In others, the disease progresses faster and
may lead to a loss of vision in both eyes. AMD is a leading cause of
vision loss in people of 60 years age and older.
AMD occurs in two forms: wet and dry.
What is wet AMD?
Wet AMD occurs when
abnormal blood vessels behind the retina start to grow under the
macula. These new blood vessels tend to be very fragile and often leak
blood and fluid. The blood and fluid raise the macula from its normal
place at the back of the eye. Damage to the macula occurs rapidly.
With wet AMD, loss of central vision can occur quickly. Wet AMD is
also known as advanced AMD. It does not have stages like dry AMD.
An early symptom of wet AMD is that straight lines appear wavy. If
you notice this condition or other changes to your vision, contact your
eye care professional at once. You need a comprehensive dilated eye
What is dry AMD?
Dry AMD occurs when the
light-sensitive cells in the macula slowly break down, gradually
blurring central vision in the affected eye. As dry AMD gets worse, you
may see a blurred spot in the center of your vision. Over time, as less
of the macula functions, central vision is gradually lost in the
The most common symptom of dry AMD is slightly blurred vision. You
may have difficulty recognizing faces. You may need more light for
reading and other tasks. Dry AMD generally affects both eyes, but
vision can be lost in one eye while the other eye seems unaffected.
|Which is more common-the dry form or the wet form?
The dry form is much more
common. More than 85 percent of all people with intermediate and
advanced AMD combined have the dry form.
However, if only advanced AMD is considered, about two-thirds of
patients have the wet form. Because almost all vision loss comes from
advanced AMD, the wet form leads to significantly more vision loss than
the dry form.
Can the dry form turn into the wet form?
Yes. All people who have the wet form had the dry form first.
The dry form can advance and cause vision loss without turning into
the wet form. The dry form also can suddenly turn into the wet form,
even during early stage AMD. There is no way to tell if or when the dry
form will turn into the wet form.
The dry form has early and intermediate stages. Does the wet form have similar stages?
No. The wet form is considered advanced AMD.
Can advanced AMD be either the dry form or the wet form?
Yes. Both the wet form
and the advanced dry form are considered advanced AMD. Vision loss
occurs with either form. In most cases, only advanced AMD can cause
People who have advanced AMD in one eye are at especially high risk of developing advanced AMD in the other eye.
Causes and Risk Factors
Who is at risk for AMD?
The greatest risk factor
is age. Although AMD may occur during middle age, studies show that
people over age 60 are clearly at greater risk than other age groups.
For instance, a large study found that people in middle-age have about
a 2 percent risk of getting AMD, but this risk increased to nearly 30
percent in those over age 75.
Other risk factors include:
Smoking. Smoking may increase the risk of AMD.
Obesity. Research studies suggest a link between obesity and the progression of early and
intermediate stage AMD to advanced AMD.
Race. Whites are much more likely to lose vision from AMD than African Americans.
Family history. Those with immediate family members who have AMD are at a higher risk of developing the disease.
Gender. Women appear to be at greater risk than men.
Can my lifestyle make a difference?
Your lifestyle can play a role in reducing your risk of developing AMD.
Eat a healthy diet high in green leafy vegetables and fish.
Maintain normal blood pressure.
Watch your weight.
|Symptoms and Detection
What are the symptoms?
Both dry and wet AMD cause no pain.
For dry AMD: the most common early sign is blurred vision. As fewer
cells in the macula are able to function, people will see details less
clearly in front of them, such as faces or words in a book. Often this
blurred vision will go away in brighter light. If the loss of these
light-sensing cells becomes great, people may see a small--but
growing--blind spot in the middle of their field of vision.
For wet AMD: the classic early symptom is that straight lines
appear crooked. This results when fluid from the leaking blood vessels
gathers and lifts the macula, distorting vision. A small blind spot may
also appear in wet AMD, resulting in loss of one's central vision.
How is AMD detected?
Your eye care
professional may suspect AMD if you are over age 60 and have had recent
changes in your central vision. To look for signs of the disease, he or
she will use eye drops to dilate, or enlarge, your pupils. Dilating the
pupils allows your eye care professional to view the back of the eye
AMD is detected during a comprehensive eye exam that includes:
1. Visual acuity test. This eye chart test measures how well you see at various distances.
2. Dilated eye exam. Drops are placed in your eyes to widen,
or dilate, the pupils. Your eye care professional uses a special
magnifying lens to examine your retina and optic nerve for signs of AMD
and other eye problems. After the exam, your close-up vision may remain
blurred for several hours.
3. Tonometry. An instrument measures the pressure inside the eye. Numbing drops may be applied to your eye for this test.
Your eye care professional also may do other tests to learn more about the structure and health of your eye.
During an eye exam, you may be asked to look at an Amsler grid. The
pattern of the grid resembles a checkerboard. You will cover one eye
and stare at a black dot in the center of the grid. While staring at
the dot, you may notice that the straight lines in the pattern appear
wavy. You may notice that some of the lines are missing. These may be
signs of AMD.
If your eye care professional believes you need treatment for wet
AMD, he or she may suggest a fluorescein angiogram. In this test, a
special dye is injected into your arm. Pictures are taken as the dye
passes through the blood vessels in your retina. The test allows your
eye care professional to identify any leaking blood vessels and
How is wet AMD treated?
Wet AMD can be treated
with laser surgery, photodynamic therapy, and injections into the eye.
None of these treatments is a cure for wet AMD. The disease and loss of
vision may progress despite treatment.
1. Laser surgery.
This procedure uses a laser to destroy the fragile, leaky blood
vessels. A high energy beam of light is aimed directly onto the new
blood vessels and destroys them, preventing further loss of vision.
However, laser treatment may also destroy some surrounding healthy
tissue and some vision. Only a small percentage of people with wet AMD
can be treated with laser surgery. Laser surgery is more effective if
the leaky blood vessels have developed away from the fovea, the central
part of the macula. Laser surgery is performed in a doctor's office or
The risk of new blood vessels developing after laser treatment is
high. Repeated treatments may be necessary. In some cases, vision loss
may progress despite repeated treatments.
2. Photodynamic therapy.
A drug called verteporfin is injected into your arm. It travels
throughout the body, including the new blood vessels in your eye. The
drug tends to "stick" to the surface of new blood vessels. Next, a
light is shined into your eye for about 90 seconds. The light activates
the drug. The activated drug destroys the new blood vessels and leads
to a slower rate of vision decline. Unlike laser surgery, this drug
does not destroy surrounding healthy tissue. Because the drug is
activated by light, you must avoid exposing your skin or eyes to direct
sunlight or bright indoor light for five days after treatment.
Photodynamic therapy is relatively painless. It takes about 20 minutes and can be performed in a doctor's office.
Photodynamic therapy slows the rate of vision loss. It does not
stop vision loss or restore vision in eyes already damaged by advanced
AMD. Treatment results often are temporary. You may need to be treated
Wet AMD can now be treated with new drugs that are injected into the
eye (anti-VEGF therapy). Abnormally high levels of a specific growth
factor occur in eyes with wet AMD and promote the growth of abnormal
new blood vessels. This drug treatment blocks the effects of the growth
The anti-VEGF agents available today are Avastin,Lucentis and Macugen.
will need multiple injections that may be given as often as monthly.
The eye is numbed before each injection. After the injection, you will
remain in the doctor's office for a while and your eye will be
monitored. This drug treatment can help slow down vision loss from AMD
and in some cases improve sight.
How is dry AMD treated?
Once dry AMD reaches the
advanced stage, no form of treatment can prevent vision loss. However,
treatment can delay and possibly prevent intermediate AMD from
progressing to the advanced stage, in which vision loss occurs.
The National Eye Institute's Age-Related Eye Disease Study
(AREDS) found that taking a specific high-dose formulation of
antioxidants and zinc significantly reduces the risk of advanced AMD
and its associated vision loss. Slowing AMD's progression from the
intermediate stage to the advanced stage will save the vision of many
|How can I take care of my vision now that I have AMD?
If you have dry AMD, you should have a comprehensive dilated eye exam
at least once a year. Your eye care professional can monitor your
condition and check for other eye diseases. Also, if you have
intermediate AMD in one or both eyes, or advanced AMD in one eye only,
your doctor may suggest that you take the AREDS formulation containing
the high levels of antioxidants and zinc.
Because dry AMD can turn into wet AMD at any time, you should get
an Amsler grid from your eye care professional. Use the grid every day
to evaluate your vision for signs of wet AMD. This quick test works
best for people who still have good central vision. Check each eye
separately. Cover one eye and look at the grid. Then cover your other
eye and look at the grid. If you detect any changes in the appearance
of this grid or in your everyday vision while reading the newspaper or
watching television, get a comprehensive dilated eye exam.
Wet AMD. If
you have wet AMD and your doctor advises treatment, do not wait. After
laser surgery or photodynamic therapy or antiVEGF injection you will
need frequent eye exams to detect any recurrence of leaking blood
vessels. Studies show that people who smoke have a greater risk of
recurrence than those who don't. In addition, check your vision at home
with the Amsler grid. If you detect any changes, schedule an eye exam
What can I do if I have already lost some vision from AMD?
If you have lost some
sight from AMD, don't be afraid to use your eyes for reading, watching
TV, and other routine activities. Normal use of your eyes will not
cause further damage to your vision.
If you have lost some sight from AMD, ask your eye care
professional about low vision services and devices that may help you
make the most of your remaining vision. Ask for a referral to a
specialist in low vision. Many community organizations and agencies
offer information about low vision counseling, training, and other
special services for people with visual impairments. A nearby school of
medicine or optometry may provide low vision services.
For more details fix an appointment with me or email me at: email@example.com
Dr Mihir Shah