As we age, the macula (the small part of the retina at the back of the eye that provides
sharpness of vision) begins to break down and produces small yellowish particles
called drusen, which are seen in a fundus photograph and in a cross-sectional diagram
above. These can be an early sign of macular degeneration, but they do not usually
cause vision loss by themselves and not all patients who develop drusen go on to
develop macular degeneration.
The dry or atrophic form of age-related macular degeneration, seen above in fundus
photography and in a cross-sectional diagram, is the most common form of macular
degeneration, accounting for about 90 percent of cases. Although this form of ARMD
does not usually cause severe vision loss, it can progress to the wet form, so patients
who have it should see their ophthalmologist regularly or assess their vision with
the Amsler grid.
The wet or exudative form of ARMD, seen here in fundus photography and in a cross-sectional
diagram, affects about 10 percent of ARMD patients. It is caused by the growth of
abnormal blood vessels at the back of the eye that can leak fluid and blood. The
wet form of ARMD typically causes significant vision problems in the affected eye
and can progress very rapidly and cause permanent vision loss.
WHAT IS MACULAR DEGENERATION?
The eye is often compared to a camera. The front of the eye contains a lens that
focuses images on the inside of the back of the eye. This area, called the retina,
is covered with special nerve cells that react to light.
These nerve cells are very close together in the middle of the retina where the eye
focuses the images that we see. This part of the retina is called the macula.
As people age, the macula tends to change in ways that cause a gradual loss of sharp
vision. Sometimes, the macula actually begins to break down and produce small particles
called drusen. In some eyes, the changes to the macula will eventually result in
the growth of new blood vessels where they do not belong.
Both of these conditions are called age-related macular degeneration. If there are
no new blood vessels being created, it is "dry" macular degeneration. When new blood
vessels start to grow, it is called "wet" macular degeneration.
WHY DO PEOPLE GET MACULAR DEGENERATION?
No cause of macular degeneration has been proven. Things like smoking, exposure to
direct sunlight over a period of years, a lack of vitamin A and some medical conditions
seem to make people more likely to get macular degeneration. Some people also seem
to inherit a tendency to have macular degeneration. None of these things can really
be said to cause macular degeneration, however, and there is no sure way to prevent
HOW DOES THE DOCTOR DIAGNOSE MACULAR DEGENERATION?
The ophthalmologist may notice some things during the examination, or the patient
may mention symptoms, that could be caused by macular degeneration. These are:
* The ability to see fine details when one is looking directly at an object,
no matter how close or far away it is, starts to decline.
* Vision changes so that straight lines look wavy or broken.
* Dark spots, lines, or shadows appear across the middle of the field of view.
When these symptoms are caused by macular degeneration, they can occur in just one
eye or in both eyes. Usually, the problem is noticed first in one eye.
If you notice any of these symptoms it is important to make an appointment with your
optometrist as soon as possible. He will use a special instrument to look inside
the eye for signs that the macula is changing and if there is a problem they will
refer you on to an ophthalmologist.
HOW IS MACULAR DEGENERATION TREATED?
Initially your ophthalmologist may recommend observation, the dry form of ARMD does
not require active treatment. You will usually be given an Amsler grid to examine
your vision every week or so. If there is a sudden change in your vision with distortion
then it is important to see an ophthalmologist for a flourescene angiogram. This
will help them to see if you have the “wet” type that is amenable to treatment. Even
though vision might not change for months at a time, macular degeneration will never
get better on its own. And when macular degeneration goes from the "dry" form to
the "wet" form, there can be a permanent loss of vision.
HOW DO I DETECT IF THINGS ARE GETTING WORSE?
People with macular degeneration can check their own vision with a simple test called
the Amsler grid.
The Amsler grid is a pattern of straight lines that make perfect squares. The patient
looks at a large dot in the middle of the grid and notices any areas where the lines
look blurry, wavy or broken. If the grid lines seem to be more distorted than before,
it might be a sign that the macular degeneration is getting worse and needs treatment.
All of the treatments for macular degeneration are considered surgery. Some treatments
just use a laser that is shined through the clear front part of the eye and focused
on the macula. In other treatments, the surgeon makes openings in the eye for special
What happens in the operations to treat macular degeneration?
The procedures for macular degeneration are usually done under a local anaesthetic.
That is, the patient is awake but does not feel the procedure.
Surgeons have several techniques to treat "wet" macular degeneration, including:
* Laser photocoagulation. This procedure is used to stop the abnormal growth
of blood vessels that happens in "wet" macular degeneration. The surgeon focuses
a laser beam onto a small spot on the macula where blood vessels are growing. The
laser beam heats up that spot, creating a tiny burn in the blood vessels and stopping
their growth. Unfortunately, vision does not come back in the areas treated with
the laser. It is also very likely that new blood vessels will grow at some time in
* Photodynamic therapy. In this treatment, a special dye is injected into the
bloodstream. This dye is actually a type of medication that only becomes active when
very strong light, such as a laser, is shined on it. The surgeon activates the medication
by focusing a laser onto the abnormal blood vessels that are growing in the macula.
The medication works from inside the blood vessels to shrink them. This treatment
causes much less damage to the macula, so there is less loss of vision. But the growth
of abnormal blood vessels still might happen again in the future.
* Macular surgery. There are two other treatments the surgeon might recommend
for severe cases of "wet" macular degeneration. In both of these procedures, the
surgeon makes openings into the eye for special instruments. One technique is to
remove the tissue where the abnormal blood vessels are growing. Another method is
to lift the macula off the area where the blood vessels are growing and place it
in a more healthy part of the retina. These procedures often do not fully restore
normal vision, however.
* Intravitreal injections. Avastin, Lucentis and Macugen can all be used in an
attempt to get these new vessels to regress. In some cases not only does it prevent
things from getting worse it can sometime lead to an improvement in the patients
DOES EVERYONE WITH MACULAR DEGENERATION GO BLIND?
No. Even though vision might be blurry or lost in the middle of the field of view,
macular degeneration does not affect vision off to the side. And with the treatments
available today, people with macular degeneration have a good chance of keeping useful
vision for many years. The best way to keep and use as much vision as possible is
to have regular eye examinations and follow your doctor's advice.