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by Ron Gallemore, MD, PhD
Discoveries in recent months provide new hope for patients
with age-related macular degeneration (AMD). As the leading
cause of blindness in this country, affecting over 20
million Americans, researcher's have worked hard to discover
not only the causes of this condition but new treatments
as well. So what is this disease and what can be done
to prevent, diagnose and treat it? |
What is AMD?
Age-related macular degeneration begins as a dry form
of which there are several kinds. Drusen are the "dry
deposits" that form beneath the retina - the light
sensitive organ of the eye. While some small drusen may
be normal, large drusen interfere with the supply of nutrients
and oxygen to the retina and may cause mild to moderate
vision loss. Dry atrophy is another form where damaged
circulation leads to thinning of the retina and potentially
severe vision loss. With dry AMD the retina may send signals
to grow new blood vessels to provide more oxygen and nutrients.
The new blood vessels represent wet AMD and are the primary
cause of severe vision loss in our patients.
Prevention
It has long been known that smoking, ultraviolet light
exposure and diet may all play a role in the development
of macular degeneration. We recommend you stop smoking,
wear sunglasses and eat a diet rich in green leafy vegetables
(e.g., spinach, kale, and collard green), grains and fruit.
This diet provides antioxidants including carotenoids
such as lutein which may help prevent the oxidative damage
that leads to AMD. The question of nutritional supplements
has now been addressed in a formal study - AREDS (Age-Related
Eye Disease Study) which examined the effects of vitamin
C, E, beta-carotene, and zinc on the clinical course,
risk factors, and prognosis for AMD. The study demonstrated
a significant improvement in vision for patients with
dry AMD. Genetics (heredity) also plays a major role in
the development of AMD. If you have a family history,
you are at much greater risk and may benefit even more
from nutritional and lifestyle changes.
Diagnosis
The key to diagnosis is a careful eye exam looking for
the early signs of macular degeneration such a drusen
and atrophy (see above). Self monitoring of vision is
the most important way to pick up wet macular degeneration.
A grid of lines on a card (Amsler grid, Figure 1) should
be monitored daily - one eye at a time. At the earliest
sign of change (broken, distorted or wavy lines), notify
you eye doctor immediately. Special tests are available
for finding the abnormal blood vessels in wet AMD including
fluorescein angiography, indocyanine green (ICG) angiography,
and optical coherence tomography (OCT).
Treatment: Dry AMD
Perhaps the greatest treatment discovery in recent months
is the potential benefit of nutritional supplements for
patients with dry AMD (see above). A more aggressive treatment,
Aphoresis, filters the blood for high molecular weight
molecules and may benefit select patients with dry AMD
- specifically those with high blood levels of cholesterol,
triglycerides, fibrin and fibrinogen. Laser for drusen
in dry AMD is another controversial treatment which may
carry increased risk for developing wet AMD and should
await refinement before general use is considered.
Treatment: Wet AMD
The abnormal blood vessels in wet AMD have traditionally
been treated with a "hot" laser to destroy the
vessels and stop leakage. This approach also destroys
the retina and the blood vessels often grow back requiring
re-treatment. If the vessels are beneath the center of
vision, vision is also lost. A new treatment, photodynamic
therapy, allows closure of the blood vessels without destroying
the retina. Treatment preserves vision in 65-90% of patients
depending on the type of blood vessels that are growing.
Not all patients are candidates for this treatment. Treatment
improves vision in only 15-20% of eyes, so early diagnosis
is key. Other treatments under study include a drug by
Eyetech which is injected into the eye to stop blood vessel
growth, transpupillary thermotherapy which may stabilize
vision is patients with "poorly defined" blood
vesssels, and steroid injections inside or around the
eye that also slow the leakage and growth of abnormal
blood vessels. Surgeries to remove the abnormal vessels
or to move the retina away for the blood vessels are also
under evaluation.
Treatment: Low Vision
For patients whom have already lost vision, there are
aids that can help you use the vision that you have more
effectively. Simple changes like extra light, large print
and magnifiers may make all the difference. Sophisticated
optical machines and computers and enhance size and contrast.
Surgical implantation if special lenses are under evaluation.
Lifestyle changes can also help you remain more self-sufficient.
In summary, there are a host of new treatments that may
stabilize or improve vision in patients with macular degeneration.
See your eye doctor on a regular basis for eye exams,
monitor you own vision at home and make the appropriate
lifestyle changes to preserve your vision.
Ron Gallemore, MD, PhD, is a member of the Retina-Vitreous
Associates Medical Group and practices at the Pacific
Eye Institute in Victorville. He is an internationally
recognized clinician, surgeon and educator. His research
has focused on the retinal pigment epithelium, a key
player in macular degeneration, and he has published
on a variety of other retinal diseases.
Pacific Eye Institute
12550 B Amargosa Rd.
Victorville, CA 92392
Monday thru Friday 8am to 5pm
Website: www.LARetina.com |
