Q: Description of macular degeneration?
A: Macular degeneration is a broad term describing
diseases that lead to a loss of central vision. Some of these diseases affect the macula directly, while age related
macular degeneration (AMD) affects the layer under the macula known as the retinal pigment epithelium, or RPE. Note
that the conditions called macular hole and epimacular membrane (also called “macular pucker”, “wrinkling”, or
“cellophane”) are not macular degeneration.
Q: Symptoms of Macular Degeneration.
A:
It can cause loss of central vision. The amount of vision loss from macular degeneration varies quite a bit from
patient to patient, and is not predictable. It can cause legal blindness, defined as 20/200 or worse best corrected
visual acuity.
Many patients describe their vision as having a dark spot in the center where they cannot see
anything. The side, or peripheral, vision, however, is not affected.
Q: Can macular degeneration
cause blindness?
A: It cannot cause total blindness.
Q: What can this loss of
central vision mean in terms of quality of life?
A: With loss of central vision, reading,
recognizing faces, and seeing straight ahead can be difficult to impossible. These patients are still able to walk
around; recognize their surroundings; and even, with the help of low vision devices, do some limited reading in many
cases.
Q: What are the types of macular degeneration?
A: Some of them are:
- Age related macular degeneration (AMD)
- Numerous other hereditary types:
- Vitelliform (Bests)
- Fundus flavimaculatus (Stargardts)
- Central areolar choroidal atrophy
- Cone degeneration
- Toxic, caused by the following drugs:
- Plaquenil (prescribed for lupus and rheumatoid arthritis)
- Certain major tranquilizers when used over
- a long term in high dosages
Q: How common is AMD?
A: It is the most common cause of irreversible central vision loss
in people age 65 and older. In the United States, 5% of people in this age group are affected by
AMD.
Q: In what way is the retina damaged in AMD?
A: AMD first damages the layer
under the retina, known as the retinal pigment epithelium (RPE). This layer has many functions, such as oxygen
transport, transfer of nutrients to the retina, and possibly the removal of waste products from the retina. In
short, this layer nourishes the retina, and, without it, the retina will not function well.
Q: What
is the underlying cause of AMD?
A: More than 35% of cases of AMD are hereditary. Probably,
multiple genes are involved. We do know these facts:
- AMD is twice as common in blue eyes, and
- Whites have much more AMD than blacks.
Certainly, there is more to the story than aging, since “age related” macular degeneration occurs in some 40 year
old patients. No single mechanism of aging seems to be responsible. Probably, singlet oxygen (and thus antioxidants)
plays some role in some aging processes, but it is not the whole story.
Q: What are
drusen?
A: Drusen are yellow spots under the retina. (“Drusen” is German for “yellow
spots”).
Q: Do drusen cause AMD?
A: No, although they are often associated with AMD.
Many patients with drusen never get AMD.
Q: Do drusen disappear without treatment?
A:
Sometimes, and very slowly.
Q: Can drusen be treated?
A: Laser treatments can
eliminate drusen. However, several long term studies showed no benefit of treatment.
Q: Does
hardening of the arteries cause AMD?
A: No. Generally speaking, circulation problems have not
been shown to have any relation to AMD. Therefore, treatments aimed at improving blood flow have no
merit.
Q: Does nutrition play any role in the development of AMD?
A: The Beaver Dam
Eye Study examined the dietary history of people with and without AMD. The study showed that there was slightly less
AMD in patients who had diets high in green, leafy vegetables. Spinach consumption had a statistical correlation
with less AMD. Kale, turnip greens, mustard greens, and collard greens had a significant but lesser correlation with
less AMD. Note that this was not a study of treatment or progression of the disease, but only diet for many years
before developing AMD. There is also evidence that eating nuts and so-called oily fish such as salmon reduce
progression rates in AMD patients. It is probable but not proven that eating fruits and vegetables high in
anti-oxidants such as blueberries, strawberries, blackberries, broccoli, peaches, green and red peppers, and other
intensely colored fruits and vegetables.
Q: Have vitamins A, E, C, beta carotene, zinc, selenium, or
bilberry, when taken as supplements, been shown to have any beneficial effect in preventing
AMD?
A: The National Eye Institute AREDS study showed that patient taking relatively high
amounts of zinc and beta carotene have a 25% reduction in progression rate of early AMD.
Q: Have the
specific antioxidant substances (zeaxanthin, lutein) in dark leafy green vegetables, when taken as supplements,
been shown to have an effect in prevention?
A: No, but they they are likely to be effective and
this is currently under study in AREDS II.
Q: Does smoking play any role in AMD?
A:
Yes. In the Beaver Dam Eye Study and Blue Mountain Eye Study, smokers were shown to have 300-500% risk of
AMD.
Q: I have drusen. Should I stop smoking?
A: Yes, since both smoking and drusen
are risk factors for AMD.
Q: Why should I be concerned about using beta carotene supplements to
prevent AMD?
A: Beta carotene supplements have been shown to increase the risk of lung cancer
deaths in smokers by 30%, so if you smoke, you should not take beta carotene.
Q: What kinds of AMD
are typically seen?
A: There are two major type of AMD, “dry” and “wet”. “Dry” and “wet” macular
degeneration can exist at the same time in patients and can independently contribute to progressive vision loss.
Q:
What is “dry” AMD?
A: Dry AMD (the medical terms for it are atrophic AMD and geographic
atrophy). It is a “cell dropout” similar to male pattern baldness (apoptosis). It is the more common form of AMD,
constituting around 90% of the cases.
Q: What is “wet” AMD?
A: The other major type
of AMD, some of the other terms associated with it are: exudative, “leakage”, fluid, bleeding, disciform, membrane,
choroidal neovascularization (CNV), and subretinal neovascularization (SRNV). It is basically an evolving scar;
bleeding and leakage are the early stages of scar formation wet AMD is not caused by bleeding, bleeding is a result
of an evolving scar.
Q: What is neovascularization?
A: It is the formation of new
blood vessels in the development of “wet” AMD, “neo” meaning “new”, and “vascular” meaning “relating to
vessels”.
Q: Why do these new vessels form?
A: They are the early stage of an
evolving scar, and can be seen as the suppliers of raw material in the formation of a scar. The associated bleeding
and “leakage” (of clear or yellow fluid called exudate) are the result of the evolving scar, not the
cause.
Q: If one eye develops a scar, will the other one?
A: Not necessarily. Many
patients develop scars in one eye only. The odds of the other eye developing a scar are about 10% a
year.
Q: What are some of the treatment options for “wet” AMD?
A: Some of the more
common are:
- laser photocoagulation – 50% success rate, works only for lesions outside the macula.
- photodynamic therapy (PDT, Visudyne) – slows down the rate of progression but rarely results in improved vision,
now virtually replaced by the off label use of intravitreal Avastin injection. - Macugen – slows down the rate of progression but rarely results in improved vision, now virtually replaced by
the off label use of intravitreal Avastin injection. - low dose radiation – not effective.
- Transpupillary thermo therapy (TTT_ – not effective.
- Plasmapheresis (Rheotherapy) – not effective.
- thalidomide – not effective.
- interferon – not effective.
- submacular surgery – not effective.
- macular translocation – risk-benefit ratio does not justify this procedure.
- RPE (macular) transplantation – not effective.
Q: How does laser treatment (photocoagulation) work?
A: The laser is used to burn, and
thus coagulate (clot), the growing neovascularization under the retina, in an effort to stop the
growth.
Q: Which patients are recommended for laser treatments?
A: Laser treatment is
only recommended for active scars threatening the macula (extra- or juxtafoveal). This is approximately 5% of the
“wet” AMD patients that have wet AMD.
Q: Is laser treatment effective?
A: The
treatment is long term effective in less than 50% of cases. Recurrences are common, and these are often more
difficult to treat and often closer to the fovea; they pose greater risks for damaging the central
vision.
Q: Are there problems associated with laser treatments?
A: If the scar is on
the macula but outside the fovea (extrafoveal), there will most likely be a dark spot off to the side of the central
vision. Reading and facial recognition, for example, would probably be preserved in this scenario.
If the
scar is actually next to the fovea (juxtafoveal), there is a risk that the laser treatment will destroy part of the
fovea, causing a substantial loss of central vision. Reading and facial recognition would be adversely affected in
this case.
Q: What is photodynamic therapy, or PDT?
A: Intravenous dye (Visudyne) is
used, followed in 15 minutes by a low dose, broad area laser for a few minutes. The dye concentrates in new vessels,
and the laser interacts with the dye to produce singlet oxygen which selectively damages abnormal vessels. Note that
in this case the laser is at a frequency not thought to harm the retina; therefore PDT can be used to treat lesions
under the macula without the possible immediate central or side vision loss incurred in traditional laser treatment.
Q:
Is photodynamic therapy effective?
A: PDT slows down the rate or progression in about 2/3 of the
cases but there is a high recurrence rate which results in many retreatments. It is not a cure and has been largely
replaced by intravitreal injection of Avastin.
Q: What is plasmapheresis, and is it
effective?
A: Plasmapheresis involves many expensive sessions of blood exchange, supposedly
removing some unknown substance damaging microcirculation of the macula. A large randomized trial (MIRA-1) failed to
meet the primary endpoint.
Q: What about submacular surgery?
A: This procedure,
developed in 1991, also requires a surgical procedure called a vitrectomy. There is a greater than 25-50% recurrence
rate after the procedure. The SST (Submacular Surgery Trial) study showed that this procedure of not effective in
AMD or most cases of histoplasmosis.
Q: Is Alpha I interferon effective?
A: Initial
studies seemed to indicate that new vessels decreased after treatment. But subsequently, many more statistically
correct studies showed that interferon had no beneficial effect.
Q: Is thalidomide
effective?
A: Again, initial studies seemed to indicate that new vessels decreased after
treatment. But subsequently, several statistically correct studies proved that thalidomide had no beneficial effect.
Q:
Is low dose radiation effective?
A: Again, while initial studies seemed to indicate that new
vessels decreased after treatment, several subsequent statistically correct studies proved that radiation had no
beneficial effect.
Q: What about macular translocation?
A: There are two forms of
macular translocation:
The first, retinal rotation, is plagued by the following problems:
- at least 30% of patients developing retinal detachment
- many cases of permanent total blindness, macular holes, and hemorrhage
- marked double vision
- marked image rotation
- The second, eye (scleral) shortening, is plagued by the following problems:
- marked astigmatism, severe image size difference compared to other eye, marked double vision, and risk of
falling. - a smaller eye with a drooping lid.
- retinal detachment, new scars, and hemorrhage.
- The risk benefit ratio does not justify performing this procedure.
Q: Is RPE (macular) transplantation effective?
A: RPE transplantation, which is the
transfer of cells in the retinal pigment epithelium, the layer that is damaged during AMD, has the following
problems:
- There is a 100% rate of rejection of the transplanted RPE, with a risk of death from the immune suppression
drugs used. - The vision does not improve because the cells do not stick to the appropriate layer (Bruchs membrane), and
vessels under the RPE (choriocapillaris) disappear. - Often, the transplanted cells develop AMD.
- The source of cells is a major problem.
- For these reasons this research procedure has been discontinued.
Q: What about alternative treatments I’ve heard about, like acupuncture, electrical stimulation, and
magnetic therapy?
A: These treatments are not effective in any patients.
Q: What measures can
I take against AMD?
A: The following:
- Stop smoking.
- Eat leafy green vegetables, especially spinach, if you have drusen, early AMD, or parents or grandparents with
AMD. - Take ICAPS or another AREDS formula anti-oxidant formulation.
- Intravitreal injection of Avastin is highly effective in wet AMD.