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:
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:
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:
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:
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:
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: