Macular Degeneration is a very common eye disease. In fact, Macular Degeneration affects more people than either cataracts or glaucoma. Macular Degeneration is the most frequent cause of blindness for patients aged 55 and above in the Western World and is estimated to affect over 100 million people worldwide (www.macular.org/disease.html).
The center of the retina is called the macula. It is the most sensitive portion of the retina and is responsible for central or “straight ahead” vision as well as the ability to see the detail of faces, reading material, colours and precise vision required for driving a car.
The likelihood that you will develop Macular Disease is directly related to your age. Age Related Macular Degeneration (ARMD) is the most common type of macular degeneration. The older we are, the greater chance that we will develop Macular Degeneration. Age Related Macular Degeneration (ARMD) is a degenerative condition of the macula that is caused by hardening of the arteries of the retina that carries oxygen and nutrients to the retina. This results in an inability of the macula to function properly. The severity of macular degeneration can vary widely from a slight distortion of your central vision to a total loss of your central vision. However, macular degeneration does NOT cause total blindness, as its effects are limited to central vision without affecting peripheral vision at all.
Types of Age Related Macular Degeneration
Age Related Macular Degeneration is typically classified as either “wet” or “dry” Macular Degeneration.
Wet Macular Degeneration accounts for approximately 10-15% of cases. It is characterized by the growth of new blood vessels-“neovascularisation”-underneath the retina. These new blood vessels are quite fragile and are predisposed to leak and bleed. If swelling, haemorrhaging or scarring occur in the macula it can lead to sudden, rapid and severe central vision loss.
Dry Macular Degeneration is by far the more common type of Age Related Macular Degeneration. Dry Macular Degeneration is characterized by the formation of small, yellow coloured deposits within the retinal layers, which are called Drusen. Dry Macular Degeneration results in a slow, gradual progressive decrease in central vision rather than the sudden rapid loss of vision as with Wet Macular Degeneration. Almost everyone over the age of 50 has some Drusen as result of the normal aging process. Drusen are only a threat if they are large. Nonetheless, some percentage of people do progress from “dry’ macular degeneration to “wet’ macular degeneration over some period of time.
Diagnosis of Macular Degeneration
Having an eye examination is the first step to allowing our Opthalmologists to make the diagnosis of macular degeneration. If you are over the age of 40-45 and have a family history of any type of macular degeneration you should have your eyes examined each year. During your examination your pupils will be dilated so that our Opthalmologists can carefully examine the macula and retina using one or more types of ophthalmoscopes and possibly high magnification lenses with the slit lamp biomicroscope. They may evaluate your colour vision to check for proper functioning of the macula and may perform an Amsler Grid Test to check for any distortion of your central vision.
The use of the Amsler Grid will allow the detection of very tiny changes in your vision that can occur when there is just a small amount of fluid under your retina. It may be advised that you actually take an Amsler Grid home and use it each morning as part of your daily routine. This is something that our experts will discuss with you, if necessary, as part of your eye examination. They will also provide an Amsler Grid and very specific instructions for how to do the text at home, if necessary.
Depending on the health of your macula and retina, our experts may wish to have retinal photographs or a fluorescein angiogram performed. A fluorescein angiogram is an outpatient test in which a coloured dye is injected into a vein in your arm. Then a special camera will be used to take pictures of the retina while the dye passes through it. These pictures will be able to show the leakage of fluid or the growth of new blood vessels under the retina. They will also show what changes have occurred in the retina and where these changes have occurred. These photographs also help us decide whether you might benefit from laser treatment. In some cases, if we diagnose the “wet” type of Macular Degeneration early enough, we may be able to prevent severe retinal damage from occurring.
Causes of Macular Degeneration
At the present time there is no real definitive cause of Macular Degeneration. However, there are a number of factors that seem to predispose patients to developing Macular Degeneration. Factors such as age, family history and genetics seem to be key factors. In addition nutrition, overall health including hypertension with arteriosclerosis and atherosclerosis, smoking and excessive exposure to sunlight also seem to play a role in increasing the risk of developing macular degeneration.
Treatment of Macular Degeneration
There are number of possible treatment options that may slow down or even help prevent vision loss from Macular Degeneration. In general, once damage has occurred from macular degeneration, no treatment will be effective in reversing the vision loss. Instead, treatment is aimed at prevention of further loss.
Macular Laser Photocoagulation
During the 1980s and mid 1990s the Macular Photocoagulation Study Group conducted several well controlled clinical trials in order to determine what particular macular conditions should be treated with lasers, what types of lasers should be used, which patients might get the best results and generally try and establish the best ways to use lasers to treat macular degeneration. A number of helpful guidelines could be established:
1.Laser treatment is only applicable to the earliest stages of “wet” Macular Degeneration.
2.Laser treatment of Macular Degeneration can only be used if the growth of new blood vessels (neovascularization) was either outside the most central part of the macular-called the fovea, adjacent to the fovea, or well below the fovea.
3.Very few neovascular areas were sufficiently outlined to be able to be treated
4.Even in cases where a successful laser treatment was performed, leakage returned in 50% of the cases within 2 years.
Thus, laser therapy for Macular Degeneration is limited in its effectiveness and may also lead to scarring of the macula and additional vision loss.
Visudyne Photodynamic Laser Therapy
In the spring of 2000, the FDA approved a new treatment option for “wet” macular degeneration, which uses a light-activated drug called VisudyneTM. This treatment for “wet” macular degeneration works through a non-thermal process that results in a selective destruction of the unwanted leaking vessels. The procedure seals off leaking vessels while leaving healthy ones intact and is believed to be a major improvement over previous laser treatments. Unfortunately, even the most successful treatments do not always prevent reoccurrence, making multiple treatments likely. However, the rate of vision loss may be slowed down and some sight may be preserved.
VEGF Injections for Macular Degeneration
A great deal of research has been done on treating “wet” macular degeneration based on work done into cancer research and the causes of angiogenesis – the growth of new blood vessels. It was discovered that there is a protein in the eye which encourages the development of blood vessels called “vascular endothelial growth factor” (VEGF). Drugs have now been developed to inhibit VEGF so that there is little or no stimulus to grow new blood vessels in the retina.
The most publicized anti-VEGF drug is the Macugen Injection, which was approved, by the Food and Drug Administration in 2004 for treating all types of “wet” macular degeneration. Another type of anti-VEGF drug is Lucentis which was approved by the Food and Drug Administration in the summer of 2006. Lucentis Injections can be given to patients who have evidence of new blood vessel formation monthly with the clinical studies showing that over 90% of patients will maintain their vision (www.fda.gov).
Macugen is an intravitreal injection, an injection that is placed directly into the vitreous of the eye. Generally it needs to be repeated every six weeks. The Macugen Injection is by prescription and injected only by an Ophthalmologist . Results will vary with each individual and our Ophthalmologists will help determine the length of treatment course for each individual patient. Should this be a treatment option that is indicated for you, we will thoroughly review the possible risks, benefits and side effects with you before you decide to proceed.
Nutrition and Age Related Macular Degeneration
A number of recent clinical studies have demonstrated a considerable link between nutrition and the development of macular degeneration. In particular, people who have a high dietary intake of fruits and vegetables (especially leafy green vegetables) have a lower incidence of macular degeneration. More studies are needed to determine if nutritional supplements can prevent progression in patients with existing disease. One of the most significant studies, called The Age Related Eye Disease Study (AREDS), which was sponsored by the National Eye Institute (www.nei.nih.gov/amd/summary.asp), indicated that taking high levels of antioxidants and Zinc could reduce the risk of developing Age Related Macular Degeneration by about 25%. While not really providing a cure for ARMD, this study needs to be viewed as a possible way to help patients who are at risk for ARMD prevent vision loss. In this study a specific formulation of nutrients was used. BEFORE starting on any course of vitamin or antioxidant supplements, you should fully discuss the risks and benefits with our experts.