Age-related Macular Degeneration (ARMD)
Macular degeneration is a disease caused by damage to or the breakdown of the macula, a tiny oval area in the retina, where the photoreceptors are most dense and where incoming images are focused.
The center of the macula is called the fovea and is responsible for fine detail vision - our central (or reading) vision, both for distance and close up. When the eye is directed at an object to be seen, whichever part is focused on the fovea will be the clearest, the most in-focus image seen. So, your ability to see fine centralized detail is directly dependent upon the condition of the macula and fovea.
In macular degeneration, something goes wrong with the macula (as explained in more detail below) and it slowly stops working. When this happens, vision fades in the middle (the fovea), usually leaving the peripheral, or side vision. It is uncommon for someone with macular degeneration to lose both macular (detail) and peripheral (side) vision, or to lose vision completely in both eyes.
If you have been diagnosed with macular degeneration you are in very good company. In the United States alone, a new case is diagnosed every three minutes, affecting:
- One in six Americans between the ages of 55 and 64
- One in four between the ages of 64 and 74
- One in three over the age of 75
Although it almost never causes total blindness, macular degeneration is the leading cause of vision loss in people over 50 in our country. Therefore, it is important that you work with your doctor to learn to identify the problem early in an attempt to keep the development of macular degeneration from getting worse or to slow it down.
Types of Macular Degeneration
There are two forms of age-related macular degeneration:
Dry Macular Degeneration (Atrophic ARMD)
Wet Macular Degeneration (Choroidal Neovascularization - CNV)
Dry Macular Degeneration
The vast majority of cases of ARMD are the dry type, which always precedes the wet type -- although it doesn't always turn into that. Dry refers to the slow degenerative process that occurs in which the macula forms yellow deposits, called drusen and then becomes progressively thinner but does not leak, and so is considered 'dry'.
Progression of dry macular degeneration takes a very long time and does not always affect both eyes equally. Most people usually maintain some central vision in at least one eye.
Wet Macular Degeneration (CNV)
Wet ARMD always arises from pre-existing dry ARMD. This occurs in about 10 to 15% of people with advanced dry macular degeneration. Newly formed, abnormal blood vessels grow underneath the retina in the area of the macula. These vessels leak fluid, bleed, and lift up the retina. When this happens central vision is reduced and is often distorted. Eventually, scar-like tissue forms under the macula and the eye loses its ability to see detail. If CNV occurs in one eye, there is an increased chance it will occur in the other eye.
Symptoms of Macular Degeneration
There is no pain associated with dry or wet macular degeneration. Vision loss usually occurs gradually and typically affects both eyes at different rates. Sometimes only one eye loses vision while the other eye continues to see well for years. If both eyes are affected, reading and close up work can become quite difficult. Even with a loss of central vision, however, peripheral vision may remain clear.
The condition may be hardly noticeable in its early stages. A very frequent and important symptom to be aware of is distortion. Straight lines will not look straight. A telephone pole or a doorframe may seem a little bent, crooked, or irregular, as though seen through heat waves on a highway. An area of the Amsler grid will appear distorted and the small boxes in the area will vary in shape and size. Also, you may see a dark gray spot similar to the aftereffect caused by a flashbulb. There may be other changes in vision: you may notice that the size of an object appears different for each eye or that colors don't look the same for each eye. These changes in eyesight are important symptoms and anyone who has these symptoms should make sure to see the eye doctor promptly. Do not assume you simple need a new pair of glasses. Make your appointment right away.
Causes of Macular Degeneration
The root causes of macular degeneration are unknown. Women are at a slightly higher risk than men. Caucasians are more likely to develop macular degeneration than African-Americans.
The macular contains many highly active and sensitive photoreceptors that require and consume a great deal of energy. Generating this energy requires a constant, rich supply of oxygen, nutrients and ions. Consequently, the macula has one of the highest volumes of blood flow through its supply vessels. Anything that interferes with this necessary rich blood supply can cause the macula to malfunction and possibly become diseased.
Smoking is one of those factors that can reduce this vital blood supply by contributing to overall narrowing of the blood vessels and thickening of the blood. A high-fat, high cholesterol diet can lead to fatty plaque deposition in the macular vessels, also hampering blood flow. Nutritional deficiencies, such as shortage of antioxidants, may increase the tendency for fatty deposits to stick to blood vessel walls.
Diagnosis of Macular Degeneration
In order to determine if you have macular degeneration and what form, your doctor will measure your vision and examine your eyes. By looking at the retina, your doctor will be able to tell if there is an abnormality. If drusen are found, you will want to schedule regular check-ups to make sure that no further damage is occurring. It may be necessary that photographs of each macula be taken to use for future comparison. The following are tests given to fully diagnose ARMD:
- Visual acuity test: to measure at a distance and close up
- Dilated pupil examination: to see the inside of the eye with an opthalmoscope to check for drusen.
- Amsler grid: a pattern fo straight horizontal and vertical lines (click here for a printable Amsler grid and instructions to use). To the person with ARMD, the lines appear wavy, distored or missing or a black spot may appear in the center of the grid.
- Optical COherence Tomography (OCT): uses light waves to create a contour map of the retina and can show areas of thickening or fluid accumulation.
- Fluorescein angiography: If your doctor finds an abnormality and suspects CNV, this special test will be done to detect blood vessels that might be leaking. During the test, a dye is injencted into the arm and quickly travels through the blood system to the eye. Photographs are taken of the eye, which will later be used during laser treatment.
Treatment of Macular Degeneration
In the early stages of dry macular degeneration, regular eye check-ups, attention to diet, in-home monitoring of vision and possibly nutritional supplements may be all that is recommended.
Currently, treatments for macular degeneration are rapidly advancing and changing as often as every three months. Various treatments are currently available, but most of these treatments are directed at the early stages of wet ARMD.
- Vitamins The National Eye Institute's Age-Related Eye Disease Study (AREDS) found that taking a specific high-dose formulation of antioxidants and zinc significantly reduces the risk of advanced AMD and its associated vision loss. Slowing AMD's progression from the intermediate stage to the advanced stage will save the vision of many people.
The specific daily amounts of antioxidants and zinc used by the study researchers were 500 milligrams of vitamin C, 400 International Units of vitamin E, 80 milligrams of zinc as zinc oxide, two milligrams of copper as cupric oxide, 10 mg lutein and 2 mg zeaxanthin. Copper was added to the AREDS formulation containing zinc to prevent copper deficiency anemia, a condition associated with high levels of zinc intake.
People who are at high risk for developing advanced AMD should consider taking the formulation. You are at high risk for developing advanced AMD if you have either:
Intermediate AMD in one or both eyes.
Advanced AMD (dry or wet) in one eye but not the other eye.
Your opthalmologist can tell you if you have AMD, it's stage, and your risk for developing the advanced form.
The AREDS formulation is not a cure for AMD. It will not restore vision already lost from the disease. However, it may delay the onset of advanced AMD. It may help people who are at high risk for developing advanced AMD keep their vision.
- Low vision training may be the only truly effective option for the vast majority of patients. Whether it is vision loss for conditions such as ARMD, glaucoma or diabetes, low vision aids help patients perform normal activities of daily living and lead independent lives.
Low vision aids range from hand-held magnifying glasses to sophisticated systems that use video cameras to enlarge a printed page. Lifestyle aids such as large print books, tape-recorded books or magazines, large print playing cards, talking clocks and scales and may other devices are also available.
Treatments for Wet AMD: Laser Photocoagulation
Until recently the only available treatment to seal leaking blood vessels associated with wet AMD was with a laser. The earliest treatment was Laser Photocoagulation. Between 1979 and 1994, the Macular Photocoagulation Study Group conducted a number of clinical trials that enrolled patients with CNV lesions (Choroidal Neovascularization) in one or both eyes. Each affected eye was randomly assigned to either laser treatment or observation. For eligible eyes with CNV in extrafoveal, juxtafoveal and subfoveal locations, laser treatment reduced the risk of severe visual loss.
Laser photocoagulation was followed by Photodynamic Therapy (PDT) with Visudyne™ (a drug injected intravenously and used to help direct the laser to the affected area). Visudyne™ therapy is a two-step procedure that can be performed in a doctor’s office. First, Visudyne™ is injected intravenously into the patient’s arm. The drug is then activated by shining non-thermal laser light into the patient’s eye. Visudyne™ therapy involves the use of a specifically-designed laser that produces the low-level, non-thermal light required to activate the drug which 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. In one large clinical trial, photodynamic therapy with Visudyne™ photosensitizer delayed or prevented loss of vision during at least one year follow-up in patients with predominantly classic CNV lesions. Unfortunately, even the most successful treatments do not preclude reoccurrence, making multiple treatments likely. However, the rate of vision loss may be slowed down and some sight may be preserved. It is important to understand that this drug is not a cure. At best it preserves the status quo: It will not restore vision that has already been lost.
In sum, there are three major limitations of laser photocoagulation treatments. First, not more than 10-15% of CNV lesions are small enough and sufficiently delineated by fluorescent angiography to be eligible for laser treatment. Second, even if laser treatment is initially successful, there is at least 50% chance that leakage will recur during the next two years. Many such recurrences are amenable to additional treatment if detected early, which means that patients need careful monitoring after the first treatment. Finally, at least half of patients post-treatment with sufficiently well-circumscribed CNV lesions still have some leakage beneath the center of the fovea. Laser treatment leads to immediate reduction in central vision in these patients with leakages, but with sufficient follow-up, the extent of visual loss is less in laser treated eyes than in untreated eyes. Nevertheless, these existing laser therapies are limited in their effectiveness and may also lead to scarring of the macula and additional vision loss.
Because of the limitations of laser treatment, researchers and physicians are in search of macular degeneration treatment breakthroughs, in order to maintain vision for a longer period of time without repeated laser use. They are also looking for new therapies which would be effective for all types of wet AMD.
Treatments for Wet AMD: Anti-VEGF Therapy
VEGF is an acronym for vascular endothelial growth factor. Currently, the most common and effective clinical treatment for wet Age-related Macular Degeneration is anti-VEGF therapy – which is periodic intravitreal (into the eye) injection of a chemical called an “anti-VEGF.” In the normal life of the human body, VEGF is a healthy molecule which supports the growth of new blood vessels. In the case of macular health, though, VEGF is unhealthy. It promotes the growth of new, weak blood vessels in the choroid layer behind the retina, and those vessels leak blood, lipids, and serum into the retinal layers. The leakage (hemorrhaging) causes scarring in the retina and kills macular cells, including photoreceptor rods and cones.
An intraocular shot of an anti-VEGF drug inhibits the formation of new blood vessels behind the retina and may keep the retina free of leakage. An injection in the eye can be a disconcerting experience, and it may take several treatments to become accustomed to the procedure. However, the shot is usually not painful because the eye has been anesthetized. The procedure takes about fifteen minutes. Usually the appointment requires an hour. The effect lasts for a month or maybe more.
Researchers report high rates of success with anti-VEGF injections, including receding blood vessels behind the retina, a far slower progression of the disease, and, in some cases, moderate gains made in vision. In some parts of the world, anti-VEGF treatments have reduced the incidence of legal blindness by 50 percent. However, they have noted that injections of even small amounts of anti-VEGF drugs could — though research is inconclusive — have an effect on vascular function in the rest of the body. Strokes and hemorrhaging are two concerns, but because cardiovascular disease is already often associated with Age-related Macular Degeneration, any data available to date about strokes or hemorrhaging has been difficult to interpret.
Types of Anti-VEGF Drugs
Several anti-VEGF drugs are being developed to inhibit VEGF by trapping it or preventing it from binding with elements which will stimulate growth. Chemically synthesized short strands of RNA (nucleic acid) called “aptamers” prevent the binding of VEGF to its receptor. The various forms of anti-VEGF injections include ranibizumab (Lucentis, made by Genentech/Novartis), bevacizumab (off label Avastin from Genentech), and the recently Food and Drug Administration-approved aflibercept (Eylea/VEGF Trap-Eye from Regeneron/Bayer). Each of these chemicals works in a different way to inhibit blood vessel growth.
Side Effects of Intravitreal Injections
Side effects of intravitreal injections may includes:
- Serious eye infection that may include eye pain, light sensitivity, vision changes
- Increased eye pressure
- Retinal detachment
- Vitreous floaters
Consult with your retinal specialist to make certain you understand what all the side effects might include.
Research on Macular Degeneration
For those patients with wet ARMD, there is significant hope in the very near future. Ongoing clinical research is investigating new treatment strategies using photodynamic therapy. These studies are underway and the preliminary results are very encouraging.
New low vision device for macular degeneration
For those patients who have already experienced vision loss and are somewhat stable, there is a new low vision device that is undergoing clinical investigation. This device is known as an intraocular miniature telescope (IMT) and is inserted into the eye at the time of cataract surgery. While this device may not help all patients with ARMD, there is a very good chance that the IMT could improve the ability to read and watch television.
Genetic research on macular degeneration
All treatments, so far, are designed to treat the vision loss associated with wet ARMD and slow the progression of the disease. None of the therapies really treat the underlying cause of ARMD. While the cause is still unknown, there is solid evidence that this is a disease with a strong genetic basis. For this reason, a great deal of research is going on to find the genes responsible for ARMD in the hope of someday developing a cure.
Home Test for Macular Degeneration
We have provided a printable Amsler grid for you. Patients can help monitor their vision regularly and can detect distortions in vision. These distortions represent the earliest stages of wet macular degeneration.
Regardless of the treatment therapy followed, patients with advanced dry macular degeneration should check the vision in each eye, one at a time, at least once a day by staring at the central point on an Amsler grid.
The eye specialists of Hudson Valley Eye Associates perform advanced technology diagnostic testing and treatment, as well as taking the time necessary to provide each patient with information needed to fully understand their condition and to achieve their best possible visual outcome.
If you would like further information, please call our office at:
Hudson Valley Eye Associates
24 Saw Mill River Road
Hawthorne, NY 10532
If you or a family member or friend have not had a recent routine eye examination, have a specific eye condition that needs addressing, or are looking for an eye specialist or professional eye consultant please take a moment to Request an Appointment.