Also known as AMD (Age-Related Macular Degeneration). For more information, you may also visit our site www.preventamdblindness.com, intended to educate and assist both those affected by AMD as well as their families.
What is Macular Degeneration?
Age-related macular degeneration (AMD) is the deterioration of the central retina, the macula. The macula is a small, specialized region of retina, and is responsible for central vision. Intact central vision is vital for reading, driving, and recognizing faces. Macular degeneration is a disease process that damages the central vision. It’s one of the leading causes of decreased vision in the United States in patients older than 50 years, and the number one cause of blindness in Americans older than 65 years. Many older people develop mild forms of macular degeneration as part of the natural aging process.
There are different kinds of macular problems, but macular degeneration is the most common macular disorder. Macular degeneration may be manifested by symptoms such as blurriness, dark areas or distortion in their central vision, and at end-stage, a permanent loss of central vision. Macular degeneration usually does not affect one’s peripheral vision. For example, with advanced macular degeneration, people can generally see the outline of a television, yet may not be able to see the text of the TV screen.
As mentioned, macular degeneration rarely occurs in people younger than 50 years and most commonly occurs in people older than 60 years. Macular degeneration is categorized into two major subsets,”wet” and”dry.”
“Dry” signs of AMD include the accumulation of drusen (small yellow-white lumps) on the undersurface of the retina, loss of cells in the macula, and deterioration of the pigmented cells under the retina. Dry degeneration comprises 80% to 95% of macular degeneration. Mild forms of dry AMD cause little or no visual effects, but severe dry AMD may lead to blindness. There currently is no known treatment to slow or stop the changes that occur with dry AMD. Many studies (A.R.E.D.S.1 and others) have shown a benefit for the intake of dietary micronutrients. The AREDS 2 analysis is currently evaluating additional micronutrients, and the full results will not be known for some time. Consumption of spinach or other green leafy vegetables, naturally colored foods rich in lutein and zeaxanthine (carrots, squash, bell peppers), and omega 3 fatty acids may help delay AMD as well.
Mild dry macular degeneration
Wet form of AMD
The”wet” form of AMD is also known as neovascular or exudative. Between 5% and 20% of all people with AMD have this form, and they may experience a more rapid loss of vision. In the wet form of AMD, new blood vessels develop beneath the retina in a layer of tissue called the choroid and grow into the macula. This process is called choroidal neovascularization, and the vascular network is called a choroidal neovascular membrane. Generally the new blood vessels develop at the outer edge of the macula and extend inward toward the center of the macula. These abnormal vessels leak serum and blood. These fluids accumulate under the retina and separate the retina from the underlying layer, creating a localized retinal detachment. The retinal cells in the affected area do not function normally. This phenomenon causes central vision to become distorted, straight lines become wavy or crooked, and eventually a blind spot usually develops in the central vision. Wet AMD often causes scarring of the central retina with an associated loss of central vision. As with dry macular degeneration, peripheral vision is rarely affected.
Severe wet macular degeneration showing blood accumulated below the retina
Symptoms of AMD include distorted vision, a dark spot seen centrally, and blurred vision. Later, there is a loss of central vision. Central vision loss affects one’s ability to read, drive, and recognize facial features. Preservation of peripheral vision permits patients to see large objects and to retain ambulatory vision.
(National Eye Institute photo)
The visual effects of end-stage macular degeneration with central vision obscured
Your ophthalmologist uses an ophthalmoscope to view the retina. Disorders in the region can be further evaluated with additional testing. An OCT (Ocular Coherence Tomography) is a non-contact test that evaluates different layers in the back of the eye. Fluorescein angiogram is a test that utilizes a fluorescent dye to assess for leaking blood vessels. These tests allow the ophthalmologist to identify the abnormal tissue in the back of the eye.
As mentioned, there is no known treatment for the”dry” form of AMD, although multivitamins and certain dietary elements (AREDS or A.R.E.D.S. 1 and 2) may help reduce the risk of progression. A low-vision evaluation at Atlanta’s Center for the Visually Impaired may offer visual benefits in the form of magnifying lenses, specialized lights, telescopic or prism glasses, and closed-circuit TV. Patients with the dry type of AMD may develop abnormal blood vessels and progress to the”wet” type of AMD.
Wet type of AMD has enjoyed several treatment breakthroughs in the last few years. Anti-VEGF (vascular endothelial growth factors) compounds are used to stop the growth of abnormal blood vessels. These medicines are administered on a regular basis and have provided hope for a previously hopeless disease. See below for more information.
Laser therapy is used to destroy abnormal blood vessels in some cases. This treatment is called laser photocoagulation, and when a laser-sensitive compound is used, it is called Photodynamic Therapy (PDT). When the diagnosis of macular degeneration is suspected, a fluorescein angiogram is first done to locate abnormal blood vessels. If the abnormal blood vessels are in a”safe zone,” intense light energy from a laser is focused onto the abnormal blood vessels. Treatment of these abnormal blood vessels helps preserve vision by preventing further bleeding or leakage of fluid. Unfortunately, not all patients with wet type of AMD are candidates for laser therapy. Sometimes, a separate type of angiogram (indocyanine green or ICG angiogram) can be used to determine if treatment is possible.
Once a patient has received treatment for AMD, he or she must continue to have regular examinations of the retina so that any additional growth of new vessels can be detected and treated. If the patient notices any new symptoms, he should be examined promptly.
As with dry AMD, a low-vision evaluation at Atlanta’s Center for the Visually Impaired may offer visual benefits in the form of magnifying lenses, specialized lights, telescopic or prism glasses, and closed circuit TV.
This class of medications was originally created as cancer drugs to inhibit tumor growth. Anti-VEGF medications are now used to treat wet macular degeneration, and they work by inhibiting growth of abnormal blood vessels in the back of the eye.
These medications are intended to prevent further vision loss, and in some cases vision may improve with the use of anti- VEGF compounds
Anti-VEGF compounds are administered as intravitreal injections, i.e., the medication is placed directly into the vitreous of the eye. A careful sterile technique is used to administer the medication. Medication treatments are given at regular intervals for a period of time, and your eye physician will evaluate you every visit and modify the schedule accordingly.
Side effects of intravitreal injections may include:
Early detection of macular changes is vital for proper treatment of macular degeneration. If you are at risk for developing macular degeneration, it is wise to check the vision in each eye daily. A self-administered test using an Amsler grid is a simple and quick way to check for sight changes. Call your ophthalmologist immediately if you notice changes on the grid.
Instructions for the Amsler Grid Home Test
If you have a family history of macular degeneration or are a cigarette smoker, you may choose to make some lifestyle changes that could help lower your risk for macular degeneration. Listed below are a few tips for macular degeneration prevention.
The information contained on this page is intended for educational purposes. Any patient with potential retina or eye disease or macular degeneration should consult an Atlanta ophthalmologist before making a judgment on their condition.