Age-Related Macular Degeneration

Introduction
Age-Related Macular Degeneration is the leading cause of loss of vision in the population over the age of 50 in the United States. It is a condition of the eye and specifically of the retina which affects both men and women. The cause of macular degeneration is unknown but a family history of this disease as well as cigarette smoking and elevated levels of cholesterol in your blood may increase the chances of developing this condition. Central vision may be lost in macular degeneration but peripheral and side vision is spared and this condition rarely causes blindness. Loss of central vision, however, may make it difficult to perform everyday activities such as reading, driving or watching television.


I. What is the Macula?
The retina is the thin, light sensitive tissue which lines the inside of the back of your eye and the macula is the very center of the retina. By receiving images of light much like camera film does, the retina enables you to see. When you use your eyes, light passes through the eye and is focused on the macula. With a healthy macula everything that you focus on will be sharp and clear. If the macula is damaged by macular degeneration, your central vision may become blurred and distorted. Vision to the side, on the other hand, depends upon the peripheral retina which is rarely affected by macular degeneration.


II. How will I know if I have Macular Degeneration?
The first symptom of macular degeneration may be difficulty reading due to blurred vision. With progression of the disease, your central vision may also become distorted or crooked. In more severe macular degeneration, you may have a central blind spot and loss of color vision making it difficult for you to recognize faces, drive a car or watch television. Since macular degeneration may affect one eye before the other, it is important to check the vision of each eye separately by covering the other eye.


III. How is Macular Degeneration diagnosed?
A complete eye examination with dilation of your pupils is the best way to determine if you have macular degeneration or any other condition which may affect your sight. Your visual acuity will be measured on an eye chart for distance and near vision. Decreased visual acuity which is not correctable by a new pair of glasses may be a symptom of macular degeneration.

The Amsler Grid, another sensitive test for macular degeneration, is used to check for distortion. When performing this test, you should cover one eye at a time and stare at the black dot in the center of the grid. With a healthy macula the checkerboard pattern should be perfectly square. In macular degeneration, the lines may be bent or distorted. By dilating your pupils with special eyedrops, your eye doctor will be able to evaluate the entire retina and determine if you have macular degeneration.

If leakage or bleeding is suspected, then a test called Fluorescein Angiography will be performed. This involves administration of a dye into one of the veins in your arm followed by several photographs of your retina. Any leakage will be detected on these photographs as the dye circulates through the retinal and choroidal blood vessels. People who have macular degeneration should be monitored regularly so that any leakage, bleeding, or new blood vessel growth can be treated promptly.


IV. Are there different types of Age-Related Macular Degeneration?
Of those people who have this condition, ninety percent will have dry macular degeneration. This form is characterized by the formation of yellow deposits called drusen beneath the macula and some thinning of the pigment layer. People with this type of macular degeneration typically complain of difficulty reading, needing more light to read, or blurred central vision. This symptoms may worsen with the progression of the disease.

Pigment Epithelial Detachment is an intermediate form of Age-Related Macular Degeneration and is characterized by the formation of a small blister of fluid beneath the pigment epithelial layer of the macula. People with a pigment epithelial detachment may also complain of distorted or crooked vision. Photographs of the retina are necessary in order to determine if there are any associated abnormal leaking vessels which might require treatment.

Only ten percent of people who have Age-Related Macular Degeneration will develop wet macular degeneration, the most severe form of this disease. This is characterized by the formation of abnormal blood vessels which may leak fluid, blood, and lipid beneath the macula. Sudden onset of blurred and distorted vision in one eye is the most common symptom. Since this condition worsens rapidly, wet macular degeneration must be evaluated and treated as soon as possible in order to prevent further loss of vision.


V. How is Macular Degeneration treated?
Dry Macular Degeneration is best managed by a dilated eye examination each year and by regular self testing at home with an Amsler Grid, which your eye doctor can give to you at the time of your examination. If you should detect any change in the appearance of the Amsler Grid, you should make an appointment to have your retinas checked as soon as possible. Currently, there is no medical or surgical treatment for dry macular degeneration. The benefit of nutritional treatment of macular degeneration by dietary supplementation with antioxidant vitamins and zinc remains unproven and this form of therapy is currently being investigated. Most patients with dry macular degeneration maintain fairly good vision in at least one eye throughout their life.

Age-Related Macular Degeneration Dry (fundus photo) Click to Enlarge

A pigment detachment must be reevaluated frequently with dilated examinations and fluorescein angiography in order to make certain that this condition has not become complicated by wet macular degeneration. If not, then pigment detachments may simply be observed for spontaneous healing or evolution into macular pigment loss. People with a pigment detachment have distorted vision and are at risk for experiencing further loss of central vision.

Wet Macular Degeneration must be evaluated immediately with a dilated retinal examination and fluorescein angiography in order to identify the presence and location of any abnormal blood vessels beneath the retina. Abnormal blood vessels located away from the center of the macula may be treated with laser photocoagulation. Even when the vessels are growing directly beneath the center of the macula, laser photocoagulation may be valuable in preventing further loss of vision. In laser photocoagulation, your eye doctor will cauterize the abnormal blood vessels with a beam of laser light aimed through a slit lamp microscope and contact lens.

Age-Related Macular Degeneration Wet (fluorescein angiogram) Click to Enlarge

Age-Related Macular Degeneration Wet (fundus photo - same patient) Click to Enlarge

Photodynamic Therapy offers hope for patients with classic abnormal blood vessels growing beneath the center of the retina. This new form of treatment involves the administration of a special dye which sensitizes only the abnormal blood vessels to a specific wavelength of light. Treatment of these blood vessels with a laser delivering this wavelength of light will seal the abnormal blood vessels with less damage to the overlying macula.

Other forms of treatment which are available include surgical removal of the abnormal blood vessels and retina translocation where the retina is surgically rotated away from the abnormal new vessels so that laser treatment can be performed. Frequent reexamination and fluorescein angiography are required after any of these treatments in order to determine if abnormal vessels have recurred and require additional treatment.

Macugen is an FDA-approved medication that blocks the message for blood vessels to grow and leak. The primary cause of rapid severe vision loss in ARMD is growth of new bad blood vessels under the retina, which tend to leak, break, bleed, and grow with an enlarging dark spot in the center of vision. By injecting the drug into the eye, the drug stops the bad blood vessels from leaking, and slows their growth.

Macugen treatment is not a cure for ARMD. It lasts in the eye for a short time, but its effects last for about 6 weeks. It treats only the eye that is injected. Current studies suggest that this treatment will need to be repeated every 6 weeks for 2 years. It is sometimes combined with photodynamic therapy, either at the start of treatment, or if blood vessels come back, despite Macugen therapy. Although it may improve vision in eyes that have recently lost vision, the main goal is to reduce the rate of vision loss, or stop further loss of vision. It is unlikely to improve vision in eyes that have been blind for a long time.

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VI. What is going to happen to my vision?
Ninety percent of people who have Age-Related Macular Degeneration have the dry type and maintain fairly good vision. The ten percent of patient who have wet type macular degeneration experience ninety percent of all severe visual loss from this disease. If you develop wet macular degeneration in one eye, there is a fifty percent chance of recurrence in that eye despite laser treatment. The chance of developing wet macular degeneration in the opposite eye if it is already present in one eye is ten percent per year.

While changing your glasses will not cure this condition, by having the best pair of glasses you will maximize your ability to see. If you have already lost central vision in both eyes from this condition, low vision aids such as magnifying lenses or closed circuit video enlargement systems may allow you to compensate for the visual loss. Using your eyes for daily living activities such as reading or watching television will not cause macular degeneration to worsen. Regular dilated eye examinations and Amsler Grid self testing are the best ways to monitor this condition so that prompt treatment can be instituted in order to prevent any further loss of vision.

Retinal Disorders

Diabetic Retinopathy
Age-Related Macular Degeneration
Retinal Vein and Artery Occlusions
Macular Hole
Macular Pucker
Retinal Tears and Detachments
What is Fluorescein Angiography?
What is Photodynamic Therapy?
What is ICG Angiography?
What is optical coherence tomography?

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