AGE-RELATED MACULAR DEGENERATION (AMD)
WHAT IS AGE-RELATED MACULAR DEGENERATION?
Age-related macular degeneration (AMD) is a disease associated with aging that can gradually destroy sharp, central vision. Central vision is needed for seeing objects clearly and for common daily tasks such as reading and driving. Macular degeneration never causes one to go “black blind.” Almost everyone with AMD, including those with severe cases, can maintain a significant degree of autonomy and independence.
AMD affects the macula, which is in the very center of the retina and allows the seeing of fine details. No type of macular degeneration causes pain.
In some cases, AMD advances so slowly that people notice little change in their vision. In others, the disease progresses faster and may lead to a loss of central vision in both eyes. AMD is a leading cause of legal vision loss in Americans 60 years of age and older. It is probably found, to some degree, in everyone over 65 years old.
Macular degeneration occurs in two forms: wet and dry.
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WHERE IS THE MACULA?
The macula is located in the center of the retina, the light-sensitive tissue at the back of the eye. The retina instantly converts light, or an image, into electrical impulses. The retina then sends these impulses, or nerve signals, to the brain.
WHAT IS DRY AMD?
Dry AMD occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye. As dry AMD gets worse, you may see a blurred spot in the center of your vision. Over time, as less of the macula functions, central vision can be gradually lost in the affected eye.
The most common symptom of dry AMD is slightly blurred vision. You may have difficulty recognizing faces. You may need more light for reading and other tasks. Dry AMD generally affects both eyes, but vision can be lost in one eye while the other eye seems unaffected.
If you have vision loss from AMD in one eye only, you may not notice any changes in your overall vision. With the other eye seeing clearly, you can still drive, read, and see fine details. You may notice changes in your vision only if AMD affects both eyes. If blurriness occurs in your vision, the staff at SoCal Eye will be more than happy to offer a complete examination and explanation of the cause. There are no specific treatments for dry AMD; fortunately, significant vision loss from dry AMD is rare.
WHAT IS WET AMD?
After dry AMD has developed, the retina may become brittle and allow underlying blood vessels to creep into the overlying retina. These blood vessels can damage the retina by bleeding, leaking, or direct injury. Wet ADM can be treated by medication or laser, if it is detected early.
Which form of AMD is more common, the dry form or the wet form?
The dry form is much more common. More than 85 percent of all people with intermediate and advanced AMD have the dry form.
Can the dry form turn into the wet form?
Yes. All people who have the wet form had the dry form first. The dry form can advance and cause changes to the central vision without turning into the wet form. The dry form also can suddenly turn into the wet form, even during early stage AMD. There is no way to tell if or when the dry form will turn into the wet form.
CAUSES AND RISK FACTORS
Who is at risk for AMD?
The greatest risk factor is age. Although AMD may occur during middle age, studies show that people over age 60 are clearly at greater risk than other age groups. Many feel that everyone develops some AMD eventually, although it may never become visually significant.
Other risk factors include:
- Smoking – Smoking may increase the risk of AMD.
- Obesity – Research studies suggest a link between obesity and the progression of early- and intermediate-stage AMD to advanced AMD.
- Race – Caucasians are much more likely to lose vision from AMD than African Americans.
- Family history – Those with immediate family members who have AMD are at a higher risk of developing the disease.
- Gender – Women appear to be at greater risk than men.
Can my lifestyle make a difference?
Your lifestyle can play a role in reducing your risk of developing AMD. At SoCal Eye, we recommend that you:
- Eat a healthy diet high in green leafy vegetables and fish.
- Don’t smoke.
- Maintain normal blood pressure and cholesterol levels.
- Watch your weight.
- Consider vitamin supplements.
- Perform daily Amsler grid testing, as noted below.
SYMPTOMS AND DETECTION
What are the symptoms?
Both dry and wet AMD cause no pain.
– For dry AMD, the most common early sign is blurred vision. As fewer cells in the macula are able to function, people will see fine details less clearly, such as faces or words in a book. Often this blurred vision will go away in brighter light. If the loss of these light-sensing cells becomes great, people may see a small—but growing—blind spot in the middle of their field of vision.
– For wet AMD, the classic early symptom is that straight lines appear crooked. This results when fluid from the leaking blood vessels gathers and lifts the macula, distorting vision. A small blind spot may also appear in wet AMD, resulting in loss of one’s central vision.
How is AMD detected?
Our doctors can detect AMD by performing a comprehensive eye exam. During an eye exam, you may be asked to look at an Amsler grid. The pattern of the grid resembles a checkerboard. You will cover one eye and stare at a black dot in the center of the grid. While staring at the dot, you may notice that the straight lines in the pattern appear wavy. You may notice that some of the lines are missing. These may be signs of AMD.
In addition to performing a physical eye exam, we also use sophisticated instruments to image the retina and allow the doctors to actually see the layers of the retina as if they were looking through a microscope. The images are similar to those obtained by an MRI, but the testing is done in the office and only takes about 60 seconds.
Distortion on this grid may indicate a problem with your macula. However, seeing a normal grid does not preclude AMD. Daily usage of an Amsler grid is often the earliest and easiest way for patients to monitor and detect wet AMD. Early detection of AMD is key to getting the best results from treatment.
Using the Amsler Grid to test your vision: Put on reading glasses, cover one eye, position yourself about 18 inches from the grid and stare at the dot in the center. You should be able to see the dot, the lines should be straight, and the squares should be square. If they are not, and the changes are new, please make an appointment with us or your eye care professional to be seen as soon as possible; do not wait more than a couple of days.
How is wet AMD treated?
At SoCal Eye, we have doctors who are fellowship trained in the treatment of diseases of the retina, including macular degeneration. We have all the latest technologies and techniques at our disposal to allow optimal results. Wet AMD can be treated with laser surgery, photodynamic therapy, and injections into the eye. None of these treatments is a cure for wet AMD. The disease and loss of vision may progress despite treatment.
- Laser surgery – This procedure uses a laser to destroy the fragile, leaky blood vessels. A high energy beam of light is aimed directly onto the new blood vessels and destroys them, preventing further loss of vision. However, laser treatment may also destroy some surrounding healthy tissue and some vision. Only a small percentage of people with wet AMD can be treated with laser surgery. Laser surgery is more effective if the leaky blood vessels have developed away from the fovea, the central part of the macula. (See illustration at the beginning of this document.) Laser surgery is performed in the office.
- Photodynamic therapy – A drug called verteporfin is injected into your arm. It travels throughout the body, including the new blood vessels in your eye. The drug tends to “stick” to the surface of new blood vessels. Next, a light is shined into your eye for 90 seconds. The light activates the drug. The activated drug destroys the new blood vessels and leads to a slower rate of vision decline. Unlike laser surgery, this drug does not destroy surrounding healthy tissue. Because the drug is activated by light, you must avoid exposing your skin or eyes to direct sunlight or bright indoor light for five days after treatment. Photodynamic therapy is relatively painless. It takes 20 minutes and can be performed in our office. Photodynamic therapy slows the rate of vision loss. It does not stop vision loss or restore vision in eyes already damaged by advanced AMD. Treatment results often are temporary. You may need to be treated again.
- Injections – Wet AMD can now be treated with new drugs that are injected into the eye (anti-VEGF therapy). Abnormally high levels of a specific growth factor occurs in eyes with wet AMD and promotes the growth of abnormal new blood vessels. These drugs block the effects of the growth factor. Multiple injections are often needed, usually once a month. The eye is numbed before each injection, and most patients report only mild pressure or discomfort. This drug treatment can help slow down vision loss from AMD and, in some cases, improve sight.
What can be done if AMD becomes advanced?
Once dry AMD reaches the advanced stage, no form of treatment can return what has been lost. However, treatment can delay and possibly prevent intermediate AMD from progressing to the advanced stage, in which vision loss occurs.
The National Eye Institute 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.
AGE-RELATED EYE DISEASE STUDY (AREDS)
What is the dosage of the AREDS formulation?
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, 15 milligrams of beta-carotene (often labeled as equivalent to 25,000 International Units of vitamin A), 80 milligrams of zinc as zinc oxide, and two milligrams of copper as cupric oxide. Copper was added to the AREDS formulation containing zinc to prevent copper deficiency anemia, a condition associated with high levels of zinc intake. There are several companies that produce vitamins that have the AREDS recommended formula. They will be labeled as such and have clear instructions on the bottle. Please inform your primary care physician if you start taking vitamins, and show them the bottle. (Note: Smokers should not take beta-carotene, as it increases the risk of developing certain types of cancer. If you are smoking, or have smoked in the past several years, there are specific eye vitamins that omit beta-carotene.)
Who should take the AREDS formulation?
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, or Advanced AMD (dry or wet) in one eye only.
The doctors of SoCal Eye can determine if you have AMD, its 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. Also, it may help people who are at high risk for developing advanced AMD keep their vision.
Can people with early stage AMD take the AREDS formulation to help prevent the disease from progressing to the intermediate stage?
There is no apparent need for those diagnosed with early stage AMD to take the AREDS formulation. The study did not find that the formulation provided a benefit to those with early stage AMD. If you have early stage AMD, a comprehensive dilated eye exam every year can help determine if the disease is progressing. If early stage AMD progresses to the intermediate stage, discuss taking the formulation with your doctor. That being said, there is no evidence that taking AREDS formula vitamins will cause harm.
How can I take care of my vision now that I have AMD?
– If you have dry AMD, you should have a comprehensive dilated eye exam at least once a year. The doctors at SoCal Eye can monitor your condition and check for other eye diseases. Also, if you have intermediate AMD in one or both eyes—or advanced AMD in one eye only—we may suggest you take the AREDS formulation containing the high levels of antioxidants and zinc.
Because dry AMD can turn into wet AMD at any time, we will provide you with an Amsler grid. Use the grid every day to evaluate your vision for signs of wet AMD. This quick test works best for people who still have good central vision. Check each eye separately. Cover one eye and look at the grid. Then, cover your other eye and look at the grid. If you detect any changes in the appearance of this grid, or in your everyday vision while reading the newspaper or watching television, get a comprehensive dilated eye exam.
– If you have wet AMD, and your doctor advises treatment, do not wait. After laser surgery or photodynamic therapy, you will need frequent eye exams to detect any recurrence of leaking blood vessels. Studies show that people who smoke have a greater risk of recurrence than nonsmokers. In addition, check your vision at home with the Amsler grid. If you detect any changes, schedule an eye exam immediately.
What can I do if I have already lost some vision from AMD?
If you have lost some sight from AMD, don’t be afraid to use your eyes for reading, watching TV, and other routine activities. Normal use of your eyes will not cause further damage to your vision. If you have lost some sight from AMD, ask us about low vision services and devices that may help you make the most of your remaining vision. In addition, there may be surgical options, including surgical implantation of an intraoculor telescope. Many community organizations and agencies offer information about low vision counseling, training, and other special services for people with visual impairments. The doctors and staff at SoCal Eye work closely with low vision specialists and organizations in our community to maximize and maintain each of our patient’s independence.
What research is being done?
The National Eye Institute is conducting and supporting a number of studies to learn more about AMD. For example, scientists are:
- Studying the possibility of transplanting healthy cells into a diseased retina.
- Evaluating families with a history of AMD to understand genetic and hereditary factors that may cause the disease.
- Looking at certain anti-inflammatory treatments for the wet form of AMD.
This research should provide better ways to detect, treat, and prevent vision loss in people with macular degeneration.
Note: This information was provided by The National Eye Institute (NEI). The NEI is part of the National Institutes of Health (NIH) and is the federal government’s lead agency for vision research that leads to sight-saving treatments. The NEI plays a key role in reducing visual impairment and blindness.