Macular degeneration - age-related
Contents
When to Contact a Medical Professional
General Information
Macular degeneration is an eye disorder that slowly destroys sharp, central vision. This makes it difficult to see fine details and read.
The disease is most common in people over age 60, which is why it is often called age-related macular degeneration (ARMD, or AMD).
Macular degeneration is a disease of the retina that affects the macula in the back of the eye. The macula is important for clear central vision, allowing an individual to see fine details. There are two types of macular degeneration, dry and wet. Dry macular degeneration is more common and is characterized by the thinning of the retina and drusen, small yellowish-white deposits that form within the retina. The dry form of macular degeneration is usually mild. Wet macular degeneration can happen more quickly and be more serious. It occurs when vessels under the retinal layer hemorrhage and cause the retinal cells to die creating blind spots or distorted vision in the central vision. The disease becomes increasingly common amongst people in each succeeding decade over 50.
The retina is at the back of the eye. It changes light and images that enter the eye into nerve signals that are sent to the brain. A part of the retina called the macula makes vision sharper and more detailed.
AMD is caused by damage to the blood vessels that supply the macula. This change also harms the macula.
There are two types of AMD:
- Dry AMD occurs when the blood vessels under the macula become thin and brittle. Small yellow deposits, called drusen, form. Almost all people with macular degeneration start with the dry form.
- Wet AMD occurs in about 10% of people with macular degeneration. New abnormal and very fragile blood vessels grow under the macula. These vessels leak blood and fluid. This type of AMD causes most of the vision loss associated with the condition.
Doctors are not sure what causes AMD. The condition is rare before age 55. It occurs most in persons 75 years or older.
Risk factors for AMD are:
- Family history of AMD
- Being caucasian
- Cigarette smoking
- High-fat diet
- Being a woman
Symptoms
You may not have any symptoms at first. As the disease gets worse, you may have problems with your central vision.
SYMPTOMS OF DRY AMD
The most common symptom of dry AMD is blurred vision. Objects in the center part of your vision often look distorted and dim, and colors look faded. You may have trouble reading print or seeing other details. But you can see well enough to walk and do most daily activities.
As dry AMD gets worse, you may need more light to read or do everyday tasks. A blurred spot in the center of vision gradually gets larger and darker.
In the later stages of dry AMD, you may not be able to recognize faces until they are close.
SYMPTOMS OF WET AMD
The most common early symptom of wet AMD is that straight lines look distorted and wavy.
There may be a small dark spot in the center of your vision that gets larger over time.
With both types of AMD, central vision loss can occur quickly. If this happens, you will need to be seen right away by an ophthalmologist. Make sure this eye doctor has experience in treating problems with the retina.
Exams and Tests
You will have an eye exam. Drops will be placed into your eyes to widen (dilate) your pupils. The eye doctor will use special lenses to view your retina, blood vessels, and optic nerve.
The eye doctor will look for specific changes in the macula and blood vessels and for drusen.
You may be asked to cover one eye and look at a pattern of lines called an Amsler grid. If the straight lines look wavy, it may be a sign of AMD.
Other tests that may be done include:
- Using special dye and camera to look at blood flow in the retina (fluorescein angiogram)
- Taking a photo of the inner lining of the eye (fundus photography)
- Using light waves to view the retina (optical coherence tomography)
Treatment
If you have advanced or severe dry AMD, no treatment can restore your vision.
If you have early AMD and do not smoke, a combination of certain vitamins, antioxidants, and zinc may prevent the disease from getting worse. But it cannot give you back vision that is already lost.
The combination is often called the "AREDS" formula. The supplements contain:
- 500 milligrams of vitamin C
- 400 international units of beta-carotene
- 80 milligrams of zinc
- 2 milligrams of copper
Only take this vitamin combination if your doctor recommends it. Make sure your doctor knows about any other vitamins or supplements you are taking. Smokers should not use this supplement.
AREDS may also benefit you if you have a family history and risk factors for AMD.
The supplements lutein and zeaxanthin may also be helpful, although they are not part of the AREDS formula.
If you have wet AMD, your doctor may recommend:
- Laser surgery (laser photocoagulation) -- a small beam of light destroys the leaking, abnormal blood vessels.
- Photodynamic therapy -- a light activates a drug that is injected into your body to destroy leaking blood vessels.
- Special medicines that prevent new blood vessels from forming in the eye are injected into the eye (this is a painless process).
Low-vision aids (such as special lenses) and therapy can help you use the vision that you have more effectively, and improve your quality of life.
Close follow-up with your eye doctor is important.
- For dry AMD, visit your eye doctor once a year for a complete eye exam.
- For wet AMD, you likely need frequent, perhaps monthly, follow-up visits.
Early detection of vision changes is important because the sooner you are treated, the better your outcome. Early detection leads to earlier treatment and often, a better outcome.
The best way to detect changes is by self-testing at home with the Amsler grid. Your eye doctor can give you a copy of the grid. Or you can print one from the Internet. Test each eye individually while wearing your reading glasses. If the lines look wavy, call your eye doctor right away for an appointment.
Outlook (Prognosis)
AMD does not affect side (peripheral) vision. This means complete vision loss never occurs. AMD results in the loss of central vision only.
Mild, dry AMD usually does not cause disabling central vision loss.
Wet AMD often leads to significant vision loss.
In general, with AMD you may lose the ability to read, drive a car, and recognize faces at a distance. But most people with AMD can carry out daily tasks without much difficulty.
When to Contact a Medical Professional
If you have AMD, your health care provider may recommend that you check your vision every day with an Amsler grid. Call your provider immediately if the lines look wavy. Also call if you notice other changes in your vision.
Prevention
Although there is no known way to prevent macular degeneration, leading a healthy lifestyle can reduce your risk of developing AMD:
- Do not smoke
- Maintain a healthy diet that is high in fruits and vegetables and low in animal fat
- Exercise regularly
- Maintain a healthy weight
See your eye care professional regularly for dilated eye exams.
Alternative Names
Age-related macular degeneration (ARMD); AMD
Source: http://www.nlm.nih.gov/medlineplus/ency/article/001000.htm