Causes, Types, Symptoms,Risk, Diagnosis, Treatment for Age-related Macular Degeneration (AMD)

Causes, Types, Symptoms,Risk, Diagnosis, Treatment for Age-related macular degeneration (AMD)

This pamphlet is designed to help people with age-related macular degeneration and their families better understand the disease. It describes the causes, symptoms, diagnosis, and treatment of age-related macular degeneration.

Age-related macular degeneration (AMD) is a disease that affects your central vision. It is a common cause of vision loss among people over age of 60. Because only the center of your vision is usually affected, people rarely go blind from the disease. However, AMD can sometimes make it difficult to read, drive, or perform other daily activities that require fine, central vision.

Symptoms,Risk, Detect and Treatment for Age-related macular degeneration (AMD)

What is the macula?

The macula is in the center of the retina, the light-sensitive layer of tissue at the back of the eye. As you read, light is focused onto your macula. There, millions of cells change the light into nerve signals that tell the brain what you are seeing. This is called your central vision. With it, you are able to read, drive, and perform other activities that require fine, sharp, straight-ahead vision.

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How does Age-related Macular Degeneration (AMD) damage vision?

AMD occurs in two forms:
  • Dry AMD affects about 90 percent of those with the disease. Its cause is unknown. Slowly, the light sensitive cells in the macula break down. With less of the macula working, you may start to lose central vision in the affected eye as the years go by. Dry AMD often occurs in just one eye at first. You may get the disease later in the other eye. Doctors have no way of knowing if or when both eyes may be affected.
  • Wet AMD--Although only 10 percent of all people with AMD have this type, it accounts for 90 percent of all severe vision loss from the disease. It occurs when new blood vessels behind the retina start to grow toward the macula. Because these new blood vessels tend to be very fragile, they will often leak blood and fluid under the macula. This causes rapid damage to the macula that can lead to the loss of central vision in a short period of time.

What causes Age-related Macular Degeneration (AMD)?

The exact causes of macular degeneration are not known. Risk factors may include:

  • genetic factors
  • nutritional factors
  • smoking
  • high blood pressure
  • exposure to direct sunlight over a period of years
  • certain medical conditions

What are the types of Age-related Macular Degeneration (AMD)?

There are two types of Age-related Macular Degeneration (AMD) – the dry (atrophic) form and the wet (exudative or neovascular) form.

The dry form of AMD affects about 85-90 percent of AMD patients and usually begins when tiny yellow deposits called drusen appear in the macula. Drusen usually do not cause serious loss of vision, but can distort vision. However, for reasons that are not yet understood, sometimes drusen are associated with macular atrophy (thinning) and tissue breakdown, slowly leading to vision loss. Patients may have blind spots in their vision; in the advanced stages, patients may even lose central vision.

The wet form of AMD occurs in about 10-15 percent of AMD patients. It is caused by the growth of abnormal blood vessels beneath the macula that can leak fluid and blood into the eye. The wet form of AMD usually causes major vision problems, such as blind spots and loss of central vision, in the affected eye, and can advance rapidly. These abnormal blood vessels eventually scar, leading to permanent retinal damage and loss of central vision.

Most patients with AMD have the dry form of the disease and will not lose central vision. However, the dry form of AMD can lead to the wet form. People who have the wet form of AMD are much more likely to have serious vision loss. For these patients, early diagnosis and treatment are important to save as much vision as possible.

Because the dry form can change into the wet form, it is very important for people with AMD to monitor their eyesight carefully and see their eye doctor on a regular basis.

Age-related Macular Degeneration may be hereditary, meaning it can be passed on from parents to children. If someone in your family has or had the condition, you may be at higher risk for developing the disease. Talk to your eye doctor about your individual risk.

Who is at risk for Age-related Macular Degeneration (AMD)?

Although AMD can occur during middle age, the risk increases as a person gets older. Results of a large study show that people in their 50s have about a two percent chance of getting AMD. This risk rises to nearly 30 percent in those over age 75. Besides age, other AMD risk factors include:

  • Gender: Women may be at greater risk than men, according to some studies.
  • Smoking: Smoking may increase the risk of AMD.
  • Family History: People with a family history of AMD may be at higher risk of getting the disease.
  • Cholesterol: People with elevated levels of blood cholesterol may be at higher risk for wet AMD.

What are the symptoms of Age-related Macular Degeneration (AMD)?

Neither dry nor wet AMD causes any pain. The most common symptom of dry AMD is slightly blurred vision. You may need more light for reading and other tasks. Also, you may find it hard to recognize faces until you are very close to them.

Symptoms,Risk, Detect and Treatment for Age-related macular degeneration (AMD)
As dry AMD gets worse, you may see a blurred spot in the center of your vision. This spot occurs because a group of cells in the macula have stopped working properly. Over time, the blurred spot may get bigger and darker, taking more of your central vision.

People with dry AMD in one eye often do not notice any changes in their vision. With one eye seeing clearly, they can still drive, read, and see fine details. Some people may notice changes in their vision only if AMD affects both of their eyes.

An early symptom of wet AMD is that straight lines appear wavy. This happens because the newly formed blood vessels leak fluid under the macula. The fluid raises the macula from its normal place at the back of the eye and distorts your vision. Another sign that you may have wet AMD is rapid loss of your central vision. This is different from dry AMD in which loss of central vision occurs slowly. As in dry AMD, you may also notice a blind spot.

If you notice any of these changes in your vision, contact your eye care professional at once for an eye exam.

How is Age-related Macular Degeneration (AMD) detected?

Eye care professionals detect Age-related Macular Degeneration (AMD) during an eye examination that includes:

Visual acuity test: This eye chart test measures how well you see at various distances.

Pupil dilation: This examination enables your eye care professional to see more of the retina and look for signs of AMD. To do this, drops are placed into the eye to dilate (widen) the pupil. After the examination, your vision may remain blurred for several hours.

One of the most common early signs of AMD is the presence of drusen. Drusen are tiny yellow deposits in the retina. Your eye care professional can see them during an eye examination. The presence of drusen alone does not indicate a disease, but it might mean that the eye is at risk for developing more severe AMD.

While conducting the examination, your eye care professional may ask you to look at an Amsler grid. This grid is a pattern that resembles a checkerboard. You will be asked to 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 to you. You may notice that some of the lines are missing. These may be signs of wet AMD (See Amsler Grid below.)

If your eye care professional suspects you have wet AMD, you may need to have a test called fluorescein angiography. In this test, a special dye is injected into a vein in your arm. Pictures are then taken as the dye passes through the blood vessels in the retina. The photos help your eye care professional evaluate leaking blood vessels to determine whether they can be treated.

Treatment for Age-related macular degeneration (AMD)

How is Age-related Macular Degeneration (AMD) treated?

Dry AMD currently cannot be treated. But this does not mean that you will lose your sight. Fortunately, dry AMD develops very slowly. You may lose some of your central vision over the years. However, most people are able to lead normal, active lives--especially if AMD affects only one eye.

Some cases of wet AMD can be treated with laser surgery. The treatment involves aiming a high energy beam of light directly onto the leaking blood vessels. Laser treatment is more effective if the leaky blood vessels have developed away from the fovea--the central part of the macula. But even if the blood vessels are growing right behind the fovea, the treatment can be of some value in stopping further vision loss.

How is laser surgery preformed?

Laser surgery is performed in your eye care professional's office or eye clinic. Before the surgery, he or she will: (1) dilate your pupil and (2) apply drops to numb the eye. In some cases, he or she also may numb the area behind the eye to prevent any discomfort.

The lights in the office will be dim. As you sit facing the laser machine, your eye care professional will hold a special lens to your eye. You may see flashes of light.

You can leave the office once the treatment is done, but you will need someone to drive you home. Because your pupils will stay dilated for a few hours, you also should bring a pair of sunglasses.

For the rest of the day, your vision may be a little blurry. Your eye may also hurt a bit. This is easily controlled with drugs that your eye care professional can suggest.

You will need to make frequent follow-up visits. During each exam, you may have fluorescein angiography to make sure that the blood vessels are not still leaking, or that new blood vessels have not developed. If the vessels continue to leak, you might need some more laser surgery. It is important to realize that laser surgery is not a cure for AMD. It is only a treatment to help stop further vision loss. The risk of new blood vessels growing back after laser treatment is relatively high.

What can you do to protect your vision?

Dry Age-related Macular Degeneration (AMD)

If you have dry AMD, you should have your eyes examined through dilated pupils at least once a year. This will allow your eye care professional to monitor your condition and check for other eye diseases as well.

You should also obtain an Amsler grid from an eye care professional to use at home. This will provide you with a quick and inexpensive test to evaluate your vision each day for signs of wet AMD. It works best for people who still have good central vision. You should check each eye separately--cover one eye and look at the grid, then cover your other eye and look at the grid. You also may want to check your vision by reading the newspaper, watching television, and just looking at people's faces. If you detect any changes, you should have an eye exam.

Wet Age-related Macular Degeneration (AMD)

If you have wet AMD, it is important not to delay laser surgery if your eye care professional advises you to have it. After surgery, you will need to have frequent eye examinations to detect any recurrence of leaking blood vessels. Studies show that people who smoke have a greater risk of recurrence than those who don't.

In addition, you should continue to check your vision (at home With the Amsler grid or other methods) as described under dry AMD and schedule an eye exam immediately if you detect any changes.

What can I expect after drug injection treatment?

After treatment, your physician may order another OCT picture, or sometimes an angiogram, to make sure there are no other areas of blood leakage. If the OCT shows that there is still leakage, more treatment is usually recommended.

Are there any side effects of the anti-angiogenesis eye injections?

Rare complications may include:

  • infection
  • damage to structures in the eye, including more rapid clouding of the lens (cataract)
  • in very rare instances, retinal detachment or severe loss of vision may occur. In studies, 1 to 2% of patients receiving the drugs had a heart attack or stroke over the next year, which appears to be a similar rate to that seen in the control group of patients.

Can treatment help if I am legally blind?

Depending upon the cause of legal blindness, it is possible that treatment may help. If recent bleeding or leakage under the retina has resulted in legal blindness, surgery is a possibility. Retinal cell transplants and stem cell therapy are under study; a new implanted electronic retinal “chip” was recently approved for human use and may be an option in highly selected cases.

Can I have treatment if lasers were used as an earlier treatment?

Because bleeding or leakage may occur beneath the retina even after the laser treatment, it is possible that treatment with injected drugs can help.

I have other medical conditions. Can I still have treatment?

Other medical conditions or age should not be a factor if you are considered an appropriate candidate for treatment, although sometimes anti-VEGF injections may be delayed after a recent heart attack or stroke.

What is the outlook for people with Age-related Macular Degeneration (AMD)?

Unfortunately, AMD can return even after successful treatment. The various treatments can slow the rate of vision loss and hopefully preserve some sight.