Tuesday, July 31, 2007

Macular Degeneration


As the Baby Boomers age, more and more people will be diagnosed with the most common type of macular degeneration, age-related macular degeneration, or AMD.

Macular degeneration is a type of vision loss caused by a detrioration of the macula, which is the part of your retina that controls your central vision.

By the time I was old enough to really know my grandfather, he was already having problems with his sight. He was a lot older than my grandmother, so when I was 5 years old, he was 86. He could still see somewhat when I was that age, but by the time he died at age 94 he was virtually blind from a combination of macular degeneration and cataracts. He kept his wits about him till the end, and enjoyed listening to opera and the Mets on the radio. But I know he missed reading, which was a great love of his, and back then they had no books on tape.

I have an elderly neighbor who started developing macular degeneration quite a few years ago. She is now 97 and can see very little; however, she still lives at home by herself and enjoys listening to books on tape. Like my grandfather, she had been an avid reader, so she is grateful for the tapes and says they "saved her life."

Now both my mother and father-in-law have been diagnosed with this condition. They both have the less severe kind, the "dry" variety, and so far their daily activities have not been impacted. But I worry about the future. And of course, being both a hypochondriac and a realist (after all, it seems to run in my family, at least on my mother's side), I worry that I will get it as I age.

What is macular degeneration?

There are two types of macular degeneration: The wet form and the dry form.

Wet AMD is caused by the growth of abnormal blood vessels behind the retina, called choroidal neovasculization. They start to grow under the macula and, because they are poorly formed and fragile, often leak blood and fluid. This distorts the macula by lifting it from its normal position and quickly damages the structure, causing scarring. The wet type of AMD is considered advanced because the vision loss can happen quickly.

Dry AMD happens when the light-sensitive cells in the macula slowly break down, gradually causing blurred central vision in the affected eye(s). Eventually, as less of the macula functions, central vision can be gradually lost.

What are the symptoms?

For Wet AMD, symptoms develop rapidly, and can include:

-Visual distortions; straight lines may appear wavy or crooked, things may look smaller or farther away than they should
-A decrease in central vision or a central blurry spot

There is another type of Wet AMD where fluids leak behind the macula but there is no sign of abnormal blood vessel growth. This is called Retinal Pigment Epithelial Detachment. It progresses less rapidly than regular Wet AMD, but eventually does develop into the more severe form.

For Dry AMD, symptoms appear more gradually. They can include:

-Need for increasingly bright light when reading or doing close work
-Difficulty adapting to a darker place, such as when entering a restaurant after being outdoors in the brighter light.
-Increasing blurriness of printed words
-A decrease in the intensity or brightness of colors
-Difficulty recognizing faces
-Gradual increase in the haziness of your overall vision
-Blurred or blind spot in the center of your visual field

One of the most common early signs of Dry AMD is the appearance of little yellow spots called "drusen" in the retina.

Dry AMD has three stages, all of which may occur in one or both eyes:

Early AMD. People with early AMD may have several small drusen or a few medium-sized drusen, with no signs of vision loss yet.

Intermediate AMD. At this stage, there may be either many medium-sized drusen or one or more large drusen. At this point, there may be a blurred spot in the central vision and the patient may need brighter light for reading and other tasks.

Advanced Dry AMD. At this stage, in addition to drusen, there will be a breakdown of light-sensitive cells and supporting tissue in the central retinal area. This can cause a blurred spot in the center of the vision. Over time, the blurred spot may get bigger and darker, making it hard to read or recognize faces.

In either type of macular degeneration, the process may affect one or both eyes.

In addition, there may be visual hallucinations as the eyesight deteriorates; this phenomenon is called Charles Bonnet Syndrome, and may include seeing geometric patterns, strange-looking faces, animals, and more.

The dry form of AMD is much more common; among people with the early and intermediate stages of AMD, 85% have Dry AMD. However, all people who have the wet form started out with the dry form of the condition. Among those with advanced AMD, 2/3 have the wet form.

In both types of AMD, it is thought that a breakdown in the waste removal system in the eye may obstruct the nutrient flow and result in either the cellular deterioration seen in Dry AMD or the growth of the abnormal blood vessels in the wet form.

How is it diagnosed?

If you are having problems with your vision, consult an ophthalmologist. He (or she) will give you a thorough eye exam, in which he will look for the signs of drusen or mottled coloring in the retina. In addition, he may use an Amsler Grid to test your eyesight, to see whether lines look wavy or distorted.

You may need to have an angiography, where dye is injected into your veins so that the doctor can see the blood vessels and pigmentation in the back of your eyes that might not be visible in an ordinary examination. There are two different types of dye that may be used - fluorescein or indocyanine green (ICG).

Another test that may be conducted is Ocular Coherence Tomography, or OCT. This is a test that can indicate the thickness of the retina and identify the presence of abnormal fluid. It is non-invasive.

How is it treated?

Most of the treatments available are for treating Wet AMD. Since this is the most severe form, it is important to stop the damage as quickly as possible, as it is usually not reversible.

Treatments include:

Photocoagulation: This is a laser treatment which seals off the abnormal blood vessels and keeps them from leaking further. It is best for treating blood vessels that are not directly under the center of the macula (called the fovea).

Photodynamic Therapy: This treatment is mainly used for abnormal blood vessel growth under the fovea. It is a cold laser treatment that is used in conjunction with a light-sensitive drug (verteporfin, brand name Visudyne)which is injected into the bloodstream. It is concentrated in the abnormal blood vessels behind the fovea and when the laser hits them, the drug causes substances to be released that close off the blood vessels.

Macular Translocation Surgery: Another treatment used for the area under the fovea is this type of surgery, in which a skilled surgeon detaches the retina, moves the fovea away from the abnormal blood vessels, removes the blood vessels, and reattaches the fovea over unaffected tissue. This is not commonly used.

Another way to treat Wet AMD is through drugs called Anti-Vascular Endothelial Antivascular Growth Factor (Anti-VEGF) medications. They include:

-Macugen (pegaptanib). It is injected into the vitreous fluid in the eye and helps stop the development of new abnormal blood vessels and prevents leaking of fluids.

-Lucentis (ranibizumab) works in a similar way. In addition to preventing additional damage, Lucentis may also reverse existing damage.

-Avastin (bevacizumab)is related to Lucentis but is not currently approved for macular degeneration. Since it is approved for colon and rectal cancer, doctors can use it off-label for other purposes, and it is believed it will work similarly to Lucentis on Wet AMD. Therefore, some doctors are using it for this condition.

For Dry AMD, there are fewer treatments, but since it progresses so much more slowly, there is a good chance that those who are diagnosed with Dry AMD will continue to live normal lives for many years.

Photocoagulation is being explored as a treatment for Dry AMD who have drusen. It is hoped that low-level laser treatments of the retina may cause regressen of the drusen and prevent vision loss. This treatment is being studied in a clinical trial.

Other therapies being studied include the use of Kenalog, a steroid that reduces inflammation; and Rheophoresis, where the blood is removed from the body and filtered to take out harmful substances that may be impeding the flow of blood in the eye.

One therapy that has been proven to delay the progress of Dry AMD in those affected is the "AREDS" (for Age-Related Eye Disease Study) supplement formula. This combination of nutrients was tested in a national clinical trial and found to be effective in preventing the progress of AMD among those who were at high risk of developing Advanced AMD. The supplement consisted of a specific combination of vitamin C, E, zinc, copper and beta carotene. It is available in drug stores. Some versions include lutein as well, which has been shown to be beneficial.

If you are looking to prevent AMD, eating a lot of healthy foods full of antioxidants should be helpful. A recent study also indicated that increased consumption of fish high in Omega-3 fatty acids may also be protective.

Be sure to wear sunglasses, don't smoke, and keep your blood pressure under control as well.

If you have Dry AMD, you should have a comprehensive dilated eye exam at least once a year so that your eye doctor can monitor the condition. Because dry AMD can turn into wet AMD at any time, you should get an Amsler grid from your doctor and use it at home to evaluate your vision daily.

If you have Wet AMD and your doctor advises treatment, don't waste any time in getting it. After laser surgery or photodynamic therapy, you will need frequent eye exams to detect any recurrence of leaking blood vessels.

There are many aids for those who have vision loss, including magnifiers, automatic readers, large print books, books on tape, and various other ways to help those with vision loss to cope. And be sure to subscribe to a website newsletter that keeps you informed of new treatments.

Will you get it?

You may, if you live long enough. Macular Degeneration is the leading cause of vision loss in those over 55. Risk factors include:

The greatest risk factor is age. A large study found that people in middle-age have about a 2 percent risk of getting AMD, but this risk increases to nearly 30 percent in those over age 75.

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: Whites 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.

Information for this post came from the following websites:

http://www.mayoclinic.com/health/macular-degeneration/DS00284/DSECTION=1 http://www.nei.nih.gov/health/maculardegen/armd_facts.asp
http://www.macular.org/
http://www.macular-degeneration.org/home.htm

Please see these websites for further details on the disease.

Another resource that may be helpful is this site:
http://www.amd.org/site/PageServer?pagename=homepage

The picture of the eye at the beginning of the article came from this site:
http://images.google.com/imgres?imgurl=http://www.retinaaustralia.com.au/images/eye6.gif&imgrefurl=http://www.retinaaustralia.com.au/RP.htm&h=396&w=565&sz=16&hl=en&start=0&tbnid=kY7c9mTnGlIwzM:&tbnh=94&tbnw=134&prev=/images%3Fq%3Deye%26gbv%3D2%26svnum%3D10%26hl%3Den%26sa%3DG

6 comments:

RUTH said...

I know Steve's (son-in-law) Dad has something that similar to this; he has to have injections in his eye. Rx

Mauigirl said...

Sounds as if it might be this then. The idea of injections in the eye sounds pretty dreadful but I guess they make sure it is numb!

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- The Macular Degeneration