Photodynamic Therapy for Age-Related Macular Degeneration

What is photodynamic therapy?

Photodynamic therapy (PDT) is a way to treat certain kinds of macular degeneration. The procedure involves using an intravenous (IV) medicine called Visudyne, which can be activated by laser light. When activated, the medicine can close abnormal blood vessels and reduce your chance of losing vision. It does not usually improve vision.

When is it used?

Photodynamic therapy may be used to treat some kinds of wet, age-related macular degeneration (AMD) and similar conditions. AMD is a disease that damages the macula in the eye and causes a loss of central vision. The wet form of AMD occurs when new, fragile blood vessels grow under the tissue at the back of the eye (retina). These vessels leak blood and fluid. They can cause scarring and loss of vision.

If your eye care provider finds abnormal blood vessels directly under the center of your retina, you will probably have a special test called a fluorescein angiogram to determine the type, size, and location of the abnormal blood vessels. Your provider will use the results of the angiogram to help determine if PDT might work for you.

How do I prepare for the procedure?

Because the medicine used in the procedure is activated by light, it is important to bring clothing that will protect your body from sunlight after the procedure. You will need sunglasses, long pants, a long-sleeve shirt, gloves, and hat.

Make sure your provider has your medical history so he or she can check what other treatments you have had. It is also important to tell the provider if you have any unusual medical conditions or are taking medicine that makes you sensitive to light (such as tetracycline medicines) or any liver diseases, such as cirrhosis or porphyria.

Do not wear eye makeup on the day of the procedure.

What happens during the procedure?

First, your provider will review your fluorescein angiogram or possibly do a new one to measure the size and position of the abnormal blood vessels. You will be weighed and measured to figure out the dose of the light-sensitive medicine you will need. The medicine will be given through a vein with an IV line for about 10 minutes. Some people have temporary back or chest pain while getting the medicine.

The provider will then place a drop of anesthetic medicine in your eye. He or she will put a contact lens on your eye and ask that you place your head on a small platform in a slit-lamp instrument. Five minutes after the medicine was given, the provider will direct a laser beam to the area of abnormal blood vessels for just over a minute. This is painless, but you need to hold relatively still. After the laser is turned off, the contact lens and IV are removed.

What happens after the procedure?

Right after the procedure, it may take a few minutes for blurry vision caused by the laser to go away.

Because you were given light-sensitizing medicine, you will need to avoid exposure to sunlight and bright indoor light for 5 days. You should wear sunglasses, long pants, a long-sleeve shirt, a hat, and gloves when you are outside. Ask your healthcare provider about the best type of sunglasses to wear during this time. Avoid bright indoor light and sunlight coming in from windows. Don't worry about light from fluorescent, incandescent, or halogen light bulbs that are used indoors. They are too weak to activate the drug. Your provider may give you a wristband to wear for the next 5 days describing the treatment you had.

Usually you will have a follow-up appointment for an exam and another angiogram 6 to 12 weeks after the procedure. Most people require more than 1 treatment of photodynamic therapy. Sometimes 5 or 6 treatments over the course of a year or so are needed.

What are the benefits of this procedure?

For some specific forms of age-related macular degeneration, PDT has been shown to reduce the risk of losing more vision over time. This, however, applies only to some kinds of abnormal blood vessels.

What are the risks associated with the procedure?

This medicine causes you to be very sensitive to sunlight, bright lights, and car headlights for several days. It is important to remain protected from sunlight and bright indoor light for 5 days after a treatment to avoid possible severe sunburns. Operating room lights can also activate the drug, so you should avoid scheduling surgery during this time. The wristband provides information for emergency healthcare providers in case you need emergency surgery during this time.

You will probably have some changes with your vision that come and go after treatment. Rarely, severe vision loss occurs soon after a photodynamic treatment.

When should I call my eye care provider?

Call your eye care provider's office if you experience any major unexpected problems after treatment, such as hives, trouble breathing, sudden loss of vision, or a severe sunburn. These problems, however, are very rare.

Reviewed for medical accuracy by faculty at the Wilmer Eye Institute at Johns Hopkins. Web site: http://www.hopkinsmedicine.org/wilmer/

Written by Joel Pearlman, MD.
Published by RelayHealth.
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