Understanding Photodynamic Therapy for Age-Related Macular Degeneration (AMD)
Photodynamic therapy is a treatment for the eyes. It uses lasers and a special medicine that works when exposed to a certain type of light. It is done to treat age-related macular degeneration (AMD). AMD is a condition that can lead to loss of eyesight. Photodynamic therapy uses a light-sensitive medicine and a laser to seal off abnormal blood vessels in your eye. It can’t restore eyesight that you have already lost. But it may slow down the damage to your central vision.
What is AMD?
The retina is a layer of cells in the back of your eye. It converts light into electrical signals. Your retina then sends these signals to your brain. The macula is the sensitive center part of your retina. This area gives you detailed vision in the middle of your visual field. AMD damages your macula. The macula may become thinner and deposits of material can develop beneath it. Blood vessels may start growing beneath your macula. This can cause fluid to leak beneath your macula. This extra fluid can lead to eyesight loss.
AMD has 2 types: dry type and wet type. Abnormal blood vessel growth is present in only the wet type. AMD is a common cause of severe eyesight loss in older adults. In rare cases, it can result in total blindness. Because AMD affects the macula, you may still have your side (peripheral) vision. But you may have a slow or sudden loss of central vision.
Why photodynamic therapy for AMD is done
Photodynamic therapy is 1 type of treatment for AMD. It is a choice only for certain people with wet type AMD. It may be advised if your eyesight loss comes on slowly over time, instead of suddenly. The treatment is used less often now that there is medicine to slow down the growth of abnormal blood vessels. But your healthcare provider may advise the therapy in addition to medicine.
How photodynamic therapy for AMD is done
You will get an injection of a light-sensitive medicine. Eye drops will be used to dilate your pupil. It will stay dilated for several hours after the procedure. A special type of contact lens will be put into the affected eye. This lens helps focus a beam of laser light on the retina using a tool called a slit lamp. Your eye care doctor will shine a laser in the exact spot in your eye. This will activate the light-sensitive medicine. It will form blood clots in the abnormal vessels beneath your macula. This seals off the abnormal blood vessels.
Risks of photodynamic therapy
All procedures have risks. The risks of this procedure include:
Temporary loss of visual sharpness, which in rare cases can be severe
A new blind spot
Reactions where you had the light-activated medicine injected
Back pain because of injection of the medicine
Photosensitivity reactions like sunburn, if exposed to sunlight right after the procedure
Only short-term relief from AMD symptoms, because the blood vessels open again
Your risks may differ according to your age, your general health, and the type of your AMD. Ask your healthcare provider which risks apply most to you.
March 21, 2017
Age-related macular degeneration: Treatment and prevention. UpToDate.
Finke, Amy, RN, BSN,Haupert, Christopher L., MD