In photodynamic therapy, a light-sensitive medicine
called verteporfin (Visudyne) is injected into the bloodstream. The medicine
collects in the abnormal blood vessels under the macula. Laser light is then
shone into the eye, which activates the medicine and causes it to create blood
clots that block the abnormal blood vessels.
By sealing the leaky
blood vessels, photodynamic therapy slows down:
The buildup of fluid under the retina that
distorts the shape and position of the macula.
The growth of scar
tissue and the abnormal membrane under the retina, both of which damage the
cells in the macula.
Central vision loss.
Photodynamic therapy takes about 20 minutes and may be done
in a doctor's office or eye clinic.
What To Expect After Treatment
The verteporfin medicine used in PDT
makes your skin and eyes more sensitive to light. After treatment, avoid direct sunlight for 2 to 5 days. And when you have to be outdoors, wear dark
sunglasses to protect your eyes.
Your doctor will want you to
come back for a follow-up exam in about a month.
Why It Is Done
Photodynamic therapy is used to treat
wet age-related macular degeneration (AMD) only. And PDT can only be used for a
minority of cases.1
the growth of abnormal blood vessels under the macula, photodynamic therapy may
help prevent the progression of wet AMD. It does not restore vision to eyes
that have already been damaged. But it may help prevent further damage to the
retina and further vision loss.
think that photodynamic therapy may be more effective and less destructive than
laser surgery. Laser treatment almost always causes some immediate, permanent
central vision loss (a central blind spot). And laser treatment does not always prevent
future growth of abnormal blood vessels. Photodynamic therapy may be better
able to target the blood vessels without damaging the nerve cells in the retina
How Well It Works
PDT can lower the risk of severe
vision loss by reducing the growth of and leakage from abnormal blood vessels
under the retina.2 How well the treatment works
depends on where and how the abnormal blood vessels are growing beneath the
retina. For some types of wet AMD, the treatment has no detectable benefit.
The effect of PDT in slowing the progress of AMD is often
temporary, and the abnormal blood vessels begin leaking again after about 3
months. Most people need multiple treatments to get the full benefits of the
A severe loss in visual clarity happens to some people who are treated with PDT. In some cases, vision partially
Other side effects that may
occur with PDT include:
Temporary visual disturbances (abnormal vision,
decreased vision, defects in the visual field).
bleeding, or inflammation at the site where the verteporfin medicine is
injected. Some people also experience low back pain related to the injection of
Photosensitivity reactions (such as sunburn).
What To Think About
Photodynamic therapy (PDT) has been
shown to be effective for only certain types of wet AMD.
The effectiveness and long-term consequences of PDT
are still being studied.
How this information was developed to help you make better health decisions.