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Photodynamic
Therapy for Age-related Macular Degeneration - What You Need to
Know |
| You may have heard about
a promising new treatment for age-related macular degeneration
(AMD) called Photodynamic Therapy (PDT). A recent report
in the Archives of Ophthalmology journal showed there is some
benefit to this treatment compared to the natural course of the
disease. However, it is important that anyone considering
PDT understand both the benefits and limitations of this treatment,
as well as the commitment one must make to undergo PDT.
The most important thing to understand is that PDT is not a cure for AMD. It slows the progression of vision loss, but does not prevent it. In the Archives study, the researchers compared patients who had undergone PDT to control subjects with AMD who did not have the treatment. When judging vision loss to be "moderate" (defined as 3 or fewer lines of vision), the percentage of people who experienced this was 61% in the PDT group, yet it was only 46% in the control (untreated) group, a difference of 15%. This benefit was significant only for patients who had a type of AMD lesion defined as "predominately classic". However, it is important to understand that on average, patients lost vision regardless of whether or not they received PDT. Before the study started, the average vision of all patients was 20/80, with 36-38% having better than 20/40 vision (the legal cut-off vision for driving in most states). However, one year later, the average vision of PDT patients decreased to 20/160 (20/200 in the control group), and only 4.7% had better than 20/40 vision (vs 1% of the control group). So while PDT has some benefit, it is limited. Patients considering PDT must also understand that the treatment requires a substantial commitment. During PDT, the patient receives an intravenous injection of a drug called Verteporfin, which is activated by light. After a short period of time, a light is aimed into the affected eye for about 1 1/2 minutes. The patient must then take care to avoid bright light exposure for 1-2 days because PDT can cause a very serious skin reaction. Also, there is a risk of a very serious complication if some of the Verteporfin leaks into the skin around the injection site. Fortunately, this risk is small. However, the PDT sessions must be repeated every 3 months in the majority of patients because AMD lesions return following most treatment sessions. Because of AMD recurrence in the Archives study, 91% of patients required a second PDT treatment 3 months after the initial treatment, 79% required another treatment 3 months later, 70% needed a fourth treatment, and 64% needed a fifth treatment. Therefore, the average patient may require at least 5 treatments of PDT for their AMD during the first 15 months. That means at least 5 office visits, 5 fluorescein angiograms, and 5 times the risk of encountering complications of the diagnostic tests and procedures. While we agree that PDT is effective in decreasing the rate of vision loss associated with the natural course of AMD, ultimately we feel you must decide if PDT is right for you. Only you can and should decide if the benefits of PDT are worth the significant effort and risks associated with the therapy. For more information please call our office or click here to send us an e-mail.
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