Do pulsed lasers produce an effective photodynamic therapy response?
John Strasswimmer1, Donald J Grande
1Wellman Center for Photomedicine, Massachusetts General Hospital, & Department of Dermatology, Harvard Medical School, Boston, Massachusetts, USA.
Lasers in Surgery and Medicine
|January 5, 2006
Summary
Pulsed light sources like IPL and PDL can activate photodynamic therapy (PDT) but are less effective than continuous-wave (CW) blue light. Ambient light may also trigger a PDT reaction.
Area of Science:
- Dermatology
- Photodynamic Therapy
- Light-based Treatments
Background:
- Traditional photodynamic therapy (PDT) uses topical aminolevulinic acid (ALA) with continuous-wave (CW) light.
- Pulsed light sources, including lasers and intense pulsed light (IPL), have been anecdotally reported for PDT.
- Clinical benefits of pulsed light PDT on sun-exposed skin are observed, but their efficacy is unproven.
Purpose of the Study:
- To compare the efficacy of pulsed light sources (PDL, IPL) versus CW blue light for PDT.
- To determine if pulsed light sources are responsible for observed PDT responses.
- To investigate the effect of ambient light on ALA-treated skin.
Main Methods:
- A placebo-controlled study using pulsed dye laser (PDL) and intense pulsed light (IPL) for PDT.
- Sun-hidden skin treated with ALA, microdermabrasion, and acetone scrub.
- Comparison with standardized CW blue light, no light, and ALA vehicle controls.
Main Results:
- IPL and PDL showed a weak dose-response for PDT activation.
- Pulsed light sources were less potent than CW blue light at equivalent fluences.
- ALA-treated skin showed activation from ambient light exposure.
Conclusions:
- Both IPL and PDL can activate PDT, but are significantly less potent than CW blue light.
- Continuous-wave (CW) sources may be preferred for a robust PDT response.
- Ambient light poses a potential risk for unintended PDT activation.
