Treatment of acne via light- and laser-therapy
Laser- and phototherapy are new components and complementary treatment modalities of modern acne therapy and may be used for the treatment of multiple closed comedones, macro-comedones and micro-cysts as well as inflammatory acne lesions.
One target of photo-therapy is eliminating propionibacterium acnes. Colonisation of the plugged follicles with these bacteria which degrade triglycerides into free fatty acids and enhance inflammation, is one of the causative factors in acne. As propionibacterium acnes also produces porphyrines, treatment with light or laser might be a new attractive treatment modality for acne-therapy, as pointed out by Antony C. Chu, London.
However, ultraviolet irridiation in acne-therapy has not met expectations; treatment-success appears to be transient, bears a potential carcinogenic risk and also induces lipid patterns that promote comedogenesis. Therefore, other forms of light-therapy might be of interest.
Target structure: Bacterial porphyrines
Porphyrines absorb light of distinct wavelengths leading to photochemical reaction that results in free radical (singulet-oxygen)-formation. This highly reactive and toxic molecule can damage membranes and thus destroy cells and tissue. As far as propionibacterium acnes is concerned, this natural metabolite thus might allow to selectively target bacteriil growth and also potentially reduce size and amount of sebum production.
The power of light
Intense blue-light-therapy (405–420 nm) as well as visible-light-therapy (430 und 1000 nm) could lead to improvement of acne lesions after several treatments, as stated by A. Troilius, Malmö.
Even better results could be achieved through irridiation with blue and red light (660 nm). It is believed that in this context antibacterial as well as antinflammatory effects work synergistically. In the case of mild to moderate acne this physical treatment was superior to topical treatment with 5% benzylperoxide.
On the way to success with laser-therapy
Specialists believe that treatment with the pulsed dye-laser may be another especially useful treatment option: A single treatment of the entire face can be performed within 15 minutes and lead to lasting therapeutic effects for up to 12 weeks. A single treatment can reduce the amount of acne lesions by 50%. Also, pulsed dye-lasers with a low fluence (energy-intensity) may enhance collagen production and thus also have a beneficial effect on existing atrophic scars, as pointed out by Chu.
Although there are no contolled therapeutic studies on photodynamic therapy for acne available, first results of US-studies with amino-laevulinic-acid and irridiation with light (417 nm) showed promising results and may result in yet another treatment option.
(wpa)
Der Deutsche Dermatologe 12·2003, S. 932, Vorträge auf dem EADV-Kongress, 16.–19. Oktober 2003, Barcelona.
