IMPACT OF EPIDERMAL THICKNESS ON PURPURA FROM THE PULSED DYE-LASER

Background and Objective: To clarify whether epidermal thickness is of importance to the purpuric reaction from treatment with the pulsed dy e laser (PDL). Study Design/Materials and Methods: Fifteen fairly pigm ented volunteers were laser treated in two test regions of varying epi dermal thicknesses: normal buttock skin and ultraviolet B (UVB)-expose d buttock skin. Laser treatments were performed with the flashlamp-pum ped PDL (585 nm). Fluences ranged from 3-6.5 J/cm(2), spot size was 7 mm, and each volunteer received at least six fluences in each treatmen t region. Assessment of the response was based on clinical evaluation (threshold dose to purpura 10 minutes and 1 day after treatment) and s kin reflectance-evaluated redness (1 and 6 days, 2 and 6 weeks after t reatment). Results: The total epidermal thickness differed between the unexposed buttock skin (median, 72.7 mu m) and the WE-exposed buttock skin (87.2 mu m) (P < 0.01). There was no correlation between the epi dermal thickness and the threshold dose to induce purpura 10 minutes a nd 1 day after laser exposure. Skin reflectance revealed no correlatio n between the epidermal thickness and the skin reflectance evaluated r edness on 1, 6 days, and 2 weeks postoperatively. A dose-response rela tion was seen within the two test regions; 6 weeks after laser exposur e, there was no remaining laser-induced skin redness. Conclusion: The epidermal thickness is unimportant to the purpuric reaction after PDL treatment. (C) 1998 Wiley-Liss, Inc.