2005 年 14 巻 4 号 p. 153-159
Ablative and nonablative skin rejuvenation procedures with lasers and intense pulsed light (IPL) systems have become very popular for photorejuvenating sun- and chronologically aged skin. Both procedures demand deposition of heat damage in the upper dermis.Anew generation of light-emitting diodes (LEDs) with laser-like wavebands and phototherapeutically useful output powers are now reported to be successful for noninvasive athermal photorejuvenation of age-damaged skin. This study was designed to examine the ultrastructural changes induced by irradiation of human skin with visible red LED energy. Six adult male volunteers who satisfied all study criteria had the skin over their fibula irradiated once per week for 8 weeks with a visible red LED-based system at an irradiance of 105 mW/cm2, 15 min/session and a radiant flux of 94 J/cm2. Skin punch biopsies taken from each subject after the second and eighth treatment sessions were routinely prepared for transmission electron microscopy (TEM) and were examined under an electron microscope. After the 2nd session, the skin showed normal undamaged tissue with slight interstitial edema and vimentin filaments notable in fibroblasts. After the 8th session, the number of fibroblasts in the dermis had increased with numerous vimentin filaments in their cytoplasm, and a mild inflammatory infiltration could be seen. The ultrastructure of human skin after 8 LED phototherapy sessions showed no damage-related abnormalities. Mild athermally-mediated inflammation was seen together with an increased fibroblast count and enhanced metabolism, which could be related to the enhanced synthesis of collagen and which in facial skin would probably result in an improved skin appearance.
