Photodermatol Photoimmunol Photomed. 2009 Jun; 25(3): 138-42Yoo KH, Ahn JY, Kim JY, Li K, Seo SJ, Hong CKBACKGROUND: Various modalities have been used to treat acne scars, but limited efficacy and considerable side effects have restricted their proper use. Recently, a new-generation fractional photothermolysis modality has been introduced that has deeper penetrating ability; however, a 1540 nm fractional photothermolysis study has not yet been performed. OBJECTIVES: To evaluate the efficacy and safety of 1540 nm fractional photothermolysis for the treatment of acne scars in Asian skin. METHODS: Sixteen volunteers (Fitzpatrick skin types III-IV) with mild to moderate acne scars were enrolled. Acne scar lesions were treated with 1540-nm fractional photothermolysis (Starlux 1540). Three treatment sessions were performed for each patient 4 weeks apart. Outcome assessments included the following four methods: (1) clinical evaluation of the photographs that were taken before and after the treatment; (2) comparison of the quality of life (QOL) of the patients before and after the treatment; (3) patients' satisfaction with the treatment; and (4) comparison of the quantity of collagen and elastic fibers in the skin biopsies before and 12 weeks after the last treatment. RESULTS: A mild to moderate clinical improvement was observed in most of the patients. Moreover, the QOL of all the patients improved, and all of them were satisfied with the results of the treatment. Significant collagen and elastic-fiber increases were also observed after the treatment, and side effects were limited to transient erythema and edema, which occurred in 50% of the patients. No severe side effect was observed. CONCLUSIONS: 1540 nm fractional photothermolysis is an effective and safe method for improving acne scar, even in Asian skin.