The Efficacy and Safety of Low- Versus High-Fluence Fractional Picosecond Nd:YAG 1064-Nm Laser in the Treatment of Acne Scars: A Randomized Split-Face Comparison Study

Background: Differences in clinical efficacy based on the fluence of fractional picosecond laser treatment for acne scars are unknown. Objective: To compare the efficacy and safety of low-fluence versus high-fluence fractional picosecond Nd:YAG 1064-nm laser treatment in acne scar patients. Methods: In this 12-week, investigator-blinded, randomized, split-face study, 25 patients with moderate-to-severe acne scars received three sessions of high-fluence laser treatment (1.0 J/cm(2)) on one side of their face and low-fluence (0.3 J/cm(2)) on the other side every 4 weeks. Patients were assessed using acne scar counts, the scar global assessment (SGA), and the ECCA scar grading scale every 4 weeks. The histological analysis compared the acne scars obtained before and 4 weeks after treatment. Results: At their last visit, 88.00% and 92.00% of the subjects achieved >30% reduction in scar counts on the low- and high-fluence sides, respectively, without a significant difference between the two sides. On both sides, the scar counts, SGA, and ECCA score significantly improved 4 weeks after the last treatment. Although the high-fluence side showed a greater reduction in scar counts (-66.73%) than the low-fluence side (-62.13%), the two sides had no significant difference in the grading scores. The high-fluence side showed significantly more severe pain and higher side-effect scores immediately and 4 weeks after treatment. Histological analysis revealed a significantly increased collagen, elastin, and vimentin expression after treatment on the low-fluence side. Conclusions: The low-fluence setting demonstrated comparable efficacy and superior safety in treating acne scars compared with the high-fluence setting.