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

Abstract 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.