Efficacy of Intense Pulsed Light AOPT‐LTL Technique in the Treatment of Melasma: An In Vivo and Clinical Study

Purpose To evaluate the efficacy and underlying mechanism of advanced optimal pulse technology intense pulsed light (AOPT) in low‐energy triple‐pulse long‐width mode (AOPT‐LTL) for melasma treatment. Methods An in vivo guinea pig model of melasma was established through progesterone injection and ultraviolet B radiation. Three sessions of AOPT‐LTL treatment were performed weekly. The mRNA levels of key melanogenic enzymes, inflammatory factors, pro‐angiogenic cytokines, and collagenolytic proteases were detected by qRT‐PCR. Protein levels of stem cell factor (SCF) and mast cell growth factor receptor (c‐KIT) were detected by immunofluorescence staining and Western blotting. Twenty melasma patients were treated with three sessions of AOPT‐LTL treatment monthly, evaluated by the Modified Melasma Area and Severity Index (mMASI) and Erythema Index (EI). Results In guinea pigs with melasma, AOPT‐LTL treatment effectively mitigated pigmentation and suppressed the expression of key genes involved in melanin production. There was a reduction in mast cell infiltration, decreased expression of inflammatory factors and pro‐angiogenic factors, inhibition of angiogenesis, and alleviation of skin photoaging. Furthermore, AOPT‐LTL also diminished the expression level of the SCF/c‐KIT ligand/receptor pathway, which is closely associated with mast cell proliferation and activation. Consistently, three sessions of AOPT‐LTL treatment effectively reduced skin melanin content, erythema severity, as well as the mMASI and EI scores in melasma patients. Conclusions AOPT‐LTL treatment significantly enhances the improvement of melasma by diminishing melanogenesis, inflammation, angiogenesis, mast cell infiltration, and collagen degeneration, potentially through the inhibition of the SCF/c‐KIT ligand/receptor pathway.