Efficacy and Safety of Small-Spot 755 nm Picosecond Laser-Induced Optical Breakdown for Novel Photomechanical Skin Ablation in Asian Patients.

OBJECTIVES: Conventional ablative and photothermal lasers are commonly used to treat superficial pigmentary lesions but often induce thermal injury and post-inflammatory hyperpigmentation (PIH), particularly in Asian skin. Picosecond 755-nm alexandrite lasers with diffractive lens arrays (DLA) create laser-induced optical breakdown (LIOB) through a non-thermal photomechanical effect. However, the efficacy and adverse events of small-spot, high-fluence, ablation-dominant LIOB remain poorly defined in Asian patients. Ablation-dominant LIOB refers to high-fluence LIOB in which photomechanical effects predominate and produce direct tissue disruption with minimal thermal injury. This study aimed to evaluate a 5-mm high-fluence LIOB approach in Asian patients. MATERIALS AND METHODS: A retrospective chart review was conducted on patients who received 5-mm high-fluence LIOB. Demographics, diagnoses, treatment parameters, and serial photographs were collected. Clinical outcomes were independently assessed by two dermatologists using the Global Aesthetic Improvement Scale (GAIS) and pigmentation clearance rate (PCR). Treatments were delivered with a 5-mm 755-nm picosecond laser at 1.3-1.5 J/cm2 and 750 ps. All adverse events were documented. RESULTS: Thirty-three patients met the inclusion criteria. Superficial pigmentary lesions associated with photoaging or melasma were the most common indications. A mean of 1.45 treatment sessions had been completed by the efficacy evaluation day, with a mean follow-up of 66 days. The mean GAIS score was 3.67, and the mean PCR was 68.25%, with 80.65% of pigmentary lesions achieving good-to-excellent clearance. Non-pigmentary conditions demonstrated limited clinical responses. In selected complex photoaging cases, adjunctive large-spot (8-mm) low-fluence treatment was used before primary 5-mm LIOB-based ablation, with a mean GAIS score of 3.59. One patient developed a mild allergic reaction; no cases of scarring or PIH were observed. CONCLUSION: A high-fluence, 5-mm small-spot picosecond LIOB treatment protocol suggests a favorable safety and efficacy profile for superficial skin ablation in pigmentary and photoaging-related lesions in Asian patients, with minimal adverse effects. Pigmentary lesions showed more favorable responses than non-pigmentary lesions. Selected complex photoaging cases treated with adjunctive large-spot therapy showed favorable clinical improvement, supporting further investigation of this combined approach. This technique may broaden the role of picosecond lasers from pigment clearance to overall skin rejuvenation. Prospective controlled studies are warranted to confirm these preliminary findings.