Efficacy and safety of the picosecond 755-nm alexandrite laser for treatment of dermal pigmentation in Asians—a retrospective study

Q-Switched laser devices have been a standard treatment modality for dermal pigmentary disorders since the 1990s. However, the adverse events are sometimes intolerable even if the efficacy has been well accepted. These adverse events stop the patient from continuing the treatment and cause other cosmetic issues. Since 2012, the first picosecond laser for cosmetic applications was approved; it seems promising for treating pigmentary disorders in a new way, but lack strong evidence. We evaluated the efficacy and safety of a 755-nm picosecond laser for treatment of dermal pigmentary disorders in Asians. This is a 2-year retrospective study. We reviewed 36 female cases, including 8 cases of nevus of Ota and 28 cases of acquired bilateral nevus of Ota-like macules. Institutional Review Board (IRB) approval was granted by the Chang Gung Memorial Hospital medical research ethics committee (IRB 201900833B0). The epidemiologic data was collected. These patients have been treated with the 755-nm picosecond laser for 1 to 4 sessions at variable treatment interval. Our parameter settings were fluence of 2.73–3.98 J/cm², with a spot size of 2.9 to 2.4 mm under the 650-ps mode. The pulse duration is 650 ps and fluence range is from 2.73 to 3.98 J/cm. Photographs were taken prior to every treatment and 1 month following the treatment. Two dermatologists conducted the clinical evaluation independently. Clinical improvement was observed in all with a minimal side effect. A total of 88.89% of patients had moderate to marked improvement in following 1 to 4 sessions. Transient swelling and erythema were observed in all patients but resolved within 24 h. Only one patient (2.78%) developed hypopigmentation and two patients (5.56%) had hyperpigmentation temporarily. Faster clearance could be achieved by the picosecond 755-nm laser for treating dermal pigmentary disorders in Asians. The treatment course is well tolerable and has minimal side effects.