Yuqing Huang,1,* Xing Liu,1,* Mengli Zhang,1 Tong Lin2 

1Department of Cosmetic Laser Surgery, Institute of Dermatology, Chinese Academy of Medical Sciences & Peking Union Medical College, Nanjing, Jiangsu, People’s Republic of China; 2Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Institute of Dermatology, Chinese Academy of Medical Sciences & Peking Union Medical College, Nanjing, Jiangsu, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Mengli Zhang, Department of Cosmetic Laser Surgery, Institute of Dermatology, Chinese Academy of Medical Sciences & Peking Union Medical College, Jiangwangmiao Street 12, Xuanwu District, Nanjing, Jiangsu, People’s Republic of China, Email zmlhlj@163.com Tong Lin, Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Institute of Dermatology, Chinese Academy of Medical Sciences & Peking Union Medical College, Jiangwangmiao Street 12, Xuanwu District, Nanjing, Jiangsu, People’s Republic of China, Email ddlin@hotmail.com

Objective: Freckles are common hyperpigmented diseases that commonly occur in Caucasians and Asians. Freckles often cause cosmetic and even psychosocial concerns. Various lasers with different wavelengths have been used to treat pigmented spots. This study aims to evaluate the efficacy and safety of a novel 730‐nm Ti: Sapphire picosecond laser in the treatment of freckles in Chinese patients.
Methods: A total of 12 patients with freckles were enrolled. Patients underwent one laser treatment and were followed-up after eight weeks. Images were captured before treatment and at the eight-week follow-up, which were independently examined by two physicians to assess the treatment efficacy, including the lesion clearance rate and global aesthetic improvement scale. Patients recorded their pain and other adverse effects. Ex vivo human foreskins were treated with 730 nm picosecond lasers for one pass with a 3.75 J/cm2 and then stained with hematoxylin and eosin (H&E).
Results: The average clearance rate as 74.46% and the mean GAIS as 4.13 ± 0.61. The pain scores were averaged at 3.08 ± 0.79. One patient exhibited hyperpigmentation (8.33%) and another patient developed hypopigmentation (8.33%) by the 8-week follow-up visit. A large number of uniform vacuoles were observed in the epidermal basal layer and the dermal papillae in the ex vivo foreskins, immediately after the treatment with 730-nm Ti: Sapphire picosecond laser. The vacuoles were uniformly sized, principally with 20– 40 μm diameter.
Conclusion: The 730‐nm Ti: Sapphire picosecond laser is safe and effective for treating freckles.

Keywords: freckles, 730-nm picosecond laser, Ti: Sapphire, GAIS, VAS