A Prospective Study in the Treatment of Lentigines in Asian Skin Using 532 nm Picosecond Nd:YAG Laser

Background and objective: To evaluate safety and efficacy of treatment with the picosecond Nd:YAG 532 nm for lentigines in Asian skin.

Study design/materials and methods: This was a prospective, open-label cohort study, using a novel picosecond 532-nm laser for the treatment of facial lentigines. Subjects received up to three laser treatments every 4-6 weeks and were assessed at 4 and 12 weeks after final treatment. Primary endpoint was degree of improvement in lentigines at 12 weeks after the final treatment, assessed by treating investigator based on Physicians Global Assessment. Secondary end-points included degree of improvement in lentigines at 12 weeks after final treatment, assessed by subject (Subject's Global Assessment), and change in mean relative Melanin index (MI) value at 3 months after final treatment as compared to baseline as assessed by mexameter measurement.

Results: A total of 20 patients (3 male, and 17 female) of Asian-descent with Fitzpatrick skin type III and IV, with lentigines on the face were included in this study. A total of 89 lesions were treated with the laser setting of 532-nm, 750 picoseconds, fluence of 0.2-0.5 J/cm ² , and spot size of 4 mm. One hundred and thirty-seven treatment sessions were given in total. Eighteen patients (90%) achieved a moderate to significant improvement at 12-week follow-up based on a 5-grade physician global assessment scale. The improvement rate of relative MI (MI in the lesion minus normal skin) was 33.30 ± 18.71 and 37.63 ± 19.25% at 4- and 12-week follow-up. Post-inflammatory hyperpigmentation (PIH) occurred in 14 of 137 sessions (10.2%), and hypopigmentation occurred in one patient with five lesions (3.6%).

Conclusion: This study demonstrates that using picosecond Nd:YAG laser 532 nm for removal of solar lentigines in darker skin type appears to be safe and effective. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Limitations: Small study group.