A Split-Face, Single-Blinded, Randomized Controlled Comparison of 532 nm Picosecond Neodymium-Doped Yttrium Aluminum Garnet Laser versus 532 nm Q-Switched Neodymium-Doped Yttrium Aluminum Garnet Laser in the Treatment of Solar Lentigines

Background: Solar lentigines are the most common form of benign epidermal pigmentation and one of the major cosmetic concerns in Korea. A 532 nm Q-switched neodymium: yttrium-aluminum-garnet (QSND) laser is typically used for the treatment, but the occurrence of post-inflammatory hyperpigmentation (PIH) is not rare. Recently, the use of picosecond (PS) lasers has emerged in pursuit of better outcomes. Objective: To objectively compare the efficacy and safety of 532 nm PS and QSND lasers for the treatment of solar lentigines. Methods: Twenty patients with solar lentigines were enrolled in a prospective, randomized split-face, single-blind study. One side of each face was treated using a 532 nm PS laser, and the other side using a 532 nm QSND laser. After one treatment, all patients were followed up for evaluation after 2, 4, 8, and 12 weeks. The clinical clearance was assessed by three blinded dermatologists using a 5-point quartile improvement scale (QIS). Subjective satisfaction, development of PIH, pain scale during treatment, and adverse problems were also recorded. Results: Clinical clearance measured by QIS showed that the PS laser was more effective than the QSND laser. Subjective satisfaction and pain scale did not significantly differ between the two groups. The incidence of PIH was 5% in sides treated with the PS laser, and 30% with the QSND laser. Conclusion: Both 532 nm PS laser and QSND laser were effective for the treatment of solar lentigines, but the PS laser was more effective with less PIH development.