Histological investigation of picosecond laser-toning and fractional laser therapy

Abstract

Rejuvenation therapy using picosecond pulse laser and picosecond pulsed fractional therapy with a fractional lens have been performed with clinical effects evaluated. However, no histological analysis of effects on photoaged skin exists. In this study, influence of laser-toning and fractional therapy using picosecond pulse laser on photoaging was histologically investigated. The flexor side forearm of a male, age 61, with photoaging was divided into three 20 cm2 areas and irradiated with approximately 400 shots of 10-Hz laser, 8 mm spot size, and nine passes at an output of 0.7, 0.9, and 1.1 J/cm2 using picosecond laser-toning therapy six times, every two weeks. Two weeks post final irradiation, 2 mm punch biopsies were taken from the irradiation fields. Fractional therapy using Micro Lens Array (MLA) attached picosecond fractional therapy was applied to the medial crural skin with marked photoaging of a male, age 63. Irradiation was applied at 0.5 and 0.7 J/cm2 through two passes, with 3 mm punch biopsies taken from each irradiation field immediately after and again two months post-irradiation. Samples were subjected to hematoxylin and eosin (HE) and Elastica van Gieson staining and compared. In the picosecond laser-toning therapy sample, photoaging-induced dermis reconstruction occurred. The picosecond fractional therapy sample showed both epidermis and dermis reconstruction, with intrinsic aging and photoaging improvements. Recovery of dermal and epidermal age related atrophy by picosecond laser-toning and picosecond fractional therapy was histologically confirmed. Picosecond fractional therapy demonstrated superior improvement.