Histological investigation of picosecond laser-toning and fractional laser therapy

Background and aims: 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.

Subjects and methods: 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.

Results: 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.

Conclusions: 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.

Keywords: Picosecond pulsed fractional therapy; Picosecond pulsed laser-toning therapy; Rejuvenation; intrinsic aging; photoaging.