Histology of ex vivo skin after treatment with fractionated picosecond Nd:YAG laser in high and low-energy settings

Abstract

<b>Background</b>: The fractionated picosecond laser produces microscopic lesions in the epidermis and dermis, which are known as laser-induced optical breakdown (LIOB) and intra-dermal laser-induced cavitation (LIC). There have been multiple histological reports on these phenomena, although some have been challenged on the grounds of similarity to artifacts. Asian skins, with a higher melanin content, may react differently to this treatment, and present literature is also lacking in this area.<b>Purpose</b>: To observe and report the histological effect of different energy levels and parameters of the fractional 532 nm/1064 nm picosecond laser on Asian skin ex vivo.<b>Methods</b>: Six skin samples were taken from clinically normal-looking perilesional areas and treated with different energy levels and parameters of the fractional 532 nm/1064 nm picosecond laser. The specimens were then sent to the lab for H&E staining, and the slides were reviewed by a dermatopathologist.<b>Results</b>: Superficial, intra-epidermal LIOBs were seen in skin treating at higher laser energies; deep, intra-dermal LICs were seen in skin treated at lower energies. Lesion sizes and depths were consistent with previously reported values on Caucasian skins, and lesions were spaced in 600-μm intervals or its multiple.<b>Conclusions</b>: The histological findings are consistent with results from other ethnicities, and the spacing of lesions is a strong indication of their validity as LIOBs or LICs.