Review of Lasers and Energy-Based Devices for Skin Rejuvenation and Scar Treatment With Histologic Correlations

Abstract

BACKGROUND Lasers and energy-based devices (EBD) are popular treatments for skin rejuvenation and resurfacing. Achieving desired outcomes and avoiding complications require understanding the effects of these devices at a histologic level. Currently, no comprehensive review summarizing the histologic effects of laser and energy-based treatments exists. OBJECTIVE To describe how lasers and EBD alter skin histology and improve the overall understanding of these devices. MATERIALS AND METHODS A PubMed search was conducted for studies with histologic analysis of fractional picosecond laser, fractional radiofrequency microneedling, nonablative lasers, and ablative lasers. RESULTS Fractional picosecond lasers induce intraepidermal and/or dermal vacuoles from laser-induced optical breakdown. Fractional radiofrequency microneedling delivers thermal energy to the dermis while sparing the epidermis, making it safer for patients with darker skin phototypes. Fractional nonablative lasers induce conical zones of coagulation of the epidermis and upper dermis. Ablative lasers vaporize the stratum corneum down to the dermis. Traditional ablative lasers cause diffuse vaporization while fractional ablative lasers generate columns of tissue ablation. CONCLUSION Lasers and EBD are effective for skin resurfacing and rejuvenation and have different mechanisms with disparate targets in the skin. Safe and effective use of devices requires understanding the histologic laser-tissue interaction.

An update on fractional picosecond laser treatment: histology and clinical applications

“…Subsequently in the focus region, the electron density increases to form a plasma, which can more effectively absorb the remaining energy of the laser pulses. The plasma then expands driving the shock wave, and finally the expansion of the vaporized material creates cavitation bubbles, which spread outward into the nearby tissue, resulting in a microcavitation structural response [8,11].…”

“…These systems all employ fractional optical delivery devices attached to picosecond lasers [11]. In this article, we review the histological characteristics and clinical applications of fractional picosecond laser treatment (Table 1).…”

Fractional picosecond laser for atrophic acne scars: A meta‐analysis

“…4 Based on fractional photothermolysis theory, the fractional laser (FL) technique induces wound healing and neocollagenesis by targeting the microscopic treatment zones of the epidermis and dermis (AFL) or dermis only (NAFL). 5 The AFL treatments, for example, carbon dioxide (CO2) and Er:YAG lasers, are the most effective for atrophic scars. However, they still have unavoidable adverse events, including prolonged social downtime, obvious pain, and the risk of post-inflammatory hyperpigmentation (PIH).…”

“…5 They can generate significant photoacoustic and less photothermal effects, allowing for precise tissue targeting and fewer side effects. 5 Incorporation of the microlens array (MLA), diffractive lens array (DLA), diffractive optical elements (DOE), or holographic beam-splitting optic to picosecond lasers generates a fractional array of focused, highfluence microspots surrounded by low fluence background. [5][6][7][8] Immediately after radiation, fractional picosecond laser (FPL) histologically creates laser-induced cavitation (LIC) in the dermis or epidermis via laser-induced optical breakdown (LIOB).…”

1540-nm fractional laser treatment modulates proliferation and neocollagenesis in cultured human dermal fibroblasts

“…In addition, these post-treatment reactions should be associated with acute inflammatory responses to skin heat damage leading to increased side effects, such as persistent erythema, skin changes, PHI, scarring, and prolonged healing time (11,12). On the other hand, the lower absorption coefficient of 1540 and 1550 nm devices results in a greater maximum depth of 1400 µm (13). This different mode of delivering laser energy reduces the post-treatment erythema and recovery times (14).…”