Wenande Emily, Jacobsen Kevin, Grove Gabriela Lladó, Paasch Uwe, Haedersdal Merete
Department of Dermatology, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Copenhagen, Denmark.
University of Leipzig, Leipzig, Germany.
J Cosmet Dermatol. 2025 Jul;24(7):e70304. doi: 10.1111/jocd.70304.
Infrared fractional lasers that target tissue water are traditionally divided into nonablative and ablative devices. The 1927 nm fractional thulium fiber laser (FTL) may, due to an intermediate water absorption coefficient, offer a range of nonablative-to-ablative effects.
This study explored dynamic 1927 nm FTL-tissue interactions produced by different pulse energies in in vivo human skin, using non-invasive optical coherence tomography (OCT) and line-field confocal OCT (LC-OCT) imaging.
FTL exposure was performed on in vivo antero-lateral forearm skin at 0, 3, 15, or 20 mJ pulse energy using two separate laser tips (spot size: 200 μm (C1); 350 μm (C5)) at 20-watt power. Immediately after, LC-OCT and OCT imaging enabled qualitative description of microthermal treatment zone (MTZ) morphology, as well as semiquantitative measurement of MTZ diameter and ablation depth.
Ranging from nonablative subepidermal effects to frank ablation, imaging revealed a variety of MTZ morphologies depending on pulse energy and laser tip. At low 3 mJ pulse energy, effects were generally limited to the epidermis, with MTZs consisting of subepidermal clefts (C5) or disruptions through the viable epidermis (C1) under a residual stratum corneum. Rising 15-20 mJ pulse energies expanded thermal effects in the lateral and vertical plane, leading to wider MTZs (e.g., C1: 3 mJ vs. 20 mJ: 213 vs. 357 μm), more extensive stratum corneum involvement, and increasing ablation depth to the superficial dermis (e.g., C1: 3 mJ vs. 20 mJ: 93 vs. 101 μm).
Visualized by combined LC-OCT and OCT imaging, FTL-tissue interactions are highly modifiable and span the nonablative to ablative spectrum depending on pulse energy and laser tip.
传统上，靶向组织水分的红外分数激光分为非剥脱性和剥脱性设备。1927纳米分数铥光纤激光器（FTL）由于其中等的水吸收系数，可能会产生一系列从非剥脱到剥脱的效果。
本研究使用非侵入性光学相干断层扫描（OCT）和线场共聚焦OCT（LC-OCT）成像，探索了不同脉冲能量在体内人体皮肤中产生的动态1927纳米FTL与组织的相互作用。
使用两个不同的激光头（光斑尺寸：200微米（C1）；350微米（C5）），以20瓦功率，在体内前臂外侧皮肤以0、3、15或20毫焦的脉冲能量进行FTL照射。照射后立即使用LC-OCT和OCT成像对微热治疗区（MTZ）形态进行定性描述，并对MTZ直径和消融深度进行半定量测量。
成像显示，从非剥脱性的表皮下效应到明显的消融，根据脉冲能量和激光头的不同，MTZ呈现出多种形态。在3毫焦的低脉冲能量下，效应通常仅限于表皮，MTZ由表皮下裂隙（C5）或在残留角质层下穿过活表皮的破坏（C1）组成。脉冲能量升至15 - 20毫焦时，热效应在横向和垂直平面上扩展，导致MTZ更宽（例如，C1：3毫焦与20毫焦：213微米与357微米），角质层受累更广泛，消融深度增加至浅表真皮（例如，C1：3毫焦与20毫焦：93微米与101微米）。
通过LC-OCT和OCT成像联合可视化，FTL与组织的相互作用具有高度可调节性，根据脉冲能量和激光头的不同，涵盖了从非剥脱到剥脱的范围。
