Fractional ablative erbium YAG laser: Histological characterization of relationships between laser settings and micropore dimensions

Background and Objectives Treatment of a variety of skin disorders with ablative fractional lasers (AFXL) is driving the development of portable AFXLs. This study measures micropore dimensions produced by a small 2,940 nm AFXL using a variety of stacked pulses, and determines a model correlating laser parameters with tissue effects. Materials and Methods Ex vivo pig skin was exposed to a miniaturized 2,940 nm AFXL, spot size 225 µm, density 5%, power levels 1.15–2.22 W, pulse durations 50–225 microseconds, pulse repetition rates 100–500 Hz, and 2, 20, or 50 stacked pulses, resulting in pulse energies of 2.3–12.8 mJ/microbeam and total energy levels of 4.6–640 mJ/microchannel. Histological endpoints were ablation depth (AD), coagulation zone (CZ) and ablation width (AW). Data were logarithmically transformed if required prior to linear regression analyses. Results for histological endpoints were combined in a mathematical model. Results In 138 sections from 91 biopsies, AD ranged from 16 to a maximum of 1,348 µm and increased linearly with the logarithm of total energy delivered by stacked pulses, but also depended on variations in power, pulse duration, pulse repetition rate, and pulse energy (r2 = 0.54–0.85, P