Selective photothermolysis in acne treatment: The impact of laser power.

BACKGROUND: Selective photothermolysis (SPT) using a 1726 nm laser has emerged as a safe and effective treatment option for acne vulgaris by targeting sebaceous glands (SG). Power output plays a crucial role in determining treatment selectivity and efficacy. AIMS: This work highlights the advantages of a higher-power laser source and outlines the limitations of lower-power laser sources and the subsequent impact on treatment. METHODS: Light transport and bioheat transfer simulations were performed to demonstrate photothermal impact on the SG and the surrounding dermis when irradiated by a high- or lower-power laser source. RESULTS: The simulations showed that a single higher-power-shorter-pulse (HPSP) selectively increases SG temperature well beyond bulk temperatures, which is desirable for SPT. Selectivity decreases linearly with power for the single lower-power-longer-pulses (LPLP) exposure. A multiple-LPLP approach elevates bulk temperatures significantly more than a single-pulse strategy, compromising selectivity. CONCLUSION: The goal of SPT is to damage SG safely and effectively by creating an intense temperature rise localized to the SG while moderately increasing the dermis temperature. This goal is mostly achieved with higher-power lasers that deliver a single HPSP. Lower-power lasers, longer pulse widths, and multi-pulse strategies result in higher bulk temperatures and lower SG selectivity, making such treatment challenging to execute while adding a higher risk of discomfort and downtime.