Multiphoton tomographic analysis of hyaluronic acid delivery: comparison of carbon dioxide laser and 1927 nm thulium laser over time.

Hyaluronic acid injections, known as skin quality boosters (SQB), improve skin hydration and quality. Laser-assisted delivery using ablative (AFL) and non-ablative fractional lasers (NAFL) enhances the uptake of topical drugs and cosmeceuticals. This study aims to compare the biodistribution of SQB as well as the morphologic and metabolic cellular changes following CO₂ and thulium (Tm) laser treatments. Healthy male and female volunteers were assigned to either the CO₂ laser or the Tm laser treatment group. Areas on their forearm were marked for following treatments: laser with SQB application, laser monotherapy, topical SQB monotherapy, and untreated control. Measurements were carried out 30 min and 30 days post-treatment using multiphoton-tomography equipped with fluorescence lifetime imaging (MPT-FLIM). Eleven volunteers were included in each group. SQB penetration reached the upper dermal layer in both groups, with larger aggregates after CO₂ treatment. The CO₂ laser induced a higher level of inflammation, which persisted as subclinical inflammation even 30 days post-treatment. In contrast, skin treated with the Tm laser showed a metabolic state similar to the untreated control after 30 days. Both CO₂ laser and Tm laser enhance cutaneous uptake of the SQB, potentially improving skin hydration and quality. While the CO₂ laser may be more effective in delivering SQB, the Tm laser may be a treatment option with minimal downtime. MPT-FLIM proved to be a suitable tool for monitoring treatment outcomes.