The effects of long-pulsed alexandrite laser therapy on facial redness and skin microbiota compositions in rosacea: A prospective, multicentre, single-arm clinical trial.

Background: Rosacea is a chronic skin disorder characterised by abnormal neurovasculature and inflammation in the central region of the face. The efficacy of pulsed-dye laser and intense pulsed light treatments for rosacea have been demonstrated in several clinical trials. However, there is currently no research on the efficacy of long-pulsed alexandrite laser (LPAL) therapy alone for rosacea-related facial redness and its effect on skin microbiota.

Aim: To evaluate the efficacy of LPAL therapy on facial redness in rosacea and assess changes in skin microbiota composition.

Methods: Subjects with rosacea (n = 21, mean age: 39.2 ± 11.3 years) were recruited from two medical institutions and received monthly LPAL treatments (Clarity II™, Lutronic Corp.) for 3 months. At each visit, clinical photographs were taken, and erythema was measured using a spectrometer. At the initial and final visits, the Dermatology Life Quality Index (DLQI) and Skin Sensitivity Questionnaire (SSQ) were evaluated. Skin swabs were obtained at the initial and final visit, and facial microbiome composition was analysed using 16S rRNA amplicon sequencing.

Results: After three LPAL treatment sessions, the average facial erythema index, measured using Mexameter® decreased significantly from 360.0 ± 96.7 at baseline to 312.0 ± 94.5 at the final visit (p < .05). The DLQI and SSQ showed significant improvement of symptoms. Skin microbiome diversity and relative abundance were altered significantly, particularly in the genera Clostridium, Lawsonella, Bacteroides, and Lactobacillus.

Conclusions: LPAL therapy alone showed favourable efficacy for the treatment of facial redness in rosacea, with some impacts on the skin microbiota composition.