Efficacy of Combined 1927nm Thulium Fiber Laser and Supramolecular Salicylic Acid in Photoaging Treatment

Purpose: 1927nm fractional thulium fiber laser (TFL) has been shown to be effective in improving skin appearance by reducing pigmentation and loss of elasticity caused by photoaging. Supramolecular salicylic acid (SSA) has been utilized for chemical peeling with rejuvenation effect. This study aims to evaluate the effectiveness and safety of combined TFL and SSA treatment for photoaging.

Methods: Thirty-six patients with moderate-to-severe photoaging were enrolled and the two sides of the participants' face were randomly assigned to receive 30% SSA combined with TFL or TFL monotherapy. TFL was administered to both sides of the face on four occasions at four-week intervals, while the side receiving combined treatment additionally underwent eight chemical peels of 30% SSA fortnightly, supplemented by daily applications of 2% SSA. For the TFL-alone side, an equivalent dose of a placebo preparation was applied. The photographs, photoaging scores, melanin index (MI), erythema index (EI), skin hydration, trans-epidermal water loss (TEWL), dermal thickness, elasticity index, and skin rebound time were assessed.

This prospective, split-face, randomized, double-blind clinical trial evaluated the efficacy of fractional thulium fiber laser (TFL) monotherapy versus TFL combined with topical succinic acid (SSA) for photoaging treatment. Eligible participants (aged 40-70 years) with symmetric facial photodamage and a modified photoaging scale score \>11 were enrolled, excluding individuals with systemic diseases, skin pathologies, recent aesthetic treatments, or SSA allergies. Following ethical approval (MR-61-23-03452; 2023019) and informed consent, subjects underwent four TFL sessions (1927 nm, 8-10 mJ, 10 W, 0.8 mm spacing) at 4-week intervals. Post-TFL, one randomized facial side received 30% SSA (or placebo, biweekly) and 2% SSA (or vehicle, daily) for 16 weeks, with allocation blinded to participants and investigators. Interventions were standardized using a clinical endpoint of mild erythema/epidermal whitening, followed by saline rinsing and medical mask application. Preprocedural anesthesia with compound lidocaine cream and postoperative protocols (ice packs for adverse events, medical masks, sun protection, and delayed cleansing until scab detachment) were implemented. Adverse events and adherence to post-treatment care were monitored. The study adhered to Declaration of Helsinki principles, with anonymized data analysis and oversight by the ethics committee of the Second Affiliated Hospital of Xi'an Jiao Tong University.

Eligibility Criteria:
Inclusion Criteria:

- Enrolled patients were scored using the Modified Photodamage Scale (total score of 16), and subjects with a score greater than 11 were ultimately included (less than 4, mild; up to 4-8, moderate; up to 8-12, advanced; and greater than 12, severe photodamage).

Exclusion Criteria

* Severe systemic disease
* Skin tumours or infections
* Currently pregnant or breastfeeding
* Recent use (within the last 6 months) of oral or topical medications or phototherapy, laser, filler or botulinum toxin treatment
* Allergy to SA
* A history of keloid scarring.