Thermal Response-Based Evaluation of Non-Ablative Fractional Er:Glass Laser Therapy for Scar Management: A Retrospective Observational Study with Forward-Looking Infrared (FLIR) Monitoring.

Background/Objectives: Non-ablative fractional lasers are widely used for scar remodeling, yet treatment parameters are often selected empirically, and thermal thresholds for consistent outcomes remain undefined. This study explored whether forward-looking infrared (FLIR) thermography can estimate laser-induced surface temperature changes during 1550 nm Er:Glass laser therapy and examined the association between post-treatment temperature elevation and early clinical improvement. Methods: A retrospective analysis was conducted on patients treated with fractional Er:Glass laser for post-surgical or traumatic scars. Skin temperature was recorded using FLIR C5 imaging at baseline (T0), after topical anesthesia (T1), and immediately post-treatment (T2). The temperature change (ΔT2) was calculated as T2 - T0. Clinical outcomes were assessed one month after treatment using standardized digital photographs and Vancouver Scar Scale (VSS) scores. Safety data were collected from post-procedure observations and patient reports. Results: Mean surface temperature increased from 32.4 ± 0.9 °C at T0 to 33.7 ± 0.7 °C at T2 (ΔT2 = +1.3 ± 0.6 °C, p < 0.001). Hypertrophic scars showed higher ΔT2 values than linear scars (p = 0.02). A moderate temperature elevation was modestly associated with early VSS improvement (r = 0.42, p = 0.003). Representative cases with ΔT2 values around 1.5-2.5 °C exhibited favorable short-term changes in texture and pigmentation. No adverse events were observed during follow-up. Conclusions: Real-time FLIR thermography may provide a non-invasive method to indirectly assess surface thermal response during non-ablative fractional treatment. A moderate temperature increase may be associated with an exploratory thermal response range linked to early clinical improvement, but the findings are preliminary. Further prospective, controlled studies with standardized treatment parameters and longer follow-up are required to clarify whether ΔT2 has clinical relevance as a physiologic parameter for temperature-based assessment in scar management.