# Quantitative Evaluation of the Effectiveness of Erbium Glass Laser Therapy for Acne Scars
## 2 Materials and Methods  
Patients  
This study included 30 patients (16 women, 14 men) with mild to moderate atrophic acne scars and no new active acne lesions. The patients' ages ranged between 28 and 40 (mean 32 years, SD = 4.2) years. The inclusion criteria encompassed overall good health, age \(\geq\) 20 years, a diagnosis of pathological acne scarring, no contraindications to laser therapy, and a willingness to comply with the study protocol and attend follow-up visits. Exclusion criteria encompassed recent isotretinoin therapy within the last 6 months, filler injections or dermat abrasion in the past year, chemical peelings in the last 3 months, a personal history of hypertrophic scars or keloid formation, pregnancy, and lactation. The study was conducted in accordance with the Declaration of Helsinki. Our research obtained a positive opinion of the Ethics Committee of SUM No. PCN/0022/KB1/12/I/20 on 19 May 2020. All volunteers signed voluntary consent to participate in the study. Treatment  
Before the procedure, the patients cleansed their skin using gentle soap. One hour prior to treatment, a topical anesthetic cream (EMLA, AstraZeneca, Stockholm, Sweden) was applied to the skin. Additionally, the treatment area was disinfected with Kodan (Schulke & Mayr, Norderstedt, Germany). The patients were treated with a fractional 1550 nm erbium glass laser. Each patient was treated for 2 treatments at monthly intervals. The treatment comprised the following: an impulse time of 2.8 ms; a pulse energy of 30-35 mJ; a 70 \(\upmu\)m beam; a spot surface of 0.0038 mm\({}^{2}\); and an energy density of 0.035 J/0.000038 cm\({}^{2}\) = 921 J/cm\({}^{2}\). The DUB SkinScanner high-frequency ultrasonography, operating in B-scan mode with a 50 MHz transducer, was utilized to evaluate skin density (echo intensity) and epidermal thickness (entrance echo). Epidermal thickness was quantified in millimeters using the A-scan, while skin density was measured directly beneath the epidermis using the \"region of interest\" (ROI) function within the DUB SkinScanner software (DUB-SkinScanner/75 5.21). Images were acquired from the designated skin area pre- and post-laser treatments, with measurements consistently conducted at the same locations to ensure reproducibility. All images were obtained under standardized settings. Prior to each measurement, ultrasound gel was applied to the skin surface, and images were captured perpendicularly with minimal operator-applied pressure to maintain measurement accuracy. Antera Measurement  
All measurements were performed in the same room with no daylight under controlled ambient conditions (22-24 \({}^{\circ}\)C, 50-60% relative humidity). After a 20 min acclimatization, the Antera 3D camera (Miravex Limited, Dublin, Ireland) was utilized to capture images of the treated area both before the initiation of the treatment and months after the second session. The evaluation scores for texture, folds, volume, and melanin levels were analyzed using the Antera Pro software (version 2.8.6; Miravex Limited, Dublin, Ireland) (Table 1). Skin measurements from the Antera 3D were obtained on a measuring area of 5.6 \(\times\) 5.6 cm. Acquisitions were performed on the face area by placing the camera directly onto the skin without excessive pressure.