Abstract: 【Abstract】 Objective To evaluate the efficacy and safety of fractional CO? laser combined with topical botulinum toxin type A （BTX-A） in the treatment of enlarged facial pores. Methods A randomized, split-face, self-controlled trial was conducted. A total of 34 patients with enlarged facial pores were enrolled from the Department of Dermatology, the First Hospital of China Medical University, and Wuxi Aiyu Medical Aesthetic Clinic between July 2022 and January 2024. The two sides of the face were randomly assigned as the combination side and the control side, respectively. All patients first received full-face fractional CO? laser treatment; immediately after laser treatment, the combination side was topically treated with 1 ml of BTX-A at 50 U/ml, while the control side with 1 ml of normal saline. The treatment was performed twice at a 3-month interval. Follow-up visits were conducted at baseline, day 3, and months 1, 2, and 3 after each treatment （9 visits in total）. The primary endpoint was the overall Physician Global Aesthetic Improvement Scale （PGAIS） score, and the secondary endpoints included the overall Subject Global Aesthetic Improvement Scale （SGAIS） score and overall patient satisfaction score. Changes in the pore diameter, area, and density were assessed using the VISIA skin analyzer; changes in the pore prominence and depth were evaluated via VISIA absolute pore scores and three-dimensional images; changes in the skin erythema and porphyrins during the recovery period were assessed using VISIA absolute scores for the red area and porphyrin. Pain was assessed using the Visual Analog Scale （VAS）. Adverse reactions were recorded throughout the treatment and follow-up periods. Between-group differences were analyzed using repeated-measures analysis of variance and paired-samples t-test, with Bonferroni correction for multiple comparisons. Results Thirty patients completed all treatments and follow-up visits, with the age being 34.5 ± 9.8 years, including 12 males and 18 females. The overall PGAIS, SGAIS, and satisfaction scores on the combination side （4.29 ± 0.22 points, 4.28 ± 0.55 points, 4.25 ± 0.39 points, respectively） were all significantly higher than those on the control side （4.08 ± 0.29 points, 4.00 ± 0.61 points, 4.11 ± 0.37 points, respectively, all P < 0.05）. At the last follow-up visit, the major diameter, minor diameter, area, and density of pores on the combination side were all significantly lower than those on the control side （all P < 0.05）; there was no significant difference in the VISIA absolute pore score between the combination side （19.22 ± 10.26 points） and the control side （20.73 ± 9.18 points, t = 1.15, P = 0.264）; the VISIA absolute score for the red area on the combination side （41.39 ± 5.88 points） was significantly lower than that on the control side （43.43 ± 7.03 points, t = 2.64, P = 0.015）; except at baseline and the final follow-up visit, the VISIA absolute score for porphyrin on the combination side was significantly lower than that on the control side at all time points （all P < 0.05）. A total of 60 treatment sessions were performed in 30 patients. The facial pain VAS score during treatment on both sides was 3.82 ± 1.99 points. Three episodes of bilateral hyperpigmentation were reported in 2 patients after treatment. Conclusion Fractional CO? laser combined with topical BTX-A was more effective than fractional CO? laser alone in the treatment of enlarged facial pores, with a comparable safety profile.

Key words: Botulinum toxins, Enlarged facial pores, Fractional carbon dioxide laser, Treatment, Split-face study, Treatment outcome, Safety