Efficacy of Minimal Blistering Dose-Based Versus Conventional Excimer Laser Therapy for Vitiligo

Excimer laser therapy is an established treatment for vitiligo, but the optimal irradiation protocol remains unclear. Irradiation based on the minimal blistering dose (MBD) was recently proposed, but its efficacy relative to conventional protocols has not been systematically evaluated. In this study, we retrospectively analyzed 43 patients with vitiligo who underwent more than 20 sessions of excimer laser therapy at Nagoya City University Hospital, including 29 treated with the conventional protocol and 14 with the MBD protocol. In the conventional group, treatment was initiated at half the minimal erythema dose (MED) and gradually increased, whereas in the MBD group, treatment was initiated at twice the MED and maintained at the MBD, with further increases after photohardening. Treatment efficacy was assessed using the Vitiligo Area Scoring Index (VASI) at baseline, and after the 10th and 20th irradiation sessions. The MBD group showed significantly greater improvement in VASI (%) compared with the 1/2 MED group (p = 0.0041). The area under the curve (AUC_₀-₂₀) for ΔVASI% over 20 sessions was also significantly higher in the MBD group (p < 0.0001). Furthermore, Kaplan-Meier analysis of time to VASI 50 achievement demonstrated that patients in the MBD group reached VASI 50 significantly earlier than those in the 1/2 MED group. Adverse events, including erythema, burning, and blistering, were mild and transient and resolved without treatment discontinuation. In conclusion, MBD-based excimer laser irradiation achieved earlier repigmentation with fewer sessions compared with the conventional protocol without a statistically significant increase in cumulative irradiation dose. This approach may reduce the treatment burden and accelerate clinical improvement in patients with vitiligo.