APPLICATION OF COLORIMETER IN THE MANAGEMENT OF MELASMA WITH FRACTIONAL ND:YAG PICOSECOND LASER

Abstract

Objectives: To evaluate the applicability of colorimetry in measuring and monitoring patients with melasma treated with fractional Nd:YAG picosecond laser.

Methods: A descriptive study of a series of cases was conducted on 31 female patients with melasma at the Department of Dermatology – Aesthetic Dermatology, University Medical Center Ho Chi Minh City from September 2024 to May 2025. L* and a* values of the melasma lesions on the face were measured before and after treatment, and MASI scores were recorded. Statistical analyses were performed to assess correlations and pre- and post-treatment changes.

Results: Skin type IV predominated (93.5%), and the centrofacial pattern accounted for 64.5%. The mean MASI score decreased significantly after treatment (p <0.001). L* increased slightly after treatment compared to baseline (58.5 ± 2.4 to 59.4 ± 2.4), while a* decreased slightly (14.9 ± 1.3 to 14.7 ± 1.3). Correlation analysis showed a strong negative correlation between L* and MASI (r = –0.799 before treatment, r = –0.746 after treatment), whereas a* showed a positive correlation with MASI (r = 0.617 before treatment, r = 0.645 after treatment), all statistically significant (p <0.05).

Conclusions: The colorimeter supports objective assessment of melasma severity through L* and a* indices, aiding in monitoring treatment effectiveness.

Keywords: melasma; colorimeter; a* index; L* index