Assessment of Facial Skin Tone Evenness After a Microdermabrasion-AHA/TXA-Peel Protocol: Instrumental Colorimetry and Time-Resolved Expert/Novice Image Evaluation

Background: Facial pigmentary unevenness is frequently perceived as distressing and is associated with lower ratings of attractiveness, health, and youthfulness. Microdermabrasion together with selected cosmeceuticals can improve superficial discoloration, however, evaluation methods for objective color comparison differ considerably. Methods: We conducted an uncontrolled prospective interventional study in adults (n=5; ≥35 years) with pronounced skin pigmentation (all skin types) during four standardized institutional sessions every 14 days including a microdermabrasion and cosmetic protocol. Standardized facial photographs were rated in randomized, time-resolved order by expert estheticians (experts n=7) and lay assessors (novice n=13) using 5-point Likert scale questionnaire. Instrumental Colorimetry (VisioFace RD) quantified distinctive spot area (dL, %) and complexion evenness (dE) at baseline and over the following 10 weeks. Results: Pigment spot appearance and overall skin tone evenness improved significantly over time. Experts and novice rated most attributes equally. Even though analysis using traditional CIEDE color distance equations did not fully reflect hu-man perception, the triangulated, time-resolved assessment captured changes more comprehensively than colorimetry alone. Conclusions: This combined regimen was associated with improved facial pigmentation and tone uniformity. Instrumental colorimetry using CIEDE2000 calculation is recommended for future work.