Directional analysis of upper eyelid wrinkles and a quantitative index for periorbital ageing

OBJECTIVE: Periorbital ageing, manifested by wrinkles, exerts significant influence on perceived age and attractiveness, making this a primary target for anti-ageing interventions. Previous quantitative assessments of periorbital ageing have predominantly focused on the number or depth of wrinkles. In this study, we aimed to develop a novel approach to quantify age-related changes in the orientation of wrinkles on the upper eyelids. METHODS: This longitudinal study (2010-2019) involved 87 healthy Japanese women (aged 22-62 years) with up to nine time points. Facial images were captured by the VISIA-Evolution system and expert-rated wrinkle scores were generated for multiple facial regions. Images of the left upper eyelid were analysed by morphological opening to decompose the wrinkle line segments into six directions (0° to 150° from vertical). We then defined a wrinkle dominance index (WDI) for each direction and investigated its association with age and expert-rated wrinkle scores. RESULTS: Of the six directions, only the 60° WDI showed an evident age-related increase (r = 0.58, 95% confidence interval [CI]: 0.51-0.64); furthermore, this trend accelerated after 40 years of age. Participants ≥ 40 years of age with higher 60° WDI values exhibited significantly higher expert-rated wrinkle scores for the right lateral periorbital area (p < 0.05) and lower eyelids (p < 0.05) after adjusting for age. No significant associations were identified for non-periorbital facial regions. CONCLUSION: The 60° WDI of the upper eyelid represents a quantitative indicator of periorbital ageing progression. This image-based, orientation-specific metric provides a practical tool for the objective evaluation of periorbital skin ageing in both clinical and cosmetic applications.