Development and Validation of the Cheek Smoothness Scale: A Photonumeric Assessment Tool for Cheek Skin Texture

Changes in cheek skin texture and surface smoothness are prominent features of facial aging and increasingly targeted by modern aesthetic interventions. However, despite rising demand for minimally invasive aesthetic procedures to improve cheek skin quality, validated site-specific photonumeric assessment tools remain limited.

To develop and validate a novel photonumeric assessment tool, the Cheek Smoothness Scale (CSS), for evaluating cheek skin smoothness and surface texture.

The CSS was developed as a five-grade photonumeric scale using standardized clinical photographs. Inter- and intra-rater reliability were assessed using Fleiss' and Cohen's kappa statistics based on single-angle (45°) and multi-angle image assessments by five board-certified dermatologists. Construct validity was further examined by objective skin surface roughness measurements (Ra values) obtained using the PRIMOS CR three-dimensional imaging system.

The CSS demonstrated excellent inter- and intra-rater reliability, with kappa values consistently in the good-to-very good range. Complete agreement between single- and multi-angle assessments supported the use of the 45° oblique view as a representative angle for evaluating cheek skin texture. CSS grades also showed a progressive increase in PRIMOS-derived Ra values, indicating strong concordance between visually assessed skin smoothness and objectively measured surface roughness.

The CSS is a reliable, reproducible, and clinically meaningful photonumeric scale for assessing cheek skin smoothness and surface texture. By integrating visual assessment with objective validation of surface smoothness, the CSS provides a valuable outcome measure for clinical research and real-world aesthetic practice.