JMC Scientific Consulting Ltd, Egham, Surrey, UK.
The Procter and Gamble Company, Reading, Berkshire, UK.
Int J Cosmet Sci. 2024 Aug;46(4):610-622. doi: 10.1111/ics.12990.
While there are a wide range of approaches for the assessment of skin hydration, it is not always clear how data from them relate to one another or to the skin itself. With the development of in vivo Confocal Raman Spectroscopy (ICRS), it has become possible to measure water concentration as a function of protein/depth within the stratum corneum (SC). This article reports a comparison between electrical skin hydration measures/visual/optical grading and water concentration profiles measured using ICRS, to better understand the relationship between these approaches.
SC hydration of lower-leg skin with varying degrees of dryness was assessed using visual grading (live and from digital images), Corneometer®, Visioscan and ICRS. In addition, a custom fingerprint sensor was used to image surface capacitance (as a surrogate of SC hydration), and SC barrier function was assessed using evaporimetry (to measure trans-epidermal water loss; TEWL).
Significant correlations were observed between a number of different skin grading/measurement approaches and ICRS data. ICRS hydration profiles also revealed a region near the SC surface with a relatively flat water profile in dry skin subjects.
The advent of quantitative in vivo analytical techniques such as ICRS, which can be used in a clinical setting, has enabled greater insight into more conventional approaches for assessing skin dryness. While traditional skin grading and biophysical methods for measuring skin hydration have varying degrees of correlation with one another, they also provide comparatively unique information about different regions within the SC. This should enable a more informed approach to product development in the future.
虽然有广泛的方法可用于评估皮肤水分，但并不总是清楚它们之间的数据如何相互关联，或者与皮肤本身如何相关。随着体内共焦拉曼光谱（ICRS）的发展，已经可以测量角蛋白层（SC）中蛋白质/深度的水分浓度。本文报告了电皮肤水合度测量值/视觉/光学分级与使用 ICRS 测量的水浓度分布之间的比较，以更好地了解这些方法之间的关系。
使用视觉分级（现场和数字图像）、Corneometer®、Visioscan 和 ICRS 评估小腿皮肤不同干燥程度的 SC 水合作用。此外，还使用定制的指纹传感器来成像表面电容（作为 SC 水合作用的替代物），并使用蒸发法评估 SC 屏障功能（测量经表皮水分损失；TEWL）。
观察到许多不同的皮肤分级/测量方法与 ICRS 数据之间存在显著相关性。ICRS 水合作用分布还揭示了干燥皮肤受试者 SC 表面附近的一个相对平坦的水分布区域。
像 ICRS 这样的定量体内分析技术的出现，可在临床环境中使用，使我们能够更深入地了解评估皮肤干燥度的更传统方法。虽然传统的皮肤分级和测量皮肤水合作用的生物物理方法彼此之间具有不同程度的相关性，但它们也提供了关于 SC 内不同区域的相对独特信息。这应该能够为未来的产品开发提供更明智的方法。
