Visualizing the in-vivo application of zinc in sensitive skin using reflectance confocal microscopy

Abstract

AbstractFindings obtained on objective assessments to evaluate sensitive skin do not correlate well with the symptomatology. We utilized reflectance confocal microscopy (RCM) to compare transepidermalapplicationof zinc in sensitive and non-sensitive skin. Thirty-six subjects participated in this study. They were divided into groups based on lactic acid sting test (LAST):‘stinger’ and ‘non-stinger’; transepidermal water loss (TEWL) measurements; and sensitivity self-assessments: ‘sensitive’ and ‘non-sensitive’. RCM images were taken to visualizetransepidermal applicationof topically-applied zinc. The intensity of zinc reflectance at different depths was measured by ImageJ software. Based on LAST scores, the ‘stinger’ group showed significantly higherreflectanceof zinc at 8 µm (stratum corneum) [face (P < 0.001), forearm (P = 0.004)], and at 80–104 µm (dermo-epidermal junction layer) on the face. High-TEWL group showed increased zincreflectanceat 8–24 µm (tight junction layer,P < 0.001). There were no significant differences amongst subjects self-reporting ‘sensitive’ and ‘non-sensitive’ skin. RCM demonstrates that in sensitive skin, there is deeper and higherreflectanceof zinc at multiple depths. Structural differences are also visualized. We suggest that RCM is a useful tool for evaluating skin barrier integrity.