Background
Under specific light illumination, particularly ultraviolet radiation (UVR), the skin produces both specular light reflectance and, possibly, specific fluorescent emission. A quenching effect of fluorescence is observed following the application of sunscreens active against UVA radiations.
Aims
To assess noninvasively in a real‐time process, the potential sunscreen remanence/substantivity after application on the skin.
Methods
The Visiopor® device was used in a real‐time procedure after application of sunscreens to the skin. A quenching effect of follicular fluorescence due to bacterial porphyrins was evaluated at 30‐min intervals. The Visioscan® device was used as a distinct UVA emitter in a control procedure of spectral analysis of specular UVR emission and reflectance by dermal fibers.
Results
Under UVA‐1 irradiations, facial skin produced different patterns of specular UVR reflectance and fluorescent emission as well. The porphyrin‐related follicular fluorescence was instantly abated by UVA blockers present in suncare products. The potential sunscreen remanence/substantivity was assessed by the follicular and interfollicular fluorescence recurrence all along the next hours.
Conclusions
All UVA blocker‐containing suncare products exhibited a similar overall quenching effect on porphyrin‐enriched facial hair follicles and dermal fibers. This effect lasted for a few hours. Differences in the fluorescence recovery were likely related to the amount in suncare application and the nature of the formulation components.