The occurrence of skin irritation and contact dermatitis is a common problem in various occupational groups. The use of barrier creams represents a frequently utilized prophylactic measure for the protection of the skin, even if their effectiveness is hotly debated. Up to now, a number of in-vivo and in-vitro methods are in existence for the evaluation of barrier creams (BC), which have shown different results regarding the effectiveness of BC. The aim of the present study was the application of the in-vivo laser scanning microscopy for the evaluation of barrier creams. Therefore, sodium fluorescein was applied topically to track its penetration. Three different barrier creams were investigated (Vaseline (B) and 2 different commercially available barrier creams (C and D)) and compared to a reference area (A). It was shown that Vaseline represents a 100% protection against sodium fluorescein as no fluorescence could be detected in the stratum corneum. For barrier cream C, only a weak fluorescent signal was detectable, while in the case of barrier cream D, the fluorescent signal was comparable to that of the reference skin area. The present study revealed that the laser scanning microscopy represents an adequate, non-invasive, quick in-vivo technique for the evaluation of BC that even tracks low differences of effectiveness, which enables the ranking of BC. µmThe penetration of sodium fluorescein through untreated skin

Often barrier creams (BC) do not fulfil their protecting behaviour, even when promised by the manufacturers. Therefore, it is of great importance to develop standardized in vivo techniques to prove the potency of BC in humans. In the present study, 3 promising techniques for the analysis of BC were evaluated: laser scanning microscopy, laser doppler flowmetry, and the tape-stripping procedure. Sodium fluorescein and glycerol trinitrate acted as hydrophilic model-penetrating substances. By means of these methods, 3 different BC were tested and compared for their potency. The investigations showed that primarily the tape-stripping procedure and also the laser scanning microscopy are promising tools for the evaluation of BC. In contrast, the laser doppler flowmetry represents a less feasible technique. In addition, the evaluation of BC showed that Vaseline enfolds a 100% barrier on the skin surface for the penetration of a hydrophilic dye, whereas BC1 only partially showed a protective effect and BC2 exhibited almost no potency. In conclusion, it can be referred that laser scanning microscopy and the tape-stripping procedure represent 2 non-invasive in vivo techniques, which enable a fast investigation concerning the potency of BC.

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