In vivo measurement of the human epidermal thickness in different localizations by multiphoton laser tomography.

Background: The in vivo measurement of epidermal thickness is still challenging. While ultrasound, optical coherence tomography and confocal laser microscopy are used with moderate success, this issue has not been addressed by multiphoton laser tomography.

Objectives: In the present study, an in vivo measurement of four different morphometric epidermal parameters is performed.

Methods: Thirty healthy volunteers aged 21-82 years were included in the study after informed consent and approval of the local ethics committee. At the dorsal forearm and the dorsum of the hand, the thicknesses of the total epidermis, viable epidermis and stratum corneum and the depth of the papillary dermis were calculated from depth-resolved intensity curves after correlation with multiphoton images.

Results: We have shown consistently that in all age groups, the four morphometric parameters are significantly higher at the hand compared with the forearm, while there were no differences between age groups. This is consistent with most previous findings.

Conclusion: The method presented here provides a novel in vivo investigation tool for the measurement of epidermal morphometric parameters that may be useful for the observation of epidermal changes over time in skin disorders, therapy side effects or in cosmetic science.