Morphometry of human epidermis in vivo by real-time confocal microscopy.

Real-time confocal microscopy has brought substantial improvements to the imaging of the human skin in vivo. On early images, the stratum corneum could be distinguished from the living epidermis and the circulatory network of the superficial dermis. We have adapted the Tandem Scanning Microscope to obtain images of the living skin, showing thinner structures such as the stratum lucidum and the dermo-epidermal junction, both of which are essential markers for micron-order measurements of the thickness of the stratum corneum and living epidermis. The measurements were corrected for the differences in the refractive index of the various cutaneous layers, and the undulation of the dermo-epidermal junction. Furthermore, nucleus size and number could be assessed from horizontal optical sections. To illustrate the sensitivity of the thickness measurements, changes in the thickness of the epidermis were recorded during and after stripping of the horny layers. This non-invasive methodology is a very promising tool for morphometric studies of the living human skin at the cellular level.