P9.116 Optical coherent tomography (OCT): A new method for online-measurement of hair shaft thickness

U. Blume-Peytavi, J. Vieten, A. Knüttel*, C. Sommer, J. Lademann

Center of Experimental and Applied Cutaneous Physiology, Department of Dermatology, Charité - Universitätsmedizin Berlin, Schumannstr. 20/21, 10117 Berlin, Germany; *ISIS Optronics GmbH, Mannheim

Measurement of hair shaft thickness is important particularly for the evaluation of influencing factors for hair growth. Human hairs are elliptical in shape, which means that the exact parameter for measurement of hair thickness is the face of cross-section and not the measurement of the diameter.

Hair shaft morphology and variations not only reflect ethnical diversity but also internal disorders or nutricial deficiency. Therefore, measurement and follow up of hair shaft thickness over several months can be a diagnostic tool but also a helpful monitor towards a successful therapy.

Optical Coherence Tomography (OCT), a non-invasive investigation method with a detection depth of approximately 1mm in human skin produces two-dimensional images with the resolution of approximately 50 µm, based on the principles of Michelson interferometry. In the present paper we demonstrate that OCT measurement could be a suitable method to determine in-vivo hair shaft thickness.

To develop this new methodology, we have analyzed hair shafts from 28 volunteers by OCT and compared these results to classical light microscopic measurements of hair shaft diameter with subsequent calculation of surface area. Image analysis of cross sections of hair shafts as well as obtained data from calculated hair shaft surface, clearly proved the superiority of the OCT measurement over other established and currently used methods. Light microscopy leads to higher variations of hair shaft values compared to OCT.

OCT is able to provide highly reproducible measurements of hair shaft thickness and is capable to reveal variations - increase, decrease stability – of hair shaft thickness. OCT presents an innovative method allowing in-vivo online measurement and follow up of hair shaft thickness.