P10.140 Exogenous hair damage: Light microscopy of human hair shafts after in-vitro damage and application of hair care products

1) Department of Dermatology and Allergy, Center for Hair and Hair Diseases, Charite´- University Medicine Berlin, Campus Mitte, Berlin, Germany

2) Department of Dermatology and Venerology, University Medical Center Schleswig- Holstein,Campus Luebeck, Luebeck, Germany

Exogenous hair damage by chemical and physical factors causes characteristic hair shaft changes that have previously always been investigated by Scanning Electron Microscopy (SEM). While the use of SEM is limited, light microscopy is an easy-to-use and readily available routine method. Our aim was to evaluate the applicability of light microscopy to reveal surface changes after in-vitro damage of hair shafts and to establish a standardized method of hair shaft examination in daily practice. We developed a semiquantitative score of light microscopic surface criteria, including surface roughness, scale edge pattern, scale lifting and cortex damage. Single untreated hair shafts were fixed on microscope slides and assessed before and after standardized application of UV- radiation, heat, mechanical abrasion, a permanent wave product and a combination of these treatments. The doses of these procedures where chosen to represent influences common in daily life. In a second series of experiments, hair care products were applied to the hair prior or after combined treatment with hair damage (pre-care and after-care). Statistical analysis showed significant and specific changes in the chemically treated hair and a cumulative effect of combined damage. In addition, a significant protective effect of the pre-treatment with hair care products could be demonstrated, whereas after-care only had a partially significant effect. These changes seen in light microsopy could be confirmed with SEM in selected hair shafts.

Our method of light microscopic evaluation provides a simple easy-to-perform diagnostic tool to assess the state of the hair shaft and the extent of exogenous damage. In conjunction with history and macroscopic evaluation, it helps the dermatologist to individually consult the patient and to develop a hair care concept.