title: A novel continuous colour mapping approach for visualization of facial skin hydration and transepidermal water loss for four ethnic groups.
abstract: OBJECTIVE
  The aim of this exploratory study was to develop a novel colour mapping approach to visualize and interpret the complexity of facial skin hydration and barrier properties of four ethnic groups (Caucasians, Indians, Chinese and Black Africans) living in Pretoria, South Africa.
  
  
  METHODS
  We measured transepidermal water loss (TEWL) and skin capacitance on 30 pre-defined sites on the forehead, cheek, jaw and eye areas of sixteen women (four per ethnic group) and took digital images of their faces. Continuous colour maps were generated by interpolating between each measured value and superimposing the values on the digital images.
  
  
  RESULTS
  The complexity of facial skin hydration and skin barrier properties is revealed by these measurements and visualized by the continuous colour maps of the digital images. Overall, the Caucasian subjects had the better barrier properties followed by the Black African subjects, Chinese subjects and Indian subjects. Nevertheless, the two more darkly pigmented ethnic groups had superior skin hydration properties. Subtle differences were seen when examining the different facial sites.
  
  
  CONCLUSIONS
  There exists remarkable skin capacitance and TEWL gradients within short distances on selected areas of the face. These gradients are distinctive in the different ethnic groups. In contrast to other reports, we found that darkly pigmented skin does not always have a superior barrier function and differences in skin hydration values are complex on the different parts of the face among the different ethnic groups.
authors.affiliation: DSM Nutritional Products Ltd, Basel, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Voegeli
authors.affiliation: AVR Consulting Ltd, Northwich, Cheshire, UK.
authors.forename: A V
authors.initials: AV
authors.lastname: Rawlings
authors.affiliation: Newtone Technologies, Lyon, France.
authors.forename: P
authors.initials: P
authors.lastname: Seroul
authors.affiliation: Photobiology Laboratory, Sefako Makgatho University, South Africa.
authors.forename: B
authors.initials: B
authors.lastname: Summers
mesh_terms: D003116:Color; D003430:Cross-Sectional Studies; D004817:Epidermis / Q000502:physiology*; D005006:Ethnicity; D005145:Face; D006801:Humans; D014867:Water
chemical_list: D014867:Water
keywords: ethnic; facial colour mapping; skin barrier; skin hydration; stratum corneum; transepidermal water loss