title: Colorimetric measurements of iris colour and their significance in East Asian patients with skin cancer.
abstract: BACKGROUND
  A light-coloured iris is considered a risk factor for skin cancer in general. However, iris colour cannot be considered a plausible risk factor for skin cancer in East Asian populations because of the relative homogeneity of iris colours. Furthermore, subjective classifications of iris colour cannot distinguish between different East Asian individuals as to their likelihood of developing cancer.
  
  
  OBJECTIVE
  To measure human iris colours quantitatively and to assess the significances of iris colours with respect to skin cancer in Korean patients.
  
  
  METHODS
  Reference Commission Internationale d'Eclairage (CIE) L*a*b* coordinates on a ColorCheck chart were recorded using a reflectance spectrophotometer and compared with computed CIE L*a*b* coordinates from digital images to determine equations to calibrate CIE L*a*b* values. We then took iris images and measured iris colours and the colours of sun-exposed and sun-protected skin in 42 Korean patients with various cutaneous malignancies and nonmalignant dermatological diseases. Results were statistically analysed with regard to iris and skin colours in CIE L*a*b* coordinates.
  
  
  RESULTS
  Patients with skin cancer had significantly lighter irises or higher L* values than dermatological patients without a malignancy (P = 0.02). Colour differences (ΔE*ab) between sun-exposed skin and sun-protected skin were greater in men (P < 0.01) and in patients with skin cancer (P < 0.01), and the lightness (L*) values of sun-exposed skins decreased with age (r = -0.32, P < 0.05).
  
  
  CONCLUSIONS
  Iris colour appears to be a possible skin cancer risk factor in East Asian populations. The larger colour differences seen between sun-protected and sun-exposed skin in men and in patients with skin cancer may have been due to chronic or excessive sun exposure.
authors.affiliation: Department of Dermatology, Korea University Medical College, Seoul, Korea.
authors.forename: J W
authors.initials: JW
authors.lastname: Kim
authors.forename: S H
authors.initials: SH
authors.lastname: Seo
authors.forename: Y C
authors.initials: YC
authors.lastname: Kye
authors.forename: H H
authors.initials: HH
authors.lastname: Ahn
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000706:statistics & numerical data; D016022:Case-Control Studies; D003124:Colorimetry / Q000379:methods; D005127:Eye Color; D005260:Female; D006801:Humans; D007723:Korea / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012878:Skin Neoplasms / Q000208:ethnology / Q000209:etiology / Q000503:physiopathology*; D012880:Skin Pigmentation / Q000528:radiation effects; D013472:Sunlight / Q000009:adverse effects; D055815:Young Adult