title: [Looking for colorectal cancer in the patients iris?].
abstract: BACKGROUND
  Iridology is a noninvasive method from the field of complementary medicine that is said to detect diseases by looking for abnormalities of pigmentation and structure in the iris. Colorectal cancer is an ideal opportunity for screening programs because of its long period of development. Our study investigated the applicability of iridology as an alternative screening method for colorectal cancer.
  
  
  METHODS
  Digital color slides were obtained from both eyes of 29 patients with histologically diagnosed colorectal cancer and from 29 age- and gender-matched healthy control subjects. The slides were presented in random order to acknowledged iridologists without knowledge of the number of patients in the two categories.
  
  
  RESULTS
  The iridologists correctly detected 51.7% and 53.4%, respectively, of the patients' slides; therefore, the likelihood was statistically no better than chance. Sensitivity was, respectively, 58.6% and 55.2%, and specificity was 44.8% and 51.7%.
  
  
  CONCLUSIONS
  Iridology had no validity as a diagnostic tool for detecting colorectal cancer in this study.
authors.affiliation: Klinik für Augenheilkunde, St.-Elisabeth-Krankenhaus Köln Hohenlind, Köln, Deutschland. praxisherber@web.de
authors.forename: S
authors.initials: S
authors.lastname: Herber
authors.forename: M
authors.initials: M
authors.lastname: Rehbein
authors.forename: T
authors.initials: T
authors.lastname: Tepas
authors.forename: C
authors.initials: C
authors.lastname: Pohl
authors.forename: P
authors.initials: P
authors.lastname: Esser
mesh_terms: D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D000529:Complementary Therapies; D004311:Double-Blind Method; D005127:Eye Color; D005260:Female; D006801:Humans; D007498:Iris / Q000473:pathology*; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data*; D008875:Middle Aged; D010781:Photography; D011237:Predictive Value of Tests