title: Reproducibility of the Wisconsin cataract grading system in the Blue Mountains Eye Study.
abstract: OBJECTIVE
  To measure the inter- and intra-grader reliability of the Wisconsin cataract grading system for grading of nuclear, cortical, and posterior subcapsular cataract (PSC) in the Blue Mountains Eye Study.
  
  
  METHODS
  Random samples of lens photographs from study subjects were regraded by each grader according to the Wisconsin cataract grading system. The results were compared using quadratic weighted kappa statistics to derive measures of inter- and intra-grader reliability for the grading of nuclear (5 grades), PSC (3 grades), and cortical cataract (3 grades).
  
  
  RESULTS
  Inter-grader reliability (quadratic weighted kappa) for grading of nuclear cataract varied between 0.82 and 0.79; kappa was 0.78 for cortical cataract and 0.57 for PSC. Intra-grader reliability was slightly higher than inter-grader reliability for all three cataract types.
  
  
  CONCLUSIONS
  In the Blue Mountains Eye Study, the Wisconsin cataract grading system provided good reproducibility, comparable to that reported from the Beaver Dam Eye Study, endorsing its usefulness in cataract epidemiology.
authors.affiliation: Department of Ophthalmology, University of Sydney, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Panchapakesan
authors.forename: R G
authors.initials: RG
authors.lastname: Cumming
authors.forename: P
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D001315:Australia / Q000453:epidemiology; D002386:Cataract / Q000145:classification* / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010781:Photography; D011897:Random Allocation; D015203:Reproducibility of Results; D017678:Sex Distribution; D011795:Surveys and Questionnaires; D014922:Wisconsin / Q000453:epidemiology