title: Cataract conversion assessment using lens opacity classification system III and Wisconsin cataract grading system.
abstract: OBJECTIVE
  To propose a general conversion approximation algorithm and illustrate its application to two cataract classification systems, the Lens Opacity Classification System III (LOCS III) and Wisconsin Cataract Grading System (Wisconsin system).
  
  
  METHODS
  Lens opacity of 3265 participants (78.7% response rate) aged 40 to 80 years from the Singapore Malay Eye study were assessed both clinically during slit-lamp examination using LOCS III, and via slit-lamp and retro-illumination photographic grading using the Wisconsin system. Collapsed contingency tables were used to convert between the LOCS III and Wisconsin System.
  
  
  RESULTS
  The conversion between the two cataract classification systems is affected by the direction of transformation. The conversion algorithm was validated and explained with an application example.
  
  
  CONCLUSIONS
  An approximate conversion algorithm for any two cataract grading systems was proposed and applied to the LOCS III and Wisconsin system. These findings provide general ways to pool and compare cataract prevalence using different grading systems in epidemiological studies.
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
authors.forename: Wan Ling
authors.initials: WL
authors.lastname: Wong
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.forename: Jialiang
authors.initials: J
authors.lastname: Li
authors.forename: Ching-Yu
authors.initials: CY
authors.lastname: Cheng
authors.forename: Ecosse L
authors.initials: EL
authors.lastname: Lamoureux
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
authors.forename: Carol Y
authors.initials: CY
authors.lastname: Cheung
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002386:Cataract / Q000145:classification*; D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D007908:Lens, Crystalline / Q000473:pathology; D008875:Middle Aged; D010781:Photography