title: Use of cobalt blue light in grading cataract and estimating vision loss.
abstract: OBJECTIVE
  To test an anecdotally reported cataract grading system predictive of a 20/50 visual threshold in cataract-induced vision loss using cobalt blue light.
  
  
  METHODS
  Hennepin County Medical Center, Minneapolis, Minneapolis VA Medical Center, Minneapolis, and Regions Hospital, St. Paul, Minnesota, USA.
  
  
  METHODS
  Four observers evaluated pure nuclear cataracts using a standardized cobalt-blue-light protocol. Observers graded a nuclear cataract as positive if the posterior capsule was visualized with cobalt blue light and negative if the posterior capsule was not visualized. Results of the grading were compared with cataract-induced vision loss in an attempt to establish a threshold for lost visual acuity in grading cataracts with cobalt blue light. The study design was prospective observation of a cohort with a visually significant cataract.
  
  
  RESULTS
  This study did not show a clear visual acuity threshold for cataract-induced vision loss using a standardized cobalt-blue-light protocol. Overall, 26.3% (95% confidence interval, 13.4-40.2) of all 20/40 or less dense nuclear cataracts had visible posterior capsules using cobalt blue light, with good estimated interobserver agreement.
  
  
  CONCLUSIONS
  Although cobalt blue light is selectively absorbed by yellow pigment in an aging nuclear cataract, its ability to predict visual acuity loss due to lens opacity was limited.
authors.affiliation: Department of Ophthalmology, University of Minnesota, Minneapolis, Minnesota, USA. dfolden@medicine.nodak.edu
authors.forename: David V
authors.initials: DV
authors.lastname: Folden
authors.forename: Charlie W
authors.initials: CW
authors.lastname: Wu
authors.forename: David R
authors.initials: DR
authors.lastname: Hardten
authors.forename: Sanaz
authors.initials: S
authors.lastname: Afiat
authors.forename: Peter
authors.initials: P
authors.lastname: Mellema
authors.forename: Gwen M
authors.initials: GM
authors.lastname: Hofman
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Voelker
authors.forename: Jill S
authors.initials: JS
authors.lastname: Melicher Larson
authors.forename: John E
authors.initials: JE
authors.lastname: Connett
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Doughman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000145:classification* / Q000503:physiopathology; D003035:Cobalt; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D007903:Lens Capsule, Crystalline / Q000473:pathology; D007907:Lens Nucleus, Crystalline / Q000503:physiopathology; D008027:Light; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012684:Sensory Thresholds / Q000502:physiology; D014786:Vision Disorders / Q000175:diagnosis* / Q000503:physiopathology; D014792:Visual Acuity / Q000502:physiology
chemical_list: D003035:Cobalt