title: Concordance and interchangeability of biometric measurements of ocular axial length in patients awaiting cataract surgery.
abstract: OBJECTIVE
  To estimate in patients awaiting cataract surgery the concordance and interchangeability of axial eye length measurements performed with the aid of various biometric methods (optical or ultrasonic) by different operators (nurses) at different times during the period prior to surgery.
  
  
  METHODS
  We selected 182 consecutive eyes from 91 patients.Ocular axial length was measured with the aid of 2 methods (IOLMaster® and Ocuscan®) by 9 randomly allocated technicians at 2 different times during the waiting period. The concordance between measurements was evaluated by means of the intraclass correlation coefficient (ICC); the interchangeability of the results was assessed with Bland Altman plots and Passing and Bablok regression.
  
  
  RESULTS
  The measurements were consistent between biometric methods (ICC 0.975, 95% confidence interval [CI] 0.968 to 0.980) and measurement dates (ICC 0.996, 95% CI 0.995 to 0.997). Interobserver agreement was more heterogeneous (ICC range 0.844 to 0.998). No systematic errors were observed among the various biometric methods and measurement dates.
  
  
  CONCLUSIONS
  Because measurement of axial length in phakic patients may be technician-dependent, the technician's experience should be noted in the protocols of ophthalmology services.
authors.affiliation: 1 Department of Ophthalmology, La Mancha Centro General Hospital, Ciudad Real - Spain.
authors.forename: María José
authors.initials: MJ
authors.lastname: Martín-Serrano
authors.forename: Carmen
authors.initials: C
authors.lastname: Roman-Ortiz
authors.forename: M Luz
authors.initials: ML
authors.lastname: Villa-Sáez
authors.forename: M Purificación
authors.initials: MP
authors.lastname: Labrador-Castellanos
authors.forename: Rosario
authors.initials: R
authors.lastname: Blanco-Carrasco
authors.forename: Felicidad
authors.initials: F
authors.lastname: Lozano-Ballesteros
authors.forename: Carmen
authors.initials: C
authors.lastname: Pedraza-Martín
authors.forename: M Teresa San
authors.initials: MT
authors.lastname: José-Herrero
authors.forename: Ana M
authors.initials: AM
authors.lastname: López-Ropero
authors.forename: José María
authors.initials: JM
authors.lastname: Tenías Burillo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058452:Axial Length, Eye / Q000033:anatomy & histology*; D001699:Biometry / Q000379:methods*; D002387:Cataract Extraction; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005260:Female; D006801:Humans; D007368:Interferometry; D019654:Lens Implantation, Intraocular; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D014463:Ultrasonography; D014850:Waiting Lists