title: Comparison of refractive outcomes using five devices for the assessment of preoperative corneal power.
abstract: BACKGROUND
  To compare keratometric values obtained with a manual keratometer (Topcon), an automated keratometer (Canon), an Orbscan II (Bausch & Lomb), the IOLMaster keratometer (Carl-Zeiss) and the Pentacam rotating Scheimpflug camera (Oculus) in cataract surgery, and to characterize the refractive outcomes generated using each device.
  
  
  METHODS
  Retrospective study conducted at a tertiary university hospital.
  
  
  METHODS
  Sixty-nine eyes of 69 patients were analysed.
  
  
  METHODS
  The keratometric values obtained with different devices (manual keratometer, automated keratometer, corneal topography, IOLMaster keratometer and Scheimpflug camera) were employed for intraocular lens power calculation. Multiple comparisons of averaged keratometric value were conducted, and the averaged keratometric value was used to calculate the predicted refraction. The absolute values of corneal astigmatism were calculated and also compared.
  
  
  METHODS
  Mean keratometric value, absolute value of astigmatism, mean error and mean absolute error from each device.
  
  
  RESULTS
  The mean keratometric values generated by manual keratometer, automated keratometry, corneal topography, IOLMaster keratometer and the Pentacam Scheimpflug system were 43.95 ± 1.39, 43.91 ± 1.39, 44.67 ± 1.53, 44.03 ± 1.41 and 42.96 ± 1.39 diopter, respectively. The absolute value of astigmatism determined via manual keratometer, automated keratometer, corneal topography, IOLMaster keratometer and the Pentacam Scheimpflug system were 0.95 ± 0.60, 0.99 ± 0.69, 1.14 ± 0.74, 1.11 ± 0.65 and 1.03 ± 0.73 diopter, respectively. The corneal topography showed statistically significant differences with other devices and produced the greater value in mean absolute errors (all P < 0.05).
  
  
  CONCLUSIONS
  Keratometric values with standard devices are a good choice for cataract surgery, whereas the corneal topography is not an appropriate method for the assessment of preoperative keratometric values.
authors.affiliation: Department of Ophthalmology and Visual Science, Catholic Institute for Visual Science, The Catholic University of Korea, Seoul, Korea.
authors.forename: Woong-Joo
authors.initials: WJ
authors.lastname: Whang
authors.forename: Yong-Soo
authors.initials: YS
authors.lastname: Byun
authors.forename: Choun-Ki
authors.initials: CK
authors.lastname: Joo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000503:physiopathology; D002387:Cataract Extraction; D003315:Cornea / Q000502:physiology*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D008297:Male; D008875:Middle Aged; D019591:Pseudophakia / Q000503:physiopathology; D012029:Refraction, Ocular / Q000502:physiology*; D012030:Refractive Errors / Q000503:physiopathology; D012189:Retrospective Studies