title: Effect of posterior corneal astigmatism on refractive outcomes after toric intraocular lens implantation.
abstract: OBJECTIVE
  To compare the prediction error after toric intraocular lens (IOL) (Acrysof IQ) implantation using corneal astigmatism measurements obtained with an IOLMaster automated keratometer and a Galilei dual rotating camera Scheimpflug-Placido tomographer.
  
  
  METHODS
  Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, California, USA.
  
  
  METHODS
  Retrospective case series.
  
  
  METHODS
  The predicted residual astigmatism after toric IOL implantation was calculated using preoperative astigmatism values from an automated keratometer and the total corneal power (TCP) determined by ray tracing through the measured anterior and posterior corneal surfaces using dual Scheimpflug-Placido tomography. The prediction error was calculated as the difference between the predicted astigmatism and the manifest astigmatism at least 1 month postoperatively. The calculations included vector analysis.
  
  
  RESULTS
  The study evaluated 35 eyes (35 patients). The preoperative corneal posterior astigmatism mean magnitude was 0.33 diopter (D) ± 0.16 (SD) (vector mean 0.23 × 176). Twenty-six eyes (74.3%) had with-the-rule (WTR) posterior astigmatism. The postoperative manifest refractive astigmatism mean magnitude was 0.38 ± 0.18 D (vector mean 0.26 × 171). There was no statistically significant difference in the mean magnitude prediction error between the automated keratometer and TCP techniques. However, the automated keratometer method tended to overcorrect WTR astigmatism and undercorrect against-the-rule (ATR) astigmatism. The TCP technique lacked these biases.
  
  
  CONCLUSIONS
  The automated keratometer and TCP methods for estimating the magnitude of corneal astigmatism gave similar results. However, the automated keratometer method tended to overcorrect WTR astigmatism and undercorrect ATR astigmatism.
  
  
  BACKGROUND
  Dr. Hamilton has received honoraria for educational lectures from Ziemer Ophthalmic Systems. No other author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Refractive Center (Zhang), 3rd Hospital of Dalian, Dalian, China; American Eye Center (Sy), Makati City, Philippines; Jules Stein Eye Institute, David Geffen School of Medicine at UCLA (Mai), the Department of Biostatistics (Yu), UCLA Fielding School of Public Health, and the UCLA Laser Refractive Center (Hamilton), Los Angeles, California, USA.
authors.forename: Lijun
authors.initials: L
authors.lastname: Zhang
authors.affiliation: From the Refractive Center (Zhang), 3rd Hospital of Dalian, Dalian, China; American Eye Center (Sy), Makati City, Philippines; Jules Stein Eye Institute, David Geffen School of Medicine at UCLA (Mai), the Department of Biostatistics (Yu), UCLA Fielding School of Public Health, and the UCLA Laser Refractive Center (Hamilton), Los Angeles, California, USA.
authors.forename: Mary Ellen
authors.initials: ME
authors.lastname: Sy
authors.affiliation: From the Refractive Center (Zhang), 3rd Hospital of Dalian, Dalian, China; American Eye Center (Sy), Makati City, Philippines; Jules Stein Eye Institute, David Geffen School of Medicine at UCLA (Mai), the Department of Biostatistics (Yu), UCLA Fielding School of Public Health, and the UCLA Laser Refractive Center (Hamilton), Los Angeles, California, USA.
authors.forename: Harry
authors.initials: H
authors.lastname: Mai
authors.affiliation: From the Refractive Center (Zhang), 3rd Hospital of Dalian, Dalian, China; American Eye Center (Sy), Makati City, Philippines; Jules Stein Eye Institute, David Geffen School of Medicine at UCLA (Mai), the Department of Biostatistics (Yu), UCLA Fielding School of Public Health, and the UCLA Laser Refractive Center (Hamilton), Los Angeles, California, USA.
authors.forename: Fei
authors.initials: F
authors.lastname: Yu
authors.affiliation: From the Refractive Center (Zhang), 3rd Hospital of Dalian, Dalian, China; American Eye Center (Sy), Makati City, Philippines; Jules Stein Eye Institute, David Geffen School of Medicine at UCLA (Mai), the Department of Biostatistics (Yu), UCLA Fielding School of Public Health, and the UCLA Laser Refractive Center (Hamilton), Los Angeles, California, USA. Electronic address: hamilton@jsei.ucla.edu.
authors.forename: D Rex
authors.initials: DR
authors.lastname: Hamilton
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000175:diagnosis / Q000503:physiopathology*; D001699:Biometry; D003315:Cornea / Q000503:physiopathology*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D008297:Male; D008875:Middle Aged; D018918:Phacoemulsification; D019591:Pseudophakia / Q000503:physiopathology*; D012029:Refraction, Ocular / Q000502:physiology*; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology