title: Prediction accuracy of preinstalled formulas on 2 optical biometers.
abstract: OBJECTIVE
  To evaluate how well partial coherence interferometry (PCI) (IOLMaster) and optical low-coherence reflectometry (OLCR) (Lenstar LS 900) predict postoperative refractions using only the formulas that come preinstalled on the machines.
  
  
  METHODS
  Private practice, Saint Joseph, Michigan, USA.
  
  
  METHODS
  Retrospective consecutive case series.
  
  
  METHODS
  Eyes were measured with 2 biometers before cataract surgery. Six formulas were ranked by machine. Formulas were also ranked for extremely long and short eyes by averaging the ranks of 6 statistics (mean error, mean absolute error, standard deviation [SD], maximum error, and percentage of eyes within ±0.5 diopter [D] and ±1.0 D of prediction).
  
  
  RESULTS
  Formulas were ranked by the SD of the prediction errors. The OLCR device outperformed the PCI device using the preinstalled formulas. The Olsen formula performed the best (0.378) but was preinstalled on the OLCR device only. Other formulas had the following SDs (OLCR device first, PCI device second): Haigis (0.393, 0.401), Holladay 1 (0.408, 0.414), Hoffer Q (0.428, 0.432), SRK/T (0.433, 0.440), and SRK II (0.623, 0.633). Rankings for long eye were (first to last) were Olsen, Haigis, SRK/T, Hoffer Q, and Holladay 1. Rankings for short eyes were Olsen, Haigis, Holladay 1, SRK/T, and Hoffer Q.
  
  
  CONCLUSIONS
  The OLCR device outperformed the PCI device using the Olsen formula. The Olsen formula also ranked first for short eyes and long eyes. Other formulas performed about the same on both machines. The SRK II formula should be avoided.
authors.affiliation: From the Department of Neurology and Ophthalmology (D.L. Cooke), Michigan State University, College of Osteopathic Medicine, East Lansing, and Great Lakes Eye Care (D.L. Cooke, T.L. Cooke), Saint Joseph, Michigan, USA. Electronic address: dcooke@greateyecare.com.
authors.forename: David L
authors.initials: DL
authors.lastname: Cooke
authors.affiliation: From the Department of Neurology and Ophthalmology (D.L. Cooke), Michigan State University, College of Osteopathic Medicine, East Lansing, and Great Lakes Eye Care (D.L. Cooke, T.L. Cooke), Saint Joseph, Michigan, USA.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Cooke
mesh_terms: D058452:Axial Length, Eye / Q000473:pathology*; D001699:Biometry / Q000295:instrumentation*; D006801:Humans; D007368:Interferometry / Q000295:instrumentation*; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D049451:Nomograms; D055095:Optics and Photonics; D018918:Phacoemulsification; D015203:Reproducibility of Results; D012189:Retrospective Studies