title: Accuracy of intraocular lens power prediction using the Hoffer Q, Holladay 1, Holladay 2, and SRK/T formulas.
abstract: OBJECTIVE
  To compare the accuracy of intraocular lens (IOL) power calculations using 4 formulas: Hoffer Q, Holladay 1, Holladay 2, and SRK/T.
  
  
  METHODS
  Tertiary care center.
  
  
  METHODS
  This study was a retrospective comparative analysis. Immersion ultrasound biometry (axial length, anterior chamber depth, and lens thickness), manual keratometry, and postoperative manifest refraction were obtained in 643 eyes of consecutive patients who had routine uneventful cataract surgery with implantation of 1 of 2 IOLs using the same operative technique by the same surgeon. Biometric data were entered into each of the 4 IOL power calculation formulas, and the results were compared to the final manifest refraction. An optimized lens constant was used for each formula. Results were also stratified into groups of short, average, medium long, and very long axial length <22.0 mm, 22.0 to <24.5 mm, 24.5 to 26.0 mm, and >26.0 mm, respectively).
  
  
  RESULTS
  No formula was more accurate than the others as measured by mean absolute error. The formulas were also equally accurate when eyes were stratified by axial length.
  
  
  CONCLUSIONS
  The 4 IOL power formulas provided equivalent refractive results in the entire group of eyes and in the subsets of axial lengths tested.
authors.affiliation: Department of Ophthalmology, Loma Linda University, Loma Linda, California, USA. narvaezjd@verizon.net
authors.forename: Julio
authors.initials: J
authors.lastname: Narváez
authors.forename: Grenith
authors.initials: G
authors.lastname: Zimmerman
authors.forename: R Doyle
authors.initials: RD
authors.lastname: Stulting
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Chang
mesh_terms: D001699:Biometry / Q000379:methods*; D002387:Cataract Extraction; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D055095:Optics and Photonics; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D012189:Retrospective Studies