title: Scheimpflug photography keratometry readings for routine intraocular lens power calculation.
abstract: OBJECTIVE
  To prospectively evaluate keratometry (K) values obtained by Scheimpflug photography in eyes scheduled for cataract surgery, compare the results with K values obtained with an autokeratometer (automated K), and evaluate the K values in commonly used intraocular lens (IOL) power calculation formulas for routine cataract surgery.
  
  
  METHODS
  Private clinical ophthalmology practice, Lynwood, California, USA.
  
  
  METHODS
  The mean simulated K power (simulated K), equivalent K (equivalent K), and true net power (true net K) readings from the Pentacam Comprehensive Eye Scanner were compared with the automated K readings. Automated K, simulated K, and equivalent K values were compared in commonly used IOL power calculation formulas.
  
  
  RESULTS
  The mean automated K value was 43.49 diopters (D)+/-1.75 (SD) and the mean simulated K value, 43.49+/-2.00 D (P> .1). The mean equivalent K value was 43.78+/-1.97 D and exceeded the mean automated K and simulated K by 0.29 D (P> .1). The mean true net K was 42.31+/-2.13 D, which was 1.18 D lower than the automated K and simulated K values (P= .015). The IOL prediction mean absolute error was 0.41+/-0.27 D using the automated K method, 0.50+/-0.36 D using the simulated K method (difference 0.09 D) (P> .1), and 0.65+/-0.35 D using the equivalent K method (difference 0.24 D) (P< .01).
  
  
  CONCLUSIONS
  The K values from Scheimpflug photography did not improve accuracy over autokeratometer values for routine IOL power calculation.
authors.affiliation: Department of Ophthalmology, University of Southern California, The Keck School of Medicine, Los Angeles, California, USA. hshammas@aol.com
authors.forename: H John
authors.initials: HJ
authors.lastname: Shammas
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Hoffer
authors.forename: Maya C
authors.initials: MC
authors.lastname: Shammas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001699:Biometry; D002387:Cataract Extraction; D003315:Cornea / Q000502:physiology*; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D010781:Photography / Q000379:methods*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology*