title: Evaluation of intraocular lens power prediction methods using the American Society of Cataract and Refractive Surgeons Post-Keratorefractive Intraocular Lens Power Calculator.
abstract: OBJECTIVE
  To evaluate the accuracy of methods of intraocular lens (IOL) power prediction after previous laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) using the American Society of Cataract and Refractive Surgery IOL power calculator.
  
  
  METHODS
  Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, and private practice, Mesa, Arizona, USA.
  
  
  METHODS
  The following methods were evaluated: methods using pre-LASIK/PRK keratometry (K) and surgically induced change in refraction, methods using surgically induced change in refraction, and methods using no previous data. The predicted IOL power was calculated with each method using the actual refraction after cataract surgery as the target. The IOL prediction error was calculated as the implanted IOL power minus the predicted IOL power. Arithmetic and absolute IOL prediction errors, variances in mean arithmetic IOL prediction error, and percentage of eyes within +/-0.50 diopter (D) and +/-1.00 D of refractive prediction errors were calculated.
  
  
  RESULTS
  Methods using surgically induced change in refraction or no previous data had significantly smaller mean absolute IOL prediction errors, smaller variances, and a greater percentage of eyes within +/-0.50 D and +/-1.00 D of refractive prediction errors than methods using pre-LASIK/PRK keratometry (K) values and surgically induced change in refraction (all P<.05 with Bonferroni correction). There were no statistically significant differences between methods using surgically induced change in refraction and methods using no previous data.
  
  
  CONCLUSIONS
  Methods using surgically induced change in refraction and methods using no previous data gave better results than methods using pre-LASIK/PRK K values and surgically induced change in refraction.
authors.affiliation: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, and a private practice, Mesa, Arizona 77030, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Warren E
authors.initials: WE
authors.lastname: Hill
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Koch
mesh_terms: D000328:Adult; D000368:Aged; D001699:Biometry / Q000379:methods*; D003315:Cornea / Q000503:physiopathology; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D009862:Online Systems; D009885:Ophthalmology / Q000295:instrumentation*; D055095:Optics and Photonics; D018903:Photorefractive Keratectomy; D012029:Refraction, Ocular / Q000502:physiology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012955:Societies, Medical; D014481:United States