title: Comparison of Newer Intraocular Lens Power Calculation Methods for Eyes after Corneal Refractive Surgery.
abstract: OBJECTIVE
  To compare the newer formulae, the optical coherence tomography (OCT)-based intraocular lens (IOL) power formula (OCT formula) and the Barrett True-K formula (True-K), with the methods on the American Society of Cataract and Refractive Surgery (ASCRS) calculator in eyes with previous myopic LASIK/photorefractive keratectomy (PRK).
  
  
  METHODS
  Prospective case series.
  
  
  METHODS
  A total of 104 eyes of 80 patients who had previous myopic LASIK/PRK and subsequent cataract surgery and IOL implantation.
  
  
  METHODS
  By using the actual refraction after cataract surgery as target refraction, predicted IOL power for each method was calculated. The IOL prediction error (PE) was obtained by subtracting the predicted IOL power from the power of the IOL implanted.
  
  
  METHODS
  Arithmetic IOL PEs, variances of mean arithmetic IOL PE, median refractive PE, and percent of eyes within 0.5 diopters (D) and 1.0 D of refractive PE.
  
  
  RESULTS
  Optical coherence tomography produced smaller variance of IOL PE than did Wang-Koch-Maloney (WKM) and Shammas (P < 0.05). With the OCT, True-K No History, WKM, Shammas, Haigis-L, and Average of these 5 formulas, the median refractive PEs were 0.35 D, 0.42 D, 0.51 D, 0.48 D, 0.39 D, and 0.35 D, respectively, the percentage of eyes within 0.5 D of refractive PE were 68.3%, 58.7%, 50.0%, 52.9%, 55.8%, and 67.3%, respectively, and the percentage of eyes within 1.0 D of refractive PE were 92.3%, 90.4%, 86.9%, 88.5%, 90.4%, and 94.2%, respectively. The OCT formula had smaller refractive PE compared with the WKM and Shammas, and the Average approach produced significantly smaller refractive PE than all methods except OCT (all P < 0.05).
  
  
  CONCLUSIONS
  The OCT and True-K No History are promising formulas. The ASCRS IOL calculator has been updated to include the OCT and Barrett True K formulas.
  
  
  BACKGROUND
  Intraocular Lens Power Calculation After Laser Refractive Surgery Based on Optical Coherence Tomography (OCT IOL); Identifier: NCT00532051; www.ClinicalTrials.gov.
authors.affiliation: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.affiliation: Casey Eye Institute, Oregon Health & Science University, Portland, Oregon.
authors.forename: Maolong
authors.initials: M
authors.lastname: Tang
authors.affiliation: Casey Eye Institute, Oregon Health & Science University, Portland, Oregon.
authors.forename: David
authors.initials: D
authors.lastname: Huang
authors.affiliation: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas.
authors.forename: Mitchell P
authors.initials: MP
authors.lastname: Weikert
authors.affiliation: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas. Electronic address: dkoch@bcm.edu.
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Koch
mesh_terms: D000368:Aged; D001699:Biometry / Q000379:methods*; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use*; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D055095:Optics and Photonics; D018918:Phacoemulsification; D018903:Photorefractive Keratectomy; D011446:Prospective Studies; D041623:Tomography, Optical Coherence