title: Accuracy of the Barrett True-K formula for intraocular lens power prediction after laser in situ keratomileusis or photorefractive keratectomy for myopia.
abstract: OBJECTIVE
  To compare the accuracy of the Barrett True-K formula with other methods available on the American Society of Cataract and Refractive Surgery (ASCRS) post-refractive surgery intraocular lens (IOL) power calculator for the prediction of IOL power after previous myopic laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK).
  
  
  METHODS
  Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, and private practice, Mesa, Arizona, USA.
  
  
  METHODS
  Retrospective case series.
  
  
  METHODS
  The accuracy of the Barrett True-K formula was compared with the Adjusted Atlas (4.0 mm zone), Masket, modified-Masket, Wang-Koch-Maloney, Shammas, and Haigis-L methods to calculate IOL power. A separate analysis of 2 no-history methods (Shammas and Haigis-L) was performed and compared with the Barrett True-K no-history option.
  
  
  RESULTS
  Eighty-eight eyes were available for analysis. The Barrett True-K formula had a significantly smaller median absolute refraction prediction error than all other formulas except the Masket, smaller variances compared with the Wang-Koch-Maloney, Shammas, and Haigis-L, and a greater percentage of eyes within ±0.50 diopter (D) of predicted error in refraction compared with the Adjusted Atlas, Masket, and modified Masket methods (all P < .05). In eyes with no historical data, the Barrett True-K no-history formula had a significantly smaller median absolute refraction prediction error and a greater percentage of eyes within ±0.50 D of the predicted error in refraction than the Shammas and the Haigis-L formulas (both P < .05).
  
  
  CONCLUSIONS
  The Barrett True-K formula was either equal to or better than alternative methods available on the ASCRS online calculator for predicting IOL power in eyes with previous myopic LASIK or PRK.
authors.affiliation: From the Department of Ophthalmology, Assaf Harofeh Medical Center, Zerifin, and the Ein-Tal Eye Center (Abulafia), Tel-Aviv, Israel; East Valley Ophthalmology (Hill), Mesa, Arizona, and the Cullen Eye Institute (Koch, Wang), Baylor College of Medicine, Houston, Texas, USA; The Lions Eye Institute (Barrett), Nedlands, Western Australia, Australia. Electronic address: adi.abulafia@gmail.com.
authors.forename: Adi
authors.initials: A
authors.lastname: Abulafia
authors.affiliation: From the Department of Ophthalmology, Assaf Harofeh Medical Center, Zerifin, and the Ein-Tal Eye Center (Abulafia), Tel-Aviv, Israel; East Valley Ophthalmology (Hill), Mesa, Arizona, and the Cullen Eye Institute (Koch, Wang), Baylor College of Medicine, Houston, Texas, USA; The Lions Eye Institute (Barrett), Nedlands, Western Australia, Australia.
authors.forename: Warren E
authors.initials: WE
authors.lastname: Hill
authors.affiliation: From the Department of Ophthalmology, Assaf Harofeh Medical Center, Zerifin, and the Ein-Tal Eye Center (Abulafia), Tel-Aviv, Israel; East Valley Ophthalmology (Hill), Mesa, Arizona, and the Cullen Eye Institute (Koch, Wang), Baylor College of Medicine, Houston, Texas, USA; The Lions Eye Institute (Barrett), Nedlands, Western Australia, Australia.
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Koch
authors.affiliation: From the Department of Ophthalmology, Assaf Harofeh Medical Center, Zerifin, and the Ein-Tal Eye Center (Abulafia), Tel-Aviv, Israel; East Valley Ophthalmology (Hill), Mesa, Arizona, and the Cullen Eye Institute (Koch, Wang), Baylor College of Medicine, Houston, Texas, USA; The Lions Eye Institute (Barrett), Nedlands, Western Australia, Australia.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.affiliation: From the Department of Ophthalmology, Assaf Harofeh Medical Center, Zerifin, and the Ein-Tal Eye Center (Abulafia), Tel-Aviv, Israel; East Valley Ophthalmology (Hill), Mesa, Arizona, and the Cullen Eye Institute (Koch, Wang), Baylor College of Medicine, Houston, Texas, USA; The Lions Eye Institute (Barrett), Nedlands, Western Australia, Australia.
authors.forename: Graham D
authors.initials: GD
authors.lastname: Barrett
mesh_terms: D000328:Adult; D000368:Aged; D001699:Biometry; D048988:Corneal Surgery, Laser; D006801:Humans; D054018:Lasers, Excimer; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D049451:Nomograms; D055095:Optics and Photonics; D018918:Phacoemulsification; D011184:Postoperative Period; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D012189:Retrospective Studies