title: Corneal refractive power estimation and intraocular lens calculation after hyperopic LASIK.
abstract: OBJECTIVE
  To identify key independent variables in estimating corneal refractive power (KBC) after hyperopic LASIK.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  We included 24 eyes of 16 hyperopic patients who underwent LASIK with subsequent phacoemulsification and posterior chamber intraocular lens (IOL) implantation in the same eye.
  
  
  METHODS
  Pre-LASIK and post-LASIK spherical equivalent (SE) refractions and topographies, axial length, implant type and power, and 3-month postphacoemulsification SE were recorded. Using the double-K Hoffer Q formula, corneal power was backcalculated for every eye (KBC), regression-based formulas derived, and corresponding IOL powers calculated and compared with published methods.
  
  
  METHODS
  The Pearson correlation coefficient (PCC) and arithmetic and absolute corneal and IOL power errors.
  
  
  RESULTS
  Adjusting either the average central corneal power (ACCP(3mm)) or SimK based on the laser-induced spherical equivalent change (DeltaSE) resulted in an estimated corneal power (ACCP(adj) and SimK(adj)) with highest correlation with KBC (PCC=0.940 and 0.956, respectively) and lowest absolute corneal estimation error (0.37+/-0.45 and 0.38+/-0.39 diopter [D], respectively). The ACCP(adj) closely mirrored published DeltaSE-based adjustments of central corneal power on different topographers, whereas DeltaSE-based SimK adjustments varied across platforms. Using ACCP(adj) or SimK(adj) in the double-K Hoffer Q, using ACCP(3mm) or SimK in single-K Hoffer Q and adjusting the resultant IOL power based on DeltaSE, or applying Masket's formula all yielded accurate and similar IOL powers. The Latkany method consistently underestimated IOL power. The Feiz-Mannis and clinical history methods yielded poor IOL correlations and large IOL errors.
  
  
  CONCLUSIONS
  After hyperopic LASIK, adjusting either corneal power or IOL power based on DeltaSE accurately estimates the appropriate IOL power.
authors.affiliation: Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9057, USA.
authors.forename: Shady T
authors.initials: ST
authors.lastname: Awwad
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Kelley
authors.forename: R Wayne
authors.initials: RW
authors.lastname: Bowman
authors.forename: H Dwight
authors.initials: HD
authors.lastname: Cavanagh
authors.forename: James P
authors.initials: JP
authors.lastname: McCulley
mesh_terms: D003315:Cornea / Q000503:physiopathology*; D019781:Corneal Topography; D006801:Humans; D006956:Hyperopia / Q000503:physiopathology / Q000601:surgery*; D007368:Interferometry; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use*; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008875:Middle Aged; D018918:Phacoemulsification; D012029:Refraction, Ocular / Q000502:physiology*; D012189:Retrospective Studies