title: Intraoperative refractive biometry for predicting intraocular lens power calculation after prior myopic refractive surgery.
abstract: OBJECTIVE
  To evaluate a new method of intraoperative refractive biometry (IRB) for intraocular lens (IOL) power calculation in eyes undergoing cataract surgery after prior myopic LASIK or photorefractive keratectomy.
  
  
  METHODS
  Retrospective consecutive cases series.
  
  
  METHODS
  We included 215 patients undergoing cataract surgery with a history of myopic LASIK or photorefractive keratectomy.
  
  
  METHODS
  Patients underwent IRB for IOL power estimation. The Optiwave Refractive Analysis (ORA) System wavefront aberrometer was used to obtain aphakic refractive measurements intraoperatively and then calculate the IOL power with a modified vergence formula obtained before refractive surgery. Comparative effectiveness analysis was done for IRB predictive accuracy of IOL power determination against 3 conventional clinical practice methods: surgeon best preoperative choice (determined by the surgeon using all available clinical data), the Haigis L, and the Shammas IOL formulas.
  
  
  METHODS
  Median absolute error of prediction and percentage of eyes within ±0.50 diopters (D) and ±1.00 D of refractive prediction error.
  
  
  RESULTS
  In 246 eyes (215 first eyes and 31 second eyes) IRB using ORA achieved the greatest predictive accuracy (P < 0.0001), with a median absolute error of 0.35 D and mean absolute error of 0.42 D. Sixty-seven percent of eyes were within ±0.5 D and 94% were within ±1.0 D of the IRB's predicted outcome. This was significantly more accurate than the other preoperative methods: Median absolute error was 0.6, 0.53, and 0.51 D for surgeon best choice, Haigis L method, and Shammas method, respectively.
  
  
  CONCLUSIONS
  The IOL power estimation in challenging eyes with prior LASIK/photorefractive keratectomy was most accurately predicted by IRB/ORA.
authors.affiliation: University of California at San Francisco, San Francisco, California. Electronic address: tianchul@yahoo.com.
authors.forename: Tsontcho
authors.initials: T
authors.lastname: Ianchulev
authors.affiliation: Department of Ophthalmology, University of California at Los Angeles, Los Angeles, California; St. Mary's Eye Center, Santa Monica, California.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Hoffer
authors.affiliation: Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida.
authors.forename: Sonia H
authors.initials: SH
authors.lastname: Yoo
authors.affiliation: Department of Ophthalmology, University of California at San Francisco, San Francisco, California.
authors.forename: David F
authors.initials: DF
authors.lastname: Chang
authors.affiliation: WaveTec Vision, Inc, Aliso Viejo, California.
authors.forename: Michael
authors.initials: M
authors.lastname: Breen
authors.affiliation: WaveTec Vision, Inc, Aliso Viejo, California.
authors.forename: Thomas
authors.initials: T
authors.lastname: Padrick
authors.affiliation: Private Practice, Long Beach, Orange, and Newport Beach, California.
authors.forename: Dan B
authors.initials: DB
authors.lastname: Tran
mesh_terms: D057128:Aberrometry / Q000379:methods; D001699:Biometry; D048988:Corneal Surgery, Laser; D006801:Humans; D007432:Intraoperative Period; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D009216:Myopia / Q000601:surgery*; D055095:Optics and Photonics; D018918:Phacoemulsification; D015203:Reproducibility of Results; D014792:Visual Acuity / Q000502:physiology