title: Accuracy and predictability of intraocular lens power calculation after photorefractive keratectomy.
abstract: OBJECTIVE
  To investigate the accuracy and predictability of intraocular lens (IOL) power calculation in postoperative photorefractive keratectomy (PRK) eyes.
  
  
  METHODS
  Gimbel Eye Centre, Calgary, Alberta, Canada.
  
  
  METHODS
  The results in 5 cataract surgery eyes that had had PRK were analyzed retrospectively. Target refractions based on actual and refraction-derived keratometric values were compared with postoperative achieved refractions. The target refractions calculated using 5 IOL formulas and 2 A-constants were also compared with the achieved refractions.
  
  
  RESULTS
  In postoperative PRK eyes, the power calculation was more accurate and predictable when the smaller of either the actual or refraction-derived keratometric value was used to calculate the IOL power. The difference between target and achieved refractions appeared smaller when the Binkhorst formula was used. No significant hyperopic shift was observed after cataract surgery.
  
  
  CONCLUSIONS
  The smaller of the actual or the refraction-derived keratometric value is recommended for calculating IOL power in post-PRK eyes.
authors.affiliation: Gimbel Eye Centre, Calgary, Alberta, Canada. hvgimbel@gimbel.com
authors.forename: H V
authors.initials: HV
authors.lastname: Gimbel
authors.forename: R
authors.initials: R
authors.lastname: Sun
authors.forename: M T
authors.initials: MT
authors.lastname: Furlong
authors.forename: J A
authors.initials: JA
authors.lastname: van Westenbrugge
authors.forename: J
authors.initials: J
authors.lastname: Kassab
mesh_terms: D000293:Adolescent; D000328:Adult; D002386:Cataract / Q000150:complications; D003315:Cornea / Q000033:anatomy & histology / Q000601:surgery; D005260:Female; D006801:Humans; D054018:Lasers, Excimer; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008433:Mathematics; D009216:Myopia / Q000150:complications / Q000601:surgery*; D018918:Phacoemulsification; D018903:Photorefractive Keratectomy; D011184:Postoperative Period; D012029:Refraction, Ocular; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014792:Visual Acuity