title: Intraocular lens calculations in patients with corneal scarring and irregular astigmatism.
abstract: OBJECTIVE
  To compare various methods of estimating corneal power for intraocular lens (IOL) calculation in patients with irregular corneal astigmatism.
  
  
  METHODS
  Pepose Vision Institute, St. Louis, Missouri, USA. Case reports and review of the medical literature.
  
  
  RESULTS
  Two patients with irregular corneal astigmatism had an IOL exchange after a "surprise" post-cataract-surgery refraction. In the first case, the patient had a post-cataract-surgery refraction of +5.50 -0.75 x 69 and in the second case, a refraction of -7.00 -1.00 x 180. The central corneal power before IOL exchange was assessed using manual keratometry, various computerized videokeratography curvature and power maps, and contact lens overrefraction. The total axial power map (Orbscan(R), Bausch & Lomb), total optical power map (Orbscan), and contact lens overrefraction method provided the most accurate estimates of central corneal power in these 2 patients.
  
  
  CONCLUSIONS
  Computerized scanning-slit videokeratography, which analyzes the anterior and posterior surfaces of the cornea, and the contact lens overrefraction method gave good estimations of corneal power in patients with irregular corneal astigmatism. This type of analysis may improve the accuracy of IOL calculation in patients with corneal pathology and irregular astigmatism.
authors.affiliation: Pepose Vision Institute, Chesterfield, Missouri, USA.
authors.forename: Irwin Y
authors.initials: IY
authors.lastname: Cua
authors.forename: Mujtaba A
authors.initials: MA
authors.lastname: Qazi
authors.forename: Steven F
authors.initials: SF
authors.lastname: Lee
authors.forename: Jay S
authors.initials: JS
authors.lastname: Pepose
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000473:pathology / Q000503:physiopathology*; D002921:Cicatrix / Q000473:pathology / Q000503:physiopathology*; D003315:Cornea / Q000473:pathology / Q000503:physiopathology*; D003316:Corneal Diseases / Q000473:pathology / Q000503:physiopathology*; D019781:Corneal Topography; D020878:Device Removal; D003936:Diagnosis, Computer-Assisted; D006801:Humans; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D055095:Optics and Photonics; D012029:Refraction, Ocular; D012086:Reoperation