title: Clinical relevance of radius of curvature error in corneal power measurements after excimer laser surgery.
abstract: OBJECTIVE
  To compare central and paracentral corneal curvature measurements after myopic excimer laser surgery performed using a large optical zone (OZ) (6.5mm).
  
  
  METHODS
  Private practice.
  
  
  METHODS
  The mean simulated keratometry (SimK) value, average central power, corneal power of Placido rings 1 to 9 and the average central corneal power over the central 3.0mm (ACCP(3mm)) were measured using a TMS-2 corneal topographer.
  
  
  RESULTS
  Forty-two patients (mean correction -5.0 diopters [D]+/-2.2 [SD]) were prospectively enrolled. The mean SimK value (38.82 D+/-1.95) and the mean average central power (38.89+/-2.02 D) were not statistically significantly different, even when the sample was stratified according to the amount of induced correction (lower or higher than -5.00 D). The difference between the central and paracentral measurements was statistically significant when considering the ACCP(3mm), whose mean value was lower than the SimK value in eyes with a myopic correction less than -5.00 D (mean 39.53+/-1.92 D versus 39.67+/-1.82 D) (P=.0013) and in eyes with a myopic correction greater than -5.00 D (37.64+/-1.75 D versus 37.9+/-1.69 D) (P<.0001).
  
  
  CONCLUSIONS
  In eyes with a large OZ, the clinical relevance of the radius error was limited, especially with myopic corrections less than -5.00 D. The mean difference between central and paracentral corneal curvature data, although more evident, was still relatively small, even in eyes that were treated for more than -5.00 D of myopia.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: GB Bietti Eye Foundation-IRCCS, Rome, Italy. giacomo.savini@alice.it
authors.forename: Giacomo
authors.initials: G
authors.lastname: Savini
authors.forename: Michele
authors.initials: M
authors.lastname: Carbonelli
authors.forename: Piero
authors.initials: P
authors.lastname: Barboni
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Hoffer
mesh_terms: D000328:Adult; D000368:Aged; D003315:Cornea / Q000503:physiopathology* / Q000601:surgery; D048988:Corneal Surgery, Laser; D019781:Corneal Topography; D006801:Humans; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology