Clinical relevance of radius of curvature error in corneal power measurements after excimer laser surgery

J Cataract Refract Surg. 2010 Jan;36(1):82-6. doi: 10.1016/j.jcrs.2009.07.038.


Purpose: To compare central and paracentral corneal curvature measurements after myopic excimer laser surgery performed using a large optical zone (OZ) (6.5mm).

Setting: 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.

Financial disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Aged
  • Cornea / physiopathology*
  • Cornea / surgery
  • Corneal Surgery, Laser*
  • Corneal Topography
  • Humans
  • Lasers, Excimer / therapeutic use*
  • Middle Aged
  • Myopia / physiopathology
  • Myopia / surgery*
  • Prospective Studies
  • Refraction, Ocular / physiology
  • Visual Acuity / physiology