title: Comparative results of corneal curvature measurements with three different keratometers after radial keratotomy.
abstract: BACKGROUND
  Corneal curvatures measured by conventional instruments after refractive surgeries were greater than the real values. This study on the instruments and methods for measuring corneal curvature was carried out with the aim of determining an accurate, simple and effective method to evaluate corneal refractive power after radial keratotomy (RK).
  
  
  METHODS
  A retrospective study was carried out on 52 eyes of 42 patients with a history of RK. The postoperative measurements after RK were performed with a manual keratometer (Rodenstock, Munchen-Hamburg, Germany), a corneal topographer (Tomey TMS-1) and an automated IOLMaster keratometer (Carl Zeiss GmbH, USA). The results obtained from analyzing clinical histories (clinical history method, CHM) were compared to the postoperative measurements with a two-way analysis of variance. Adjusted keratometry was used to correct the corneal central refractive power (K) values of the three keratometers. The CHM results were also compared to the corrected K values obtained with the three keratometers using the same statistical method.
  
  
  RESULTS
  The smallest mean value was found for the CHM ((36.61 ± 2.23) diopters). The K values obtained with the CHM were very different from the results obtained with the three different instruments. The corrected K values obtained with the IOLMaster were the closest to the K values from the CHM.
  
  
  CONCLUSIONS
  It was shown that K values from measurements with the three instruments were higher. When the power of the intraocular lens of the patients after RK was calculated, the errors of the K values measured with the instruments should be taken into consideration.
authors.affiliation: Department of Ophthalmology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhao
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Yan-Ling
authors.initials: YL
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
mesh_terms: D000328:Adult; D003315:Cornea / Q000033:anatomy & histology*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007646:Keratotomy, Radial; D008297:Male; D012189:Retrospective Studies