Accuracy of Corneal Power Measurement Using Scheimpfl ug Camera After Myopic Refractive Surgery

Abstract

Purpose: To investigate the accuracy of ray tracing (RT) using the Sirius rotating Scheimpfl ug camera (Sirius), combined with Placido disc corneal topography (CSO, Florence, Italy), to measure corneal power (CP) in eyes which had undergone excimer laser surgery for myopia. Materials and Methods: We retrospectively reviewed the medical records of 59 eyes of 31 patients who had undergone refractive laser surgery for myopia. We collected different CP values calculated by RT according to entrance pupil diameter (ranging from 2.5 to 7.0 mm), which was called mean pupil power (MPP) by the manufacturer, and simulated keratometry (simK) value using the Sirius. We then compared these values with those obtained with the clinical history method (CHM). Results: The mean refractive change after laser surgery was 3.14 ± 1.70 diopters (D). Using one-way analysis of variance with Dunnett’s multiple comparisons test; 4.5 mm MPP, 5.0 mm MPP and 5.5 mm MPP values were similar to those obtained with the CHM (40.31 ± 1.99 D) [p> 0.05]. Using the Pearson correlation, 4.5 mm MPP, 5.0 mm MPP and 5.5 mm MPP values were signifi cantly correlated with the CHM (r: 0.907, 0.906 and 0.905, respectively; p