Precision of Corneal Aberrations Measured by a New SD-OCT/Placido Topographer and Its Agreement with a Scheimpflug/Placido Topographer.

PURPOSE: To evaluate the precision of corneal aberra- tions measured by a new SD-OCT/Placido topographer, the MS-39 (CSO), and to compare them with those provided by a Scheimpflug/Placido device, the Sirius (CSO), in normal eyes.METHODS: This study enrolled 90 normal eyes of 90 patients. Total root mean square (RMS), higher order RMS, coma, trefoil, spherical aberration, and astigmatism II were analyzed. The within-subject standard deviation (Sw), test-retest repeatabil- ity, and intraclass correlation coefficient (ICC) were calculated to assess the precision. Bland-Altman plots and 95% limits of agreement (LoAs) were calculated to assess the agreement.RESULTS: For intraobserver repeatability of anterior and total corneal aberrations, most of the ICCs were greater than 0.869, except for trefoil and astigmatism II. Regarding the posterior corneal surface, the ICCs of total RMS, coma, and spherical aberration were higher than 0.878, whereas the ICCs of higher order RMS, trefoil, and astigmatism II were lower than 0.626. All test-retest repeatability values were 0.17 & mu;m or less. In terms of interobserver reproducibility, the Sw values were 0.04 & mu;m or less, Test-retest repeatability values were less than 0.11 & mu;m, and all ICCs ranged from 0.532 to 0.996. Regarding agree- ment, 95% LoAs were small for all Zernike coefficients, and the mean difference was close to zero. CONCLUSIONS: The new SD-OCT/Placido device exhibited excellent repeatability and reproducibility for anterior and total surface, whereas total RMS, coma, and spherical aber- rations showed high precision on the posterior surface. High agreement was confirmed between the SD-OCT/Placido and Scheimpflug/Placido devices.