Agreement Between Pentacam and Handheld Auto-Refractor/ Keratometers for Keratometry Measurement

Purpose: This study purposed to evaluate the level of agreement in keratometry measurements with Pentacam and handheld Auto-Refractor/ Keratometers. Methods: This analytical cross-sectional study was conducted on the right eyes of 579 people. Keratometry measurements were conducted with Pentacam and the handheld auto-refracto-keratometer. The SPSS Software version 22 was used to estimate descriptive statistics, paired t-test, the Pearson correlation coefficient, and 95% limits of agreement (LoA).Results: In the total sample, the inter-device difference in mean flat and steep keratometry values were -0.266 diopter (D) (P-value<0.001) and 0.052 D (P-value=0.093), respectively. There was a significant difference in mean flat keratometry between the two devices in all groups of refractive error (paired difference <0.5 D and P-value <0.001). The difference in mean steep keratometry was significant only in myopic subjects (P-value = 0.046). The 95% LoA for the two devices was less than 1.0 D only in the under 6-year age group. Conclusion: The difference between two devices in measurements of steep keratometry was small and clinically acceptable in the total sample as well as in groups by refractive error. However, given the wide 95% LoA, the two devices should not be used interchangeably in the study of refractive error and age groups, except under 6-yearolds in which the 95% LoA is less than 1.0 D, and thus, the handheld auto-refracto-keratometer can serve as a substitute for Pentacam in situations such as screening.