Comparison of Corneal Higher-order Aberrations Measured by Scheimpflug Camera and Placido Disc-based Topography in Korean Patients

Purpose: We compared corneal higher-order aberration (HOA) measurements between the Pentacam (R) HR (PC), which uses the Scheimpflug principle, and the iTrace (TM) aberrometer (IT), which evaluates Placido disc topography.Methods: We retrospectively analyzed 109 eyes of 87 patients without a history of ocular surface disease during the period from January 2021 to December 2022; both devices were used on the same day. We calculated the root mean square values (mu m) of corneal total HOA and of the corneal 3rd-and 4th-order HOA at a pupil diameter of 4 mm. Data were compared by Bland-Altman plots for agreement analysis and Pearson correlation coefficient for correlation analysis.Results: There was no significant difference in the total HOA (p = 0.145), coma (p = 0.309), or secondary astigmatism (p = 0.080) between the PC and IT measurements; all other HOAs significantly differed between devices (p < 0.001). In the correlation analysis, the total HOA (r = 0.605, p < 0.001) and coma (r = 0.634, p < 0.001) were moderately correlated between the two devices; the other HOAs showed low degree of correlations. In the Bland-Altman plot analysis, all HOAs showed low agreement between the two devices.Conclusions: Corneal total HOA and coma measured by the two devices were significantly correlated between the two devices, but other HOAs showed significant differences in measurement and low correlations. Therefore, corneal HOA measurements cannot be interpreted interchangeably between the two devices.