Agreement of Total Keratometry and Posterior Keratometry Among IOLMaster 700, CASIA2, and Pentacam

The purpose of this study was to compare total keratometry (TK) and posterior keratometry (PK) obtained by two swept-source optical biometers (IOLMaster 700 and CASIA2) and one Scheimpflug-based topography (Pentacam AXL).

The TK and PK in cataract surgery candidates obtained by IOLMaster 700, CASIA2, and Pentacam AXL were compared. Intraclass correlation coefficients (ICCs), limit of agreement, and Bland-Altman plots were used to assess the agreement.

One hundred two patients with a mean age of 68.21 ± 8.70 years were included. There were significant differences among IOLMaster 700, CASIA2, and Pentacam AXL in the mean TK (TKm) (44.23 ± 1.59 diopters [D] vs. 43.25 ± 1.53 D vs. 43.94 ± 1.68 D; all P < 0.001), mean PK (PKm; -5.90 ± 0.24 D vs. -6.25 ± 0.25 D vs. -6.37 ± 0.26 D; all P < 0.001) and TK-J0 (-0.34 ± 0.65 D vs. -0.23 ± 0.53 D vs. -0.12 ± 0.62 D; all P < 0.001). We also observed significant differences in PK-J45 between IOLMaster 700 and Pentacam AXL as well as between CASIA2 and Pentacam AXL (both P < 0.001). There was a good agreement in TKm, TK-J0, TK-J45, and PK-J0 (ICC = 0.887, 0.880, 0.751, and 0.807, respectively), a moderate agreement in PK-J45 (ICC = 0.626), and a poor agreement in PKm (ICC = 0.498) among these 3 biometers.

TK, PK, and the corresponding astigmatism obtained by IOLMaster 700, CASIA2, and Pentacam AXL showed significant differences, and could not be used interchangeably.

Our study may help to guide preoperative keratometry measurement for intraocular lens (IOL) power calculation and astigmatism evaluation for patients with cataract.