Abstract
Purpose :
To compare differences and agreement for ocular parameters and target refractive error in Chinese emmetropic (AL 22-24 mm), hypermetropic (AL <22 mm) and myopic eyes (> 26 mm) obtained by two optical biometric instruments; the CASIA2 AS-OCT (Tomey, Japan) and Pentacam AXL (Oculus, Germany) using two different IOL power calculation formulae.
Methods :
In this random population-based cross-sectional study, 174 consecutive subjects aged 50 and over underwent biometric assessment using the CASIA2 and the Pentacam AXL devices. The right eye of each subject was used for analysis. Ocular parameters and target refractive error were compared between devices using a constant IOL SEQ equal to 19.50. Measurements were expressed as mean and standard deviation. Differences between devices, using Barrett UII and SRK/T formulae, and across emmetropes, hypermetropes and myopes were determined using Wilcoxon signed-rank test and Kruskal-Wallis test. The agreement in ocular biometry and IOL power between the 2 devices was evaluated by the Bland-Altman method.
Results :
Overall, 174 eyes of 174 subjects were analyzed. Mean age was 60.49 (± 6.58). Based on axial length and refractive error, 134 were emmetropes, 7 were hypermetropes and 33 were myopes. 66.67% of subjects were female. There were no significant differences in measured ocular parameters between devices and across emmetropes, hypermetropes and myopes. For target refractive error, statistically significant differences between devices were noted for all three groups, with the difference being highest using Barrett UII formula and in myopes (0.31 ± 0.22), followed by emmetropes (0.26 ± 0.27), and then hypermetropes (0.25 ± 0.29). For each device, there were no statistically significant differences in target refractive error between the two formulae.
Conclusions :
Despite using different imaging principles, parameters obtained by the CASIA2 and Pentacam AXL devices are comparable. There were statistically significant differences in target refractive error between devices, but would be within a clinically acceptable margin of error. Both devices are comparable across a range of axial lengths.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.