Comparison of corneal power and astigmatism in normal eyes using 4 different devices

Abstract

AbstractPurpose To compare corneal power and astigmatism in normal subjects obtained from dual Scheimpflug analyzer (Galilei), single Scheimpflug analyzer (Pentacam), optical low coherence reflectometer (Lenstar) and autokeratometer (AR)Methods Forty‐eight eyes of 27 subjects were evaluated with 4 different devices. Steep, flat and mean keratometry (K) values and astigmatism magnitude were measured. Corneal power vectors, J0 and J45, were calculated using Jackson cross cylinder. Repeated‐measured ANOVA with Bonferroni post hoc analysis was performed to compare the measurements, and correlation was accessed by Pearson correlation test. Agreement was assessed by Bland‐Altman analysis and 95 % limit of agreement (LoA) was calculated.Results Mean K values measured by Galilei, Pentacam, Lenstar, and AR were 44.34 ± 1.03 diopters (D), 44.52 ± 1.03 (D), 44.30 ± 0.98 (D), and 44.44 ± 0.92 (D), respectively. Steep K, J0, and J45 did not show significant differences (all p > 0.05), however, mean K, flat K, and astigmatism were significantly different (p= 0.002, 0.002, 0.005, respectively). All measured parameters were significantly correlated with each other (Pearson correlation test, all p < 0.05). For corneal power and astigmatism, 95% LoA varied from 1 to 2 (D).Conclusion Even though the measurements of corneal power and astigmatism were correlated with each other, some values showed significant differences and the agreements were not good. Therefore, the measurements of each device couldn’t be used interchangeably in clinical practice.