Repeatability and reproducibility of the galilei G6 and its agreement with the pentacam® AXL in optical biometry and corneal tomography

Abstract

Objectives: To assess the repeatability and reproducibility of corneal measurements performed by the Galilei G6 and determine its agreement with the Pentacam® AXL.

Methods: 105 eyes underwent examination by both devices, measuring nine parameters. Paired t-tests, Deming Regression, and Bland-Altman plots were used to determine agreement. Analysis of Variance was used to determine repeatability and reproducibility.

Results: Measurements showed no clinically significant differences between the two devices. On average, the Galilei G6 measured axial length longer than the Pentacam® AXL by 0.05 mm ± 0.03 mm (p < 0.001), just 0.2% of the mean value and therefore clinically insignificant. It measured central corneal thickness and anterior chamber depth 3.77 μm ± 7.71 μm longer (p < 0.001) and 0.04 mm ± 0.07 μm shorter (p < 0.001), respectively. They are also clinically insignificant, constituting just 0.7% and 1% of the mean values. The results showed evidence of repeatability and reproducibility. Only measurements of corneal cylinder showed some clinically significant variance.

Conclusions: The Galilei G6 and Pentacam® AXL measurements show evidence of repeatability, reproducibility, and agreement for examined parameters. Certain caution needs to be applied in cases with moderate or severe corneal cylinder, due to discrepancies in repeatability and reproducibility of corneal cylinder measurements with the Galilei G6.

Keywords: Scheimpflug imaging; White-toWhite/Horizontal limbus diameter; anterior chamber; corneal cylinder; corneal thickness; keratoconus; optical biometry; placido’s disc; tomography; topography.