Consistency of Corneal Thickness and Anterior Chamber Depth Measured by Pentacam and VX120

Objective: To compare the consistency of central corneal thickness (CCT), minimum corneal thickness (MinCT) and anterior chamber depth (ACD) measured by Pentacam and VX120. Methods: In this case series study, 71 myopia patients with (142 eyes) who planned to receive refractive surgery were enrolled from the March 2018 to April 2018, in Beijing Tongren Hospital. All subjects were under CCT, MinCT, ACD measurement by Pentacam and VX120. Due to that data of both eyes were used, thus a Rosner-Glynn-Lee method was used to make correction. The clustered rank sign test was used to compare the measurements of different equipment. The intra-class correlation coefficient (ICC) and Bland-Altman 95% limits of agreement were used to measure the consistency of measurement of different equipment. Results: CCT, ACD measured by the VX120 was lower than Pentacam (Z=3.524, 7.446, all P<0.001). There was no statistical difference in the measurement of MinCT between VX120 and Pentacam (Z=0.679, P=0.497). The ICC of MinCT measured by VX120 and Pentacam was 0.9 and the Bland-Altman plot showed that 93.7% of the data were distributed within the confidence interval. The 95% limits of agreement of MinCT were -27.81 to 29.26 μm for these two devices. Conclusions: VX120 has a high consistency with Pentacam on the measurement of MinCT. However, the measurements acquired by VX120 should not be directly interchangeable with Pentacam measurements in clinical practice. Key words: VX120; Pentacam; consistency; corneal thickness; minimum corneal thickness; anterior chamber depth