Comparative Study of Vault Measurement by Pentacam, Casia2, and RTVue in Myopic Eyes After Implantable Collamer Lens Implantation.

Purpose: To compare vault measurement using Pentacam (Oculus, Germany) and two optical coherence tomography (OCT) instruments, Casia2 (Tomey Corporation, Japan) and RTVue (Optovue Inc. USA).

Methods: This comparative study recruited 95 eyes of 50 patients (mean age: 28.40±4.51, male/female 15/35) who underwent implantable collamer lens (ICL) implantation for myopia correction. All patients underwent a series of ophthalmic examinations at 3 and 6 months postoperatively, and the vault was measured using three instruments in the same order at both follow-ups. Intraclass coefficients (ICC) and Bland-Altman plots were used to analyze intra-equipment reproducibility and agreement between two instruments. A multivariate regression model was used to analyze the factors influencing the vault differences between the devices.

Results: The ICC values for intra-observer and inter-observer reproducibility of each piece of equipment were above 0.9. The ICC values and mean differences of vault measurement of Casia2 vs Pentacam, Casia2 vs RTVue, and RTVue vs Pentacam were 0.763 and 139.81 μm, 0.960 and -17.18 μm, 0.739 and 151.86 μm, respectively. An average of 96.2% of the points fell within the limit of agreement in the Bland-Altman plots. No difference was found in the inter-device agreement between the 3- and 6-month vaults. The difference in pupil diameter, anterior chamber depth, and anterior chamber angle could influence the vault difference between the Pentacam and the two OCT instruments.

Conclusion: All three instruments demonstrated good intra-equipment reproducibility. Casia2 and RTVue showed excellent agreement in the vault measurements. The Pentacam's vault readings were significantly lower than those measured by Casia2 and RTVue; therefore, their vault measurements were not interchangeable.