The comparison of white-to-white via triple person-times caliper measuring and machine- measuring in V4c implantable collamer lens implantation

Abstract Background: This study aimed to compare the differences in white-to-white (WTW) values obtained using the triple-person-times caliper measurement, IOL-Master 700, Pentacam HR, and UBM before V4c Implantable Collamer Lens (ICL) Implantation. The objective of this study was to analyze the characteristics of these measurements and assess their correlation with the vault. Methods: A total of 930 myopia patients (1842 eyes) who were interested in undergoing ICL surgery were assessed before the procedure using various instruments. The WTW measurements were obtained using a triple person-times caliper, Pentacam HR, and IOL-Master 700, whereas the angle-to-angle (ATA) measurements were obtained using UBM. The size of the ICL was subsequently calculated using triple person-times caliper measurements. The vault of the ICL was assessed using Pentacam HR three months after the surgery. Results: The WTW was determined to be 11.31 ± 0.31mm, 11.49 ± 0.34mm, and11.86 ± 0.37mm, respectively, using the triple person-times caliper, Pentacam HR, and IOL-Master 700. The measurement of ATA was 11.58 ± 0.51mm, as done by UBM. The ICL vault was measured to be 411.49 ± 197.59 µm when examined with Pentacam HR three months after the procedure. The results from all four methods in horizontal WTW, triple person-times caliper, Pentacam HR, IOL - Master 700, and UBM, were compared and p < 0.001 was considered statistically significant. The four measures correlated well (r > 0.38, p = 0.000). The highest correlation was found between IOL-Master and Pentacam HR (r = 0.783, p = 0.00). The lowest correlation was found between UBM and Pentacam HR (r = 0.38, p = 0.00). Bland–Altman analysis showed that the 95% limits of agreement (LoA) were the triple person-times caliper and Pentacam HR (–0.59, 0.29) and the triple person-times caliper and IOL Master (–1.12,–0.03). This indicated a strong agreement between the triple person-times caliper and Pentacam HR and a lack of agreement between the triple person-times caliper and IOL Master. Conclusions: Triple person-times caliper measurements offer excellent maneuverability, practicality, and reliable outcomes for determining ICL vaults. Measurements obtained using the triple-person caliper were less differece than those obtained using the Pentacam HR.