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

Abstract

This study aimed to compare the differences and characteristics of white-to-white (WTW) values obtained before V4c implantation using triple person-times caliper, IOL-Master 700, Pentacam HR, and UBM, and to assess their correlation with vaulting. 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. The WTW was determined to be 11.30 ± 0.29 mm, 11.43 ± 0.29 mm, and11.86 ± 0.38 mm, respectively, using the triple person-times caliper, Pentacam HR, and IOL-Master 700. The measurement of ATA was 11.57 ± 0.51 mm, as done by UBM. The ICL vault was measured to be 400.97 ± 198.46 µm when examined with Pentacam HR three monthsafter the procedure. The linear regression analyses of ICL size and WTW of triple person-times caliper, ICL vault and WTW were (R = 0.703, p < 0.001; R = 0.0969, p < 0.001) respectively. The highest correlation was found between IOL-Master and Pentacam HR (r = 0.766, p = 0.000). The lowest correlation was found between UBM and Pentacam HR (r = 0.358, p = 0.002). Bland-Altman analysis showed that the 95% limits of agreement (LoA) were the triple person-times caliper and Pentacam HR (- 0.573, 0.298) and the triple person-times caliper and UBM (- 1.15, - 0.605). 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 UBM. 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.

Keywords: Caliper; ICL; IOL-Master; Pentacam HR; UBM; White-to-white.

Figure 1

Method of triple person-time caliper measurements. Step 1: Measurement of the corneal diameter is taken from 3 to 9 points using an eye gauge caliper while the patient is seated at the slit lamp. Step 2: Tip of the eye gauge scratches on thermal paper. Step3: Digital vernier calipers measure the size of scratches.

Figure 2

The linear regression lines of ICL size and horizon WTW of four methods.

Figure 3

The linear regression lines of ICL vault and horizon WTW of four methods.

Figure 4

The Bland–Altman graphical representation between the means of each pair of measures versus the difference between devices. (A) Difference vs. average: Bland–Altman of triple-blind caliper and Pentacam HR. (B) Difference vs. average: Bland–Altman of triple person-times caliper and IOL—master 700. (C) Difference vs. average: Bland–Altman of triple person -times caliper and UBM. (D) Difference vs. average: Bland–Altman of Pentacam HR and IOL-mater. (E) Difference vs. average: Bland–Altman of Pentacam HR and UBM. (F) Difference vs. average: Bland–Altman of IOL-master 700 and UBM.