Consistency analysis of UBM and ArcScan Insight 100 measurements in the anterior segment of the myopic eye

Objective  To evaluate the repeatability of anterior segment biometry measurements obtained using ultrasound biomicroscopy (UBM) and the ArcScan Insight 100, and to compare the agreement between the two devices.

Methods  A cross-sectional study was conducted.Seventy myopic patients (70 eyes) who underwent V4c implantable collamer lens implantation at Henan Eye Hospital from March to May 2023 were included.The ArcScan Insight 100 and UBM were used to measure the following parameters three times: angle-to-angle distance (ATA), sulcus-to-sulcus distance (STS), anterior chamber depth (ACD), crystalline lens rise (CLR), anterior chamber width (ACW), ciliary body inner diameter (CBID), anterior chamber angle (ACA), trabecular-ciliary angle (TCA) and maximum ciliary body thickness (CBTmax). The repeatability of anterior segment biological measurements obtained using the two devices was assessed by intraclass correlation coefficient (ICC). The consistency between the two instruments was evaluated by Bland-Altman consistency test.This study complied with the Declaration of Helsinki and was approved by the Ethics Committee of Henan Eye Hospital (No.HNEECKY-2021[13]). All patients understood the purpose and significance of this study and signed the informed consent form.

Results  The repeatability of ATA, STS, ACD, CLR, ACW, CBID, ACA, TCA and CBTmax measured by UBM and ArcScan Insight 100 was good (all ICC>0.9). There was no significant difference in ACD, ACW, and ACA between the two instruments ( t=0.696, -1.025, -1.447; all P>0.05). ATA, STS, CLR and CBID measured by UBM were lower and TCA and CBTmax were higher than those measured by UBM ArcScan Insight 100, and the differences were statistically significant ( t=-8.586, -12.551, -4.481, -4.420, 4.535, 7.812; all P<0.05). The differences of ATA, STS, ACD, CLR, ACW, CBID and CBTmax between UBM and ArcScan Insight 100 were 0.38, 0.47, -0.01, 0.07, 0.3, 0.26 and -0.21 mm, respectively, with the 95% limits of agreement (LoA) of (-0.34, 1.10), (-0.15, 1.09), (-0.28, 0.26), (-0.20, 0.35), (-0.33, 0.93), (-0.71, 1.23) and (-0.64, 0.23)mm, respectively, which showed good coherence.The differences in ACA and TCA measurements were 2.26° and -7.81°, respectively, and the 95%LoA values were (-23.36°, 27.89°) and (-36.05°, 20.43°), respectively, with poor coherence.There was a strong positive correlation in ACD measurements measured by UBM and ArcScan Insight 100 ( r=0.827, P<0.05). There were moderate positive correlations in ATA, STS, CLR, ACW and CBID ( r=0.678, 0.749, 0.617, 0.765, 0.519; all P<0.05). There was no significant correlation in ACA, TCA and CBTmax ( r=0.270, 0.032, 0.178; all P>0.05).

Conclusions  The repeatability of ArcScan Insight 100 and UBM in measuring anterior segment biological parameters is good.However, the consistency of ACA, TCA and CBTmax measured by the two instruments is poor and may be affected by self-regulation of the body.ATA, STS, ACD, CLR, ACW and CBID have good consistency and can be used interchangeably.

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