Authors: Xue Yanzhen, Zhou Qizhi
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To compare the agreement of central vault measurements between anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) in the eyes with posterior chamber phakic intraocular lens implantation and analyze the association sculus to sculus (STS) diameter and white-to-white (WTW) diameter of cornea with central vault.
A cross-sectional study was carried out.Medical records of 150 phakic eyes of 75 myopic patients who underwent implantable collamer lens (ICL) surgery for the correction of myopia were collected in Chongqing Aier Eye Hospital from December 2017 to March 2018.The postoperative central vault were measured with AS-OCT and UBM.Intraclass correlation coefficient (ICC) and Bland-Altman plot were used to evaluate the repeatability and agreement of the measurements between two devices.The affecting factors of central vault measurements were assessed.
Mean central vault in the 150 phakic eyes after ICL surgery was (0.73±0.25)mm by AS-OCT and (0.76±0.31)mm by UBM, respectively with the ICC of 0.91 for the measurements of AS-OCT and UBM.Bland-Altman analysis showed that the 95% limits of agreement of central vault measurements were -0.38—0.31 mm between the two devices.Five values were beyond the 95% consistency interval, and the maximum absolute value of the difference was is 0.31 mm, which was beyond the clinical acceptable range, showing an non-interchangeable difference in the central vault measurements between the devices in ICL implanted eyes.WTW was a affecting factor for vault with a regression equation of Y=0.145 3X-0.960 1(t=2.272, P<0.05). Horizontal and vertical STS were the indirect affecting factors for vault by the association with WTW with the regression equation of Y=0.524 1X+ 5.362 4 and Y=0.613 4X+ 4.658 3, respectively.
Central vault measured by UBM is higher that than AS-OCT after ICL surgery, and the measurements are uninterchangeable between the two devices.Accurate measurement of STS distance is essential for the selection of appropriate lens before operation.