Comparative study of anterior segment measurements using 3 different instruments in myopic patients after ICL implantation

BACKGROUND: To compare and correlate anterior segment measurements of myopic eyes implanted with Implantable Collamer lens (ICL V4c) by using anterior segment optical coherence tomography (AS-OCT), Pentacam and ultrasound biomicroscopy (UBM). METHODS: Anterior chamber depth (ACD), distance between corneal endothelium and anterior surface of ICL(C-ICL) and central vault were measured in 82 phakic myopic eyes of 82 patients who underwent ICL surgery, by using AS-OCT, Pentacam and UBM consecutively at 3 months follow up. The correlation and agreement of instruments were accessed by using Intraclass correlation coefficient (ICC) and the Bland-Altman plot. RESULTS: AS-OCT showed higher ACD, C -ICL and central vault measurements than both of Pentacam and UBM (P < 0.001), while Pentacam showed lower measurements than UBM (P < 0.05). The Pearson correlation coefficient (r) was 0.91 to 0.96, and ICC was 0.95 to 0.98 for all measurements between difference devices (all P < 0.001). The 95% limits of agreement of ACD, C-ICL, vault measurements were 0.13 to 0.38 mm, - 0.07 to 0.27 mm, 0.08 to 0.34 mm between AS-OCT and Pentacam, - 0.03 to 0.33 mm, - 0.16 to 0.31 mm, - 0.10 to 0.26 mm between AS-OCT and UBM, and - 0.29 to 0.07 mm, - 0.25 to 0.20 mm, - 0.31 to 0.05 mm between Pentacam and UBM, respectively. CONCLUSIONS: AS-OCT demonstrated significantly higher value, while Pentacam demonstrated significantly lower value than UBM for ACD, C-ICL and central vault measurements in myopic eyes after ICL surgery. Measurements with these instruments were highly correlated, but could not replace each other especially for vault. This study provided valuable information about how to judge the results of anterior segment parameters of eyes implanted with ICL V4c from different devices. TRIAL REGISTRATION: Registration number: ChiCTR-OOC-16008987 . Retrospectively registered: 08 August 2016.