Swept-source optical coherence tomography and ultrasound biomicroscopy study of anterior segment parameters in primary angle-closure glaucoma

Purpose To evaluate the agreement between swept-source OCT (CASIA2) and UBM in primary angle-closure glaucoma. Methods Eighty eyes of 40 participants diagnosed with primary angle-closure glaucoma were examined. Parameters measured included angle opening distance (AOD), angle recess area (ARA), trabecular iris space area (TISA), trabecular iris angle (TIA), lens vault (LV), anterior chamber depth (ACD), and anterior chamber width (ACW). Angle images of nasal, temporal, superior, and inferior were acquired by the anterior segment mode of CASIA2 and UBM. One-way analysis of variance and paired t -test were used for statistical analysis, and the agreement was analyzed by internal correlation coefficient (ICC) and Bland–Altman method. Results One-way ANOVA pairwise comparison showed that CASIA2 or UBM had the narrowest superior chamber angle and the widest temporal chamber angle in patients with primary angle-closure glaucoma. The paired t -test showed that inter-device AOD, TIA, ARA, and TISA of superior chamber angle had significant differences ( p < 0.001). There was no significant difference in the measured values of LV, ACD, and ACW ( p > 0.05). The agreement of all parameters is good through the Bland–Altman method comparison. ICC result showed moderate agreement in other angle parameters except for superior ARA500 (0.739). Conclusion In the anterior chamber angle measurement process, we should pay more attention to the superior chamber angle covered by eyelids. Although the agreement is acceptable between CASIA2 and UBM, the measurements could not be considered interchangeable due to the tremendous statistical difference between the two devices.