Prospective comparison of ultrasound biomicroscopy and anterior segment optical coherence tomography for evaluation of anterior chamber dimensions in European eyes with primary angle closure

Abstract

To compare the accuracy in measurement of the anterior chamber (AC) angle by anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) in European patients with suspected primary angle closure (PACS), primary angle closure (PAC), or primary angle-closure glaucoma (PACG). Cross-sectional study. In all, 55 eyes of 33 consecutive patients presenting with PACS, PAC, or PACG were examined with AS-OCT, followed by UBM. The trabecular-iris angle (TIA) was measured in all four quadrants. The angle-opening distance (AOD) was measured at 500 microm from the scleral spur. The Bland-Altman method was used for assessing agreement between the two methods. The mean (+/-SD) superior TIA was 19.3+/-15.8 degrees in AS-OCT and 15.7+/-15.0 degrees in UBM (P=0.50) and inferior TIA was 17.9+/-12.9 degrees (AS-OCT) and 16.7+/-14.1 degrees (UBM) (P=0.71). The superior AOD(500) was 0.17+/-0.16 mm in UBM and 0.21+/-0.16 mm in AS-OCT (P=0.06). Bland-Altman analysis showed a mean SD of+/-9.4 degrees for superior and inferior TIA and a mean SD of +/-0.10 mm for superior and inferior AOD(500). This comparative study shows that AS-OCT measurements are significantly correlated with UBM measurements but show poor agreement with each other. We do not believe that AS-OCT can replace UBM for the quantitative assessment of the AC angle.