Diagnostic Disagreement Between Gonioscopy and Ultrasound Biomicroscopy in Eyes With Occludable Angle

Disagreement in the angle closure assessment was seen between gonioscopy and ultrasound biomicroscopy (UBM), to which not only anterior, but also posterior chamber configuration UBM parameters were significantly related.

To study diagnostic disagreement and its relating factors in assessing the angle classified as "occludable" by gonioscopy and by ultrasound biomicroscopy in eyes with van Herick grade 2 or less (eyes ≤VH2).

In 93 eyes ≤VH2 (93 subjects) with no peripheral anterior synechia, gonioscopy, UBM, and anterior segment-optical coherence tomography (AS-OCT) were performed in dark, the number of eyes with ≥2 ITC-positive quadrants (contact ≥180 degrees) based on UBM (eyes ≥2-ITC UBM Quad) and that with the angle classified as occludable by gonioscopy (eyes≥2-ITC GONIO Quad) were determined, and the number of eyes not meeting these criteria, that is, eyes <2-ITC UBM Quad (contact <180 degrees) and eyes <2-ITC GONIO Quad, was also determined. Multivariable logistic regression analysis was performed with systemic, ocular, UBM, and AS-OCT parameters as explanatory variables.

Out of the 93 eyes, 49 were diagnosed as eyes ≥2-ITC GONIO Quad based on gonioscopy, 63 as eyes ≥2-ITC UBM Quad on UBM, 37 as both eyes ≥2-ITC GONIO Quad and eyes ≥2-ITC UBM Quad (agreement between gonioscopy and UBM), 12 as eyes ≥2-ITC GONIO Quad base on gonioscopy, but as eyes <2-ITC UBM Quad on UBM (UBM under-diagnosing), and 26 as eyes <2-ITC GONIO Quad based on gonioscopy, but as eyes ≥2-ITC UBM Quad on UBM (UBM over-diagnosing), respectively (McNemar test, P =0.0388). Longer axial length ( P =0.0002), deeper anterior chamber depth ( P =0.0121), greater angle-opening distance at 500 μm ( P =0.0159), and smaller iris convexity ( P =0.0031) were related to UBM over-diagnosing, while a greater angle-opening distance at 500 μm ( P =0.0046) and smaller trabecular ciliary angle ( P =0.0158) to UBM under-diagnosing.

Both anterior and posterior chamber configuration parameters determined based on UBM were significantly related to disagreement between gonioscopy and UBM in assessing the appositional angle closure.