Purpose: To compare pretreatment anterior segment parameters between eyes with acute primary angle closure (APAC) and chronic primary angle closure (CPAC), and to identify the characteristics of eyes with APAC.
Study design: Retrospective.
Methods: We measured pretreatment anterior chamber depth (ACD), iris convexity (IC), and pupil diameter in eyes with APAC and CPAC using anterior segment optical coherence tomography. The risk of APAC associated with anterior segment parameters was investigated using multiple logistic regression. Eyes with APAC were discriminated from eyes with CPAC using the receiver-operating characteristic (ROC) curve and area under the curve (AUC). The best cutoff for these variables was determined.
Results: Thirty-four eyes with APAC and 60 eyes with CPAC were included. The mean intraocular pressure was 52.3 ± 12.6 mmHg in APAC and 15.5 ± 3.5 mmHg in CPAC (P < .001). Eyes with APAC had a shallower ACD (1.407 ± 0.301 mm vs. 1.960 ± 0.205 mm, P < .001) and less IC (0.233 ± 0.087 mm vs. 0.294 ± 0.068 mm, P < .001) than eyes with CPAC. In multivariate analysis, significant variables associated with APAC were ACD (P < .001) and IC (P = .001). The AUC for ACD was 0.931 and for IC, 0.742. The best cutoff for ACD was 1.699 mm (sensitivity 0.824, specificity 0.917) and for IC, 0.282 mm (sensitivity 0.853, specificity 0.533).
Conclusions: Eyes with APAC had a shallower ACD and less IC. Eyes with an ACD < 1.7 mm may be at risk for APAC.
Keywords: Acute primary angle closure; Angle closure; Anterior chamber depth; Anterior segment optical coherence tomography; Iris convexity.