Ocular Biometric Characteristics in Preoperative Diagnosis of Acute Angle Closure Secondary to Zonular Laxity

Abstract Purpose To investigate the ocular biometric characteristics of eyes with acute angle closure (AAC) secondary to zonular laxity to further explore the sensitive parameters for preoperative diagnosis. Methods This study included 50 patients with AAC secondary to zonular laxity and 54 patients with acute primary angle closure (APAC). Demographic data, ocular examination results and biometric parameters on ultrasound biomicroscopy (UBM) images were compared between the affected and fellow eyes in two groups. Parameters significant in the multiple linear regression model were included in a regression equation and the diagnostic efficiency was evaluated by area under the curve (AUC). Results In patients with AAC secondary to zonular laxity, the binocular difference of central anterior chamber depth (ACD), lens vault (LV) in affected eyes and binocular difference of LV were significantly larger than those in patients with APAC respectively and these three parameters were all significant in multiple linear regression analysis (all P < 0.001). The AUC of binocular difference of ACD, LV in affected eyes and binocular difference of LV were 0.972, 0.796, and 0.855, respectively, with the cut-off value of 0.23 mm, 1.28 mm and 0.19 mm, respectively. The regression equation containing these three parameters was: ln (p/(1-p)) = -4.322 + 1.222[LV in affected eyes (mm)] + 3.657[binocular difference of LV (mm)] + 6.542[binocular difference of ACD (mm)], with the accuracy of prediction reaching 94.05%. Conclusion Binocular difference of ACD, LV in affected eyes, and binocular difference of LV had high efficiency in diagnosing AAC secondary to zonular laxity.