Novel Discoveries of the Relationship Between the Vitreous Zonule and the Anterior Segment Characteristics in Eyes With Primary Angle-Closure Disease

PURPOSE: To investigate the presence of the vitreous zonule (VZ) in different subtypes of primary angle-closure disease (PACD) and to explore the relationship between VZ and anterior chamber angle characteristics. METHODS: Patients with clinical diagnoses of acute primary angle-closure (PAC)/PAC glaucoma (APAC[G]) or chronic PAC/PAC glaucoma (CPAC[G]) and healthy subjects were enrolled. A total of 300 eyes of 180 subjects were included. Anterior segment parameters and the presence of the VZ were assessed by ultrasound biomicroscopy. The presence of VZ was compared among different subtypes of PACD. Anterior segment parameters were compared between eyes in vitreous zonule group (VZG) and no vitreous zonule group (NVZG). Logistic regression analysis was conducted to identify factors associated with the presence of VZ. RESULTS: APAC(G) eyes had lower VZ presence compared to the fellow eyes of APAC(G) (P < 0.001). VZ was more likely to be seen in the eyes of healthy subjects and PAC suspect than in the eyes of PAC and PAC glaucoma (PACG) (P < 0.05). NVZG had shorter angle opening distance 500/750 (P < 0.001), smaller trabecular iris angle 500/750 (P < 0.001), smaller trabecular-iris space area 500/750 (P < 0.001), smaller trabecular–ciliary angle (P = 0.009), smaller iris area (P = 0.010), and greater lens vault (P = 0.004) compared to VZG. Greater lens vault (LV) was independently associated with absence of VZ (odds ratio = 0.253; 95% confidence interval, 0.109-0.586; P = 0.001). CONCLUSIONS: VZ was less likely to be observed in PAC/PACG eyes. PACD eyes with less VZ had narrower angle, more anteriorly rotated ciliary body, and greater LV.