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Purpose : To assess the clinical significance of vitreous zonule (VZ) in primary angle closure (PAC) and primary angle closure glaucoma (PACG).
Methods : 91 eyes of 92 participants patients with PAC or PACG who had visited the glaucoma clinic of Asan Medical Center, Seoul, South Korea, from April of 2015 to April of 2017. Anterior chamber and angle parameters were measured using anterior segment optical coherence tomography images and presence of VZ was assessed with ultrasound biomicroscopy.
Results : Eyes with absent VZ had smaller anterior chamber area than VZ present eyes (13.6 mm2 vs 15.1 mm2; p = .020) but there was no significant difference between two groups in anterior chamber depth (1.97 mm vs 2.08mm; p = .119), anterior chamber width (12.0 mm vs 11.9 mm; p = .351) and lens vault (1.21 mm vs 1.13 mm; p = .337). Compared to eyes with VZ present, eyes with absent VZ had smaller scleral spur angle (11.5° vs 17.4°, p < .001), angle opening distance at 500 μm (105 μm vs 168 μm; p < .001) and 750 μm (164 μm vs 247 μm; p < .001), angle recess area at 750 μm (0.099 mm2 vs 0.134 mm2; p = .017), trabecular-iris space area at 500 μm (0.047 mm2 vs 0.063 mm2; p = .022) and 750 μm (0.081 mm2 vs 0.117 mm2; p = .003), trabecular-ciliary process angle (75.7° vs 81.9°, p = .029) and trabecular-ciliary process distance (0.97mm vs 1.06mm, p = 0.007). There was no significant difference between two groups in iris and related parameters and ciliary body thickness 1 mm posterior to the scleral spur.
Conclusion : Eyes with absent VZ appear to have a narrower angle despite similar anterior chamber dimensions or iris configuration and seem to have worse clinical course than eyes with visible VZ.
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