Peripapillary Microvascular Improvement and Lamina Cribrosa Depth Reduction after Trabeculectomy in Primary Open-Angle Glaucoma

Abstract

Purpose: To evaluate peripapillary microvascular changes in patients with primary open-angle glaucoma (POAG) after trabeculectomy using optical coherence tomography (OCT) angiography, and to determine the influence of lamina cribrosa (LC) displacement on changes in peripapillary microvasculature. Methods: The peripapillary retinal microvasculature and LC were imaged using OCT angiography and OCT-enhanced depth imaging, respectively. The microvasculature and LC depth (LCD) were measured before, and 1 week, 1 month, and 3 months after trabeculectomy. The microvascular improvement was arbitrarily defined as a reduction > 30% of the area of vascular dropout (blue/black areas with < 20% vessel density on the color-coded vessel density map). LCD was determined as the mean of vertical distance between the anterior LC surface and a reference plane of Bruch’s membrane. Results: Thirty-one eyes of 31 POAG patients were included. At 3 months’ postoperatively, intraocular pressure (IOP) and LCD were significantly decreased from 26.3±11.8 mmHg to 12.5±3.6 mmHg, and 501.1±130.2 μm to 455.8±112.7 μm, respectively (all p<0.001), compared with baseline. The microvascular improvement was observed in 19 eyes (61.3%) at 3 months after trabeculectomy. The maximal reductions in IOP and LCD were significantly greater in eyes with improved microvasculature compared to eyes without improvement (p=0.020 and p=0.005). The microvascular improvement was significantly associated with maximal reduction in LCD (odds ratio, 1.062; p=0.026). Conclusions: Trabeculectomy can improve peripapillary retinal microcirculation in patients with POAG. This finding suggests that the reduction of LCD induced by lowering IOP may affect peripapillary microvascular improvement in eyes with POAG.