Optical Coherence Tomography Angiography of the Retinal Circulation Following Trabeculectomy for Glaucoma

Precis:Despite successful trabeculectomy, eyes with similar levels of peripapillary and macular vessel densities but with worse preoperative visual field mean deviations may experience functional and vascular decline after surgery. Purpose:To evaluate the retinal microcirculation change after trabeculectomy according to glaucoma severity using optical coherence tomography angiography (OCTA). Methods:We enrolled 59 eyes of primary open angle glaucoma patients who underwent trabeculectomy. The eyes were categorized into 3 groups by preoperative visual field (VF) mean deviation (MD), group 1: MD>-12.0 dB, group 2: MD -12.0 to -20.0 dB, and group 3: MD <-20.0 dB. OCTA was performed preoperatively and 1 year after trabeculectomy. The differences in the radial peripapillary capillary vessel density (pVD) and macular VD between preoperative and postoperative assessment were analyzed and compared in each group. Factors associated with the VD change after trabeculecomy were determined using linear regression analysis. Results:Mean postoperative IOP and IOP reduction did not differ among the 3 groups after trabeculectomy. Preoperative pVD (37.2 vs. 36.6%, P=1.00) and macular VD (39.0 vs. 38.4%, P=1.00) did not differ between groups 1 and 2. Group 1 and 3 showed no changes in VD parameters after trabeculectomy (all, P>0.05). However, group 2 showed statistically significant decreases in pVD (36.6 vs. 32.9%, P<0.001) and macular VD (38.4 vs. 36.0%, P=0.010) after trabeculectomy. The reduction of pVD was associated with a decrease of IOP (Coefficient (beta); 0.14, P=0.032) and VF MD (beta; 0.15, P=0.0116) in group 2, respectively. Conclusion:Following successful trabeculectomy surgery for uncontrolled glaucoma with similar IOP reduction, glaucoma eyes with advanced visual field loss showed reduced pVD and macular VD measured by OCT-A. These findings may be relevant to disease progression.