OCT angiography measured changes in the foveal avascular zone area after glaucoma surgery

Background/Aims To evaluate quantitative changes in the foveal avascular zone (FAZ) area after glaucoma surgery using swept-source optical coherence tomography angiography (SS-OCTA). Methods Fifty-four consecutive patients with primary open-angle glaucoma (POAG) who met the inclusion criteria and underwent unilateral glaucoma surgery to reduce intraocular pressure (IOP) between April 2018 and July 2019. Eyes underwent IOP-lowering glaucoma surgery and their fellow (non-surgical) eyes were included. OCTA of the macula was performed in both eyes before glaucoma surgery and 3 months postoperatively. Two blinded examiners reviewed the image quality. Within- and between-group comparisons of the FAZ area and correlation of the FAZ area with age, IOP, central sensitivity and clinical variables. Results The mean (+/- SD) age was 66.7 +/- 11.3 years. After surgery, the IOP and FAZ area significantly decreased from 22.1 +/- 9.5 mmHg to 10.3 +/- 3.5 mmHg and from 0.485 +/- 0.193 mm(2) to 0.446 +/- 0.174 mm(2), respectively (both p<0.001). Conversely, in the non-surgery group, the preoperative and postoperative mean FAZ areas (0.398 +/- 0.119 mm(2) and 0.396 +/- 0.110 mm(2), respectively) did not significantly differ (p=0.469). Change in the FAZ area significantly correlated with the preoperative FAZ area, preoperative foveal sensitivity and change in IOP (all p<0.05). Conclusions The FAZ area is decreased with IOP-lowering surgery in patients with POAG, and change in the FAZ area was significantly correlated with both preoperative foveal sensitivity and change in IOP.