Effect of Reducing Intraocular Pressure on Vessel Density after Trabeculectomy Using Optical Coherence Tomography Angiography

ABSTRACT

Purpose@#To evaluate peripapillary and macular vessel density changes in glaucoma patients after lowering intraocular pressure (IOP) by trabeculectomy, using optical coherence tomography (OCT) angiography. @*Methods@#A retrospective study was conducted on 20 glaucomatous eyes that underwent trabeculectomy. Preoperative and postoperative IOP, peripapillary retinal nerve fiber layer (RNFL) thickness, macular ganglion cell-inner plexiform layer thickness, peripapillary and macular vessel density measured by OCT, and OCT angiography were analyzed by the Wilcoxon signed-rank test. A regression analysis was performed to identify the factors influencing the change in vessel density. @*Results@#The mean IOP was 31.0 ± 11.80 mmHg prior to surgery, 11.47 ± 4.52 mmHg at 1 month (p < 0.001), and 11.52 ± 3.34 mmHg at 6 months (p < 0.001). Peripapillary RNFL thickness (p = 0.002) increased significantly 6 months postoperatively. Peripapillary vessel density increased significantly 6 months after surgery (p = 0.007) and the magnitude of the reversal of peripapillary vessel density was significantly associated with a greater reduction in IOP (p < 0.001), and the lower preoperative peripapillary vessel density value (p = 0.003) and change in peripapillary vessel density increased significantly. The improvement in peripapillary RNFL thickness was associated with a greater reduction in the IOP (p = 0.011). @*Conclusions@#Measuring peripapillary vessel density using OCT angiography was useful to identify the reversible changes in optic nerve damage caused by reducing IOP after trabeculectomy.