Comparison of the Retinal Microvascular Density Between Open Angle Glaucoma and Nonarteritic Anterior Ischemic Optic Neuropathy.

Purpose To compare optical coherence tomography angiography (OCT-A) retinal vasculature measurements between nonarteritic anterior ischemic optic neuropathy (NAION) and open angle glaucoma (OAG) with altitudinal hemifield visual field defects. Methods This retrospective cross-sectional study included 10 NAION eyes and 16 OAG eyes, both demonstrating hemifield visual field defects, and 27 normal eyes serving as controls. The peripapillary and macular OCT-A scans were acquired. The retinal vessel density data were compared among NAION, glaucomatous, as well as control eyes. Results There was statistically significant difference in peripapillary whole image vessel density (wiVD), circumpapillary vessel density (cpVD), macular wiVD, and perifoveal vessel density (pfVD) between the three groups (P < 0.05 for all). In comparison between OAG and NAION groups, the NAION group demonstrated marked decrease in average cpVD (P = 0.008) and in most sectors of cpVD except the inferior one, while the OAG group demonstrated significant decreased macular wiVD and pfVD (P = 0.03 and 0.003, respectively). Multivariate analysis indicated that average thickness of retinal nerve fiber layer was the only predictor for peripapillary wiVD and cpVD (P = 0.005 for both). By contrast, thickness of ganglion cell complex was the only predictor for macular wiVD (P = 0.007). Conclusions OCT-A detected significant difference in peripapillary and macular retinal vessel densities between OAG and NAION eyes. These differences might provide comparative insight into the pathophysiology of these two diseases.