Peripapillary and macular vascular changes in unilateral nonarteritic anterior ischemic optic neuropathy: An optical coherence tomography angiography study

Purpose: To assess optical coherence tomography angiography (OCTA) changes in acute nonarteritic anterior ischemic optic neuropathy (NAION) eyes compared to fellow unaffected eyes and describe the longitudinal OCTA changes within the first 12 weeks of onset while the disc is still edematous. Design: A prospective observational study. Methods: A total of 30 patients, diagnosed with unilateral acute NAION, were included. Bilateral OCT and OCTA of the macula and optic nerve head (ONH) were done. Scans were performed at presentation and then at 6 weeks and 12 weeks thereafter. Results: Nerve fibre layer thickness (NFLT) and ganglion cell complex thickness (GCC) were significantly lower in diseased eyes after resolution of edema. Similarly, ONH and peripapillary vessel densities were significantly reduced in NAION eyes throughout the three visits, while macular superficial vessel density demonstrated a statistically significant decrease only from the second visit onward. Conversely, deep macular and foveal avascular zone (FAZ) vessel density (VD) showed no significant change in NAION eyes except at the third visit with lower VD in NAION eyes. However, all VD biomarkers of NAION eyes, including deep macular and FAZ VD, demonstrated a significant decrease in the 6-week and 12-week visits compared to baseline. Conclusions: OCTA VD changes in NAION demonstrated a temporal sequence where radial peripapillary capillary vascular density was the first to decrease, followed by macular superficial vascular density and last the macular deep vascular density. Moreover, there was a progressive decrease in all OCTA VD measurements in NAION eyes during follow-up.