Reduction of Peripapillary Vessel Density by Optical Coherence Tomography Angiography from the Acute to the Atrophic Stage in Non-Arteritic Anterior Ischaemic Optic Neuropathy

Purpose: To analyse superficial peripapillary vascularizationin non-arteritic anterior ischaemic optic neuropathy (NAION) at acute and atrophic (3 months) stage. Procedures: Prospective case-control study including 6 patients with NAION and 10 age-matched healthy controls evaluated with optical coherence tomography angiography (OCT-A; Angioplex-Cirrus) at acute and atrophic stage. Apart from the commercially provided measurements for vessel density (VD) and perfusion density (PD), a custom image analysis was used to quantify the peripapillary capillary density (PCD). Results: NAION-group demonstrated a significant decrease in the PCD, VD and PD compared with fellow unaffected and control groups at acute and atrophic stage. At 3 months, the averageand the temporal sector in PCD correlated with logMAR VA (-0.943, p = 0.005 and -0.829, p = 0.042 for average and temporal sectors respectively) and with MD (0.943, p = 0.005; and 0.899; p = 0.015, respectively). Over 3 months, there was a significant PCD reduction at the temporal sector and at the inner circle in VD and PD, which correlated with ganglion cell-inner plexiform layer (GCIPL) thinning over the 3 months period after the acute NAION (0.749, p = 0.020; 0.885, p = 0.002; 0.767, p = 0.016 respectively). Conclusion: Both strategies demonstrated a significant peripapillary microvascular dropout in NAION, but the customized analysis detected them earlier. A progressive vessel reduction occurs within the first 3months, which correlates with GCIPL thinning.