Analysis of Vessel Density Using OCTA in Nonarteritic Anterior Ischemic Optic Neuropathy

Purpose: To investigate the intraocular vessel density in patients with nonarteritic anterior ischemic optic neuropathy (NAION) using optical coherence tomography angiography (OCTA).Methods: Medical records of patients with NAION were retrospectively analyzed. Their age, sex, best corrected visual acuity, color vision results, mean deviation of visual field test were analyzed. Using results of OCT and OCTA that was performed at first visit within 3 weeks of symptom onset, vessel densities in eyes with NAION were evaluated by comparing contralateral unaffected eyes. Furthermore, in only affected eyes, the correlation between visual acuity at the time of diagnosis and anatomical factors such as mean vessel density and retinal nerve fiber layer (RNFL) thickness was investigated.Results: Twenty-five patients (11 males and 14 females) were enrolled in this study and the mean age was 65.92 ± 9.37 years. Whole RNFL thickness in affected eye was significantly lower than that in unaffected eye (p < 0.001). The average peripapillary vessel density was also significantly lower in affected eyes, 45.63% ± 7.60% compared to that in the contralateral eyes, 51.44% ± 3.40% (p = 0.004). In analysis of only 25 affected eyes, there was no significant correlation between each sectoral peripapillary RNFL thickness and vessel density. There was also no significant correlation between the visual acuity and the vessel density and retinal nerve fiber layer thickness in the ischemic peripapillary hemisphere. However, there was a significant negative correlation between the visual acuity and the un-ischemic peripapillary hemisphere with a coefficient of -0.608 (p = 0.001).Conclusions: The higher vessel density of nonaffected sector, the better visual acuity at the time of diagnosis in patients with NAION. Patency of blood supply in the preserved peripapillary intraretinal vessel density sector may affect the visual function.