ABSTRACT
Objective:To observe the changes in blood flow density of radial retinal peripapillary capillary (RPC) around the optic disc in patients with non-arteritic anterior ischemic optic neuropathy (NAION) at different stages of the continuous course of the disease.Methods:A prospective cohort study. From January to December 2020, 29 cases of 29 eyes of NAION patients diagnosed in the Eye Center of the Second Affiliated Hospital of Zhejiang University School of Medicine were included in the study. Among them, there were 18 males with 18 eyes and 11 females with 11 eyes. The average age was 53.62±6.67 years old. The affected eye underwent routine eye examination and visual field, optic cohenrence tomography angiography (OCTA) examination. Visual field inspection was performed to obtain the average visual mean defect (MD) value. OCTA was used to measure the thickness of the peripapillary retinal nerve flayer (pRNFL) around the optic disc, the whole en face image vessel density (wiVD), intro disc vessel density (diVD), RPC blood flow density around the optic disc, and macular ganglion cell complex (GCC). The course of disease ≤3 weeks was defined as the acute phase; 4-12 weeks was defined as the subacute phase; >12 weeks was defined as the chronic phase. The changes of visual field MD, optic disc RPC blood flow density, pRNFL thickness and macular GCC thickness were observed in the acute, subacute and chronic phases (12-24, >24 weeks). A completely randomized design of variance analysis was used to compare the differences in visual field MD, RPC blood flow density, GCC, and pRNFL thickness in different courses. Pearson correlation analysis was used to analyze the correlation between pRNFL thickness, macular GCC thickness, visual field MD changes and RPC blood flow density around the optic disc sex.Results:The wiVD of the eyes in the acute phase, subacute phase, and chronic phase (12-24 weeks, >24 weeks) were (44.96±2.76)%, (41.50±3.49)%, (39.08±5.43)%, (38.56±6.48)%. There was a statistically significant difference in wiVD of eyes with different disease courses ( F=8.939, P<0.001). The average difference of wiVD between 12-24 weeks and >24 weeks in the chronic phase was -0.984, and the difference was not statistically significant ( P>0.05). There was no statistically significant difference in diVD of patients with different courses of disease ( F=1.079, P=0.365). The blood flow density of RPC around the optic disc of the affected eye, except for the lower part, the blood flow density of the nasal side, the temporal side, and the upper quadrant, decreased significantly with the progression of the disease, and the difference was statistically significant ( F=8.816, 6.069, 8.943; P<0.05). In the chronic phase, the average difference of blood flow density between the nasal, temporal, and upper sides of the eyes between 12-24 weeks and more than 24 weeks in the chronic phase was -0.984, -0.230, -0.198, and the difference was not statistically significant ( P>0.05). There was no statistically significant difference in the visual field MD of patients with different courses of disease ( F=0.277, P=0.842); the overall pRNFL thickness and average macular GCC thickness were compared with statistical significance ( F=47.122, 14.954; P<0.001, <0.001), all became significantly thinner with the progression of the disease. The results of Pearson correlation analysis showed that the blood flow density of the entire optic disc wiVD, the blood flow density of RPC in the temporal quadrant around the optic disc and the visual field MD ( r=-0.225, -0.268; P<0.05), and the average thickness of GCC ( r=0.480, 0.436; P<0.01) were all related. Conclusion:The blood flow density of RPC in the entire optic disc and around the optic disc (except the lower quadrant) of NAION eyes gradually decrease with the progression of the disease, and stabilize after 12 weeks of the disease.