Retinal thickness and microvascular alterations observed by optical coherence tomography in antineutrophil cytoplasmic antibody-associated vasculitis: a cross-sectional study

Background: As an autoimmune disease, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) often affects multiple organs, including the ocular system. This study aims to investigate differences in retinal thickness (RT) and retinal superficial vascular density (SVD) between patients with AAV and healthy controls (HCs) using optical coherence tomography angiography (OCTA). Currently, these differences are not clear. Methods: A total of 16 AAV individuals (32 eyes) and 16 HCs (32 eyes) were recruited to this crosssectional study conducted in the First Affiliated Hospital of Nanchang University from June 2023 to September 2023. The study protocol conformed with the tenets of the Declaration of Helsinki (as revised in 2013). Each image observed by OCTA was divided into 9 regions using the Early Treatment Diabetic Retinopathy Study (ETDRS) subzones as a guide. Results: In the full layer, the RT of AAV patients was found to be significantly reduced in the inner superior (IS, P<0.001), outer superior (OS, P=0.003), inner temporal (IT, P=0.003), and outer temporal (OT, P<0.001) regions; inner RT was significantly lower in the IS (P=0.006), OS (P<0.001), inner nasal (IN, P=0.005), outer nasal (ON, P<0.001), and center (C, P=0.01) regions than that in HCs. Outer RT of AAV patients showed a reduction in the IS (P<0.001), as well as IT (P=0.008), and OT (P<0.001) regions. No statistically significant differences were seen in the different subregions in other different layers (P>0.05). Only the inner inferior (II) and outer inferior (OI) regions of SVD in AAV patients did not differ significantly from controls. All other regions showed a reduction in SVD. The details are as follows: IS (P<0.001), OS (P<0.001), IT (P=0.005), OT (P<0.001), IN (P<0.001), ON (P<0.001), and C (P=0.003). According to receiver operating characteristic (ROC) curve analysis, the full IS region [area under the curve (AUC): 0.8892, 95% confidence interval (CI): 0.8041-0.9742, P<0.001] had the highest diagnostic value for AAV-induced reduction in RT. The IS (AUC: 0.9121, 95% CI: 0.8322-0.9920, P<0.001) region was also the most sensitive to changes in SVD of AAV individuals. In addition, we found that SVD in the IN region (r=-0.4224, 95% CI: -0.6779 to -0.0757, P=0.02) as well as mean visual acuity (r=-0.3922, 95% CI: -0.6579 to -0.0397, P=0.03) of AAV patients were negatively correlated with disease duration. However, we did not find an association between SVD and RT in this study. Conclusions: The findings from OCTA indicated a reduction in RT and SVD among patients with AAV. OCTA allows for the evaluation of AAV-related ocular lesions and holds promise for monitoring of disease progression through regular evaluations.