Optical coherence tomography angiography findings in axial spondylarthritis

The aim of this study is to evaluate the density of retinal vascular structures and their relationship with disease duration and activity in patients with axial spondylarthritis (axSpA) using optical coherence tomography angiography (OCT-A). In this case-control study, 56 eyes of 29 axSpA patients and 61 eyes of 31 healthy controls (HCs) were evaluated using OCT-A. The capillary plexus density (CPD) of vessels in the parafovea and perifovea regions was evaluated from the superficial capillary plexus (SCP) and deep capillary plexus (DPC) flow areas. The CPD of vessels in the fundus was evaluated from the radial peripapillary capillary (RPC) flow area. Foveal avascular zone (FAZ) size was measured. In axSpA patients and HCs, the mean CPD (%) in the whole retina was 50.75 ± 2.59 and 52.43 ± 2.10 (p < 0.001) in SCP, 54.00 ± 5.83 and 58.37 ± 4.36 (p < 0.001) in DCP, and 50.13 ± 2.32 and 50.13 ± 2.26 (p = 0.984) in RPC flow areas, respectively, and the mean FAZ (mm) was 0.275 ± 0.10 and 0.294 ± 0.07 (p = 0.281), respectively. A significant negative correlation was detected between the CPD and disease duration in the parafovea (ρ: - 0.306, p = 0.022), parafovea superior-hemi (ρ = - 0299, p = 0.025), parafovea inferior-hemi (ρ = - 0.270, p = 0.044), parafovea temporal (ρ = - 0.349, p = 0.008) and parafovea nasal regions (ρ = - 0.356, p = 0.007) in the DCP flow area. CPD was found to be lower in the macula, while similar in the fundus region in axSpA patients compared to HCs. The decrease in CPD was correlated with disease duration, but not with disease activity in axSpA. Small vessel structures may be affected in axSpA. OCT-A may be used to detect subclinical vasculitis in axSpA patients.