Characteristics of Macular Microvascular Changes in Patients with Systemic Lupus Erythematosus

Objective: To observe the characteristics of early macular microvascular changes in patients with systemic lupus erythematosus using optical coherence tomography angiography (OCTA). Methods: This was a retrospective series of case study. Thirty-one patients (62 eyes) who were diagnosed with SLE by the Second Affiliated Hospital & Yuying Children's Hospital of Wenzhou Medical University from May to November 2018, were divided into a lupus retinopathy (LR) group of 10 patients (17 eyes) and a non-lupus retinopathy group of 24 patients (45 eyes). At the same time, 35 healthy subjects (35 eyes) who were matched by age and sex with the disease groups were recruited as a control group. All subjects had a 3 mm×3 mm area of the macula scanned by OCTA to obtain superficial and deep retinal microvascular images of the macular area, and retinal blood flow density maps were skeletonized and analyzed by a custom automated algorithm. The total annular zone (TAZ), with a diameter of 2.5 mm, was obtained after excluding the foveal avascular zone (FAZ, 0.6 mm), and the superficial and deep retinal skeletonized capillary densities (RCD) of the TAZ were further divided into 4 regions (S, T, I, N). In addition, disease activity of the patients was assessed using the SLE disease activity index (SLEDAI). Data analysis was performed using a t test and analysis of variance. Results: The RCD of the superficial retinal capillary plexus (SRCP) were found to be significantly lower in the NLR and LR groups than in the control group, and the LR group was even lower than the NLR group and the difference was significant (P<0.05). In the deep retinal capillary plexus (DRCP), the difference between the three groups was not as obvious as that in the superficial layer. Only the RCD of the LR group in the N region was significantly lower than that in the NLR group (P=0.022), which were also lower than those in the control group (P<0.05) except for the T region. In addition, the score of SLEDAI in the LR group was significantly higher than in the NLR group (P=0.006), and the incidence of SLE complications such as lupus nephritis and neuropsychiatric SLE were higher in the LR group (50% vs. 25%, 10% vs. 4% respectively). Conclusions: OCTA can effectively detect early changes in macular microvascular morphology in the patients with SLE. In patients with SLE without significant fundus and visual impairment, the RCD of SRCP is significantly altered, suggesting that it may be used as an early biomarker for monitoring SLE retinal damage. Key words: systemic lupus erythematosus; retinal capillary density; lupus retinopathy; score of systemic lupus erythematosus disease activity index