Abstract
Purpose :
To evaluate capillary density loss and prevalence of microaneurysms at each capillary plexus in diabetic retinopathy using OCT-A.
Methods :
One eye each from 15 controls and 45 diabetic patients (15 diabetics without retinopathy - DMnoDR, 15 NPDR, and 15 PDR) were imaged using a commercial OCT system (Avanti RTVue-XR; Optovue). Ten 3x3mm scans centered at the fovea were obtained per subject. OCT-As and respective OCT-Rs were then registered and averaged using ImageJ (PMID:31065407). Structural FAZ was delineated on the averaged OCT-R. After removal of large vessels and structural FAZ areas on each OCT-A, capillary density (area, %) was determined on the full capillary plexus (FCP), superficial capillary plexus (SCP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP) (Fig. 1). Kruskal-Wallis test compared capillary density at each plexus between controls and each stage of diabetic retinopathy. Number of microaneurysms was also counted in each plexus for all subjects.
Results :
In controls, DMnoDR, NPDR, and PDR respectively, the median±interquartile range for capillary density (%) were 51.2±0.7, 50.8±0.6, 46.7±3.1, and 42.6±9.2 for FCP; 44.9±3.0, 45.6±3.1, 38.1±7.9, and 33.5±12.2 for SCP; 49.3±1.0, 49.7±0.9, 46.7±2.8, and 41.7±8.4 for ICP; and 35.1±2.9, 35.2±4.6, 27.2±3.8, 23.0±3.8 for DCP. Kruskal-Wallis test found significance between groups at all plexuses (P-values <0.00001). Post-hoc Dunn Test revealed significance between subgroups, apart from controls vs DMnoDR (P-values>0.30) and NPDR vs PDR (P-values>0.57). Area under receiver operating characteristic curves (AROC) indicated that the FCP was the most sensitive for differentiation of retinopathy (AROC=0.998), followed by ICP (AROC=0.988); DCP (AROC=0.963); and SCP (AROC=0.958). Microaneurysms were found in all plexuses of patients with retinopathy, with SCP, ICP, and DCP showing a mean±SD of 4.6±3.9, 8.3±4.5, and 5.6±4.9 microaneurysms in NPDR and 3.0±3.0, 4.8±2.9, and 2.3±2.1 in PDR.
Conclusions :
OCT-A enabled plexus-specific characterization of capillary density and quantification of microaneurysms. In all plexuses, capillary density was lower in NPDR and PDR compared to controls, and each plexus displayed high predictability for retinopathy. Microaneurysms were predominantly observed in ICP, with more observed in NPDR than PDR.
This is a 2020 Imaging in the Eye Conference abstract.