Patterns of Progression of Nonproliferative Diabetic Retinopathy Using Non-Invasive Imaging.

Purpose: To identify progression of nonproliferative diabetic retinopathy (NPDR) in patients with type 2 diabetes by combining optical coherence tomography angiography (OCTA) metrics and color fundus photography (CFP) images. Methods: This study was a post hoc analysis of a prospective longitudinal cohort study (CORDIS, NCT03696810) with 2-year duration. This study enrolled 122 eyes. Ophthalmological examinations included OCTA and CFP. OCTA metrics included skeletonized vessel density (SVD) and perfusion density (PD) at the superficial capillary plexus (SCP) and deep capillary plexus (DCP). Microaneurysm turnover analysis and Early Treatment Diabetic Retinopathy Study (ETDRS) grading for diabetic retinopathy (DR) severity assessment were performed on 7-field CFP. Results: Eyes graded as ETDRS level 20 showed significant capillary nonperfusion predominantly in the inner ring area in the SCP (P < 0.001), whereas eyes graded as ETDRS level 35 and ETDRS levels 43 and 47 showed significant capillary nonperfusion in both the SCP and DCP in both inner and outer rings (P < 0.001). When evaluating rates of progression in capillary nonperfusion for the 2-year period of follow-up, changes were found predominantly in the DCP for SVD and PD and were better identified in the outer ring area. Microaneurysm turnover contributes to the characterization of NPDR progression by discriminating ETDRS level 35 from ETDRS levels 43 and 47 (P < 0.001), which could not be achieved using only OCTA metrics. Conclusions: Patterns of progression of NPDR can be identified combining OCTA examinations of the superficial and deep retinal capillary plexi of central retina and determination of microaneurysm turnover from fundus photographs. Translational Relevance: Our study reports results from a registered clinical trial that advances understanding of disease progression in NPDR.

Characterization of central-involved diabetic macular edema using OCT and OCTA.

PURPOSE: To characterize the occurrence of diabetic macular edema and the presence of abnormal retinal fluid accumulation in nonproliferative diabetic retinopathy (NPDR). METHODS: In this two-year prospective study, a total of 122 eyes with diabetes type 2 underwent optical coherence tomography (OCT) and OCT-Angiography in association with OCT-Fluid imaging, a novel algorithm of OCT analysis allowing quantification of abnormal accumulation of fluid in the retina through low optical reflectivity ratios (LOR). Early Treatment Diabetic Retinopathy Study (ETDRS) grading for diabetic retinopathy (DR) severity assessment was performed using 7-field color fundus photography. Best corrected visual acuity was also recorded. RESULTS: During the 2-year follow-up, 23 eyes (19%) developed central-involved diabetic macular edema (CI-DME) and 2 eyes (2%) developed clinically significant macular edema (CSME). In the two-year period of the study, eyes that developed CI-DME showed a progressive increase in central retinal thickness (CRT) (ß = 7.7 ± 2.1 µm/year, p < 0.001) and in LOR values (ß = 0.009 ± 0.004 ratio/year, p = 0.027). The increase in CRT and abnormal retinal fluid, represented by increased LOR ratios, are associated with increased retinal perfusion in the deep capillary plexus (DCP) (skeletonized vessel density, p = 0.039). In contrast, the eyes with CSME showed decreased retinal perfusion and abnormal fluid located in the outer layers of the retina. CONCLUSIONS: CI-DME and CSME appear to represent different entities. Eyes with CI-DME show increases in abnormal retinal fluid associated with increased retinal vascular perfusion in the DCP. Eyes with CSME are apparently associated with decreased retinal vascular perfusion in the DCP and abnormal fluid in the outer retina.