Characterization of One-Year Progression of Risk Phenotypes of Diabetic Retinopathy

Abstract

Introduction: We characterized the progression of different diabetic retinopathy (DR) phenotypes in type 2 diabetes (T2D). Methods: A prospective longitudinal cohort study (CORDIS, NCT03696810) was conducted with three visits (baseline, 6 months, and 1 year). Demographic and systemic data included age, sex, diabetes duration, lipid profile, and hemoglobin A1c (HbA1c). Ophthalmological examinations included best-corrected visual acuity (BCVA), color fundus photography (CFP), and optical coherence tomography (OCT and OCTA). Phenotype classification was performed at the 6-month visit based on microaneurysm turnover (MAT, on CFP) and central retinal thickness (CRT, on OCT). Only risk phenotypes B (MAT\6 and increased CRT) and C (MAT C 6 with or without increased CRT) were included. ETDRS grading was performed at the baseline visit based on seven-field CFP. Results: A total of 133 T2D individuals were included in the study; 81 (60%) eyes were classified as phenotype B and 52 (40%) eyes as phenotype C. Of these, 128 completed the 1-year follow-up. At baseline, eyes with phenotype C showed greater capillary closure (superior capillary plexus, deep capillary plexus, and full retina, p\0.001) and increased foveal avascular zone (FAZ) area (p\0.001), indicating more advanced microvascular disease. Neurodegeneration represented by thinning of the ganglion cell layer ? inner plexiform layer (GCL ? IPL) was present in both phenotypes. Whenanalyzing the 1-year progression of each phenotype, only phenotype C revealed a significant decrease in BCVA (p = 0.02) and enlargement of the FAZ (p = 0.03). A significant progressive decrease in the vessel density of the deep capillary layer and in MAT occurred in both phenotypes, but these changes were particularly relevant in phenotype C and ETDRS grades 43–47. During the 1-year period, both phenotypes B and C showed progression in GCL ? IPL thinning (p\0.001). Conclusions: In the 1-year period of follow-up, both phenotypes B and C showed progression in retinal neurodegeneration, whereas phenotype C showed more marked disease progression at the microvascular level.