Multimodal imaging features of non-proliferative and proliferative diabetic retinopathy based on SD-OCT and fundus autofluorescence

Purpose To characterize and compare multimodal imaging features of non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR) using spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF). Methods This cross-sectional observational study included 132 patients (219 eyes) with DR (120 NPDR eyes and 99 PDR eyes) and 73 healthy controls (129 eyes). All participants underwent comprehensive ophthalmic examinations, including fundus photography, fundus fluorescein angiography (FFA), FAF, and SD-OCT. OCT biomarkers, including hyperreflective foci (HRF), intraretinal cystic cavities (IRC), diabetic macular edema (DME), disorganization of retinal inner layers (DRIL), epiretinal membrane (ERM), posterior vitreous detachment (PVD), subretinal fluid (SRF), and disruption of the external limiting membrane (ELM) and ellipsoid zone (EZ) were systematically evaluated and compared between groups. Results Hyperreflective foci, IRC, DME, PVD, and ERM were significantly more frequent in PDR eyes than in NPDR eyes (all P < 0.05). ERM was highly prevalent in both NPDR (80.0%) and PDR (84.8%) eyes. FAF effectively demonstrated intraretinal and preretinal hemorrhages, DME, and fibroproliferative membranes, while SD-OCT provided superior visualization of microstructural retinal alterations. Subfoveal choroidal thickness was significantly increased in both NPDR and PDR compared with healthy controls ( P < 0.05), but did not differ considerably between NPDR and PDR. Conclusion Spectral-domain optical coherence tomography and FAF provide complementary information for evaluating structural and functional retinal alterations in DR. FAF is particularly useful for visualizing hemorrhage, DME, and fibroproliferative membranes. In contrast, SD-OCT enables detailed assessment of multiple retinal biomarkers. The high prevalence of epiretinal membranes highlights their potential role in DR progression.