Retinal neurodegeneration in type 2 diabetic individuals with mild retinopathy is independent of retinopathy severity progression: a 5-year longitudinal study

Abstract

Purpose : Diabetic Retinopathy (DR) has always been considered a microvascular disease, but it has been suggested that neurodegeneration also plays a key role in this complex pathology. In the context of a 5-year prospective longitudinal study, we evaluated the progression of DR neurodegenerative events and its correlation with microvascular events and disease severity progression.

Methods : 142 patients with type 2 diabetes (T2D) and mild NPDR (ETDRS grades 20 or 35) were followed in a 5-year longitudinal study. Ophthalmological examinations were performed at baseline, 6-months and annually.
Optical coherence tomography (OCT) was performed to evaluate average thickness of the ganglion cell layer (GCL). An aged-matched population of 58 healthy individuals was evaluated with OCT as a control for layer segmentation. ETDRS and severity progression was assessed in T2D individuals by grading of 7-fields CFP performed at the initial and last visits. Microaneurysm turnover (MAT) was evaluated using the RetMarkerDR.

Results : At baseline GCL thickness (80.06 ± 7.71 µm) in T2D individuals was significantly reduced when compared to controls (82.67 ± 5.46 µm, p=0.0201), indicating the presence of neurodegenerative changes since in the initial stages of retinopathy (ETDRS 20 and 35). Ganglion cell layer average thickness remained stable through the 5-year period in T2D individuals, showing no significant associations with baseline ETDRS, severity progression or MAT (Table 1).

Conclusions : Neurodegeneration, represented by GCL thinning, is present since the initial stages of non-proliferative DR, however it does not progress significantly over a 5-year period and is independent of the microvascular alterations (considering MAT), ETDRS grade and DR severity progression.

This is a 2021 ARVO Annual Meeting abstract.