Assessment of the radial peripapillary capillary plexus and retinal nerve fiber layer thickness in diabetic patients in comparison to normal age-matched individuals

Diabetic retinopathy (DR) is a major complication of diabetes, leading to vision impairment and blindness worldwide. As early detection is crucial, our study investigated the potential of radial peripapillary capillary plexus (RPCP) and retinal nerve fiber layer (RNFL) thickness as biomarkers for retinal assessment in diabetic patients. We conducted a cross-sectional study involving 48 participants, categorized into three groups: healthy controls, diabetic patients without DR (No DR), and patients with mild to moderate nonproliferative DR (NPDR). Vascular density (VD) and RNFL thickness were evaluated using optical coherence tomography (OCT), and OCT-Angiography (OCT-A). The study showed a significant difference in VD among the three groups. The mean whole image VD% in the control group was 51.28%, while the No DR and NPDR groups had mean percentages of 49.27% and 49.46%, respectively (P=0.015). These differences were also significant for peripapillary VD (P=0.003), superior-hemi VD (P=0.035), and inferior-hemi VD percentage (P=0.002). Conversely, there were no significant differences in RNFL thickness among the groups (P=0.138). In the NPDR group, positive correlations were found between RNFL thickness and VD percentages, including superior-hemi RNFL thickness and superior-hemi VD% (r=0.724, P<0.001), average whole RNFL thickness and whole image VD% (r=0.655, P<0.001), and average whole RNFL thickness and peripapillary VD% (r=0.647, P<0.001). This research emphasizes the value of assessment of retinal VD thickness of the radial peripapillary plexus as an early indicator for preclinical diabetic retinal changes in diabetic patients.