ObjectiveTo observe the changes of peripapillary vessel density and retinal nerve fiber layer parameters (RNFL) in diabetic mellitus (DM) patients with early diabetic retinopathy (DR).MethodsA retrospective clinical study. From January to December 2018, twenty-eight DM patients (47 eyes, DM group) and 20 normal subjects (40 eyes, control group) in Eye Hospital of Wenzhou Medical University at Hangzhou were included in the study. There was no significant difference between the two groups in age (t=－1.397, P=0.169) and sex composition ratio (χ2=0.039, P=0.843). The optic nerve head was scanned by OCT angiography (OCTA) with HD 4.5 mm ×4.5 mm imaging scanning mode for all subjects. The peripapillary radial peripapillary capillaries vessel density (ppVD) and peripapillary retinal nerve fiber layer (pRNFL) thickness were measured. The changes of ppVD and pRNFL thickness between the two groups were observed. Pearson correlation analysis was used to analyze the correlation between ppVD and pRNFL in each quadrant.ResultsCompared with the control group, the mean ppVD and superior-hemi part, inferior-hemi part, superior, nasal, inferior and temporal quadrant ppVDs of DM group were all significantly lower than those of control group (t=5.107, 4.360, 3.713, 4.007, 2.806, 4.046, 2.214; P＜0.05). The mean and all quadrants pRNFL thickness were lower in eyes of DM group compared with the control, and the superior and inferior quadrant pRNFL thickness were statistically significant (t=2.117, 2.349; P＜0.05), while the mean pRNFL and superior-hemi, inferior-hemi part, nasal and temporal quadrant were not statistically significant (t=1.867, 1.717, 1.869, 0.720, 0.303; P＞0.05). Pearson correlation analysis showed that the significant high-positive correlation was found between ppVD and pRNFL thickness in the nasal quadrant (r=0.734, P＜0.001).ConclusionIn early DR patients, ppVD decreased and pRNFL thinned.