Methods: This retrospectively reviewed, and the cross-sectional study included 64 right eyes of 64 diabetic patients (Diabetic group) and 60 right eyes of 60 healthy (Control group) subjects. The diabetic group included two subgroups of patients with proliferative diabetic retinopathy (PDR) and patients with non-proliferative diabetic retinopathy (NPDR). The groups and subgroups were compared in terms of the bestcorrected visual acuity (BCVA), intraocular pressure and OCT/OCTA measurements, including central macular thickness (CMT, um), macular flow area (mm²), foveal and parafoveal vessel density (VD, %) in the superficial and deep retinal layers.

Results: The mean values of BCVA and CMT were 0.42±0.32 and 0.86±0.17 (p<0.001), and 313.33±119.54 and 250.44±26.70 µm (p=0.002) in the diabetic and control groups, respectively. The mean macular flow area values were 1.29±0.20 and 1.36±0.16 mm² (p=0.044), the mean superficial retinal parafoveal VD measurements were 48.38±5.2 and 51.83±5.22 (p=0.002), and the mean deep retinal parafoveal VD measurements were 42.82±6.29 and 46.38±4.74 (p=0.019) in the diabetic and control groups, respectively. Excluding a lower mean CMT value, the mean values of BCVA, macular flow area, and all VD measurements were higher in the NPDR group than the PDR group (p<0.05 for all).

Conclusion: OCTA imaging enables the analysis of superficial and deep retinal vessel density in diabetic patients. Thus, it is possible to assess the association of retinal vasculature with visual acuity and macular flow area. Worsened visual acuity, impaired macular flow area and a tendency of decreased vessel density were observed in diabetic patients. Keywords : Optical coherence tomography angiography, Vessel density, Macular flow area