Background: Diabetic retinopathy [DR] is a prevalent ocular ailment that is a primary contributor to blindness.
The Aim of the work: To detect early findings of diabetic retinopathy before the appearance of clinical signs by determining retinal layers vasculature affected by diabetes via optical coherence tomography angiography imaging.  
Patients and Methods: A comparison analysis included 20 patients with history of diabetes type 2 for 10 years and no diabetic retinopathy was determined by fundus examination versus 20 control persons. To get pictures, we used XR Avanti Optical Coherence Tomography Angiography. With the software's non-flow area tool, which allows for automatic FAZ segmentation, the flow area of the choriocapillaris was assessed in the superficial vascular plexus.
Results: There were statistically significant differences in FAZ area, parafoveal vessel density of SCP, DCP and choriocapillaris flow area between healthy control [group A] and diabetic patients without DR [group B]. The mean FAZ area of the healthy control [group A] was 0.23 ± 0.05 mm² compared with 0.34 ± 0.06 mm² in the diabetic [group B]. In addition, the mean of the choriocapillaris flow area [mm2] of group A was 2.15 ± 0.09 in compared with 2.07 ± 0.06 in the group B. Finally, we found that among the 40 eyes of 20 patients with DM with no diabetic retinopathy [group B] there were 10 eyes [25%] with microaneurysms by OCTA which weren't detected by fundus examination.
Conclusion: OCTA provides structural and topographic analysis of microvascular abnormalities that occur in diabetic patients before the onset of clinically evident retinopathy by assessment of the FAZ dimensions and vascular density. So, OCTA offers an early biomarker for efficient screening of DR, before the onset of clinically evident complications.