Objective: The aim of this study is to use optical coherence tomography (OCT) versus OCT-Angiography (OCTA) in assessment of retina and retinal vessels of diabetic patients with and without diabetic retinopathy (DR).

Patients and Methods: This case control study involved 64 eyes of 64 participants differentiated into 4 equal groups each of 16 eyes. Group (1); normal healthy individuals (control group), group (2): diabetic patients without DR, group (3): diabetic patients with non-proliferative DR, group (4): diabetic patients with proliferative DR. All included eyes had best-corrected visual acuity (BCVA) greater than 0.5 Log MAR in the studied eye at baseline (to ensure proper execution of examination). Both sexes with age between 30-60 years were included, while patients with elevated intra-ocular pressure (IOP), high myopia, and those with media opacity were excluded.

Results: Comparison of foveal thickness between the four groups showed statistically highsignificant difference (p=0.002), while parafoveal areas showed non-significant difference. However, central and all paracentral quadrants choroidal thickness showed statistically significant difference. Comparison of vascular patterns by OCTA showed highly significant difference (p <0.001) between the four studied groups. Post-Hoc test displaying the difference between each group and the other and mostly significant differences regarding retinal or choroidal thickness and density.

Conclusion: The results of this study suggested that OCTA can identify preclinical DR before the manifestations of clinically apparent retinopathy. They highlight the potential role of OCT-A in monitoring and quantifying retinal vascular alterations in diabetes.