Purpose: of this study is to assess changes and to assess ischemia that may occur post. Injection using OCT and OCTA and its relation with BCVA. Methods: prospective, observational, cohort study with a total 49 eyes were enrolled in the study to evaluate changes in central macular thickness, visual acuity, foveal avascular zone and vascular density following intravitreal injection of ranibizumab used in patients diagnosed with central involving diabetic macular edema. Results: There was highly significant improvement in BCVA (p <0.0001). As regard macular thickness there was significant reduction of macular thickness (p < 0.0001). There is high relation between IS-OS integrity, DRIL and BCVA. We found improvement of IS-OS line post. Injection as regard FAZ there was non-significant enlargement of FAZ post. Injection (p =0.16). Vascular density in superficial capillary plexus was statistically highly significant (decreased) when we compare before and after injection as a whole density, fovea, parafovea &perifovea while it is not significant changes when we compare values between (1&6 m) and between (3&6m). While vascular density in deep capillary plexus It was statistically significant (reduction) only in fovea and perifoveal superior (p= 0.02) while non-statistically significant reduction of vascular density elsewhere. Conclusion: Our result concluded that intravitreal injection of ranibizumab is an influential treatment for diabetic macular edema with minimal ischemia and minimal effect on macular perfusion. Anatomical and functional factors other than central macular thickness are also related to best corrected visual acuity. So, OCT and OCTA are very helpful during follow -up cases with DME to assess macular thickness, inner and outer retinal integrity, degree of macular ischemia and any complication as ERM that may result from injection.