Purpose: Assessment of perpapillary and macular vessels density estimated with OCT- Angiography in glaucoma patients and effect of intra ocular pressure reduction on them in 0, 1, 3, 6 months. Patients and methods: This is a prospective observational study that included 40 eyes of 35 patients with glaucoma (open, closed angles) at Sohag Investigation Center from April 2018 to April 2021. The study population underwent 4.5×4.5 MM scans centered on the optic nerve head & 3×3 MM scans centered on the macula using Optical Coherence Tomography Angiography (OCTA) (RTVue XR Avanti Optovue, Fremont, CA) for measuring the perpapillary vascular density, RNFL thickness, GCL thickness and macular vascular density in glaucomatous eyes before and after treatment by 1, 3 months and 6 months. Results: Mean age of the study population was 42.6 years with SD 12.29 years and range from 30 to 63 years. There was a significant reduction of IOP from (30.075 ± 8.3939 mmHg) at baseline to maximum reduction at 6 months (17.175 ± 3.257 mmHg, P = <0.001). There was a non-significant increase in thickness peripapillary RNFL & GCL from baseline to 6 months following IOP reduction (P = 0.479, 0.234 respectively). There was a slight significant increase in thickness of the superior, inferior, temporal, nasal peripapillary vascular density (more significant in superior and nasal quadrants) & laminal vascular density (VD ID) from baseline to 6 months post treatment (P = 0.01, 0.019, 0.046, 0.032, 0.003) & there was a significant increase of macular VD in response to IOP reduction at 1, 3, 6 months (P = 0.054). There was found a strong significant correlation between all these items improvement with IOP reduction. Conclusion: IOP has a closed relation with macular and ONH vascularity that prove that vascular insult has a close relation of development or prognosis of glaucoma. OCTA is the new novel era that allows early diagnosis and good follow up for glaucoma patients.