Introduction: Primary open angle glaucoma (POAG) is a multi-factorial progressive optic neuropathy that results in gradual vision loss. Alongside an elevated intra ocular pressure (IOP), other factors influence the progression of retinal ganglion cells loss in POAG. Blood flow dysregulation and oxidative stress are believed to be important risk factors in the evolution of glaucomatous degenerative lesions. Magnesium is an essential cation for many reactions and enzyme activities in the human body. One of its crucial roles is vascular regulation and blood flow improvement by modifying endothelial function through endothelin (ET-1) and nitric oxide (NO) pathways. It is also considered as a neuro-protective molecule as it reduces the harmful effect of oxidative stress on retinal ganglion cells. Objective: the objective of this study is to assess the impact of daily intake of Magnesium on the stabilization of the glaucomatous damages on optic nerve. Methods: it is a nonrandomized monocentric clinical study. Patients having only POAG with an IOP values ≤ 19 mmHg and a visual acuity > to 5/10 were included. All patients had a daily supplementation of Magnesium for a period of at least 6 months each. All patients were assessed before the start of the study (T0), after 3 months of treatments (T1) and after 6 months of treatments (T2). At each visit, patients were given a full eye examination including IOP measures, perimetry, RNFL and GCC using OCT. Results: 46 patients with a mean age of 54 years old and a mean IOP of 16 mmHg were included. At T1 and T2 the values of mean deviation have regressed compared to T0. The mean IOP have significantly lessened and the RNFL and GCC values on OCT were stabilized. Conclusion: daily supplementation of Magnesium in patients with POAG has shown to be of great help on reducing the rate of progression of glaucomatous functional damage, therefore improving visual function and patients’ quality of life.