Primary open-angle glaucoma (POAG) is an optic neuropathy, characterized by progressive loss of visual field, loss of retinal ganglion cells (RGC) and optic nerve damage. The diagnosis and management of POAG involves tests such as static perimetry, tonometry and optical coherence tomography (OCT) to track progressive structural and functional changes. All these methods have limitations. Advancements in the discovery of metabolomic plasma-derived biomarkers may improve clinical outcomes, through identifying susceptible individuals, predicting disease progression, and assessing treatment efficacy in POAG. We reviewed the current state of POAG management, identified limitations and need for biomarkers that could potentially fill the gap and current landscape of POAG plasma metabolomics, providing an overview of future potential biomarkers. Advances in the identification of metabolomic biomarkers can improve current clinical practices. These biomarkers can complement existing diagnostic tools, allowing for earlier detection and personalized treatment strategies. However, challenges remain, including a lack of standardization in metabolomics protocols, variability in disease progression and finally, recording treatment non-response currently also suffers from a lack of standardization toward depicting treatment outcomes. Future research should focus on standardizing procedures, increasing diversity in study populations, and conducting longitudinal studies to validate biomarkers in clinical settings.