Background: Primary Open-Angle Glaucoma (POAG) is a progressive optic neuropathy and a leading cause of irreversible blindness worldwide. Early detection of retinal ganglion cell (RGC) loss is crucial in preventing vision loss. Swept-source optical coherence tomography (SS-OCT) enables high-resolution imaging of the macular ganglion cell layer (GCL), which may aid in detecting early glaucomatous changes. Methods: This hospital-based, cross-sectional observational study was conducted from February 2021 to January 2022. Patients aged 40 years or older, diagnosed with early POAG, were included. Exclusion criteria comprised patients with angle-closure glaucoma, significant refractive error, or a history of intraocular surgery. SS-OCT was used to measure GCL thickness in six sectors, while visual field testing was done using the Humphrey Field Analyzer (HFA) with 24-2 SITA Standard protocols. Data were analyzed using ANOVA for intergroup comparisons .Results: A total of 96 eyes from 96 participants were analyzed, with 48 diagnosed with early POAG and 48 as controls. Significant thinning was observed in the GCL's inferior and inferonasal sectors in the POAG group (p = 0.046 and p < 0.001, respectively) compared to the control group. A moderate correlation between GCL thinning and visual field loss was found in the inferior sector (p < 0.001). Conclusion: Macular GCL thinning, especially in the inferior and inferonasal sectors, serves as an early marker of glaucomatous damage in POAG patients. SS-OCT is effective in detecting early structural changes, which could facilitate earlier diagnosis and better management of glaucoma.