Correlation of Visual Field Parameters with Optic Disc and OCT Findings in Primary Open-angle Glaucoma: A Cross-sectional Study

Introduction: Primary Open-Angle Glaucoma (POAG) is a chronic, progressive optic neuropathy characterised by optic disc changes and corresponding Visual Field (VF) loss. This study aimed to evaluate the pattern of VF defects and correlate them with optic disc and Optical Coherence Tomography (OCT) parameters in patients diagnosed with POAG. Aim: This study aimed to evaluate the pattern of VF defects and correlate VF parameters with optic disc and OCT parameters in patients diagnosed with POAG. Materials and Methods: The present cross-sectional study included a total of 76 eyes from 38 patients with POAG attending a tertiary healthcare center in Western Maharashtra, India between September 2023 and March 2025. All 38 patients were diagnosed with bilateral POAG, and both eyes met the eligibility criteria of reliable VF and OCT data. Therefore, all 76 eyes included in the study were from bilateral cases. There were no unilateral cases in the final dataset. Complete ophthalmic examination including Goldmann Applanation Tonometry (GAT), fundus evaluation, Humphrey VF testing and spectral-domain OCT {Retinal Nerve Fiber Layer (RNFL) and Ganglion CellInner Plexiform Layer (GCL-IPL)} analysis were performed. VF patterns were classified and correlated with Neuroretinal Rim (NRR) thinning and OCT-based parameters. Results: The most common VF defect was tunnel vision, observed in 21 eyes (27.6%), followed by 18 eyes (23.7%) and with superior paracentral scotomas and 11 eyes (14.5%) with inferior paracentral scotomas. Optic disc analysis showed Neuroretinal Rim (NRR) thinning in all quadrants in 27.6% and inferior quadrant alone in 26.3%. OCT revealed an average RNFL thickness of 61.9 µm and GCL+IPL thickness of 71.9 µm. Significant correlations were observed between VF indices Mean Deviation (MD), Pattern Standard Deviation (PSD), and Visual Field Index (VFI) with both RNFL and GCL+IPL thickness. Additionally, inverse correlations were found between Vertical Cup-Disc Ratio (VCDR) and these OCT and VF parameters. VF loss patterns corresponded topographically to optic disc thinning. Conclusion: Tunnel vision and paracentral scotomas were common in moderate to advanced POAG. Structural changes in RNFL and GCL+IPL showed strong correlation with functional VF defects. OCT-based metrics, particularly GCL+IPL thickness, are valuable tools for assessing glaucomatous progression.