EVALUATION OF RETINAL NERVE FIBER LAYER AND GANGLION CELL-INNER PLEXIFORM LAYER THICKNESS IN GLAUCOMA: A PROSPECTIVE STUDY USING OPTICAL COHERENCE TOMOGRAPHY

Purpose: This study aims to assess the structural changes in retinal nerve ber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness across different stages of glaucoma and evaluate their correlation with functional visual eld (VF) to understand disease progression and diagnostic utility. Methods: Across-sectional study was conducted on 100 glaucoma patients categorized into early (n=55), moderate (n=25), and advanced (n=20) stages. Optical coherence tomography (OCT) was used to measure RNFL and GCIPL thickness, while VF were assessed using standard automated perimetry. Data analysis was performed using IBM SPSS 23, with ANOVAand Pearson's correlation tests applied to compare groups and assess relationships between structural and functional parameters. Results: Signicant progressive thinning of RNFL and GCIPL was observed with increasing glaucoma severity (p < 0.001). RNFL showed the greatest thinning in the superior and inferior quadrants, with average thickness declining from 80.3 μm in early glaucoma to 62.5 μm in advanced stages. GCIPL also showed marked thinning, with average thickness reducing from 74.0 μm to 59.8 μm. Strong correlations between RNFL(r = 0.477, p < 0.001) and GCIPL(r = 0.397, p < 0.001) with VF parameters were evident in early to moderate glaucoma. In advanced stages, superior GCIPLexhibited the strongest correlation with VF indices (r = 0.495, p < 0.001), overcoming the oor effect observed in average RNFL and GCIPL measurements. Conclusion: GCIPL analysis provides valuable diagnostic insights, especially in advanced glaucoma, where RNFLmeasurements are less reliable. OCT-based RNFLand GCIPLevaluations are indispensable tools for early detection and monitoring of glaucoma progression.