Correlation Of Macular Ganglion Cell-Inner Plexiform Layer Thickness And Retinal Nerve Fiber Layer Thickness With Visual Field Defects In Primary Open Angle Glaucoma: A Cross-Sectional Study

Background: Primary open angle glaucoma (POAG) is characterized by progressive retinal ganglion cell loss and corresponding visual field defects. Optical coherence tomography (OCT) measurements of ganglion cell-inner plexiform layer (GCIPL) and retinal nerve fiber layer (RNFL) thickness provide objective structural assessment. This study aimed to evaluate the correlation between GCIPL thickness, RNFL thickness, and visual field parameters in POAG patients.

Methods: A cross-sectional observational study was conducted on 50 patients with confirmed POAG. All participants underwent comprehensive ophthalmological examination including spectral-domain OCT for GCIPL and RNFL thickness measurements and standard automated perimetry for visual field assessment. Pearson correlation coefficients were calculated to determine relationships between structural and functional parameters. Multiple regression analysis was performed to identify predictive factors for visual field mean deviation.

Results: Mean RNFL thickness was 72.4±12.8 μm and mean GCIPL thickness was 68.3±10.2 μm. Strong positive correlations were found between average GCIPL thickness and visual field mean deviation (r=0.74, p<0.001) and between average RNFL thickness and mean deviation (r=0.68, p<0.001). Sectoral analysis revealed strongest correlations in inferior quadrants. Multiple regression analysis showed GCIPL thickness was the strongest predictor of visual field mean deviation (β=0.52, p<0.001).

Conclusion: Both GCIPL and RNFL thickness measurements demonstrate strong correlations with visual field defects in POAG. GCIPL thickness shows marginally stronger correlation with functional loss, suggesting its potential value in glaucoma assessment and monitoring.