Comparative Analysis of Peripapillary Retinal Nerve Fiber Layer and Macular Parameters Using Spectral-Domain Optical Coherence Tomography in Primary Open-Angle Glaucoma and Normal Eyes: A Cross-Sectional Observational Study

Abstract

Purpose: The purpose of the study is to compare peripapillary retinal nerve fiber layer (RNFL) thickness and macular parameters measured by spectral-domain optical coherence tomography (SD-OCT) between normal subjects and patients with primary open-angle glaucoma (POAG) and to correlate RNFL thickness with age, spherical equivalent, central corneal thickness (CCT), disc area, and rim area. Materials and Methods: This is a cross-sectional study of 109 eyes (55 normal, 54 POAG). All subjects underwent perimetry, pachymetry, and Cirrus SD-OCT (fast RNFL and macular cube protocols). Groups were compared using the unpaired t-test/Mann–Whitney U test; correlations were assessed using Pearson’s coefficient. Results: Mean RNFL thickness was lower in POAG than in normal eyes (68.13 ± 10.9 vs. 96.64 ± 8.3 μm; P < 0.001), as were all four quadrants (P < 0.001 each). Average macular thickness, central macular thickness, and average macular volume were all significantly reduced in POAG (P ≤ 0.011). RNFL thickness correlated negatively with age (r = −0.86/−0.84) and positively with spherical equivalent (r = 0.76/0.74) in both groups (P < 0.001), with no significant CCT correlation. Conclusion: SD-OCT-derived macular volume, macular thickness, and peripapillary RNFL thickness are all significantly reduced in POAG, and macular parameters track RNFL loss closely enough to serve as a useful adjunct to disc and RNFL assessment.