Abstract

Primary open-angle glaucoma (POAG) is a progressive optic neuropathy characterized by retinal ganglion cell death and optic nerve head changes, leading to irreversible vision loss if left untreated. This study aimed to evaluate and compare peripapillary retinal nerve fiber layer (RNFL) thickness and macular layer thickness measurements using spectral domain optical coherence tomography (SD-OCT) in patients with POAG versus healthy controls. A total of 120 participants were enrolled, including 60 patients with confirmed POAG and 60 age-matched healthy controls. All participants underwent comprehensive ophthalmic examination including visual field testing, intraocular pressure measurement, and SD-OCT imaging using Heidelberg Spectralis OCT. Peripapillary RNFL thickness was measured in four quadrants (superior, inferior, nasal, and temporal), while macular thickness measurements included ganglion cell layer (GCL), inner plexiform layer (IPL), and total macular thickness. Results demonstrated significantly reduced peripapillary RNFL thickness in all quadrants in the POAG group compared to controls (p<0.001). Mean peripapillary RNFL thickness was 78.4±12.6 μm in POAG patients versus 96.7±8.9 μm in controls. Macular GCL-IPL thickness was significantly thinner in POAG patients (67.8±9.4 μm) compared to controls (82.3±6.7 μm, p<0.001). The inferior and superior quadrants showed the most pronounced RNFL thinning, consistent with the typical glaucomatous pattern of damage. Strong correlations were observed between RNFL thickness measurements and visual field parameters, with correlation coefficients ranging from 0.72 to 0.84. SD-OCT demonstrated excellent diagnostic capability with area under the receiver operating characteristic curve values of 0.92 for average RNFL thickness and 0.89 for macular GCL-IPL thickness. These findings confirm that SD-OCT is a valuable tool for early detection and monitoring of structural changes in glaucoma, providing objective quantitative measurements that correlate well with functional visual field defects and can aid in clinical decision-making for glaucoma management.