Background: Primary open-angle glaucoma (POAG) represents the most prevalent form of glaucoma globally, characterized by progressive optic neuropathy and distinctive intraocular pressure (IOP) patterns. Understanding IOP variations and comprehensive clinical profiles is essential for optimizing therapeutic strategies and preventing irreversible vision loss. Methods: This prospective observational study was conducted at a tertiary care hospital, enrolling 284 patients diagnosed with POAG. Participants underwent comprehensive ophthalmic examination including Goldmann applanation tonometry, diurnal IOP measurements (8 AM, 12 PM, 4 PM, 8 PM), optical coherence tomography (OCT) for retinal nerve fiber layer (RNFL) analysis, visual field testing using Humphrey perimetry, and gonioscopy. Demographic data, disease severity, systemic comorbidities, and treatment responses were systematically documented. Statistical analysis employed paired t-tests, ANOVA, correlation analysis, and multiple regression modeling. Results: Mean patient age was 58.6 ± 11.4 years with male predominance (61.3%). Baseline mean IOP was 24.8 ± 5.6 mmHg, demonstrating significant diurnal variation with peak pressures at 8 AM (26.4 ± 6.2 mmHg) and trough at 8 PM (21.6 ± 4.8 mmHg, p<0.001). Mean IOP fluctuation was 4.8 ± 2.4 mmHg over 12 hours. Advanced disease was present in 38.7% of patients, moderate in 42.3%, and early-stage in 19.0%. Mean RNFL thickness was significantly reduced (68.4 ± 18.6 μm) compared to normative data (p<0.001). Visual field mean deviation averaged -12.8 ± 8.4 dB. Significant correlations existed between IOP fluctuation magnitude and disease severity (r=0.58, p<0.001), RNFL thinning (r=-0.52, p<0.001), and visual field defects (r=0.48, p<0.001). Hypertension (44.4%), diabetes mellitus (28.2%), and positive family history (31.7%) were prevalent comorbidities. After 6 months of topical therapy, mean IOP reduction was 7.2 ± 3.4 mmHg (29.0% reduction, p<0.001). Conclusion: POAG patients demonstrate substantial diurnal IOP variations strongly correlated with structural and functional damage severity. Comprehensive IOP profiling beyond single-point measurements is essential for accurate disease assessment and individualized treatment planning.

primary open-angle glaucoma, intraocular pressure, diurnal variation, retinal nerve fiber layer, visual field defects, optical coherence tomography, glaucoma severity