To evaluate the correlation between RNFL thickness measured by OCT and visual field defects assessed through static perimetry in POAG patients

Abstract BACKGROUND: Primary Open Angle Glaucoma (POAG) is a chronic, progressive optic neuropathy characterized by retinal ganglion cell degeneration and corresponding visual field defects. Accurate assessment of retinal nerve fiber layer (RNFL) thickness using Optical Coherence Tomography (OCT) and its correlation with static perimetry is critical for diagnosing and monitoring disease progression. OBJECTIVE/AIM: To evaluate the correlation between RNFL thickness measured by OCT and visual field defects assessed through static perimetry in POAG patients. METHOD: This cross-sectional observational study, conducted at Jaipur National University, Institute for Medical Sciences and Research Centre, Jaipur, spanned 1.5 years and included 80 POAG patients aged over 40 years. Comprehensive examinations including gonioscopy, OCT (Nidek RS-330), and Humphrey Field Analyzer-based static perimetry were performed. Patients were classified into early, moderate, and severe POAG based on Mean Deviation (MD) values. RNFL thickness was analyzed in relation to visual field indices, including MD, Pattern Standard Deviation (PSD), and Visual Field Index (VFI). RESULTS: A statistically significant correlation was observed between RNFL thinning and worsening visual field defects, particularly in inferior and superior RNFL sectors. Mean RNFL thickness values were 56.17±14.92 µm in severe, 76.27±11.79 µm in moderate, and 98.05±13.46 µm in mild glaucoma cases. Correspondingly, MD values were -12.4±3.2 dB, -8.5±2.6 dB, and -4.2±1.8 dB, respectively. These findings affirm that OCT-derived RNFL measurements effectively predict glaucomatous damage as reflected by static perimetry changes. CONCLUSION: This study highlights the significance of RNFL assessment in glaucoma management, enabling early detection of structural changes before advanced visual field loss. Limitations included the unavailability of Fluorescein Angiography (FFA) and a relatively short follow-up, restricting longitudinal analysis. Future studies should incorporate larger samples and extended follow-up to explore neuroprotective interventions.