Analysis of Retinal Nerve Fibre Layer and Optic Nerve Head by Optical Coherence Tomography in POAG

Abstract

Introduction: Glaucoma is the second leading cause of blindness. Early identification of disease is important, as treatment can slow the disease progression and preserve vision. Aim: The purpose of our study was to evaluate the Retinal Nerve Fibre Layer (RNFL) and Optic nerve head (ONH) using Optical Coherence Tomography (OCT) in primary open angle glaucoma (POAG) and to determine if any correlation exists between the two. Materials and Methods: In a Cross-sectional study including, 73 eyes of 39 patients with POAG, aged 40 years and above, we evaluated retinal nerve fiber layer (RNFL) and optic nerve head (ONH) changes using optical coherence tomography (OCT). The statistical analysis was done using Epi Info software. Results: The mean age was 62.82±9.78 years and IOP was 24.25±3.685 mmHg. Mean thickness of RNFL was 101.67±25.8μm, 60.21±14.02μm, 98.67±25.10μm, 72.44±21.914μm of superior, temporal, inferior and nasal quadrants respectively. The ONH parameters and the RNFL thickness were quantified and analyzed. It was found that most of the patients had more thinning in the superior and inferior quadrants. Superior RNFL and the vertical ONH parameters showed best correlation (-0.439, p-value 0.005). Conclusion: SD-OCT is a powerful objective and structural assessment tool in diagnosing and managing glaucoma and hence should be a part of routine glaucoma evaluation. Correlation of ONH topography with RNFL thickness may be of value in patients with suspicious disc picture. Superior quadrant of the RNFL was found to be the most reliable parameter in primary open angle glaucoma.

Keywords

• cup disc ratio
• disc area
• glaucoma
• peripapillary nerve fiber thickness