Evaluation of Correlation among Retinal Nerve Fibre Layer Thickness, Cup Disc Ratio and Perimeteric Indices in Primary Open Angle Glaucoma and Glaucoma Suspects

Background: Primary open angle glaucoma (POAG) is the most common type of glaucoma which is considered chronic progressive optic neuropathy, accompanied by a characteristic cupping and atrophy of the optic disc, visual field loss, open angle and no obvious systemic or ocular cause. This study aims at evaluating the correlation between optic disc parameters like Cup - to - Disc Ratio (CDR) and retinal nerve fibre layer thickness (RNFL - T) with Visual Field (VF) defect parameters like Mean Deviation (MD) and Pattern Standard Deviation (PSD) in Primary Open - Angle Glaucoma (POAG) patients and Glaucoma suspects. The study also aims to detect early structural changes in Glaucoma suspects. Methods: This prospective study was conducted at Sankara Eye Hospital, Ludhiana from July 2019 to June 2020.50 eyes with diagnosed POAG and glaucoma suspects were analyzed each. Various optic disc parameters like CDR and RNFL - T was correlated with MD and PSD on perimetery. Results: Mean age of study population was 62.16?8.22 years in glaucoma group and 57.48?9.34 in suspects. There was a statistically significant difference in RNFL - T, CDR and perimeteric findings between POAG and glaucoma suspects (Pless than0.005). Average RNFL thickness was 67.31?16.56 in POAG and 84.63?3.21 in glaucoma suspect which is statistically significant (Pless than0.05). There was significant correlation of CDR with RNFL - T and MD in POAG where as no such correlation exist in suspects. Conclusion: There is significant direct correlation between average retinal nerve fibre layer thinning and visual field mean deviation in patients with POAG. Optic disc parameters get severely affected as the stage of glaucoma progresses which has also strong correlation with visual field changes and RNFL thickness. In Glaucoma suspects, these parameters are minimally affected or may show no change at all.