Role of Ganglionic Cell Complex, Retinal Nerve Fibre Layer in Glaucoma Evaluation

Abstract

Introduction: Glaucoma is a multifactorial disease characterised by damage to Retinal Ganglion Cells (RGCs) that inturn results in damage of nerve fibers resulting in functional visual impairment. Aim: To evaluate the sensitivity and specificity of Ganglion Cell Complex (GCC) parameters and Retinal Nerve Fibre Layer (RNFL) thickness obtained with Spectral Domain-Optical Coherence Tomography (SD-OCT) and to determine their role in the diagnosis of primary open-angle glaucoma patients. Materials and Methods: A case control observational study was conducted on 55 patients of Primary Open Angle Glaucoma (POAG) cases and 50 normal (control) patients presenting to the Eye OPD at tertiary eye hospital over a period from August 2015 to November 2017. Institutional ethical clearance was taken and tenants of a declaration of Helsinki were adhered to. Apart from complete ophthalmic examination, all patients underwent reliable standard automated perimetry (30-2) testing and SDOCT imaging for RNFL thickness, Optic Nerve Head (ONH) analysis and GCC. Receiver Operating Characteristic Curves (ROC) were studied for all parameters. Results: The diagnostic ability for distinguishing between normal and glaucoma patients were same when we consider average RNFL thickness and avgerage GCC thickness. Diagnostic accuracy increases when we consider both RNFL and GCC thickness. There was a significant difference in both RNFL and GCC thickness between normal and glaucoma patients (p<0.001). The Mean Deviation (MD) showed a significant correlation with all the parameters in eyes with glaucoma (<0.001). Conclusion: GCC thickness seems to have higher sensitivity and specificity for the detection of early glaucoma. Diagnostic accuracy increases when we include other parameters like RNFL and visual fields.

Keywords

• optical coherence tomography
• optic nerve head
• primary open angle glaucoma
• visual fields