Relationship between peripapillary retinal nerve fiber layer and visual field severity indices in primary open angle glaucoma

Background: Optical Coherence Tomography (OCT) and visual field (VF) are devices for diagnosis and management of glaucoma. Using both techniques enable us to detect the functional and anatomical changes occur in glaucomatous eyes. Objectives: In this study, we aimed to determine the relationship between optical coherence tomography (OCT) parameters and visual field severity indices computed by standard automated perimetry (SAP) in patients with primary open angle glaucoma and to know the correlation between OCT disc parameter and ganglion cell layer (GCL). Methods: The study included 94 subjects (160 eyes) divided into two groups. Group1 included 54 subjects with primary open angle glaucoma (cases) (92 eyes) Group 2 included 40 healthy non-glaucomatous subjects (controls) (68eyes).OCT disc &macula and VF using standarded automated perimetry were performed for all participants in both groups. Correlations between OCT parameters and VF parameters and between OCT disc parameters and GCL were detected. Area under curve (AUC) was used to detect most important factor to differentiate cases from control. Results: We found strong correlations between MD and each of total , Inferior , Superior p RNFL respectively , PSD is moderately correlated with total ,inferior and superior p RNFL and vertical CDR respectively ,Inferior p RNFL is strongly correlated to inferior GCLcomplex. Regarding the "area under curve (AUC)" : the most important factors to differentiate cases from control are in order: total GCC, followed by inferior GCC, then total p .RNFL. Conclusion : macular scans may be a good alternative to p. RNFL thickness assessment for the detection of glaucoma, we should perform VF test with both macular and p.RNFL scanning in all subjects suspected or known to have glaucoma for better and earlier diagnosis as they improve the sensitivity of glaucoma detection.