Retinal nerve fiber layer thickness in glaucomatous and normal patients using spectral domain optical coherence tomography and standard automated perimetry-a comparative analysis

Glaucoma is characterized by a combination of structural changes in the retina and optic nerve head and functional perimetric damage. Examination and documentation of the retinal nerve fiber layer are essential for the diagnosis and monitoring of glaucoma. Spectral domain Optical coherence tomography (OCT) is a high resolution imaging device capable of obtaining reproducible retinal nerve fiber layer thickness measurements. Aim: The purpose of this study is to compare the efficacy of optical coherence tomography (OCT) and standard automated perimetry (SAP) in glaucoma versus normal patients. Materials and methods: It was a case control study. Patients diagnosed of primary open angle glaucoma were taken as cases in this study. They underwent visual field analysis using Humphrey SITA standard threshold 30-2 program and optical coherence tomography of the optic nerve head. Data analysis: The mean deviation of the visual field analysis and average RNFL thickness were compared in cases and controls. Results: A total of 19 patients of primary open angle glaucoma and 8 normal patients were included in this study. In our study, a significant difference was found among mean deviation, pattern standard deviation, average retinal nerve fiber thickness and temporal retinal nerve fiber thickness between cases and controls. Also, area under the receiver operating characteristics (ROC) curve showed that both mean deviation and average retinal nerve fiber thickness have very sensitivity in detecting glaucoma (0.992 and 0.930) and correlation was found between the mean deviation on visual field analysis and average retinal nerve fiber thickness by OCT. Conclusion: Our study concludes that there is a correlation between the structural and functional tests.