Introduction: Of the irreversible causes of blindness, glaucoma ranks second which can be treated by early identification of disease and to slow its progression and preserve vision. Aim: The purpose of our study was to calculate the RNFL and ONH parameters using OCT in primary open angle glaucoma (POAG) patients and to determine if any correlation exists between the two. Materials and methods: The study included 95 eyes of 50 patients above 40 years of age with POAG. Central corneal thickness was calculated using optic pachymetry, IOP measurement using applanation tonometry. SD-OCT was used to calculate the RNFL and ONH parameters. Results: The ONH parameters and the RNFL thickness were tabulated and correlation between them was analysed. Superior and inferior quadrants thinning of RNFL was evident in most of the patients. Superior RNFL and the vertical ONH parameters showed best correlation (-0.442, p-value 0.005). Conclusion: The RNFL thickness were well correlated to optic disc parameters. OCT helps in acquiring high resolution accurate images, reproducible RNFL and retinal thickness measurement. OCT has shown to have greater diagnostic accuracy in RNFL measurements, there by helping the ophthalmologists to identify subtle changes of the normal RNFL pattern, ONH parameters before visual field defects develop.

Keywords: RNFL; ONH; POAG; SD-OCT