Aim: To compare the relationship between ocular parameters such as Intraocular pressure, Central cornea thickness, Axial length and Refractive state in primary open angle glaucoma (POAG) and controls in South-West Nigeria. Materials and Methods: This hospital-based case control study was carried out over a period of six months (June - November, 2020) among one hundred and eighty-four newly diagnosed primary open angle glaucoma and control adult subjects. Ocular parameters such as central cornea thickness, intraocular pressure, axial length and refractive state were measured in each subject. Data collected was entered into a computer spread sheet and analysed using Statistical Package for Social Sciences version 23.0. Test of significance between proportions in categorical variables were assessed using chi square test (χ2). The mean of the parameters were compared using independent t-test while correlation between parameters were analysed using Pearson correlation coefficient. Results: The mean age of the POAG patients was 61.0 + 13.4 years and the mean age of the control was 55.1 + 15.3 years. The ocular parameters were strongly correlated in the right and left eyes of both primary open angle (Refractive status: r= 0.831, Central cornea thickness: r =0.743, Axial length: r= 0.831) and control subgroup (Refractive status: r=0.829, Central cornea thickness: r= 0.866, Axial length: r= 0.858). Thus, for the purpose of this study only the right eye was analysed. The mean intraocular pressure in the POAG group was 30.2 + 8.9mmHg and control was 14.2 + 2.6mmHg (p<0.001), there were no significant differences between both groups for central cornea thickness (p=0.213), axial length (p=0.341) and refractive state (p=0.261). Myopes and subjects with long axial length were found to be higher in the POAG group compared to controls. With an increasing axial length, central cornea thickness tends to be xv thicker in both groups, this correlation was significant in the POAG group (r = 0.741, p= 0.02) but not significant in the control group (r = 0.531, p=0.06). As myopic refractive state increased, central cornea thickness and axial length increased in the POAG (r = -0.401,p=0.61), (r = -0.841, p=0.06) and control groups (r= -0.639, p=0.07), (r= -0.591, p= 0.101) respectively while an increase in intraocular pressure was observed with an increase in myopic refraction in the POAG group (r= -0.702) and vice versa in the control group (r= 0.677).