Glaucoma is one of the main causes of blindness worldwide that has been considered as a major public health issue. It is usually associated with an intraocular pressure above the normal range. The normal range is considered to be 10-21mmHg. Elevated intraocular pressure is a major risk factor for development and/or progression of glaucoma, and intraocular pressure reduction is a well-known treatment strategy for slowing the progression of the disease. The main objective of this study was to identify factors/covariates which affect intraocular pressure on glaucoma patients taking into consideration various demographic, socio-economic and clinical factors. A retrospective longitudinal cohort study was conducted; the study was based on data from all glaucoma patients who visit at least 3 times were collected repeatedly six waves from January 2015 to December 2016 at Felege Hiwot Referral Hospital Eye Clinic. Profile plots, univariate and multivariate linear mixed effect models were used to explore the major risk factors for the progression of intraocular pressure of a patient. Gender (p-value=0.0218), occupation (p-value=0.0025), blood pressure (p-value, 0.0263), diabetes (p-value=0.0139), ocular problem (p-value=0.0290) and type of treatment (p-value=0.0176) had statistically significant effect on intraocular pressure of glaucoma patient. From the interaction effects, time with age (p-value<.0001), time with ocular problem (p-value=0.0002), time with cataract surgery (p-value=0.0002), time with duration of treatment (p-value=0.0014) and time with type of treatment (p-value=0.0262) had statistically significant effect on intraocular pressure of glaucoma patient. Gender, occupation, blood pressure, diabetes, ocular problem, and treatment type of patients were significant predictors of the progression change of intraocular pressure. And also age, ocular problem, cataract surgery, duration of treatment and type of treatment over time were identified as significant predictors