OBJECTIVES: The aims of this research were to explore difference in the central corneal thickness (CCT) among patients with primary open-angle glaucoma (POAG) between groups with regard to the class of applied prostaglandin analogues; difference in CCT among patients with POAG with regard to therapy duration; and difference in CCT among patients with POAG with regard to age after received therapy. STUDY DESIGN: Cohort study PARTICIPANTS AND METHODS: The study included 91 participants admitted at the Clinic for eye diseases of the Clinical Hospital Centre (CHC) Osijek. All the participants suffered from POAG and had been receiving a monotherapy consisting of prostaglandin analogues (latanoprost, travoprost, bimatoprost) for at least 6 months and up to 2 years. The study excluded patients who suffered injuries to both eyes, had surgical procedures on the front or back segment of the eye and/or suffered inflammations which potentially resulted in changes within the front segment of the eye. During the regular follow-up appointments, participants underwent the pachymetry to measure the CCT again. Other than data on the CCT, the research included data on age, class of applied prostaglandin analogue and therapy duration. RESULTS: A significant reduction in CCT was observed in patients with POAG (P<0.001 for right and left eye) after prostaglandin analogues therapy. CCT after the therapy and age were negatively correlated (Rho=-0.276, P=0.009 for the right eye; Rho=-0.300, P=0.004 for the left eye). CONCLUSION: Prostaglandin analogues significantly reduce CCT in POAG patients. The corneal thickness is reduced after the therapy in older patients.