Aim: Glaucoma is an optic neuropathy causing progressive impairment of visual functions. We aimed to assess the alterations in thiol-disulfide homeostasis and serum ischemia modified albumin (IMA) levels, which are the determinants of antioxidant status, in patients with primary open-angle glaucoma (POAG).Material and Method: A total of 140 eyes from 70 patients with POAG and 174 eyes of 87 healthy, control cases were included in the study. All study participants underwent a complete ophthalmic evaluation. Alterations in serum thiol-disulfide homeostasis and IMA levels were measured in all participants.Results: IMA levels were significantly higher in glaucoma group (p:0.001). Native thiol, Total thiol and Native/Total thiol ratio were significantly decreased while Disulfide, Disulfide/Native thiol, and Disulfide/Total thiol ratios were significantly higher in glaucoma group (p:0.001). There was no significant difference regarding central corneal thickness (CCT), iridocorneal angle, albumin, IMA and adjusted IMA levels in patients with different stages of glaucoma. In correlation analysis, there was a negative correlation between Native thiol, Total thiol and Native/Total thiol ratio and disease period, number of daily drops required and stage of the disease in glaucoma patients. There was also a positive correlation between Disulfide, Disulfide/Native thiol and Disulfide/Total thiol levels and the disease activity.Conclusion: In patients with POAG, thiol-disulfide homeostasis is disturbed in the favor of pro-oxidant molecules and IMA levels are increased, indicating the presence of augmented oxidative stress. In that aspect, systemic and local anti-oxidant treatments may be new targets in glaucoma treatment. Larger, prospective studies about the role of anti-oxidants in prevention and treatment of POAG are warranted.