Evaluation of total antioxidant and oxidant status in the serum of patients with seasonal allergic conjunctivitis. Ümit Doğan 1* , Sümeyra Ağca 1 , Buket KınTekçe 2 1 Department of Ophthalmology, Faculty of Medicine, Abant Izzet Baysal University, Bolu, Turkey 2 Department of Biochemistry, Faculty of Medicine, Abant Izzet Baysal University, Bolu, Turkey Abstract Purpose: To investigate the relationship between seasonal allergic conjunctivitis (SAC) and oxidative stress by measuring serum total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI). Methods: A total of 95 participants, 49 patients with SAC (18 female, 31 male) and age and gender matched 46 controls (23 female, 23 male) were included during allergy season in this observational case- control study. Serum samples were obtained from all participants. The measurements of serum TAS and TOS levels were made by automatic colorimetric method and OSI was calculated. Results: Serum TAS levels of the patient and control group were measured as 1.45 ± 0.19 mmol Trolox Equ/L and 1.46 ± 0.15 mmol Trolox Equ/L, respectively. The median serum TOS values of the patient and control group were 3.60 (1.34-36.27) µmol H 2 O 2 Equ/L and 3.29 (1.00-12.96) µmol H 2 O 2 Equ/L respectively. OSI values of the patient and control group were calculated as 37.67 ± 39.32 and 26.78 ± 15.38, respectively. There was no statistically significant difference between serum TAS, TOS and OSI values of two groups (p: 0.974, 0.544 and 0.372, respectively). Conclusion: We found no significant difference in levels of serum oxidative stress markers in patients with SAC and control group. There may be localized oxidative stress only in the ocular surface, which does not affect serum values in patients with SAC. Keywords: Oxidative stress index, Seasonal allergic conjunctivitis, Total antioxidant status, Total oxidant status. Accepted on December 05, 2017 Introduction Seasonal allergic conjunctivitis (SAC) is the most common ocular allergy and its incidence ranges from 5 to 22% [1]. SAC is characterized by itching, eyelid edema and erythema, conjunctival hyperemia and edema. It has relapsing-remitting intervals causing decrease in the quality of life. In the SAC etiology, environmental factors such as pollens, industrialization, and dietary take are being blamed [2]. SAC occurs via the IgE-mediated type 1 hypersensitivity reaction triggered by environmental allergens [3]. As a result of these reactions, histamine and reactive oxygen species (ROS) such as hydroxyl radicals, superoxides, peroxides released from mast cells cause inflammation [4]. ROS are the mediators necessary for the maintenance of vital functions in physiological concentrations. Therefore, it is constantly produced in certain amounts in the organism and excess part of it is destroyed by antioxidant molecules. Oxidative stress is called as the imbalance in favor of oxidants [5]. Oxidative stress has been associated with many diseases such as inflammation, asthma, rhinitis, obesity, rheumatological diseases, cardiovascular diseases, neurodegenerative diseases [4,6-11]. It is impractical and almost impossible to measure each of the multiple ROS in order to assess oxidative stress. Therefore, it is more practical and reliable to evaluate serum total antioxidant status (TAS) and serum total oxidant status (TOS) levels, which show the total levels of all systemic antioxidants and oxidant molecules [12,13]. Studies in the literature that investigate the relationship between allergy and oxidative stress are generally related to asthma. There are a few studies about the SAC and oxidative stress but we did not find a study examining serum TAS and TOS levels in SAC. We aimed to investigate the relationship between SAC and oxidative stress by measuring serum TAS and TOS levels in our study. Methods Subjects A total of 95 subjects, 49 patients with SAC and 46 controls were included in this observational case-control study. All SAC patients applied to the ophthalmology department of the Abant Izzet Baysal University, Faculty of Medicine between May and August 2017, the allergy season in Bolu. The control group was randomized from age and gender-matched healthy ISSN 0970-938X www.biomedres.info Biomed Res 2018 Volume 29 Issue 5 1048 Biomedical Research 2018; 29 (5): 1048-1051