Influence of timolol, benzalkonium-preserved timolol, and benzalkonium-preserved brimonidine on oxidative stress biomarkers in the tear film.

Purpose: The objective of this study was to investigate the influence of topical preservative-free timolol, benzalkonium chloride(BAC)-preserved timolol, BAC-preserved timolol, and BAC-preserved brimonidine on total protein concentration, advanced oxidation protein products (AOPP) content, total sulfhydryl groups content, the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as Total Oxidant Status (TOS), Total Antioxidant Response, and Oxidative Stress Index (OSI) in the tear film.

Methods: The patients were divided into four groups: group C ( = 25)-control group-subjects who did not use topical antiglaucoma medications, group T ( = 17)-patients using topical preservative-free timolol, group T + BAC ( = 24)-patients using topical BAC-preserved timolol, and group BR + BAC ( = 19)-patients using topical BAC-preserved brimonidine.

Results: The SOD, CAT, and GPx activities as well as AOPP, TOS, and OSI were found to be higher in the tear film of patients treated with BAC-preserved topical timolol or brimonidine in comparison with patients treated with preservative-free timolol or patients who did not use antiglaucoma topical medications.

Conclusions: This indicates that using BAC-preserved topical medications increases oxidative stress in the tear film and may, in the long-term, contribute to the clinical presentation of dry eye disease.