The issue of preservatives in light of evidence based medicine

Glaucoma is the leading cause of irreversible blindness worldwide. Most patients will require drug therapy for the rest of their lives. Preservatives play a key role in the development of topical medications whose primary role is to provide antimicrobial activity to maintain sterility. The most common preservative is benzalkonium chloride, which has antibacterial, antifungal, and antiviral properties. This article was written based on the latest research in MEDLINE and other major bibliographic databases for studies published in English by August 1st, 2021. Our meta-analyses confirm that eye drops side effects are not caused solely by the presence of preservatives, and the effectiveness of anti-glaucoma drugs containing benzalkonium chloride and those without preservatives is comparable. During the COVID-19 pandemic, studies showed the protective effect of preservatives against SARS-CoV-2.