Ocular Surface Parameters in Glaucoma Patients Treated with Topical Prostaglandin Analogs and the Importance of Switching to Preservative-Free Eye Drops—A Systematic Review

<b>Background:</b> The use of preservative agents in eye drop solutions may worsen symptoms of ocular surface disease, which is a highly prevalent syndrome worldwide. Preservatives are often used in pharmacotherapy of glaucoma, another disease concerning tens of millions of people around the globe. These numbers are predicted by the World Health Organization and are predicted to increase with time due to constant aging of populations. <b>Methods:</b> PubMed and Scopus databases were searched for articles investigating the topic of ocular surface disease in relation with glaucoma pharmacotherapy, according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The aim of this review is to summarize the effect of various solvents used in drug formulations and ways to quantify their impact on the ocular surface. <b>Discussion and Conclusions:</b> Topical ophthalmic preservative-free formulations are better tolerated and less burdensome for all patients. They should be considered especially for glaucoma patients, who are expected to take medications for years, up to decades or a lifetime in many cases. Due to the chronicity of dry eye disease and the lack of reliable ways for lacrimal and meibomian gland renewal, primary prophylaxis is of uttermost importance. Unfortunately, despite the development of many measuring devices, the standardization of diagnostic methods poses a challenge due to high variability of results which are influenced by a myriad of factors-local, internal, and external.