Rationale for Preservative-free Glaucoma Drops.

Benzalkonium chloride (BAK) is the most widely used preservative in multidose glaucoma eye drops. Medical management of glaucoma often requires the chronic use of preserved eye drops, resulting in a high incidence of BAK‑associated ocular discomfort, ocular surface disease, accumulation within ocular structures, and inflammatory tissue changes. The use of BAK has also been associated with reduced surgical success in trabeculectomy. Although alternative preservatives exist, they have also been associated with some toxic effects. Switching from BAK‑containing formulations to preservative‑free (PF) formulations results in significantly fewer side effects, improved ocular surface disease, and enhanced patient comfort. However, barriers such as cost and ease of use have impeded the more widespread adoption of PF glaucoma drops.