Topical eye-drops remain the cornerstone of treatment for ocular diseases, including glaucoma. Preservatives are added to multi-dose medication bottles to reduce the risk of microbial contamination, to extend the validity of the product and to allow an easily use of the bottles. However the repetitious use of ophthalmic medications containing preservatives, particularly when treating chronic diseases, has been linked to adverse effects and ocular surface disease (OSD). Therefore, this presentation provides an overview of glaucoma and OSD, the role of preservatives in ophthalmic preparations, and the impact of preservatives on the ocular surface.