Topical glaucoma therapy is a long termed, usually lifelong. Antiglaucomatous drugs have toxic effects on ocular surface, due to preservative toxicitiy or the drug itself. Adding a lubricant eyedrops to antiglaucomatous therapy, especially if considering the preservative used, can have protective effect. The purpose of this study was to evaluate the stabilty of precorneal tear film in glaucoma patient prior and after administration of lubricant eye drops with different tipe of preservatives. The study showed the protective role of ocular surface lubrication especially when using drugs with less harmful preservatives.