Purpose: To determine variations in cytokine levels of glaucoma patients treated either with preservative-free latanoprost or preserved latanoprost, relative to healthy individuals. Methods: Tear samples were collected from 39 healthy subjects, 20 glaucoma patients treated with preserved latanoprost, and 20 patients treated with preservative-free latanoprost. A set of 27 inflammatory cytokines was analyzed in each group, including interleukin (IL)-1 beta, IL-1ra, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL9, IL-10, IL-12 (p70), IL-13, IL-15, IL-17, eotaxin, fibroblast growth factor (FGF) basic, granulocyte colony stimulating factor (G-CSF), granulocyte monocyte colony stimulating factor (GM-CSF), interferon (IFN)-gamma, interferon gamma-induced protein (IP)-10, monocyte chemo attractant protein (MCP)-1MCAF, macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, platelet-derived growth factor (PDGF)-BB, regulated on activation, normal T cell expressed and secreted (RANTES), tumor necrosis factor (TNF)-alpha and vascular endothelial growth factor (VEGF). Cytokine concentrations were obtained by the Bio-Plex Human Cytokine Immunoassay. Non-invasive tear breakup time (NI-TBUT), tear meniscus height, corneal fluorescein staining, conjunctival hyperemia and ocular surface disease index (OSDI) were assessed in patients treated with preservative-free and preserved latanoprost. Results: The levels of IL-2, IL-5, IL-10, IL-12 (p70), IL-13, IL-15, IL-17, FGF basic, PDGF-BB, and TNF-alpha were significantly higher in patients receiving preserved latanoprost, compared to normal controls (p < 0.05). The expression of all the cytokines studied remained statistically invariable in patients receiving preservative-free latanoprost, compared to healthy subjects (p > 0.05). Ocular surface parameters were not significantly different in both glaucoma groups, and no correlation between these clinical parameters and cytokine levels was observed. Conclusions: Treatment with preserved latanoprost has a direct impact on tear cytokine levels, whereas this effect is not observed upon preservative-free latanoprost instillation.(C) 2017 Elsevier Inc. All rights reserved.