AIM:To determine the effect of topical 0.05% cyclosporine A (CsA) on corneal endothelium in patients with dry eye disease.METHODS: Observational, prospective, case series study. Fifty-five eyes of 29 consecutive patients (9 males and 20 females; median age:66.8 years, interquartile range:61-73.2 years) with moderate-severe dry eye disease were evaluated. All patients were treated with topical 0.05% CsA ophthalmic emulsion twice a day in addition to lubricant eyedrops 5 times a day. The follow-up period was 12 months. Before treatment and at 3 and 12 months post-treatment central corneal specular microscopy was performed. The endothelial cell density (ECD), coefficient of variation of cell size (CoV), and percentage of hexagonal cells (Hex %) were analyzed.RESULTS: The median ECDs pre-treatment and at 3 and 12 months post-treatment were 2 352.5/mm² (interquartile range, 2 178-2 548.5), 2364/mm² (interquartile range, 2 174.25-2 657.5), and 2366 cells/mm² (interquartile range, 2 174.75-2 539.75), respectively (P=0.927, one way ANOVA). The median CoVs pre-treatment and at 3 and 12 months post-treatment were 34.5 (interquartile range, 30-37), 35 (interquartile range, 30-38), and 34 (interquartile range, 30.75-38.25), respectively (P=0.7193, one way ANOVA). The median Hex % values pre-treatment and at 3 and 12 months post-treatment were 53 (interquartile range, 47-58), 54 (interquartile range, 45.75-59), and 50.5 (interquartile range, 45.75-58), respectively (P=0.824, one way ANOVA).CONCLUSION: Treatment of patients with dry eye disease for 12 months with topical 0.05% CsA does not seem to cause substantial changes on corneal endothelium.