IntroductionDiquafosol is a P2Y2 receptor agonist that has been shown to be effective in the treatment of dry eye disease (DED) in short-term studies; however, its long-term safety and effectiveness have not been evaluated in a real-world setting.MethodsThis prospective, multicentre, open-label observational study was conducted in patients with DED over 12 months. Safety endpoints included the incidence of adverse drug reactions (ADRs) and serious ADRs. Effectiveness endpoints included change from baseline in keratoconjunctival staining score, tear film break-up time (BUT) and Dry Eye-related Quality of Life Score (DEQS).ResultsA total of 580 patients were included, most of whom were female (82.9%). The proportion of patients who completed 12 months of observation was 55.0%, the most common reason for discontinuation was patient decision (54.6%). The incidence of ADRs was 10.7% and was highest during the first month of treatment (5.5%); no serious ADRs were reported. Compared with baseline, significant improvements in all effectiveness outcomes, including keratoconjunctival fluorescein staining score, BUT and DEQS summary score, were observed at each evaluation during the treatment period (p < 0.001).ConclusionThe present, real-world study showed that diquafosol 3.0% ophthalmic solution was well tolerated and effective in the long-term treatment of DED.Electronic supplementary materialThe online version of this article (10.1007/s12325-019-01188-x) contains supplementary material, which is available to authorized users.