The objective of this study was to evaluate efficacy, local tolerability, and safety of this first-in-class preservative-free prostaglandin preparation in patients with ocular hypertension and glaucoma.Patients with glaucoma or ocular hypertension who required a change of medication or were naïve to treatment were included in this noninterventional and observational study. Noninterventional means that no influence was made upon the decision of the physicians to include specific patients and upon the treatment algorithm used. German law for observational studies does not allow any influence on the choice of drugs used, patient selection, masking, and comparator treatment regimens. The main aim of this observational study was to collect "real-life data" on the efficacy and safety of a new medical treatment after approval in a large patient population. Participating ophthalmologists were asked to provide anonymous patient data collected during regular visits by filling a simple data entry form. Intraocular pressure (IOP) readings were recorded at baseline (previous therapy or untreated) and 6-12 weeks after changing medical treatment to or initiating treatment with preservative-free tafluprost once daily. Changes in the IOP were evaluated over the study period for all patients as well as for specific pretreatment subgroups. Local comfort was determined using a five-point scale (very good, good, satisfactory, less satisfactory, not acceptable) before and after the change of medical treatment. All adverse events were recorded.Data from 2123 patients with glaucoma or ocular hypertension were considered for the final evaluation. Medication was changed in 41.1% of patients due to tolerability issues and in 25.6% of patients due to insufficient efficacy with prior medication. In all patients preservative-free tafluprost 0.0015% lowered IOP from 19.5 ± 4.4 mmHg (baseline) to 16.4 ± 2.9 mmHg after 6-12 weeks. Preservativefree tafluprost also significantly lowered the IOP in all monotherapy subgroups: treatment-naïve patients (n=440): 22.6 ± 3.9 mmHg (baseline) to 16.7 ± 2.7 mmHg (week 6-12); beta blockers (n=307): 20.3 ± 3.5 mmHg (baseline) to 16.7 ± 2.6 mmHg (week 6-12); carbonic anhydrase inhibitors (n=158): 19.0 ± 3.6 mmHg (baseline) to 16.0 ± 2.6 mmHg (week 6-12); prostaglandin analogs (PGAs; n=447): 16.8 ± 2.9 mmHg (baseline) to 15.8 ± 2.6 mmHg (week 6-12). Local comfort was rated as "very good" or "good" by 85.6% of patients at the final visit (P<0.001). Only few adverse events occurred during the treatment period: 18 patients (0.8%) discontinued medical treatment with preservative-free tafluprost due to local intolerance; six patients (0.3%) due to efficacy issues; four patients complained about systemic side effects (0.2%); and two patients preferred to use a multidose treatment regimen (0.2%).Although this study was limited by its observational design the results demonstrate that preservative-free tafluprost 0.0015% was effective, generally well tolerated, and safe in a broad and heterogeneous patient population.