This is a comparative, open label, parallel group, non interventional study to further demonstrate the efficacy and tolerability of BAT04. In addition the efficacy and safety shall be compared to Hyaluronic acid (HA)-Product. The patient applies BAT04 or HA-Product according to the instructions for use six times daily in both eyes over a period of 28 days. Response to treatment is recorded at day 28.

Inclusion Criteria:

• Male or female person aged 18 years
• Demonstrated mild to moderate keratoconjunctivitis sicca ( "dry eye")
• Acute symptoms of dry eye: DEWS 1-3
• tear break-up time TBUT <10s
• agreement to abide by the routinely provided doctor's appointment for follow-up (reflected in the planned visits of observation plan resist)

Exclusion Criteria:

• inflammation of the anterior segment or trauma
• Contact lens wearers
• Any disease that can, in the opinion of the treating physician to affect the outcome of the study.
• Patients with known intolerance to one of the substances used
• Surgical procedures to the eyes in the last 6 weeks before inclusion in the trial
• patients with addictive disorders or substance abuse fallow in the past 12 months, as well as persons incapable of giving consent

primary care clinic The selection of appropriate patients for the observational study is made by the individual physician in his treatment decisions in consultation with the individual patient