Effect of Single Instillation of Three Different Topical Lubricants on Tear Film Thickness in Patients With Dry Eye Syndrome

Inclusion Criteria Patients will be eligible for inclusion if all these criteria are respected: 1. Age of at least 18 years 2. Provides written informed consent prior to study-related procedures at the screening visit 3. Is able to understand and willing to comply with the procedures and the actions asked of him/her 4. History of dry eye syndrome for at least 3 months 5. Reports at least 2 of the following symptoms related to dry eye syndrome: foreign body sensation, pain, itching, stinging, epiphora, photophobia or blurred vision 6. Tear Break Up Time (BUT) ≤ 10 seconds or Schirmer I test ≤ 10 mm 7. OSDI score ≥ 23 points 8. Normal ophthalmic findings except dry eye syndrome Exclusion Criteria Patients will be excluded under the following circumstances: 1. Participation in a clinical trial in the 3 weeks preceding the study 2. Symptoms of a clinically relevant illness in the 3 weeks before the first study day 3. Presence or history of a severe medical condition as judged by the clinical investigator 4. Intake of parasympathomimetic or anti-psychotic drugs 5. Wearing of contact lenses 6. Glaucoma in the medical history 7. Treatment with corticosteroids in the 4 weeks preceding the study 8. Topical treatment with any ophthalmic drug except topical lubricants in the 4 weeks preceding the study 9. Ocular infection or clinically significant inflammation not related to dry eye syndrome 10. Ocular surgery in the 3 months preceding the study 11. Sjögren's syndrome 12. Stevens-Johnson syndrome 13. History of allergic conjunctivitis 14. Pregnancy, planned pregnancy or lactating 15. Known hypersensitivity to any component of the study medication