Assessment of Tear Film Thickness by Optical Coherence Tomography in Healthy Subjects and Subjects With Dry Eye Disease

Inclusion Criteria: Inclusion criteria for healthy subjects: * Men and women aged over 18 years * Normal findings in the medical history unless the investigator considers an abnormality to be clinically irrelevant * Normal ophthalmic findings, ametropia \< 6 Dpt * Schirmer I test \> 10 mm and BUT \> 10 sec Inclusion criteria for patients with dry eye syndrome: * Men and women aged over 18 years * Normal findings in the medical history unless the investigator considers an abnormality to be clinically irrelevant except DES * Normal ophthalmic findings, ametropia \< 6 Dpt * History of dry eye syndrome for at least 3 months * Tear Break Up Time (BUT) \< 10 seconds or Schirmer I test \< 7 mm * At least 2 symptoms of dry eye syndrome (foreign body sensation, burning, photophobia, blurred vision, pain, itching) * Normal ophthalmic findings except dry eye syndrome Exclusion Criteria: * Regular use of medication (except contraceptives), abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study * Treatment in the previous 3 weeks with any drug * Symptoms of a clinically relevant illness in the 3 weeks before the first study day * Ametropia \>= 6 Dpt * Pregnancy * Difference of more than 3 mm in Schirmer I test or difference of \> 3 sec in BUT between the two eyes * Known medical history of allergy, hypersensitivity or poor tolerance to any components of the medication or medical product used in the study