Effect of Lipid Based Eye Drops on Tear Film Lipid Layer Thickness

Inclusion Criteria: All groups * Men and women aged over 18 years * Normal findings in the medical history unless the investigator considers an abnormality to be clinically irrelevant * Ametropy \< 6 dpt * No application of eye drops or ointments in the 24 hours preceding the screening visit as well as the study day Dry eye disease group * History of dry eye disease ≥ 3 months * Schirmer I test ≤ 10 mm and ≥ 2 mm or BUT ≤ 10 sec * Normal ophthalmic findings with the exception of DED Meibomian gland disease group * Dry eye disease most likely caused by MGD, no other cause identifiable which is more likely (e.g. intake of concomitant medication that could induce DED, systemic diseases such as systemic arthritis or diabetes), as judged by the investigator * History of dry eye disease ≥ 3 months * Normal ophthalmic findings except dry eye disease * BUT ≤ 10 seconds Blepharospasm group * Clinical diagnosis of blepharospasm * Normal ophthalmic findings with the exception of blepharospasm and dry eye * Schirmer I test \> 10 mm and BUT \> 10 sec Exclusion Criteria: All groups * Clinically relevant illness in the 3 weeks before the screening or study day * Ametropy ≥ 6 dpt * Pregnancy or planned pregnancy * Difference of more than 5 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 medical device used in the study * Treatment with topical or systemic steroids, immune suppressants, NSAIDs: ongoing or in the last 4 weeks * Treatment with medication known to have a detrimental effect on tear film (e.g. antidepressants, anxiolytics, neuroleptics, antihistaminic drugs, cholinergic drugs, antimuscarinic drugs, phenothiazine, beta blockers): treatment duration ≤ 4 weeks or changed dose since ≤ 4 weeks or during the study * Alcohol abuse * Contact lens wear Meibomian gland dysfunction group * Sjögren's syndrome