Dry eye syndrome (DES) is a highly prevalent ocular condition with severe consequences for the patients reaching from ocular discomfort in its simplest form up to visual impairment and corneal ulceration in severe cases. Data from epidemiological studies indicate that DES is a common disease, especially in the elderly population, affecting up to 20% of adults aged 45 years or older. Topical lubricants are a mainstay of therapy, but data on its effect on tear film thickness and the corneal residence time are lacking.

Recently, a new objective method for assessment of tear film thickness by optical coherence tomography has been developed. The present study aims to investigate the corneal residence time of an established topical lubricant compared to placebo in patients with DES and healthy controls.

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