Evaluation of the Corneal Residence Time of Chitosan-N-acetylcysteine Eye Drops in Patients With Dry Eye Syndrome After Single and Multiple Instillation

In the elderly population, dry eye syndrome is a highly prevalent ocular disease. One mainstay of therapy for patients suffering from dry eye syndrome is the use of topically administered lubricants. One of the main disadvantages of the formulations currently available for the treatment of DES is the short residency time on the ocular surface, which increases the need for a frequent instillation of the lubricant. Recently, Croma Pharma has introduced chitosan-N-acetylcysteine eye drops, designed for treatment of symptoms related to DES. Based on theoretical considerations and animal experiments, the new chitosan derivative may show an increased adhesion to mucins of the ocular surface and may therefore considerably increase the residence on the ocular surface. This, in turn, would limit the need for frequent treatment and decrease the burden for the patients. It has been shown in recent Phase I studies that chitosan-N-acetylcysteine eye drops are safe and well tolerated after single and repeated instillation. The current study seeks to investigate the ocular residency time after a single dose and after 5 day b.i.d. treatment. For this purpose 2 cohorts are planned: In Cohort I, chitosan-N-acetylcysteine eye drops will be instilled once in one randomly chosen eye, whereas the fellow eye will receive placebo. Measurements of tear film thickness will be performed with optical coherence tomography (OCT) before instillation and 10 minutes, 1 hour, 2 hours, 4 hours, 8 hours, 10 hours, 12 hours and 24 hours after instillation. In addition, ocular scattering of the tear film will be assessed with an Optical Quality Analysis System (OQAS) at the same timepoints. Determination of break up time (BUT) will be performed before and after instillation of the eye drops. In Cohort II, chitosan-N-acetylcysteine eye drops will be instilled once daily in one eye and b.i.d. in the fellow eye on five consecutive days. Measurements of tear film thickness with OCT and OQAS will be perfo