Eye Drops for Early Morning-Associated Corneal Swelling of the Cornea

Efficacy of Hyperosmolar Eye Drops in Diurnal Corneal Edema in Fuchs Endothelial Dystrophy: a Double Blind Randomized Controlled Trial

This study evaluates the efficacy of hyperosmolar eye drops on early morning edema of the cornea in patients with Fuchs' endothelial corneal dystrophy (FECD). Each participant will receive hyperosmolar eye drops in one eye and lubricating eye drops in the fellow eye.

Hyperosmolar eye drops are lubricating eye drops with 5% of sodium chloride. Hyperosmolar eye drops are thought to temporarily deswell the cornea.

During morning hours, patients with Fuchs' endothelial corneal dystrophy (FECD) typically report poor vision and disturbing glare because of corneal edema. To improve vision in advanced stages of the disease, corneal endothelial transplantation has become the treatment of choice. Many patients with Fuchs' endothelial corneal dystrophy (FECD) use hyperosmolar eye drops before transplantation. At present, it is unclear, how much hyperosmolar eye drops help reducing corneal edema in Fuchs' endothelial corneal dystrophy (FECD). Based on our previous work that determined the amount of additional corneal edema in the morning in patients with Fuchs' endothelial corneal dystrophy (FECD), the investigators will assess if hyperosmolar eye drops speed up the deswelling process.

Inclusion Criteria:

• Diagnosis of advanced Fuchs' endothelial corneal dystrophy (FECD)
• Indication for corneal endothelial transplantation (Descemet Membrane Endothelial Keratoplasty - DMEK)
• Must be able to speak and understand German or English.

Exclusion Criteria:

• Other corneal diseases (i.e. epithelial defects except for bullae caused by Fuchs' endothelial corneal dystrophy (FECD), corneal scars, postoperative / bullous keratopathy, corneal degenerations / dystrophies, corneal inflammation / infection)
• Regular use of drugs potentially affecting the cornea (i.e. amiodarone, chloroquine, triptan, isotretinoin, constant use of antihistamines, use of contact lenses in past four weeks, anesthetic eye drops, corticosteroid eye drops, antibiotic eye drops in past four weeks, glaucoma drops, hyperosmolar eye drops within the past 24 hours)
• Systemic diseases that affect the cornea (e.g. connective tissue disease, complicated diabetes mellitus)
• Lack of fixation during corneal tomography