Elegible patients were included in the study and underwent treatment with a solution of citicoline 1% eye-drops, 0.2% high molecular weight hyaluronic acid and 0.01% benzalkonium chloride prior to surgery. The vitreous samples were taken at the beginning of the surgery and analyzed for qualitative/quantitative determination of vitreous concentration of citicoline and its metabolites by means of high performance liquid chromatography.

At the visit all patients underwent comprehensive ophthalmological examination including best corrected visual acuity assessment, slit lamp evaluation, IOP measurement using Goldmann applanation tonometry, and fundus dilated indirect ophthalmoscopy.

Additionally, all patients had central retinal thickness measurements with spectral-domain optical coherence tomography associated with central corneal thickness (CCT) and corneal endothelial cells density (ECD) evaluations.

Patients started the treatment with 1 drop of a solution of citicoline 1% eye-drops, 0.2% hyaluronic acid and 0.01% benzalkonium chloride for 3 times/day over a total time of 14 days before surgery and 1 drop 2 hours prior to the surgery.

Five patients served as controls and received a vehicle solution without citicoline.

The primary aim of the study was to evaluate the presence and concentration of citicoline and its metabolites (choline, cytidine and uridine) in the vitreous body in vivo in human eyes after topical eye-drops administration by means of high performance liquid chromatography.

Secondary aims were the comparison of citicoline and its metabolites concentration in the vitreous of treated phakic and pseudophakic eyes and the correlations with age and ocular biometric parameters including CCT and ECD.

Inclusion Criteria:

• age > 18 years
• ability to understand and sign the written informed consent
• diagnosis of epiretinal membrane (ERM) with surgical indication for pars-plana vitrectomy

Exclusion Criteria:

• laser treatments and ocular surgery in the past 6 months
• hypersensitivity to the active ingredients used in the study
• other systemic or ocular diseases different from ERM that could affect the outcome of the study
• aphakia or previous complicated cataract surgery
• intraocular lens (IOL) in the anterior chamber
• treatment with systemic citicoline or other potential neuroprotective agents in the past 6 months
• pregnancy or breastfeeding