Evaluation of a cyclosporine A ophthalmic ointment in an experimental mouse model of dry eye

Purpose Dry eye syndrome is a common disease with multifactorial causes. Symptoms typically include irritation, dryness, burning and decreased or fluctuating vision. Anti‐inflammatory drugs are widely used for the treatment of the inflammation produced by the disease with corticoid or cyclosporine A (CsA). Restasis ® (Allergan), a CsA emulsion, was approved by the FDA but is not available in Europe. Here we propose to show the action of Optimmune ® ( MSD Animal Health) a marketed veterinary ophthalmic ointment that contains CsA in an experimental mouse model of dry eye induced by scopolamine, a tropane alkaloid drug with muscarinic antagonist effects. Methods Animals were divided in three groups of ten pigmented mice: Two groups were exposed to desiccating conditions (relative humidity <25%, air‐flow 15 L/min, temperature 20‐22°C) with transdermal scopolamine administration (0.5 mg/72 h) for 14 days. Animals were treated topically three times a day with 0.2% CsA ointment or vehicle. Controls were saline‐treated animals placed in a normal environment. Tear production was measured with the phenol red thread test, corneal defects were examined by slit‐lamp observation using blue light after 0.5% fluorescein eye drop. These examinations were performed in both eyes before exposure and on days 3, 7 and 14. A histological study was performed at the end of the study. Results Cyclosporine A eye ointment appeared to show efficacy in this model. Conclusions Cyclosporine A eye ointment significantly reduced clinical signs of dry eye by decreasing corneal defect more than cyclosporine A ophthalmic emulsion (internal studies).