Effects of a New Lipid Tear Substitute in a Mouse Model of Dry Eye

Abstract

The present investigation is aimed to evaluate the effect of a new lipid artificial tear on tear volume and ocular surface signs in a mouse model of dry eye and to test the hypothesis that the combined application with sodium hyaluronate can improve the performance of the treatments. A new oil-in-water emulsion, a 0.2% sodium hyaluronate solution, or their combined administration were given to dry eye mice maintained in a controlled environment chamber and treated with scopolamine (0.75-mg transdermal patch). Mice were treated 4 times a day with (a) sodium hyaluronate, (b) emulsion, and (c) sodium hyaluronate followed by emulsion. A control group of mice exposed to controlled environment chamber remained untreated (CTRL+). Tear volume and corneal damage were assessed after 3 and 7 days of treatment by cotton thread test and fluorescein staining. As regards tear volume, sodium hyaluronate did not show a statistically significant effect at either end point; the emulsion was effective after 7 days, whereas their combined administration counteracted the lacrimal decrease induced by the model both at 3 and 7 days. Corneal damage was reduced in all treated groups with respect to CTRL+. This effect was statistically significant after 3 days when the emulsion alone or in combination with sodium hyaluronate was used, while hyaluronate improved this clinical sign after 7 days. Our data suggest that the new lipid tear substitute can be used to treat clinical signs of dry eye and that the combined administration with hyaluronate can decrease the lag time before the effect, when the evaporative and the aqueous-deficient components are present.