Differential contribution of hypertonic electrolytes to corneal epithelial dysfunction

Abstract

The surface of the eye is covered by a protective tear film consisting of an aqueous-mucus layer and a superficial lipid layer, which are vital for light refraction and protection of vision. The aqueous component of the tear film contains electrolytes and a large variety of proteins, peptides and glycoproteins secreted by the lacrimal and meibomian glands, and apical cells of the corneal and conjunctival epithelia (Ohashi, Y. et al., 2006; Ruiz-Ederra, J. et al., 2009). Maintenance of a precise osmotic gradient of electrolytes between the tear film and the ocular surface epithelia is of paramount importance in regulating cell function and homeostasis. An imbalance of electrolytes is a hallmark of many pathologies, including dry eye, a disease affecting between 6 and 43 million people in the United States alone (Gilbard, J.P., 1994; Pflugfelder, S.C., 2011).