Characteristics of Hyaluronic Acid and Its Use in Ocular Surface Diseases Including Dry Eye

Hyaluronic acid (HA) is a polysaccharide found in the extracellular matrix of the epithelial, nervous, and connective tissues of vertebrates. It is widely used in the treatment of ocular surface diseases (OSDs), including dry eye, due to its high water-retaining capacity, viscoelasticity, and role as a signaling molecule in inflammation and wound healing. This paper reviews the physicochemical and biological properties of HA related to the treatment of OSDs and the results of published preclinical studies, clinical trials, and meta-analyses on the effects of HA eye drops on the tear film, the mechanism of action of HA eye drops, and its clinical effects and adverse events in OSDs, such as corneal/conjunctival epithelial defects, dry eye, and postoperative dry eye. This review should help inform clinical judgments by providing clinical evidence and precautions on the use of HA eye drops in OSDs, including dry eye.