Ophthalmic Viscosurgical Devices (OVD) are viscoelastic solutions or gels used to protect the corneal endothelium from mechanical trauma and to maintain intraocular space during eye surgery.

They usually contain one or more of hyaluronic acid, sodium salt, chondroitin sulfate or methylcellulose. As these are polymeric, they tend to be viscoelastic with their properties strongly dependent on factors such as concentration, molecular weight and molecular architecture, as well as intra or inter-molecular interactions in solution.

OVDs can be classified according to their cohesiveness or dispersiveness, which are ultimately related to their rheological properties. Cohesive OVDs are high-viscosity materials that adhere to one another through molecular associations.