VISMED® is currently marketed in Europe under the CE mark as a viscoelastic lubricant eye drop. The proprietary formulation contains a highly purified specific fraction of sodium hyaluronate. Sodium hyaluronate is a natural polymer which is also present in the structures of the human eye. Its main physical characteristic is viscoelasticity. This means that VISMED® has a high viscosity between blinks and a low viscosity during blinking ensuring efficient coating of the surface of the eye. It is believed that this protective coating of the surface of the eye helps prevent dryness and irritation. Sodium hyaluronate also possesses mucoadhesive properties and the ability to entrap water, thus resembling tear mucus glycoprotein. This, together with the coating properties of sodium hyaluronate, results in an increased pre-corneal residence time and tear film break-up time (BUT) and therefore longer lubrication of the eye surface. VISMED® is completely free of preservatives. As a result, it is non-irritating to ocular tissues and can be used frequently and for extended periods without harming the surface of the eye (e.g. without causing superficial punctate keratitis). Some preservatives are known to cause toxic or allergic reactions, the symptoms of which include stinging, burning and redness of the eyes. To further maximize patient comfort, the pH of VISMED® is adjusted to 7.3, similar to that of the natural tear film.