General considerations concerning viscous materials in ophthalmic surgery.

Currently available viscous substances are Methylcellulose, Chondroitin sulphate and Hyaluronic acid. All of them consist of large molecules that vary in their degree of viscosity, electrical charge and elasticity. Viscous substances are tools for spatial tactics. An analysis of the physical properties leads to the indication for their use in surgery. Like every other instrument, a special technique has to be learned in order to get maximum benefit and to avoid side effects.