Abstract: A process for improving the impact resistance of a coated plastic substrate, particularly those polymers having a high refractive index, comprising applying an aqueous polyurethane dispersion as a primer layer to at least one surface of the plastic substrate, at least partially curing the aqueous polyurethane dispersion by air drying at ambient temperature, applying a coating composition over the polyurethane primer layer, and curing the coating composition to form an abrasion resistant hard coat. Preferably, the aqueous polyurethane dispersion is air dried at ambient temperature for less than one hour before application of the abrasion resistant coating composition. The process provides an impact enhancing, abrasion resistant coating system having strong interfacial adhesion that is preferably transparent for application onto preferably transparent plastic articles, such as ophthalmic lenses and safety eye wear.