Method for assessing an optical property of kth order of an optical element at an evaluation point. The optical element has a boundary surface formed of a refractive base surface and a phase-modifying optical element. The method includes determining the properties of a wavefront in the local surrounding of the evaluation point by means of a local wavefront tracing, anddetermining the optical property at the evaluation point based on the properties of the wavefront in the local surrounding of the evaluation point,wherein the local wavefront tracing has a local wavefront tracing upon passage through the boundary surface, and the local wavefront tracing upon passage through the boundary surface is performed according to the equation for the local wavefront tracing through the refractive base surface, the equation being supplemented by an additive additional term PK(k).