The invention relates to a method for determining an actual value of at least one system parameter or a deviation from a set value of at least one parameter of a system for the treatment of an eye using a treatment laser beam emitted by said system. According to the invention, the surface of a calibrating body is ablated with at least a partial beam of the treatment laser beam with a predetermined ablation program. The surface ablated by the treatment laser beam is examined by means of aberrometry and/or profilometry. The actual value of the system parameter or the deviation from the set value of the system parameter is determined on the basis of the examination data detected during the examination.
