A method for determining an optical system of a personalized progressive lens for a given wearer including: a) providing a mean direction of gaze determined for the wearer in a reference frame tied to the head of the wearer; b) determining a target value for at least one optical design parameter as a function of the mean direction of gaze determined in a); c) calculating the optical system of the progressive lens by an optical optimization procedure on the basis of target values, wherein the target value of each optical design parameter as a function of the mean direction of gaze determined in b) is a target value.