A method for carrying out eye surgery comprises a comparison of images recorded before surgery with images recorded during surgery in order to generate a marker which represents a target orientation of an intraocular lens or a difference between a current orientation and the target orientation of the intraocular lens. An eye surgery system respectively comprises an imaging system which is used during a surgery and has a camera, and a diagnostic system which is used before surgery and which also has a camera. The imaging system used during surgery comprises an image processing device in order to perform a computation based on the recorded images, and in order to determine a respective orientation value, from which a representation of a marker representing the target orientation of the intraocular lens is obtained.