1. A method for establishing refraction of an eye by means of a refractometer, comprising: establishing an orientation of a visual axis of the eye before establishing the refraction while a patient having the eye is under general anesthesia or the eye is anesthetized in a retrobulbar fashion; aligning the refractometer with respect to the visual axis of the eye by matching an orientation of the refractometer with the orientation of the visual axis so that a refraction measurement takes place on the visual axis of the eye; and establishing the refraction after the alignment, wherein the orientation of the visual axis of the eye is established based on a position of a Purkinje image of at least one light source used to illuminate the eye and a relationship between the position of the Purkinje image and the orientation of the visual axis, and wherein the relationship between the orientation of the visual axis and the position of the Purkinje image on the eye is established during a reference measurement, the reference measurement includes determining a set of positions for a plurality of Purkinje images for a plurality of viewing directions.