The invention relates to a method for determining optical parameters of a test subject with measurement accuracy in order to adapt a pair of eyeglasses by means of a stereo camera system (4), a mirror (3) arranged at the height of the stereo camera system, and a data-processing and data output device, in which additionally the correction data of the cameras of the stereo camera system (4), the image scales of said cameras, and information about the position of said cameras in space are stored. The test subject (1) directs his view at the mirror image of his head arising in the virtual mirror plane (5) (null viewing direction), while both cameras simultaneously record an image of the region of the head of the test subject (1) provided with the eyeglass frame (2). The direction, distance, and height position of the optical data are determined means of the software and by using the stored correction data, image scales, and position information, wherein existent size changes and distortions due to position are offset by means of correction calculations. Thus, only one recording of the face of the test subject is required to determine the centering data of the pair of eyeglasses, whereby the measurement time and thus the time burden for the test subject are significantly reduced.