The invention relates to a vision testing system (10) and to a method for testing the eyes of a subject, comprising a display device (11, 12, 13) by means of which optotypes can be visualized to at least one eye of the subject, comprising a control device (14) for controlling the display device, the display device comprising a backlit screen (19, 30, 35), the screen having an adjusting device for adjusting a screen luminance of the screen to an ambient luminance, the adjusting device having a measuring means for measuring the screen luminance.
