A method for determining at least one characteristic relating to the posture of the head (10) of a person (1) wearing spectacles (100) including a frame (110) and two lenses (150G, 150D), using a determining device including an image sensor, at least one light source and a computation unit, the method includes steps of: a) acquiring an image (301) of at least part of the wearers head, in which the spectacles are illuminated by the light source b) in the image, locating reflections (160D, 160G, 161D, 161G) from the light source, reflected by the two lenses of the spectacles and c) deducing the wearers head posture characteristic in relation to the image sensor, as a function of the position of the reflections in the image.
