Method for determining at least one head posture characteristic of a person wearing spectacles

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 wearer's 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 wearer's head posture characteristic in relation to the image sensor, as a function of the position of the reflections in the image.