The method includes capturing at least one digital image of the wearer's face with a portable image capture appliance (1) and processing the captured image to determine a geometrico-physionomic parameter. Before capturing the image, the operator positions the image capture appliance manually in a first configuration in which an observation line connecting the pupil (7) of the image capture appliance with a predetermined remarkable point associated with the wearer's face or with the frame is substantially horizontal. Image capture is performed in a second configuration of the image capture appliance such that the altitude of the image capture appliance is identical to its altitude in the first configuration. The calculation of the geometrico-physionomic parameter includes identifying on the image, the image of the predetermined remarkable point.
