Abstract: The invention concerns an optical device for producing a visual illusion by holding a mirror under a user's eyes. More particularly, the invention concerns a device for fixing on a user's head a horizontal support comprising a mirror and located just below his eyes. It consists of a support on which is fixed a mirror. Two perpendicular stop elements, resing on the user's cheeks, maintain the horizontal support. Two linknig branches with fixing straps are attached with the fixing straps to the branches so as to press one against the other above the user's head, thereby enabling adjustment of theheight of the device. Two fixing straps are attached to the branches to press one against the other behind the user's head so as to keep the whole device pressed against the user's face.