The present invention relates to a new device for fixing a pair of lenses to the ends of a bridge and to the ends of hinge elements of the arms of spectacles, particularly for the so­called "ultra-light" spectacles, that means spectacles without a front piece structure and thus without the ordinary rims containing the lenses. One feature of the present invention is to provide the fixing of the two ends (31) of the bridge (30) and of one of the ends (21) of the lateral pair of front pieces (20) to the respective edge of each lens (L1) by means of a corresponding movable clamp (10) that can slide along a respective threaded shank (24, 34), on which the position of said clamp (10) can be adjusted by a nut (1) that can be screwed onto said shank (24 and 34), said nut (1) pushing the clamp (10) against the edge of the lens (L1 and L2) to be blocked. In this way, the lens is closed between the rough inner surface of the arm (13) of said clamp (10) and the inner rough surface (22) and (32) of the front piece (20) and of the bridge (30), where the respective shanks (24 and 34) are fixed.