The invention relates to an optical device for imparting an asymmetrical light beam. The optical device comprises a lens (10) having an exit diopter (12) having an exit surface consisting of a convex surface (16) defining a curved rear portion (18) having a first curvature and a curved front portion (19) having a second curvature different from the first curvature. Furthermore the lens (10) comprises an entry diopter (11) including at least one concave lodging (13) for lodging at least one light source, the surface of the concave lodging (13) facing at least partly the curved rear portion (18).