A tool for surface treatment of an optical surface, includes a rigid support having a transverse end surface, an elastically compressible interface which is applied against and overlaps the end surface, and a soft buffer designed to be applied against the optical surface and which is pressed against and overlaps at least partly the interface opposite and perpendicular to the end surface. The buffer includes a so-called central part which is located between the end surface and a so-called peripheral part which is located transversely beyond the end surface, elastic return elements connecting the peripheral part to the support.