A method for manufacturing an ophthalmic lens by machining, includes the steps of providing and mounting a blank on a first supporting device having a first machining reference frame in a first position in which a lower surface of the blank is opposite the first device; machining, in the first position in the first reference frame, an upper surface of the blank, machining in a second predetermined machining reference frame which is known relative to the first at least one mechanical referencing element on the blank, and providing a second supporting device including at least one complementary mechanical referencing element configured such as to engage with the at least one mechanical referencing element so that the latter is positioned and supported on the second device in a second predetermined position.