Disclosed are systems and processes for generating a finished or semi-finished lens, such as a spectacle lens, from a lens blank that includes an intermediate functional layer. Some embodiments of the process involve locating the functional layer and positioning the lens blank according to the location of the functional layer. The location of the functional layer can be ascertained by measuring the thickness of one or more layers of the lens blank. The lens blank can be surfaced on one or both sides to form a finished or semi-finished lens. Other embodiments are also described.