A method of preparing an ophthalmic lens (30) to be fitted into a surround of a spectacle frame, includes: acquiring a longitudinal profile (50) of the surround; centering the longitudinal profile; acquiring the geometry of at least one part of an optical face of the ophthalmic lens; calculating a treatment setpoint for treating the ophthalmic lens; and treating the ophthalmic lens. The acquiring operation includes a step of calculating the bidimensional coordinates of a plurality of measurement points (P′i, P″i) situated along two distinct longitudinal strands (51, 52) which are chosen in such a way that they define between them a band which extends along the longitudinal profile, and a step of examining the ophthalmic lens to acquire the tridimensional coordinates for the measurement points with a view to calculating the treatment setpoint.