A METHOD OF MODIFYING AN DIOPTRIC FUNCTION OF AN OPHTHALMIC LENS SURFACE

A method implemented by computer means of modifying an initial dioptric function of an initial ophthalmic lens surface, for manufacturing an ophthalmic lens, the method comprising: - an initial surface providing step (S1), during which an initial surface Sini associated with a first coordinate system is provided, said initial surface Sini comprising a plurality of surface points P1, each surface point P1 having a mean sphere Sph(P1) and a cylinder Cyl(P1), said initial surface Sini providing said initial dioptric function, - a modifying surface selection step (S2), during which a number n of nonzero modifying surfaces Smod1,..., Smod n is selected, said modifying surfaces Smod1,..., Smod n being associated with a second coordinate system, the modifying surface Smod 1 comprising a plurality of surface points P i1, ...P i j, ..., P i mi, each surface point P i j having a mean sphere Sph(P i j ) and a cylinder Cyl(P i j ), n, i, j, m i being integers with n ≥ 1, 1 ≤ i ≤ n, 1 ≤ j ≤ m i and m i ≥ 1, - an orientation step (S3), during which the relative position and orientation of the first coordinate system and the second coordinate system is determined, a combining step (S4), during which the initial surface Sini and the n modifying surfaces are combined to obtain a functionalized ophthalmic lens surface according to the expression : Sfunc = Sini +∑i=n i=1 alphai.S modi. wherein the normalized sphere standard deviation of the normalized sphere values Sph' Smodi of a normalized modifying surface SNmod i is smaller than or equal to 0.2, with : the normalized modifying surface SNmod i corresponding to the modifying surface Smod i to which the best sphero-toric surface has been subtracted, and the normalized sphere values over the normalized modifying surface SNmod i at a point P ij of Smod i having the coordinate (x,y,z) being : (I) Sph N Smod,i (x,y) being the sphere over the normalized modifying surface SNmod i, at the point of SNmod i having the coordinate (x,y), 30 max(Sph N Smod,i ) being the greatest value of sphere over the normalized modifying surface SNmod i, min(Sph N Smod,i ) being the smallest value of sphere over the normalized modifying surface SN mod i, alpha i being a nonzero weighting coefficient.