Patent ID: 8840245

Claim:
A computer-implemented method for calculating an individual spectacle lens design for a progressive spectacle lens having a variably adjustable, individual vertical position of a distance and a near reference point, comprising the following steps: specifying a starting design exhibiting a predetermined vertical position of the distance and the near reference point; calculating, by a processor-based computer, the individual spectacle lens design such that it exhibits the required, individual vertical position of the distance and the near reference point, wherein the calculation of the individual spectacle lens design comprises a calculation of a target value S target (y) for the spatial distribution of at least one optical property of the individual spectacle lens using a mapping S target (y)=S′ target (y′) and a transform Y: y y′, y y′(y)=y−Δy(y) of a corresponding target value S′ target (y′) of the starting design, wherein y′ is the vertical coordinate of the target value of the starting design and y is the vertical coordinate of the transformed target value of the individual spectacle lens design, wherein it holds true for the transform Y that: Δ y ( y )= f ( y )+ y 0 , and where: for f′(y)>0, the transform causes a local stretching, and for f′(y)<0, the transform causes a local compression of the starting design, wherein the transform Y depends on the difference of the vertical position of the distance and the near reference point of the individual spectacle lens design and the difference of the vertical position of the distance and the near reference point of the starting design, wherein it holds true for the transform coefficients a, b, c, d, m: m = 1 ; d = - y F + y N 2 c = 2 ⁢ ⁢ ln ⁡ ( ɛ 2 + ɛ ) l f M = 1 + ⅇ - c ⁢ ⁢ l 2 ; f P = 1 + ⅇ c ⁢ ⁢ l 2 a = l - l D f P - 1 - f M - 1 b = f M ⁡ ( l - l D ) f P - f M y 0 = y F - y F ⁢ ⁢ D where: l D =y FD −y ND is the progression length of the starting design; l=y F −y N is the progression length of the individual spectacle lens design; y F is the vertical position of the distance reference point of the individual spectacle lens design; y FD is the vertical position of the distance reference point of the starting design; y N is the vertical position of the near reference point of the individual spectacle lens design; y ND is the vertical position of the near reference point of the starting design; and 1+ε is the factor that determines to what extent the distance a between the distance and the near portion asymptote of the function ƒ(y) exceeds the change of the progression length, and wherein the function ƒ(y) is a double-asymptote f ⁡ ( y ) = b + a ( 1 + ⅇ c ⁡ ( y + d ) ) m with transform coefficients a, b, c, m, d.