Variable progressive lens design

An apparatus for creating a progressive spectacle lens design by transforming a predetermined starting design that includes specification of a principal line, specifications for target astigmatism values A(u=0,y) along the principal line, and specifications for the course of at least one base target isoastigmatism line, which is described by a one-dimensional function of the form uG(y)=ƒ(y), and manufacturing a progressive spectacle lens, the apparatus comprising:

• a modification unit configured to modify the course of the base target isoastigmatism line;
• and
• a calculation unit configured to calculate the target astigmatism values A(u,y) of the spectacle lens design by an interpolation between the target astigmatism values A(u=0,y) on the principal line and the target astigmatism values A(u′G(y),y) on the modified base target isoastigmatism line,
• wherein
• u designates the horizontal distance from the principal line of a point (u,y) of the spectacle lens design,
• y designates the vertical coordinate of the point (u,y) of the spectacle lens design,
• uG(y) designates the horizontal distance from the principal line of a point (uG(y),y) on the base target isoastigmatism line, and
• u′G(y) designates the horizontal distance from the principal line of a point (u′G(y),y) on the modified base target isoastigmatism line;
• and
• manufacturing, based on the target astigmatism values, the progressive spectacle lens.

A non-transitory computer program product for calculating a progressive spectacle lens design, which when loaded on a computer and executed by a processor of the computer, causes the processor to:

• define a starting design that comprises specification of a principal line, specifications for target astigmatism values A(u=0,y) along the principal line, and specifications for the course of at least one base target isoastigmatism line, which is described by a one-dimensional function of the form UG(y)=ƒ(y);
• modify the course of the base target isoastigmatism line uG(y)→u′G(y);
• and
• calculate the target astigmatism values A(u,y) of the spectacle lens design by an interpolation between the target astigmatism values A(u=0,y) on the principal line and the target astigmatism values A(u′G(y),y) on the modified base target isoastigmatism line,
• wherein
• u designates the horizontal distance from the principal line of a point (u,y) of the spectacle lens design,
• y designates the vertical coordinate of the point (u,y) of the spectacle lens design,
• uG(y) designates the horizontal distance from the principal line of a point (uG(y),y) on the base target isoastigmatism line, and u′G(y) designates the horizontal distance from the principal line of a point (u′G(y),y) on the modified base target isoastigmatism line.

A non-transitory storage medium with a computer program stored thereon for calculating a progressive spectacle lens design, which when loaded on a computer and executed by a processor of the computer, causes the processor to:

• define a starting design that comprises specification of a principal line, specifications for target astigmatism values A(u=0,y) along the principal line, and specifications for the course of at least one base target isoastigmatism line, which is described by a one-dimensional function of the form uG(y)=ƒ(y);
• modify the course of the base target isoastigmatism line uG(y)→u′G(y);
• and
• calculate the target astigmatism values A(u,y) of the spectacle lens design by an interpolation between the target astigmatism values A(u=0,y) on the principal line and the target astigmatism values A(u′G(y),y) on the modified base target isoastigmatism line,
• wherein
• u designates the horizontal distance from the principal line of a point (u,y) of the spectacle lens design,
• Y designates the vertical coordinate of the point (u,y) of the spectacle lens design,
• uG(y) designates the horizontal distance from the principal line of a point (uG(y),y) on the base target isoastigmatism line, and
• u′G(y) designates the horizontal distance from the principal line of a point (u′G(y),y) on the modified base target isoastigmatism line.