Patent ID: 7207675

Claim:
Progressive multifocal ophthalmic lens having a power addition prescription and presenting a complex surface having: a fitting cross; a far vision zone with a control point, a near vision zone with a control point and an intermediate vision zone; a principal meridian of progression passing through these three zones, the lens having, when being worn and relative to a plane far vision prescription by adjustment of the radii of curvature of at least one of its faces: a reduced root mean square deviation, normalized to the addition prescription, of less than 0.025 microns per dioptre over a zone that includes the far vision control point and covering a sector whose apex lies on the meridian of progression at approximately 4° below the fitting cross with an angular aperture of between 150° and 160°, the reduced root mean square deviation being calculated by setting to zero the 1st- and 2nd-order coefficients in the Zernike polynomial expansion of a wavefront passing through the lens; and a progression length of 25° or less, the progression length being defined as the angle of lowered viewing from the fitting cross down to the point on the meridian for which the wearer optical power reaches 85% of the addition prescription.