Patent ID: 7125118

Claim:
A progressive multifocal lens for correcting eyesight comprising: a progressive refracting interface, said progressive refracting interface is located on a side of an eyeball or on a side of an object, wherein the progressive refracting interface comprises: a distance portion, a near portion with different refractive powers, and a progressive portion of which refractive power varies progressively therebetween, wherein the eyeball-side refracting interface or the object-side refracting interface is a combined refracting interface comprising an original progressive refracting interface set only to exhibit a desired eyesight corrective characteristic and an original toric surface set only to exhibit a desired astigmatism corrective characteristic, wherein, when z-axis is an axis passing through the center of the progressive refracting interface from the object toward the eyeball, x-axis is cylinder axis of the original toric surface, and y-axis is an axis perpendicular to the x-axis and the z-axis, value z p in any point P (x p , y p , z p ) in the combined refracting interface is expressed by a first expression (1) or a second expression (2) by using approximate curvature Cp of the original progressive refracting interface, curvature Cx in the x-axis direction, and curvature Cy in the y-axis direction, wherein the first expression (1) is expressed as z p = ( c p + c x ) ⁢ x 2 + ( c p + c y ) ⁢ y 2 1 + 1 - ( ( c p + c x ) ⁢ x 2 + ( c p + c y ) ⁢ y 2 ) 2 x 2 + y 2 ( 1 ) and wherein the second expression (2) is expressed as z p = ( c p + c x ) ⁢ x 2 1 + 1 - ( c p + c x ) 2 ⁢ ( x 2 + y 2 ) + ⁢ ⁢ ( c p + c y ) ⁢ y 2 1 + 1 - ( c p + c y ) 2 ⁢ ( x 2 + y 2 ) . ( 2 )