Patent ID: 6412948
Filing Date: 2002-07-02
Classification: G02C

Abstract:
A series of progressive power multifocal lenses having a plurality of base curves designed to have substantially the same basic lens specifications, each lens having a far vision correction portion corresponding to a distant vision, a near vision correction portion corresponding to a near vision, and a progressive portion for continuously connecting the refracting powers of the surfaces of the both portions between said far vision correction portion and said near vision correction portion along the principal meridian for dividing the refracting surface of each lens into the nasal side portion and the temporal side portion, characterized in that:the following condition (1) is satisfied at least in either one of said nasal side portion and said temporal side portion with respect to said principal meridian which satisfies 15&lE;|x|&lE;20: &Dgr;PS(x,0)>&Dgr;PL(x,0)â€ƒâ€ƒ(1), â€ƒWhere: in a first progressive power multifocal lens having a first base curve BCL selected from said plurality of base curves, the mean surface refracting power of a point on a lens refracting surface which is separated by x (mm) in the horizontal direction from an eyepoint for a distance vision in a state in which the lens is worn is defined as PL(x,0) (diopter), and the mean surface additional refracting power which is obtained by subtracting said first base curve BCL from said mean surface refracting power is defined as &Dgr;PL(x,0) {=PL(x,0)âˆ’BCL} (diopter); and in a second progressive power multifocal lens having a second base curve BCS which has a substantially smaller curvature than said first base curve BCL and selected from said plurality of base curves and having substantially the same additional power as the additional power of said first progressive multifocal lens, the mean surface refracting power of a point on a lens refracting surface which is separated by x (mm) in the horizontal direction from the eyepoint in a state in which the lens is worn as PS(x,0) (diopter), and the mean surface additional refracting power which is obtained by subtracting said second base curve BCS from said mean surface refracting power is defined as &Dgr;PS(x,0) {=PS(x,0)âˆ’BCS} (diopter).