Essilor International

Sandrine Francois

Bernard Bourdoncle

Jean-Pierre Chauveau

Francoise Ahsbahs

A multifocal ophthalmic lens comprising a far vision region, a near vision region an intermediate vision region and a main meridian of progression passing through these three regions is provided in which a principal length of progression, defined as a ratio between power addition and maximum slope of mean sphere along the meridian is less than 16 mm, sphere varies in a monotonous fashion as a function of angle on a 20 mm radius circle centered on a geometric center of the lens at both sides of said meridian, and in which the far vision region includes an angular sector having its origin at the geometric center of the lens with an included angle greater than 150&deg;. This provides a good distribution of isocylinder and ionosphere lines over the lens, ensuring progression is very gentle.

Multifocal ophthalmic lens

In a progressive multifocal ophthalmic lens having an aspherical surface comprising a far vision region (VL), a near vision region (VP), an intermediate vision region, a main meridian of progression passing through these three regions, and a mounting center (CM), the far vision region includes an angular sector with its apex at the mounting center and a central angle of 110&deg;, within which values of sphere and cylinder are less than or equal to 0.50 diopters, and a region of the lens above the near vision reference point and extending substantially up to the middle of the intermediate vision region has a maximum variation in values of cylinder 20 mm to both sides of the meridian limited to less than or equal to 0.30 diopters, and to less than or equal to 10% of the power addition of the lens. The lenses obtained, generally of power addition greater than or equal to 2.50, have wider near and intermediate vision regions, as well as a distribution of sphere and cylinder which is as homogeneous as possible over the complete surface of the lens.

Progressive multifocal ophthalmic lens

The invention relates to a pair of progressive ophthalmic spectacle lenses; each lens has an aspherical surface with a far vision zone, an intermediate vision zone and a near vision zone, and good monocular and binocular foveal vision along the principal meridian. At each point of the aspherical surface there is a mean sphere which is proportional to the half sum of the maximum and minimum radii of curvature expressed in meters, and to the refractive index of the lens material. The invention suggests reducing, for a given direction of sight, the absolute value of the difference between a binocularity parameter for two points in the object space. The binocularity parameter is defined for a point in the object space as the relative difference &Dgr;S of the mean sphere for the points of the aspherical surface of the right and left lenses through which the wearer sees said point.

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Paris, France

Sandrine Francois