Abstract: An ophthalmic lens with an aspherical face is provided having a near vision region which is larger in size and wider than that of conventional multifocal lenses, and having reduced aberrations and, notably, astigmatism. Using .DELTA. to signify a difference in mean sphere between the near vision control point and the geometrical center of the lens, this is achieved by making a surface area defined by points less than 20 mm from the geometrical center of the lens, and for which cylinder is comprised between 0.42.DELTA. and 0.84.DELTA. greater than the surface area defined by points less than 20 mm from the geometrical center, and for which cylinder is less than 0.42.DELTA..

Abstract: A progressive multifocal ophthalmic lens is provided having an aspherical surface comprising a distance vision portion, a near vision portion and an intermediate vision portion, in which the maximum mean sphere gradient value is situated in the intermediate vision portion of the principal meridian of progression of the lens, and the cylinder gradient over the whole aspherical surface of the lens is less than the product obtained by multiplying the power addition value at each point by a constant value coefficient.

Abstract: The front surface, for example, of a progressive ophthalmic lens has a central area whose curvature varies progressively over at least part of at least one meridian and constitutes its optically active area. Surrounding this central area is a peripheral joining area merging tangentially with it. The optically active central area of the front surface is delimited by a closed curve which, when projected onto a plane perpendicular to the geometrical axis of the lens, is generally oval shape. The value and/or sign of the radius of curvature of the radial cross-section of the peripheral joining area varies in the circumferential direction so that the thickness of the lens is substantially the same all along its peripheral edge. Progressive ophthalmic lenses of this kind are easier to manufacture, lighter in weight and more esthetic.

Abstract: A positive power ophthalmic lens has a central optically active area the diameter of which is at most equal to the diameter of its geometrical contour. It has an optional peripheral merging area around the central optically active area, between the latter and the geometrical contour. The diameter D.sub.1 in millimeters of the central optically active area is related to the power P of the lens in diopters by a general equation of the type:D.sub.1 =a-b.pwhere a is a numerical parameter taking a value between 84 and 89 and b is a numerical parameter taking a value between 4 and 4.9. This equation makes it possible to obtain well corrected positive power ophthalmic lenses with a large diameter that are relatively light in weight.

Abstract: An ophthalmic lens is described having a front face which is a surface of revolution and is located entirely in front of the transverse plane tangential to its center. The curve representing the half-meridian of this front face corresponds to the following general formula:x=ay.sup.2 +by.sup..alpha. +cy.sup..gamma.in which the coefficient a is different from zero and negative, at least one of the coefficients b and c is different from zero and positive, .alpha. is a real number which is greater than or equal to 3 and less than 4, and .gamma. is a real number which is greater than or equal to 4.