Abstract: A central processing unit of a calculation server apparatus includes a reference design data selection unit for selecting reference design data from a plurality of reference design data stored in reference design data storage of storage memory, and an arrange design unit 123 for processing the reference design data so acquired on the basis of prescription data. The reference design data has point groups having coordinates of points and obtained by dividing a progressive surface as a reference into a lattice form.

Abstract: A method for providing design data and a system for providing design data that enable a lens processor to manufacture a desired inner-surface progressive addition lens corresponding to prescription data. A design data providing system is a system such that a design data creator provides design data of an inner-surface progressive addition lens to a lens processor in the case where the lens processor has agreed upon a contract to the effect that the lens processor receives provision of the design data of the inner-surface progressive addition lens from the design data creator on the condition that the lens processor pays a consideration. The design data providing system has a server device as a host computer device, a terminal computer device, and a network for connecting the server device to the terminal computer device.

Abstract: A progressive addition power lens with a length of the intermediate corridor in the range of 22 to 28 mm, and a clear visual region, which is defined as a region where astigmatism is 0.5 diopters or less, has a horizontally maximum width thereof in the distant dioptric power region, which is twice as thick as or less than a horizontally minimum width in the intermediate corridor. Furthermore, the clear visual region defined as a region where astigmatism is 0.5 diopters or less has a width of 30 mm or more horizontally in the near dioptric power region. In addition, a position, where astigmatism distributed at the sides of the lens has the maximum value, is located in an almost horizontal direction with a far point positioned above the intermediate corridor or is located above the far point.

Abstract: There is provided a multifocal contact lens having a lens curve formed by altermately arranging a plurality of curved surfaces for far vision and a plurality of curved surfaces for near vision in the form of concentric zones, and a die for forming the contact lens, and a method for producing the contact lens. Each of the curved surfaces (F1, F2, . . . ) for far vision of the lens curve (2) has a center (O.sub.F1, O.sub.F2, . . . ) of curvature on an optical axis and a radius (R.sub.F1, R.sub.F2, . . . ) of curvature, which is set so that a ray being incident on the corresponding curved surface and being parallel to the optical axis forms an image at a location near a single focal point (F.sub.F) for far vision on the optical axis, and each of the curved surfaces (N1, N2, . . . ) for near vision of the lens curve (2) has a center (O.sub.N1, O.sub.N2, . . . ) of curvature on the optical axis and a radius (R.sub.N1, R.sub.N2, . . .

Abstract: In a contact lens (1) provided with a front curve (2) formed with a plurality of distance portion curved surfaces (F.sub.1, F.sub.2, . . . ) for seeing a distant place . . . )and a plurality of near portion curved surfaces (N.sub.1, N.sub.2, for seeing a near place arranged alternately and repeatedly in concentric zone shape, the distance portion curved surfaces formed at least a central zone of the front curve have respective curvature centers (O.sub.F1, O.sub.F2, . . .

Abstract: An aspherical spectacle lens having a positive power. The lens has a front refractive surface and a rear refractive surface. The curvature of an arbitrary meridian passing through a predetermined point on the lens is a function C(r) of the distance r from the predetermined point. The first-order derivative dC/dr of the function C(r) decreases initially as the meridian moves away from the preselected point toward the edge of the lens and then the derivative increases.

Abstract: An improved eyeglass lens which includes a front and back surface, one of which is refractive surface. The lens is defined by a meridian on the refractive surface which substantially increases for at least 15 mm in the direction of the outer periphery of the lens from the optical axis. The change in curvature of the meridian may remain constant within the at least 5 mm from the optical axis. The curvature of the meridian is represented by C(r) as a function of a distance r from the optical axis, and the linear differential coefficient dc/dr of the function C may increase at least once and then decrease as the distance from the optical axis increases providing a thinner lens edge to improve lens appearance while maintaining superior optical efficiency.

Abstract: Progressive multifocal ophthalmic lenses are provided having a far vision viewing zone, a near vision viewing zone and an intermediate vision viewing zone therebetween. A central basic curve extends essentially vertically through the far, intermediate and near vision viewing zones. The sizes of the zones and configuration of the zones are set by predetermined conditions and equations. The construction provides improved lenses for use especially where intermediate and near vision viewing is required.

Abstract: A progressive multifocal ophthalmic lens having a refractive lens surface divided into a far vision viewing zone, an intermediate viewing zone and a near vision viewing zone and defining a substantially vertical principal meridian curve. The optical center of the far vision viewing zone is at the lower end of the principal meridian curve in the far vision viewing zone and an optical center of the near vision viewing zone is at the upper end of the principal meridian curve in the near vision viewing zone. The curvature of the principal meridian curve changes between the optical center of the far vision viewing zone and the optical center of the near vision viewing zone in accordance with a prescribed law to define the additional power of the lens.

Abstract: A progressive multifocal ophthalmic lens. The lens includes a lens surface having a far vision viewing, a near vision viewing zone and an intermediate vision viewing zone disposed therebetween. A prism having a base is added to the lens. The base lies in the direction of 90.degree. to the lens surface. The prism is added in order to improve chromatic aberration and not to remedy squint.

Abstract: Ophthalmic lenses wherein the curvature of the refractive surface changes along the principal meridian between the optical center of a far vision viewing zone and the optical center of a near vision viewing zone in accordance with a predetermined law is provided. The refractive surfaces of the lenses are divided into a far vision viewing zone, an intermediate vision viewing zone and a near vision viewing zone by a curve which intersects the principal meridian curve at the optical center of the far vision viewing zone and a second curve which intersects the principal meridian curve at the optical center of the near vision viewing zone. An angle made by a line normal to the refractive surface from each point of an intersection of an arbitrary plane which is parallel to a plane including the principal meridian curve and the refractive surface of the lens and a plane including the principal meridian curve is constant in the far vision viewing zone and in the near vision viewing zone.

Abstract: Progressive multifocal ophthalmic lenses are provided having a far vision viewing zone, a near vision viewing zone and an intermediate vision viewing zone therebetween. A principal meridian curve extends vertically through the far, intermediate and near vision viewing zones. The surface power along the principal meridian curve in the intermediate vision viewing zone varies progressively. The sizes of the zones and configuration of the zones are set by predetermined conditions and equations. The construction provides improved lenses for use in activities such as sports, driving, shopping and the like.