Abstract: A rigid contact lens is provided for correcting an irregularly curved cornea, comprising a front surface (2) and a rear surface which consists of (3) a central optical zone (4) and a peripheral zone (5). The central optical zone (4) has such an aspherical rotationally symmetric or non-rotationally symmetric design that, with equal central curvature radius in the center (Z) of the central optical zone (4), the sagittal depth (Sellip) of the central optical zone (4) is increased as compared with a spherical optical zone.

Abstract: A rigid contact lens is provided for correcting an irregularly curved cornea, comprising a front surface (2) and a rear surface which consists of (3) a central optical zone (4) and a peripheral zone (5). The central optical zone (4) has such an aspherical rotationally symmetric or non-rotationally symmetric design that, with equal central curvature radius in the center (Z) of the central optical zone (4), the sagittal depth (sellip) of the central optical zone (4) is increased as compared with a spherical optical zone.

Abstract: A contact lens or intraocular lens is provided having a near zone (1) and a distance zone (2) concentrically surrounding the former. In order to achieve functionally correct vision, the said optimum surface consists of a bielliptical or a spheroelliptical combination.

Abstract: A device for manufacturing bifocal contact lenses is provided. It comprises a rotating head stock provided with an eccentric head supporting a lense holder for holding a lense blank. The lense holder is displaceable with respect to said eccentric head in a radial direction perpendicular to the axis of rotation. A sled is provided for supporting a cutting tool. Said sled pivotable around an axis which coincides with said axis of rotation and in addition displaceable to change the radii.For avoiding a step which would result at the junction line dividing the distant vision segment and the near vision segment, a control is provided for adjusting the tool to a first radius R1 for cutting the distant vision segment and for adjusting said tool to a second radius R2 for cutting said near vision segment. After cutting the distant vision segment during a first operation, the near vision segment is cut during a second operation such that a continuous transition is achieved between both segments.

Abstract: Contact lens (1) comprising a rear contact surface (2) presenting a spherical region described by an arc of a circle passing by the vertex (S). In order to improve the optical properties while improving the adaptability and compatibility, the contact lens (1) presents an aspherical region adjacent to the spherical region; the curve representing the aspherical region and the arc of a circle representing the spherical region have in the transition a substantially equal curvature radius (R.sub.o) and a substantially equal slope.