CONTACT LENSES

摘要

The present invention provides a contact lens having an orientation feature that does not provide a prism optical distortion and can maintain a predetermined orientation of the lens on an eye. A contact lens of the invention comprises an anterior surface and an opposite posterior surface. The anterior surface includes a vertical meridian, a horizontal meridian, a central optical zone, a blending zone extending outwardly from the central optical zone, a peripheral zone surrounding the blending zone, and an edge zone circumscribing and tangent to the peripheral zone. The presence of the blending zone ensures that the peripheral zone, the blending zone and the central optical zone are tangent to each other. The peripheral zone has a surface that, in combination with the posterior surface, provides a lens thickness, in the peripheral zone, which is characterized by having a lens thickness which increases progressively from the top of the lens downwardly along each of the vertical meridian and lines parallel to the vertical meridian until reaching a maximum value at a position between the optical zone and the edge zone and then decreases to the edge of the edge zone; or alternatively by having a mirror symmetry with respect to a plane cutting through the vertical meridian, by having a substantially constant thickness in a region around the horizontal meridian and by having a thickness which decreases progressively from the horizontal meridian to the top or bottom of the contact lens along each of the vertical meridian and lines parallel to the vertical meridian.