| 摘要 |
A fused bifocal contact lens having "no jump" characteristics at all points of the segment line separating the distant vision segment of zone from the near vision zone. The lens include conventional convex and concave surfaces on the exterior portions, but, by reason of the construction of the bifocal segment, the wearer does not experience double vision when his line of sight crosses the segment line and the wearer does not notice the presence of the bifocal segment when not looking therethrough. In one form, a full, concentric bifocal segment is provided, and in another form, a lens is provided in which the bifocal segment is of a bi-curve form, lies principally in the lower portion of the lens and is defined by an upper, outer curve and an inner curve forming a partially circular segment line across which there is no jump. Methods of forming such lenses, including the method of forming the near vision segment, forming a composite blank including both distant and near vision segments, and forming a bifocal lens from the composite blank, are described. |
