| 摘要 |
A prism ballast type contact lens having a front and a back surface, a center axis of the front surface being offset from that of the back surface which is a geometric center axis of the lens, such that the lens has a thickness which continuously increases in a downward direction of the lens, the lens further having a slab-off area provided in at least a lower portion of the front surface, wherein at least an optical portion of the back surface and the lower portion of the front surface are formed by molding using a mold assembly including a male and a female mold half which are closed to define a mold cavity that gives a lens blank which is formed into the prism ballast type contact lens, the male mold half having a convex molding surface whose profile follows that of the optical portion of the back surface, the female mold half having a concave molding surface whose profile follows that of at least the lower portion of the front surface, the mold cavity being defined by the convex and concave molding surfaces, so as to provide the lens blank having a thickness sufficient to give at least an optical portion of the front surface by cutting.
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