Molded toric contact lenses

Claim 2

A process for producing a contact lens (24) having a front convex optical surface and a back concave optical surface, one of said optical surfaces being a toric optical surface, and prism ballast, in a mold assembly comprised of a first mold portion (4) including a hollow cylindrical portion (12) with an open upper end and a closed lower end in the shape of a concave optical molding surface (16) and a second mold portion (2) including a cylindrical portion (7) terminating in a convex optical molding surface (10) and whose cross-sectional outer diameter is substantially smaller than the internal diameter of the said hollow cylindrical portion (12), one of said optical molding surfaces being a toric optical molding surface; each of said molding surfaces having a principal longitudinal axis of curvature (y, y') which process comprises charging a contact lens-forming material on to the molding surface (16) of said first mold portion (4), closing the mold assembly by positioning said second mold portion (2) in touching and lens-forming relationship with said first mold portion (4) and subjecting said lens-forming material to activating conditions for a period of time sufficient to produce said contact lens (24), characterized in that said second mold portion (2) and said first mold portion (4) in such lens-forming relationship are adjusted to form an angle θ of about 2 degrees to about 8 degrees, said angle θ being defined by the principal longitudinal axis of curvature (y, y') of said first molding surface and said second molding surface, thereby producing a toric contact lens (24) which exhibits cylinder power and prism ballast.

Claim 3

The process of claim 1 wherein said toric contact lens (24) is hydrophilic.

Claim 4

The process of claim 1 wherein said toric contact lens (24) is hydrophobic.

Claim 5

The process of claim 2 wherein said toric contact lens (24) is a polymer of 2-hydroxyethyl methacrylate.

Claim 6

The process according to claims 1-4 wherein external pressure is applied to the closed mold assembly (2, 4) during said activating conditions.

Claim 7

A contact lens mold assembly for casting toric contact lenses (24) possessing significant cylinder power, which comprises (i) a male mold portion (2) including a substantially cylindrical support portion (7) and a convex molding surface (10) having a principal longitudinal axis (y'), said convex molding surface (10) having a predetermined curvature to form a concave optical surface of said desired contact lens; (ii) a female mold portion (4) including a concave molding surface (16) having a principal longitudinal axis (y), said female molding surface having a predetermined curvature to form a convex optical surface of said desired contact lens, said female portion (4) comprising a hollow cylindrical portion (12) having an open upper end and a closed lower end for receiving the cylindrical portion (7) of said male mold portion (2); (iii) said male mold portion (2) and/or said female mold portion (4) being flexible and constructed of thermoplastic material; (iv) the cross-sectional outer diameter of the cylindrical support portion (7) of said male mold portion (2) being substantially smaller than the internal diameter of the hollow cylindrical portion (12) of said female mold portion (4); (v) adjustment means operatively associated and in contact with a flexible, thermoplastic mold portion for flexing the optical surface thereof and imparting a predetermined toric surface thereto; characterized in that means (23) are provided to maintain said male mold portion (2) and said female mold portion (4) in a fixed positional relationship at an angle θ, said angle 6 being of about 2 degrees to about 8 degrees and being the angle formed by the principal longitudinal axes (y, y') of said male (2) mold portion and said female mold portion (4).

Claim 8

A contact lens mold assembly for casting toric contact lenses (24) possessing significant cylinder power, which comprises (i) a male mold portion (2) including a substantially cylindrical support portion (7) and a convex molding surface (10) having a principal longitudinal axis (y'), said convex molding surface (10) having a predetermined curvature to form a concave optical surface of said desired contact lens; (ii) a female mold portion (4) including a concave molding surface (16) having a principal longitudinal axis (y), said female molding surface having a predetermined curvature to form a convex optical surface of said desired contact lens, said female portion (4) comprising a hollow cylindrical portion (12) having an open upper end and a closed lower end for receiving the cylindrical portion (7) of said male mold portion (2); (iii) said male mold portion (2) and/or said female mold portion (4) being flexible and constructed of thermoplastic material; (iv) the cross-sectional outer diameter of the cylindrical support portion (7) of said male mold portion (2) being substantially smaller than the internal diameter of the hollow cylindrical portion (12) of said female mold portion (4); (v) adjustment means operatively associated and in contact with a flexible, thermoplastic mold portion for flexing the optical surface thereof and imparting a predetermined toric surface thereto; characterized in that means (23) are provided to maintain said male mold portion (2) and said female mold portion (4) in a fixed positional relationship at an angle θ, said angle 6 being of about 2 degrees to about 8 degrees and being the angle formed by the principal longitudinal axes (y, y') of said male (2) mold portion and said female mold portion (4).

Claim 9

The contact lens mold assembly of claim 6 which is characterized by means to maintain external pressure to the closed mold assembly during the casting of the toric lens.

Claim 10

The contact lens mold assembly of claims 6 and 7 wherein said adjustment means comprise means (18) to impinge and distort the outer hollow cylindrical portion of the said female mold portion (4) to impart toricity to its molding surface (16).