Method of casting a contact lens
AssigneeNational Research Development Corporation
InventorsRonald S. Hamilton, William E. Seden
Life of this patent
Estimating the term…
Abstract
A mould for cast moulding a contact lens comprises a first cup member having a male mould surface and a second cup member with a female mould surface. The two cup members form a piston and cylinder and are used in a pressure vessel so as to apply loading pressure to deflect the mould surfaces to maintain the surfaces in contact with a lens being cast. The mould is opened with the mould surface facing upwardly. Hydrating fluid is added to the first cup member and a cover sealed to the top of the first cup member.
Claims14
A method of cast moulding a contact lens comprising the steps of:
- placing a monomer in a mould having a mould cavity between relatively movable male and female mould surfaces, either one of the mould surfaces having a rigid shoulder integral therewith for forming a peripheral seal between the two mould surfaces to close the cavity, at least one of the mould surfaces being flexible under a loading pressure;
- closing said mould cavity with monomer filling the cavity;
- placing the mould in a pressure vessel;
- applying a superatmospheric pressure so that said loading pressure acts on the mould surfaces and forms a pressurized seal around said rigid shoulder;
- and
- curing the monomer whereby said loading pressure causes deflection of one of the mould surfaces to maintain the surfaces in contact with the lens as the monomer shrinks during polymerisation.
A method of cast moulding a contact lens comprising the steps of:
- polymerising a monomer in a mould cavity between a male mould surface in a first mould part and a female mould surface in a second mould part;
- opening the mould to expose the cast lens while supported on said male mould surface;
- and
- sealing the lens in a package by sealing a cover member onto said first mould part.
Dependencies are inferred from the claim text.