Method of cast moulding a translating multifocal contact lens
AssigneeEzekiel Nominees Pty Ltd
InventorDonald Frederick Ezekiel
Life of this patent
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Abstract
There is provided a contact lens (60) which is produced by cast moulding. The cast moulding is achieved by the use of an anterior face mould insert (30) which has a cap (24) with a domed surface (26) and a body (10). The domed surface has provision for a distance vision segment (31) and a reading segment (32) separated by a demarcation (33). Further, the cap (24) has a cutaway portion (20) for producing a lower ledge and the body (10) has a projection (18) for producing a lower truncation in the resultant lens. Means is also described for forming a posterior face of the contact lens (60).
Claims6
A method of cast moulding an alternating vision multifocal contact lens made of flexible material by producing a first mould insert having a surface which is used to produce a first mould having an internal face and a second mould insert having a surface which is used to produce a second mould having an external face, wherein the first mould represents a shape of an anterior face of a contact lens and the second mould represents a shape of a posterior face of a contact lens, wherein the first and second moulds are brought together with the external face of the second mould juxtaposed with the internal face of the first mould so as to define a volume therebetween, the volume between the first and second juxtaposed moulds is filled with contact lens material, the contact lens material in the volume is allowed to cure to produce the multifocal contact lens, characterized in that the volume defined by the first and second juxtaposed moulds is configured so as to form without lathing a translating contact lens having a lower end with a lower truncation and a forwardly projecting ledge at the lower end thereof such that the truncation and the forwardly projecting ledge are arranged to engage with a lower eyelid of a user to facilitate lens/lid interaction to allow lens translation to occur.
A method according to any one of the preceding claims, characterized in that the contact lens material is applied onto the internal face of the first mould and/or onto the external face of the second mould and the first and second moulds are subsequently juxtaposed to define the volume for production of the contact lens filled with contact lens material.
A method according to any one of the preceding claims, characterized in that the first mould insert is formed in two parts the first part defining the shape of the anterior face incorporating the bifocal lens powers and the forwardly projecting ledge and the second part the lower truncation of the contact lens
Dependencies are inferred from the claim text.