The present invention relates to a method of cast moulding a translating multifocal contact lens.
In Australian Patent Number 769719 there is described and claimed a multifocal contact lens wherein the contact lens is made of flexible material and the contact lens is arranged to translate on an eye.
The entire disclosure of Australian Patent Number 769719 is incorporated herein by reference.
The present invention provides a means of manufacturing a lens of the type described in Australian Patent Number 769719.
In accordance with one aspect of the present invention there is provided a method of cast moulding a multifocal translating contact lens which comprises 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 being filled with contact lens material, allowing the contact lens volume in the moulds to cure to produce the cast moulded contact lens, wherein the volume defined by the first and second moulds is configured so as to form a contact lens with a lower truncation.
Preferably, the volume defined by the first and second juxtaposed moulds also has an internal configuration which produces a forwardly projecting ledge at a lower end of the cast moulded contact lens.
More preferably, the internal face of the first mould produces an anterior face of the cast moulded contact lens with distance and close range vision segments. The resultant cast moulded contact lens preferably has an anterior face with an upper distance vision segment and a lower close range vision segment.
The present invention will now be described with reference to the accompanying drawings, in which:
In
In
The member 20 is also provided with a cap 24 which is generally circular in plan view as shown in
The moulding members 10 and 20 are arranged to be joined together as shown in
In
The mould insert 30 is arranged to produce a mould for an anterior face of a contact lens of the type described in Australia Patent Number 769719 referred to hereinabove. This may be done by any convenient means such as by injection moulding.
In particular, the upstanding projection 18 on the rim 16 is designed to produce a lower truncation in the moulded lens. Further, the cut away portion 28 is arranged to produce a lower forwardly projecting ledge in the moulded lens. As shown in
As described in Australian Patent Number 769719 the truncation and the forwardly projecting ledge are arranged to engage with a lower eyelid of a user to facilitate translation.
To form a posterior face in a moulded contact lens it is simply necessary to produce a mould insert with a standard curvature. This incorporates the lens base curve that is necessary to fit an eye and may be spherical, toroidal or aspheric in shape or it may be a combination of curves. The posterior surface may also comprise a peripheral design (not shown) in known manner to facilitate translation when the ledge engages with a lower eyelid in looking down. A typical mould insert 54 for the posterior face is shown in
The mould inserts 30 and 54 may be produced by any convenient method but the use of a precision computer-controllable manufacturing lathe to produce the moulding tools is preferred. This device is used to lathe the components of the mould inserts 30 and 54 to the precise specifications needed to produce a mould surface which is then replicated on the anterior and posterior surface of the lens with the required curvature. Further, the mould insert 30 is configured to produce simultaneously the truncation and the forwardly projecting ledge.
The mould insert 30 is preferably made in two parts as described but it can be made in one part if desired. However, producing it in two parts has the advantage that the domed surface 26 containing the power curvatures for the anterior surface is formed separately so as to customise the curvature to suit the different power needs without the need to be concerned about formation of the truncation with each moulding member 10.
An anterior face contact lens mould may be manufactured using the mould insert 30 of the present invention by using the mould insert 30 to form a plastics material or glass mould 40 or the like for the front face of a lens as shown in
Similarly, a contact lens mould 50 as shown in
In
A typical contact lens 60 cast moulded by the method of the present invention is shown in
To cast mould a contact lens in accordance with the present invention to the design as described in Australian Patent number 769719 referred to hereinabove, as shown in
The material is then subjected to curing in known manner to achieve polymerisation. The mould is then opened and the resulting lens removed.
Further, in addition to lower reading vision and upper distance vision portions the) anterior face of the lens may be provided with an intermediate vision portion or a progressive close portion. Also, the resulting lens may be provided with peripheral lenticulated portions in known manner to reduce bulk.
Modifications and variations such as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2012/000948 | 8/10/2012 | WO | 00 | 7/28/2014 |
Publishing Document | Publishing Date | Country | Kind |
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WO2013/033752 | 3/14/2013 | WO | A |
Number | Name | Date | Kind |
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5517259 | Blum et al. | May 1996 | A |
5611970 | Apollonio et al. | Mar 1997 | A |
5861114 | Roffman et al. | Jan 1999 | A |
20040075807 | Ho et al. | Apr 2004 | A1 |
20040263776 | Ezekiel | Dec 2004 | A1 |
Number | Date | Country |
---|---|---|
769719 | Jun 2001 | AU |
1856729 | Nov 2006 | CN |
2031432 | Mar 2009 | EP |
0142002 | Jun 2001 | WO |
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Number | Date | Country | |
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20150084218 A1 | Mar 2015 | US |