The present invention relates to the manufacture of intraocular lenses (IOLs) for implantation in an eye. The present invention more particularly relates to an apparatus and method for molding IOLs.
A common and desirable method of treating a cataract eye is to remove the clouded, natural lens and replace it with an artificial IOL in a surgical procedure known as cataract extraction. In the extracapsular extraction method, the natural lens is removed from the capsular bag while leaving the posterior part of the capsular bag (and preferably at least part of the anterior part of the capsular bag) in place within the eye. In this instance, the capsular bag remains anchored to the eye's ciliary body through the zonular fibers. In an alternate procedure known as intracapsular extraction, both the lens and capsular bag are removed in their entirety by severing the zonular fibers and replaced with an IOL which must be anchored within the eye absent the capsular bag. The intracapsular extraction method is considered less attractive as compared to the extracapsular extraction method since in the extracapsular method, the capsular bag remains attached to the eye's ciliary body and thus provides a natural centering and locating means for the IOL within the eye. The capsular bag also continues its function of providing a natural barrier between the aqueous humor at the front of the eye and the vitreous humor at the rear of the eye.
Although there are many different IOL designs, all IOLs have an optic for directing and focusing light on the retina, along with means for anchoring the IOL in the correct position within the eye. In one common IOL design, the anchoring means comprises two resilient filaments called haptics which extend in a curved fashion from opposite sides of the optic. In the so-called “one-piece” IOL design, the haptics are integrally formed with the optic, for example by milling the optic and haptics from a single blank of IOL material. In the so-called “three-piece” design, the haptics are mechanically attached to the optic, typically by inserting an end of the haptic into a respective anchoring hole in the optic. In this design, adhesives are sometimes also used to ensure the haptics are securely attached to the optic.
Three-piece IOL designs are typically more difficult to manufacture due to the added steps required to mechanically anchor the haptics to the optic, and also because adhesives can be difficult to apply and have adverse physiological affects should the adhesive come into contact with the delicate tissues of the eye. There is also the possibility that the mechanical anchoring means may inadvertently cause glare or create other interference with the normal passing of light into the eye through the IOL.
IOLs may be manufactured by molding, milling, lathing, or a combination thereof. Of these manufacturing methods, molding is generally the least expensive method of manufacture and hence more desirable than lathing and/or milling. Prior art molding methods include compression molding, injection molding, and transfer molding, for example. Many of these prior art methods are directed at three-piece IOL designs which suffer from the drawbacks mentioned above. Prior art molding methods of one-piece IOLs also have drawbacks such as the requirement for a number of auxiliary processing steps, as well as difficulty to implement in a high-speed, robust manufacturing process. It would therefore be highly desirable to have an apparatus and method for molding a single-piece IOL design in an inexpensive manner which is adaptable to a high speed production facility.
The present invention address the need for an inexpensive yet robust apparatus and method for molding single-piece IOLs by providing a mold having two mating halves each having an optic forming surface and one or more haptic forming surfaces. Means for properly aligning the mold halves are included so that as the mold halves are brought together, the optic forming surfaces and haptic forming surfaces on each mold half are in correct alignment so that they together form a mold cavity in the shape of the IOL to be formed therein. In a first embodiment, the mold halves are formed in a generally cylindrical configuration which may be press-fit together to form the mold cavity. In another embodiment, the mold halves are formed in a generally plate-like configuration which are snap-fit together to form the mold cavity.
A first embodiment of the invention described herein is for molding an IOL having two open-looped haptics. In this first embodiment, the free end of one haptic is connected to the injection port for delivery of the IOL material into the mold cavity while the free end of the opposite haptic is connected to a venting port to vent air from the mold cavity as the IOL material is injected into the injection port of the opposite haptic. A pinch valve may be provided adjacent the free end of each haptic so that the injection port and venting port may be closed off from its respective haptic after injection of the IOL material into the mold cavity. Once the mold cavity has been filled, the liquid lens material is cured (e.g., using UV and/or thermal means) to form the IOL. Once curing is complete, the mold halves are opened and the IOL is released from the mold.
A second embodiment of the invention described herein is for molding an IOL having two closed-looped haptics. In this second embodiment, the injection port is positioned to extend from one of the closed-looped haptics while the venting port is positioned to extend from the opposite closed-looped haptic.
In an advantageous embodiment of the invention, the molds are placed in a vacuum during mold filling and curing to reduce the occurance of pits and bubbles in the finished IOL.
Referring now to the drawing, there is seen in
An injection port “IP” is defined in the assembled mold by facing injection port surfaces 34a and 36a which are provided on each mold half 26,28, respectively, extending from a respective haptic forming surface 26c and 28c to the peripheral wall 26′,28′ of the assembled mold for access by an injection nozzle (not shown). The injection port “IP” is configured the same for the first and second embodiments of the invention and is shown in the views of
Once the mold material has cured (e.g., by thermal and/or UV means), the mold halves are separated and the molded IOL is removed therefrom for further processing as required (e.g., polishing, sterilization, packaging, etc.). It may thus be realized that a single-piece open-looped IOL 10 may be easily molded with the haptics integrally formed with the optic using the inventive molding apparatus and method.
The mold material used to form the IOL may be any polymerizable material useful in making IOLs, examples of which are hydrogels, silicones, polymethylmethacrylate, etc. Also, more than one type of material may be used to form different parts of the IOL. For example, a PMMA may be used to fill and form the haptics while a hydrogel is used to fill and form the optic. This may be accomplished in the present invention by using a sequential filling process whereby the first injection of PMMA fills the haptic cavity attached to the venting port VP, the second injection of hydrogel fills the optic cavity, and the last injection of PMMA fills the haptic cavity connected to the injection port IP. During curing of the assembled mold, the different mold materials polymerize together to form a single-piece IOL. Another method for making such an IOL made of different materials would be to place already formed haptics (e.g., made of PMMA) into the respective haptic cavity and inject the optic material (e.g., a hydrogel) into the optic cavity through the alternate injection port AIP. In this instance, both the injection port IP and the venting port VP would act as venting ports.
Referring now to
An injection port IP′ is defined in the assembled mold by injection port surfaces 134a, 134b and 136a, 136b which are provided on each mold half 126, 128, respectively, extending from haptic forming surfaces 126b, 128b and 126c,128c to the peripheral walls 126′, 128′ of the assembled mold for access by the injection nozzle (not shown). As stated above, the configuration of the injection ports IP′ on the embodiment of
Once the mold cavity is completely filled, a pair of pinch valves PV3 and PV4 on mold half 128 and a pair of aligned pinch valves PV3′ and PV4′ on mold half 126 are actuated to close the mold cavity off from the injection port IP′ and venting port VP′, respectively. Once the mold material has cured (e.g., by thermal and/or UV means), the mold halves are separated and the molded IOL is removed therefrom for further processing as required (e.g., polishing, sterilization, packaging, etc.). It may thus be realized that a single-piece closed-looped IOL 18 may be easily molded with the haptics integrally formed with the optic using the inventive molding apparatus and method.
Attention is now turned to
Referring still to
An alternative injection port AIP is defined in the assembled mold by alternative injection port surfaces 54c and 56c formed in mold halves 50 and 52, respectively, extending from optic forming surfaces 50a, 52a to the peripheral walls 50′, 52′, respectively. In this embodiment, the injection port IP″ would serve as a second venting port for evacuation of air from the mold cavity as it is being filled through alternative injection port AIP.
Referring still to
An alternative injection port AIP is defined in the assembled mold by alternative injection port surfaces 154c and 156c formed in mold halves 150 and 152, respectively, extending from optic forming surfaces 150a, 152a to the peripheral walls 150′, 152′, respectively. In this embodiment, the injection port IP″ would serve as a second venting port for evacuation of air from the mold cavity as it is being filled through alternative injection port AIP.
It is noted that in the embodiments of
A clamping tool 200 seen in
Lower base 204 includes a clamp plate 216 having a top surface 216a upon which the assembled, but as yet unclamped, mold halves 50,52 sit. It is noted that mold halves 50, 52 are being used for the purpose of description only and that other embodiments of the invention may also be clamped using tool 200. With mold halves 50,52 being placed upon top surface 216a, upper tool base 202 is lowered with alignment pins 212, 214 extending through holes 218, 220, respectively, formed in lower tool clamp plate 216 as seen in FIG. 5B. In this position, second clamp plate 208 of the upper tool base 202 is in contacting, covering relation to lower clamp plate 216. Upper clamp base 202 is then further lowered which compresses spring 210 and causes first clamp plate 206 to come into engagement with second clamp plate 208. The resultant force against second clamp plate 216 and also now lower clamp plate 216 presses mold halves 50,52 together until the bosses 60a, 58a snap-fit through respective apertures 58b,60b thereof. Once so assembled, the top tool base 202 is raised and the assembled mold halves 50,52 as seen in
Once the mold cavity has been filled, the mold material is cured (e.g., by thermal and/or UV means), whereupon the mold halves are separated which may be accomplished using the same tool 200 which has been fit with a pair of shearing pins 220, 222 as seen in
Although the present invention has been described with reference to an open-loop IOL 10 and closed-looped IOL 18 as shown herein, it is understood that the present invention is applicable to other IOL designs having one or more haptics which may be of any desired configuration. It will thus be appreciated that the configuration of the mold cavity defined by the facing surfaces of the mold halves may vary depending on the IOL design being manufactured.
Number | Name | Date | Kind |
---|---|---|---|
4284591 | Neefe | Aug 1981 | A |
4786444 | Hwang | Nov 1988 | A |
4789324 | Akhavi | Dec 1988 | A |
4815690 | Shepherd | Mar 1989 | A |
4834750 | Gupta | May 1989 | A |
4847020 | Akhavi | Jul 1989 | A |
4971732 | Wichterle | Nov 1990 | A |
4993936 | Siepser | Feb 1991 | A |
5071101 | Wood | Dec 1991 | A |
5104590 | Blake | Apr 1992 | A |
5141677 | Fogarty | Aug 1992 | A |
5169569 | Ingram | Dec 1992 | A |
5322649 | Rheinish | Jun 1994 | A |
5507806 | Blake | Apr 1996 | A |
5545366 | Lust | Aug 1996 | A |
5611968 | Grisoni | Mar 1997 | A |
5620720 | Glick | Apr 1997 | A |
5645665 | Salazar | Jul 1997 | A |
5656210 | Hill | Aug 1997 | A |
5674283 | Stoy | Oct 1997 | A |
5674435 | Blake | Oct 1997 | A |
5762836 | Bos | Jun 1998 | A |
5837156 | Cumming | Nov 1998 | A |
5861031 | Namdaran | Jan 1999 | A |
6015511 | Yasuda | Jan 2000 | A |
6039899 | Martin | Mar 2000 | A |
6258299 | Yamashita | Jul 2001 | B1 |
6276920 | Doke | Aug 2001 | B1 |
6305661 | Kennedy | Oct 2001 | B1 |
6391230 | Sarbadhikari | May 2002 | B1 |
Number | Date | Country |
---|---|---|
0059713 | Oct 2000 | WO |
Number | Date | Country | |
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20030234456 A1 | Dec 2003 | US |