HK1039269A - Medical implants of stretch-crystallizable elastomers and methods of implantation - Google Patents

Description

Stretch-crystallizable elastomeric medical implants and methods of implanting same

Field of the invention

The present invention relates generally to stretch-crystallizable elastomeric medical implants and methods of inserting and placing such medical implants, particularly optical lenses. More particularly, the present invention relates to a flexible, highly extensible implant made of a stretch-crystallizable elastomer, preferably silicone, which upon extension induces the formation of stable but reversible, relatively high melting point crystals within the implant, thereby deforming the implant into a stable, elongated, small cross-sectional shape for use in small incision implantation techniques. Within a few seconds of implantation in the body, at normal body temperature, the crystals formed by the induction of elongation melt away to restore the implant to its original size, shape and physical characteristics.

Background of the invention

There have been many advanced applications and techniques in the art for replacing or augmenting natural organs of the human body with medical implants. These medical implants can be divided into two broad categories. The first category includes implants that fulfill their primary function by virtue of various mechanical properties such as strength and elasticity. Such grafts are: prosthetic heart valves and prosthetic joints. The second category includes implants that rely on the physical shape of the implant rather than its structural or mechanical properties to perform its primary function. Such grafts are: cosmetic devices for replacing or augmenting defective tissue, and more importantly, artificial optical lenses for augmenting or replacing the natural lens of the eye.

The second type of implant, although successfully used for many years, is not without its problems in its use. One of the major problems is the physical trauma caused by the surgical incision required to implant the graft into the body. Known to the medical community are: reducing the size of the incision required for implantation reduces trauma to the body. Currently, the best way to reduce the size of a surgical incision is to reduce the size of the implanted graft. In addition, research and development efforts are currently focused on minimizing the size of the surgical incision itself. The use of arthroscopic or microsurgical techniques and instruments often allows the implantation procedure to be performed through a small, delicate incision. These small incisions are significantly less traumatic to the human body than conventional incisions. Thus, the use of small incision techniques can greatly reduce patient discomfort, healing time, and post-operative complications.

This study is not easy, mainly because the volume, size and certain rigidity of conventional implants practically limit the further reduction of incision size. Artificial optical lenses (also known as intraocular lenses or "IOLs") are more typical of the problems in this regard than are many orthopedic and cosmetic implants. These artificial lenses are implanted in the human eye to replace or augment the natural crystalline lens, which focuses light to the fundus. The shape and volume of the lens and the refractive index of the lens material are used to ensure that light rays entering the eye can be correctly focused on the fundus after passing through the lens so as to obtain a clear image.

Currently, implanting intraocular lenses typically requires a 3mm to 4mm incision. In most cases, the intraocular lens is implanted after removal of the damaged or cataractous natural lens. The minimum incision required to remove the natural lens is now 3mm to 4 mm. Intraocular lens implants typically include a collecting lens portion and a small, projecting structural portion (haptic) for placement and support of the lens after implantation. Currently available IOLs have a minimum diameter of 6mm and a minimum thickness of 1mm to 2 mm. In addition, so-called "full-size lenses" used to completely replace the natural lens have a minimum diameter of 8mm to 13mm and a thickness of at least 3mm to 5 mm. The surgical incision required is then at least as large as the smallest dimension of the implant. Any incision in the eye, particularly those greater than 3mm to 4mm, has significant disadvantages. These include post-operative astigmatism or corneal deformation, and can increase the likelihood of complications and can lead to longer healing times.

One known method of reducing the incision size of an intraocular lens implant is to make the lens of a relatively elastic material that can be folded or rolled to reduce the size of the implant in one direction prior to implantation in the eye. Once implanted, the lens unfolds to return to its original shape. Although foldable lenses may meet certain needs, they have drawbacks that limit their use in small incision implantation procedures, making them impractical. For example, after being folded, the size of one dimension (diameter or width) of the three-dimensional size can be reduced only by half. At the same time, the dimension of the other dimension (thickness) must be doubled, while the dimension of the third dimension remains unchanged. In this way the incision size can only be reduced to half the maximum one-dimensional size, which still has to be 4-6 mm in the case of currently available intraocular lenses. Further folding of the lens in half may cause permanent creasing or distortion of the optic portion, resulting in distortion of the image formed by the implanted implant.

Another way to reduce the size of the incision is to use a material such as a hydrogel to make the inflatable lens. The hydrogel lens dries to reduce its volume before implantation in vivo. After implantation, the hydrogel material expands to its original size by rehydration. Although hydrogel lenses can be greatly reduced in size, current hydrogel materials require 3 to 24 hours after implantation to complete the rehydration process. Such a long time is not practical because it is not possible to judge whether the lens placement is correct before complete hydration. The transplant physician is reluctant to use such a lens because the physician must wait for a period of time before closing the transplant incision until the physician is certain that there is no longer a need to adjust the lens position.

Other methods of implanting intraocular lenses with small incisions have been less successful. One proposal has been to implant a transparent balloon lens into the eye through a small incision, in an empty or uninflated state. Once implanted in the eye, a high refractive material is filled into the lens to bring it to the desired shape. Such balloon lenses have proven impractical to date, primarily because they are difficult to manufacture and the degree of filling cannot be accurately controlled after implantation. In addition, there are other problematic problems such as elimination of air bubbles and stitching of lenses.

In addition, it has been proposed to replace the natural lens with an injectable lens, i.e. a liquid polymer is injected into the naturally occurring lens capsule at the time of surgery to bring it to the desired shape. However, the current technology cannot produce such lenses because it is difficult to produce a product with predictable optical properties and resolution from materials with biocompatibility.

A more practical way to reduce the size of the incision required to implant an intraocular lens is disclosed in co-pending U.S. patent application No. 08/607417. According to this technique, the lens is made of a memory material, i.e. a material that has the ability to deform and substantially eliminate the deformation in all directions, such as an elastic or gel-like material. The lens made in this way can be implanted into the eye through a small incision using a small diameter tubular emitter. The gel lens can immediately restore its pre-implantation shape and configuration after implantation to facilitate the physician in determining whether the implantation site is correct to terminate the implantation procedure.

However, even this technique can be improved, for example, by deforming the lens into a tubular emitter, which increases the surface area to volume ratio of the lens when the lens is forcibly deformed. In this case, the lens exerts a strong elastic force on the tubular emitter when the deformed lens tries to recover its original size and shape. This elastic force, coupled with the large surface area to volume ratio, may make it difficult for the deformed lens to leave the tubular emitter and enter the human eye.

It is therefore an object of the present invention to provide a method of implantation that allows for rapid and easy implantation of a graft into the body through a very small surgical incision compared to the size of the graft, and which does not require complicated or sophisticated techniques or graft delivery systems.

It is another object of the present invention to provide a surgical implant, such as an intraocular lens, which can be implanted into the body through a very small incision compared to the shape, size and volume of the implant.

It is another object of the present invention to provide a stretch-crystallizable silicone intraocular lens which is optically clear, has a high refractive index, and can be stretched to form a long rod or sheet, which crystallizes at a temperature below normal body temperature and is stable, and which can recover its pre-stretch-crystallizable shape, and physical properties within a few seconds of implantation in an eye.

Summary of The Invention

The material compositions, implants, methods of implantation and related devices for rapid and easy implantation of stretch-crystallizable medical implants into the human body disclosed herein achieve the objects of the invention. The medical implants of the present invention are formed from novel, biocompatible, stretch-crystallizable elastomers, preferably silicone, which have the desired physical properties of elongation of up to 300% or more when they are significantly elongated and of forming molecular crystals with a higher melting point due to a rearrangement of the molecular structure after elongation. Thus, they can be extended to deform into stable, easily handled, elongated rods or sheets at sub-normal body temperatures without the temperatures required being so low that they require expensive or difficult means. Once implanted in the body, the relatively high melting point crystals formed by stretching are melted by the heat, thereby allowing the implant to immediately recover its original size, shape, configuration and characteristics.

According to the teachings of the present invention: implants made from this novel stretch-crystallizable elastomer with an available crystalline melting point can be readily stretch-crystallizably deformed into a stable configuration suitable for small incisions in a short period of time at near ambient temperature. The implant can also be stretched by cooling to accelerate the formation of internal crystallites which act as transient cross-linked fillers linking the molecules, thereby deforming the implant into a stable but reversible shape. This crystallographically deformed shape is maintained by simple cooling so that the implanting physician can implant the implant without any special tools or cooling equipment and without fear of the implant prematurely "melting" back to its original shape. Implants made from these stretch-crystallizable materials provide a practical means of greatly reducing the size of the surgical incision required for implantation.

Such stretch-crystallizable materials are useful in any procedure in which it is desirable to implant an implant into the body through an incision that is smaller than the original size of the implant in accordance with the teachings of the present invention. One of the major benefits of using the stretch-crystallizable materials described in the present invention is: this material is capable of stretch crystallization at sub-body temperature (about 37 ℃). In addition, medical implants made in accordance with the teachings of the present invention can be implanted into the body directly through a very small surgical opening or with the aid of a small diameter, generally tubular, implantation device that is relatively minimally invasive.

The novel materials described in the present invention, and the implants and methods of implantation associated therewith, provide a number of features and advantages over like products. For example, such stretch-crystallizable elastomeric materials are biocompatible, and optically transparent for optical purposes, and also have a high refractive index similar to the natural lens. In addition, the elastomer can be tailored by the manufacturing process to have a stretch crystallization temperature that is tunable between ambient or room temperature (about 20 ℃) to body temperature (about 37 ℃). The elastomer can also be stretched and its tensile strength is enhanced because the higher melting crystallites formed during the stretching act as transient enhancers. This material also recovers 100% of its original shape after elongation, since no reinforcing filler such as fumed silica cross-linker, which is used in the prior elastomers, is used in this material. It is important that it can be melted at body temperature to recover its original shape. Therefore, the material can be prepared to have the temperature range of-100 ℃ to 50 ℃ for the stretching crystallization and the temperature range of 25 ℃ to 50 ℃ for the recovery of the original shape.

With this material, an unprecedented graft suitable for small incision implantation can be produced. For example, the graft of the present invention can be stretched in at least one direction to 300% to 600% of its original size. Since the volume of the graft remains constant, the three-dimensional shape of the graft can be changed to a stable shape that can be easily implanted into the body directly through a very small incision or with the aid of a small bore graft device. When using an implant device, stretching the crystallized implant does not exert a large elastic force on the inner wall of the tool used. Thus, a relatively small amount of force is required to push the crystallized graft into or out of the graft device for implantation at a target site in the body. Stretching the crystallized graft may also eliminate its deformation within a few seconds of implantation into the body. Thus, it is possible to quickly determine whether the transplantation operation is successful without taking any complicated operation or technique after the transplantation.

The invention is particularly suited for the fabrication and implantation of optical and contact lenses for implantation in the human eye for corrective or replacement (use as pseudolenses). The optical lens implants described herein are made of a biocompatible, stretch-crystallizable silicone elastomer. Exemplary silicone elastomers described herein are prepared using F, such as methyl (3,3, 3-trifluoropropyl) siloxane, which is well known in the art₃Monomer and other ratio F₃D, such as hexaphenylcyclotrisiloxane, known in the art as the higher refractive index of monomers₃Homopolymers or copolymers obtained by polymerization of (2Ph) monomers, exemplary of which is used₃The cis/trans ratio of the monomers is between about 40/60 and 100/0. Exemplary polymers prepared contain 60% to 100% F₃Monomers and from 0% to 40% of D₃A monomer. These exemplary stretch-crystallizable elastomers are biocompatible and optically clear, with a refractive index of 1.4, making these elastomers well suited for fabricating IOLs. The optical lens can be made into full-size lens with diameter of 8-13 mm and center thickness of 3-5 mm, which can completely fill intraocular capsular bag, or conventional-size, single-piece or multi-piece lens with center thickness of 1-2 mm and specification of 5-mm-7mm, wherein the lens can be packagedComprising one or more radially extending contact support structures. The cross-section of the optical lens may be of any shape, such as: plano-convex, biconvex, convergent crescent, divergent crescent, plano-concave, biconcave, and balloon shapes.

One embodiment of the related transplantation method described in the present invention comprises: the elastomeric graft is stretch crystallized at a temperature below normal body temperature and the deformed graft is then implanted directly into a target site in the body. For example, when the implant is crystallized to become an elongated, relatively rigid rod, the physician can use forceps or other similar instruments to insert the implant through a relatively small incision into the body. Once the graft is in the body and exposed to normal body temperature, the graft can recover its pre-stretched, pre-crystalline size and shape in a few seconds.

In another embodiment of the implantation method, the stretched crystallized graft is loaded into a small-bore, generally tubular-ported, implantation instrument. The grafting instrument is then inserted into the target site within the alignment body, and the graft is pushed from the tubular port into the target site. The tubular port of the implantation instrument can also be made small enough to allow it to self-form the implantation channel as a piercing cannula similar to a hypodermic needle, if desired. Alternatively, a small incision may be made using conventional surgical incision techniques, and the tubular port may then be inserted through the incision.

In other embodiments, it is described that the intraocular lens of the invention may be implanted into an eye through a small incision having a size of between 1mm and 4.5 mm.

Other objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings. It is noted that the inventive principles are illustrated herein for an IOL implant by way of example only, and that the present invention also encompasses other implants that include an elastomeric portion.

Brief description of the drawings

FIG. 1 is a perspective view of an exemplary stretch-crystallizable implant, such as an intraocular lens, according to the present invention, particularly illustrating the configuration of the implant when it is not stretched;

FIG. 2 is a cross-sectional view taken along line 2-2 of the unstretched graft shown in FIG. 1;

FIG. 3 is a perspective view of a stretch-crystallizable implant as described herein, particularly illustrating the configuration of the implant after stretching;

FIG. 4A is a cross-sectional view of the stretched implant taken along line 4-4 of FIG. 3;

FIG. 4B is a cross-sectional view of the stretched implant taken along line 4-4 of FIG. 3 in another configuration;

fig. 5 illustrates an exemplary stretch-crystallizable implant in an eye and in a stable configuration after stretching, particularly to illustrate the implantation procedure described herein.

FIG. 6 shows the eye and exemplary stretch crystallizable implant shown in FIG. 5 to illustrate another step in the implantation procedure;

figure 7 illustrates the eye and exemplary stretch crystallizable implant shown in figure 6 to illustrate the implant in an unstretched configuration after implantation and restoration of shape and physical characteristics.

FIG. 8 is a cross-sectional view of an implantation device for implanting the stretch-crystallizable implant according to the present invention;

FIG. 9 is a sectional view of an eye and an implantation device in stages to illustrate a first step in an exemplary implantation procedure according to the present invention;

FIG. 10 is a sectional view of an eye and an implant device in stages to illustrate an operation step subsequent to that shown in FIG. 9;

FIG. 11 is a sectional view of an eye and an implant device in stages to illustrate an operation step subsequent to that shown in FIG. 10;

FIG. 12A is a sectional view of an eye and an implant device in stages to illustrate a step of operation subsequent to that shown in FIG. 11;

FIG. 12B shows a staged cross-sectional view of an eye and an implant device to illustrate implantation of another implant;

FIG. 13 is a perspective view of an apparatus for forming an exemplary stretch crystallizable implant according to the present invention into a stretched crystallized post-crystallization configuration, illustrating the apparatus prior to implant formation;

fig. 14 is a view similar to fig. 13, illustrating the device after implant formation;

figure 15 is a cross-sectional view of another embodiment of a stretch-crystallizable implant according to the present invention in the form of an intraocular lens.

Detailed description of the embodiments

Referring to the drawings in greater detail, FIGS. 1 and 2 illustrate an exemplary stretch-crystallizable and deformable medical implant 10 according to the present invention. The shaping of implant 10 into the shape of the intraocular lens shown in the drawings is intended to illustrate the uniqueness of the present invention in a simplified context and this embodiment is for exemplary purposes only and does not limit the scope of the present invention. Those skilled in the art will envision other embodiments within the scope of the invention. One skilled in the art will also appreciate that the lens implants described herein must be transparent, and that the implant must also have the correct optical power to function as a lens. These additional features are not necessary for all implants made in accordance with the teachings of the present invention.

The exemplary implant 10 is formed from a stretch-crystallizable elastomer such as silicone as described herein. When the elastomer elongates significantly, these new elastomers may form molecules or "micro-sized" crystals with a higher melting point than in the unstretched state, due to the rearrangement of the elastomer molecules in the stretched state. Fig. 1 and 2 show the implant 10 in a non-stretched state, and fig. 3, 4A and 4B show the implant in a stable stretched state, the implantation process of which is not complicated and can be performed through a small incision. One skilled in the art will appreciate that some stretching is necessary to induce crystallization. This is quite different from the simple local deformation employed with foldable implants.

Due to the unique design of the present invention and the physical properties of the stretch-crystallizable elastomer, such as good consistency, the implant 10 is capable of being quickly and easily formed into a stable yet reversible, stretched configuration within a predetermined, practical temperature range that is easy to manipulate and that can be maintained without the need for expensive equipment or manipulation. For example, the predetermined temperature range may be set between-100 ℃ and 50 ℃. Preferably, the temperature range is set from about freezing (e.g., about 0℃.) to about or approximately equal to normal human body temperature (e.g., about 40℃.). Adopts simple refrigeration equipment, liquid nitrogen and liquid CO₂Or simply inserting the implant 10 into an ice bath or cold water to maintain the exemplary predetermined stretch-crystallizable temperature.

The use of stretch-crystallizable temperatures will depend on the physical properties of the stretch-crystallizable elastomers employed in accordance with the teachings of the present invention. Many of the novel silicone elastomers disclosed herein have unique stretch-crystallizable temperatures that make them well suited for making medical implants that can be deformed to a stable configuration suitable for small incisions as shown in fig. 3, 4A, 4B at about ambient temperature (20 c-25 c). Implant 10 can be stably deformed into an implant having a crystalline configuration upon exposure to the correct predetermined temperature for a few minutes or seconds. It should be noted that once stabilized, the elastomer will generally appear rigid, and its elasticity, stretchability or compressibility will decrease. Cooling the elongatable crystallized graft may accelerate the formation of crystals within the contracted graft and may allow the deformed shape to stabilize more quickly. However, cooling is not necessary to practice the invention, and the crystals formed will necessarily stabilize over time, as long as the implant maintains the deformed configuration required for stretch crystallization to occur.

After the implant 10 is formed into the stretch-deformed configuration shown in fig. 3 to accommodate small incision surgery, the implant 10 may be stored, transported, or otherwise manipulated with minimal difficulty without fear of returning the implant to its original, non-stretch-crystallized configuration. This would greatly facilitate the grafting process described herein. It is also important that the implant 10 rapidly recover its original, non-stretch-crystallized configuration and corresponding properties at body temperature after implantation in vivo. This recovery process should occur within a few seconds after implantation and does not require any other manipulation by the implanting physician. The substantially 100% recovery of the original configuration and properties referred to herein includes the following meanings: restoring its original size and three-dimensional shape, as well as the correct refractive index and optical transparency. In accordance with the present invention, the melting point of the implant 10 should preferably be in the range of about 25 ℃ (slightly greater than ambient temperature) to about 37 ℃ (normal body temperature of the human body).

Preferably, the elastomer from which the graft 10 is made increases in size in at least one direction by at least about 300% to about 600% over the original same direction when stretched to a stretched crystalline configuration. For example, implant 10, having the shape of an intraocular lens as shown in figures 1 and 2, has a diameter D of about 9mm and a center thickness of about 4.5mm when undeformed; and after stretch-transformation into a rod-like or sheet-like shape suitable for small incision procedures, the graft 10 changes to the shape shown in figure 4A having a length 1 of about 40mm to 50mm and a diameter d of about 1mm to 3 mm. Figure 4B shows a cross-sectional view of another graft deformed into a sheet, which is similar to the shape of a surgical incision. It can be seen that the graft changes from its original diameter D of about 9mm to a length of about 150mm in a certain direction, which means that the graft increases by about 350% in that direction. With this increase in direction, implant 10 necessarily shrinks in at least one other direction. In this example, the reduction in the thickness T of the graft 10 from about 4.5mm to a diameter or cross-sectional minor diameter d of about 1mm as shown in FIGS. 4A and 4B can be calculated to be about 75% in this direction. The implant 10 has been reduced to approximately 1mm in one direction, which means that the implant 10 can be inserted into the patient's eye through an incision that is smaller than the incision required for the implant 10 when undeformed. In this example, a cut of less than about 2mm may be required to graft a deformed implant 10 having a rod shape as shown in fig. 4, as opposed to a cut of greater than 9mm as would be required to graft an unstretched implant.

Those skilled in the art will appreciate that the volume of the implant before and after the tensile deformation is relatively constant. This limits the range of extension that the implant can be extended, since a reduction of the implant in one direction necessarily causes an increase of the implant in at least one other direction. Therefore, the straight d as shown in fig. 4A becomes too small, the length 1 shown in fig. 3 becomes very long. Again, too much stretching of iol implant 10 as shown in fig. 1 may make the deformed rod-shaped implant too long to be implanted in the eye. Thus, for a conventionally used 6mm sized IOL implant weighing about 20mg, it is capable of being stretched crystalline deformed into a shape of up to about 20mm and about 1mm in diameter, while for a large sized IOL implant weighing about 160mg, it is capable of being stretched crystalline deformed into a shape of up to about 20mm to 30mm and about 2mm to 3mm in diameter. If the large size IOL implant is deformed to a diameter of 1mm, the length of the large size IOL implant is correspondingly deformed to 160mm, which prevents the large size IOL implant from being implanted into an eye. If the implantation position of the implant in the patient is changed, the size limit is changed accordingly.

It should be noted that one particularly unique advantage of the present invention is the functional impact on the intraocular lens implants disclosed herein. Implantation of large format intraocular lenses is difficult to achieve today because of the large implantation incision required. The external trauma caused by the large incision negates the advantages of large-format IOLs in eliminating decentration, decentration or decentration of the lens after implantation. However, large-format IOLs have been implanted through a very small 3mm-4mm implantation incision in accordance with the present invention. This unique advantage of the present invention illustrates the correlation between the illustrated IOL embodiments and the typical, unprecedented properties and advantages offered by the present invention.

With a further understanding of the non-limiting nature of the IOL implants exemplified herein, a broad application of the implantation method provided in accordance with the teachings of the present invention will now be described with reference to figures 5-7. Broadly, the transplantation method of the present invention comprises the steps of: providing a stretch-crystallizable implant; deforming the graft to have a stable shape suitable for small incision implantation; the stretch-crystallized graft is implanted into the body through a small incision. This implantation method may further comprise the step of accelerating the stretch crystallization process by cooling to form an implant having more stable, stronger microcrystals. On the other hand, the stretch-crystallized graft suitable for small incision surgery must also be sufficiently rigid to make the graft easier to manipulate so that it can be implanted directly into the patient through a small incision in the appropriate location.

Pulling opposing portions of implant 10 away from one another using a medical instrument such as forceps stretches implant 10 to deform it into a shape suitable for a small incision. The stretching process of the implant 10 preferably occurs at ambient or room temperature. Once the implant 10 has assumed the stretched shape (as shown in fig. 3), the lens implant 10 is stabilized in this shape for small incision implantation by maintaining the implant 10 in tension until the induced crystallization reaches a point where deformation can be maintained. The above process may take from a few seconds to a few minutes, and the specific time spent will depend on the materials, properties and volumes used. Since stretch crystallization actually causes the melting temperature of the crystals to be higher than the melting temperature of the unstretched implant material, the predetermined stretching environment temperature is lower than the new, higher melting point, which causes the implant to cool to a stable, deformed shape. Preferably, the small incision graft is elongated and has a cross-sectional shape that is circular, oval, or paddle-shaped as shown in figures 3, 4A, and 4B in accordance with the teachings of the present invention. As can be seen from the above, the stabilization process of a stretch-crystallization deformed graft can be accelerated by: the stretched graft is inserted into ice or cold water at a temperature of about 0 c to about 4 c. In this embodiment, the graft 10 is stabilized in the post-stretch-crystallization configuration for a short period of time, about 20 seconds.

Referring to fig. 5, implant 10 may be inserted into the eye through incision 14 by any suitable method. The end of the stretched graft may be held, for example, by forceps 16 and fed through the incision. Forceps 16 are cooled to a temperature below the melting point of implant 10 to prevent undue heating of the implant. As discussed above, implant 10 has some rigidity after stabilization, which allows implant 10 to be easily manipulated during insertion. As shown in figure 6, when the crystallized graft 10 is stretched into the anterior chamber 18 of the eye 12, the graft 10 is at normal body temperature within the eye. The implant 10 thus begins to decrystallize and returns to its original, unstretched, crystalline configuration. Within a few seconds of full insertion of implant 10 into the eye, implant 10 will return fully to its original unstretched shape when placed in the desired destination location, such as posterior chamber 20, as shown in figure 7.

Referring to fig. 8, in another embodiment of the implantation method, an implantation device 22 is used to implant the implant 10 into an eye. The exemplary graft device 22 includes a sleeve-like tubular portion 24 and a plunger 26. The plunger 26 includes an end piece 32 that fits smoothly within the chamber 28. The sleeve-like portion 24 includes an inner chamber 28 and a port 30. The graft 10, which is stretch-crystallized into a long rod or sheet suitable for small incisions, is housed within the chamber 28.

As shown in fig. 9, rather than inserting a stretch-crystallized, small incision-compatible graft 10 directly through an incision 14 into an eye 12, a port 30 of an implantation device 22 is first directed to a target site for placement of the graft 10 in vivo. The diameter of the sleeve-like portion 24 is made relatively small so that it can function like a hypodermic syringe. The cannula portion 24 may form an incision or passage through tissue itself, thus eliminating the need to take additional steps to form an incision.

The sleeve portion 24 is cooled below the melting point of the implant 10 to maintain the implant in a stable, stretched, crystallized shape. The sleeve-like portion 24 also serves to isolate the graft 10 from the relatively hot, body temperature environment at the implantation site, which isolation will continue until the graft is pushed off of the implantation device 22. Maintaining the graft 10 in the stable, stretched, crystallized shape allows the graft to exert force against the walls of the chamber 28 so that only a small amount of force is required to push the plunger 26 into the sleeve-like portion 24, thereby pushing the graft 10 out of the port 30 and into the target site of implantation. A viscoelastic fluid such as Healon from Pharmacia can be used^Into the chamber 28 for lubrication.

Regardless of whether the port 30 is self-piercing or simply passed through a small surgical incision, once the port 30 of the sleeve portion 24 is directed to the target site of implantation (as shown in fig. 10), the plunger 26 may be pushed into the sleeve portion 24 to place the graft 10 at the target site of implantation. The target site in the embodiment shown in fig. 9-12A is referred to as the posterior chamber 20 of the eye 12, and the implant 10 used in this embodiment is a full-size iol implant.

In addition, when the implant is configured to position 10 in front of the natural lens of a human eye to function as an implantable contact lens, the use of the implant device 22 allows the implant to be placed in the target location through a small incision. A 3mm-4mm incision, which is required for conventional cataract removal, is not necessary for implantation of an implantable contact lens. That is, only a single puncture or a very small incision is required to form the desired graft passageway using the graft device 22. Therefore, only 1mm-2mm sized incisions are necessary to employ the method of the present invention. Such small incisions are not sutured after surgery, as shown in fig. 12B, and are implanted either through the sclera directly into the posterior chamber 20 of the eye 12, or through the cornea-sclera into either the anterior chamber 18 or the posterior chamber 20. Again, it is emphasized that the principles of the present invention are illustrated herein with an IOL implant, but this is not meant to limit the invention to only IOL implants.

The graft of the present invention may also be subjected to a stretch-crystallization transformation using another method, as shown in fig. 13 and 14. Instead of simply pulling the opposite ends of the graft 10 to stretch them in one direction, a compression clamp 32 is used to deform the graft 10 into a stable shape suitable for small incisions, as shown in fig. 13. The extrusion fixture 32 includes a female die 34 and a male compression die 36. The female mold 34 includes a receiving slot 38 and a mold cavity 40. The male compression die 36 includes a projecting guide 42 slidably inserted into the receiving slot 38. The male guide member 42 has a mating surface 44, and when the male guide member 42 is fully inserted into the receiving slot 38, the mating surface 44 cooperates with the mold cavity 40 to define a complete shape for the small incision graft. In use, a stretch crystalline implant, such as the exemplary implant 10, is placed in the receiving channel 38 and the male guides 42 of the male compression die 36 are pressed into the receiving channel 38 to push the implant 10 into the mold cavity 40. The implant 10 is pressed into the mold cavity 40 with a pressing action such that the implant 10 extends along the transverse axis of the mold cavity 40. Water or a viscoelastic fluid may be used to lubricate the process of pressing the implant 10 into the mold cavity 40. The female and male dies 34, 36 may also include a guide structure that guides the protruding guide blocks into the receiving slots 38 in a stable, controlled manner.

Those skilled in the art will appreciate that: the stretching of the graft 10 will not be completely uniform throughout the graft material. Thus, different portions of the implant 10 will stretch to different degrees. However, when the male compression die 36 is fully inserted into the receiving slot 38 as shown in figure 14, the implant 10 is deformed into an elongated, sheet-like or rod-like shape suitable for small incisions. Only by the above-described method is it possible to form transitional stable stretch crystalline bonds within the material of the graft 10, so that a stable, deformed, stretch crystalline graft is obtained. In addition, cooling the stretched crystalline graft 10 in the compression clamp 32 may speed up and enhance the process. The cooling may be achieved by inserting the graft and compression clamp into a water bath or by simple refrigeration. In the embodiment of the compression clamp 32 shown in fig. 13 and 14, the cross-sectional diameter or width m of the mold cavity 40 is 2.5mm or less and its length ranges between 30mm and 50 mm. This shape is suitable for tensile crystallographic deformation of large-format intraocular lens implants. Other suitable dimensions will occur to those skilled in the art.

It should be noted that: although the exemplary implant 10 shown in fig. 1 and 2 is a bi-convex lens, it is contemplated that the present invention encompasses optical lenses of various shapes, the specific shape of which will depend on the light gathering requirements or lens function designed and the target location in which the lens is to be placed. For example, a lens having the following cross-sectional shape may be used: biconvex, plano-convex, plano-concave, biconvex, crescent, and the like, as is known in the art. The invention also encompasses lenses having other cross-sectional shapes.

Additionally, while the exemplary implant 10 shown in FIG. 1 does not have any support structure or structure referred to as a "haptic", it is contemplated that the implant 10 of the present invention may incorporate some haptic support structure as is known in the art. Such support structures need not be formed from stretched crystalline elastomers and may be planar, annular or generally planar, rounded or the like. Other shapes of support structures may also be used in the present invention, and the particular shape will depend on the individual patient or the particular needs of the lens design.

Lens implants made in accordance with the teachings of the present invention can also be made in the shape of a balloon as shown in implant 50 in fig. 15. The balloon graft 50 includes an elastic membrane 52 which forms a lumen in which a relatively flowable substance 54 is present. Exemplary membrane 52 may be made about 0.2mm thick, with substance 54 preferably having a diopter between about 1.38 and 1.46. The exemplary balloon-shaped graft 50 may be crystallized by stretching or deformed by compression as shown in fig. 13 and 14. At least film 52 is made from a stretch-crystallizable elastomer as taught by the present invention for the passport. In addition, both the film 52 and the elastic substance 54 of the contents may be made of stretch-crystallizable elastomers, although this is not necessary to practice the invention.

It will be appreciated by those skilled in the art that the unique advantages of the present invention allow the creation of a balloon-shaped lens and the implantation of the balloon-shaped implant into the body through a small incision. This avoids the complicated problem of inflating the balloon-shaped lens after implantation. More specifically, the balloon-shaped lens 50 of the present invention can be made to have the proper size and the proper optical characteristics prior to implantation. This is particularly advantageous for implanting full-size implants in the posterior chamber occupied by the natural lens. Since the stretch-crystallizable elastomeric film 52 of the balloon graft 50 can be deformed significantly without tearing or permanently deforming, the balloon lens of the present invention can be implanted through a small incision while maintaining the desired optical characteristics of the individual patient.

In addition, it is conceivable that: it is also within the scope of the invention to implant an empty or flattened balloon-shaped lens into the body. Then, a certain therapeutically effective elastomer may be injected into the graft to expand it into the desired shape. Since the therapeutic contents 54 are enclosed within the biocompatible elastomeric film 52, complex biological reactions can be avoided. As with the pre-filled balloon graft 50 discussed above, the use of a biocompatible film 52 allows for better tailoring of the physical properties of the contents 54 with less consideration of biocompatibility. In this way, the biocompatibility to be considered in the case where the content 54 is in direct contact with human tissue or body fluid may not be considered, but only for optical purposes, and the diopter of the content 54 may be considered to the maximum extent. In addition, various physical properties such as viscosity or density can also be optimized for those non-optical implants that are implanted at different target locations in the body without taking into account excessive biocompatibility concerns.

Once again, the emphasis is: the scope of the present invention and the various teachings are not limited to the exemplary embodiments of intraocular lens implants. It is to be understood that the scope of the invention is to be broadly construed and that any suitable technique known in the art may be used to make the graft in accordance with the teachings of the invention. The implant may be made by any suitable method such as casting, compression molding, injection molding, die cutting or other similar methods. This broad manufacturing possibility of the present invention is particularly significant for small gauge implants such as intraocular lenses. Since the stretched crystalline material of the present invention is suitable for fabrication using casting and molding techniques, problems associated with the precise fit of small-gauge implants in structures can be avoided. Thus, the elastomeric compound can be used to make a significant portion of the implant, while other structural elements of the implant, such as the lens support, can be made by casting, without the usual manufacturing techniques.

The crystallizable portion of the implant may be provided with optimal tensile crystallization and melting temperatures, optimal optical clarity, optimal diopter strength, optimal density, optimal resiliency, optimal volume, and optimal post-implant tensile recovery for implant purposes in accordance with the teachings of the present invention. Since the elastomeric materials of the present invention do not require cross-linking fillers to increase strength, they do not permanently deform upon expansion and contraction. This allows the resilient material to return 100% to its original, unstretched shape, which is important for a concentrating implant. The stretch crystalline elastomeric material may be adjusted in composition to adjust the stretch crystallization and melting temperatures to values best suited for simple implantation.

It is not uncommon for modern physicists to store the lens or other implant in a refrigerated environment prior to implantation, so it is preferable to stretch crystallize the elastic implant of the present invention at 0-25 c (normal room temperature) to deform it into a suitable small incision implant, or to chill the deformed implant at that temperature. The melting temperature of the stretched crystalline elastomer is preferably adjusted to a temperature close to the normal body temperature (about 37 ℃). Once the elastomer begins to lose its original structure or molecular arrangement upon induction of stretching, its melting point is reduced relative to that of the stretched crystalline material so that the implant will fully return to its original, unstretched, crystalline shape after implantation in the body. The loss of biocompatibility and free monomer in the elastomeric material allows the implant to also prevent post-implantation complications.

Known stretch-crystallizable elastomeric materials generally have melting points below normal body temperature. Such elastomeric materials cannot be used in practice to make medical implants because they do not maintain a stable, deformed small incision shape and are not easily manipulated. In addition, the implants need to have light gathering capabilities, which known stretch-crystallizable materials do not meet because they are opaque and do not have the correct power required for lens implants. Since the natural lens of the human eye has a diopter of 1.4, the stretch-crystallizable elastomeric material used to make the lens implants of the present invention preferably has a refractive index of 1.3 to 1.4 or greater. Higher refractive indices reduce the size, thickness and volume of the lens while ensuring the desired optical properties. More specifically, the use of a material having a refractive index of 1.4 or higher allows the optical lens to be produced with a diopter of greater than 20. While the lens made of the stretch-crystallizable material having a lower refractive index has a refractive power of only 15 or less.

Whether or not it is desired that the graft have polyThe optical property should be adjusted to a temperature close to or slightly lower than the body temperature of the stretch crystalline material used. An exemplary stretch crystallizable elastomeric material capable of meeting the stated requirements may be designated as F₃Homopolymers or copolymers of the monomers. For example, poly (methyl (3,3, 3-trifluoropropyl) siloxane) is a stretch-crystallizable elastomeric material of the siloxane type. The cis/trans ratio of the material is preferably between 40/60-100/0. The stretch crystalline melting temperatures of these materials are tunable. It was found that cis contributes to the stretch crystallization, and therefore higher melting materials can be obtained if the cis/trans ratio is between 40/60 and 100/0. Accordingly, by increasing the cis/trans ratio, a material with a higher stretch crystalline melting point can be obtained.

If the light-concentrating implant is made of a stretch-crystallizable elastomeric material, it is desirable to use a compatible monomer having a higher refractive index than F₃And (3) monomer phase copolymerization. Such as D, as is known in the art₃The refractive index of the monomer is generally higher than that of the F3 monomer. Biphenyl D known as hexaphenylcyclotrisiloxane₃Is also a monomer with a higher refractive index. 60 to 100 percent of F₃Monomers and from 0% to 40% of D₃The refractive index of the copolymer formed by the monomers is adjustable. In the copolymer D₃The higher the monomer content, the greater the refractive index of the copolymer. As can be appreciated by those skilled in the art, it is difficult to incorporate more than 40% of D in the copolymer₃A monomer.

The following non-limiting examples will further enable those skilled in the art to understand the present invention. The following examples illustrate the modification of the physical properties of stretch crystallizable elastomeric materials by varying the composition. Here, it is to be emphasized that: the following examples are merely illustrative of the principles of the present invention and are not meant to limit the scope of the invention to these examples.

Example 1

The first step in forming the stretch-crystallizable elastomer in accordance with the teachings of the present invention is: a bifunctional initiator was prepared for use in the formation of homopolymers and copolymers. The description is made here by taking a silicone elastomer as an example. 2g of diphenylsilanediol were dried at 110 ℃ under vacuum for 30 minutes. After cooling to room temperature again, purging with argon, 7.5ml of toluene and 7.5ml of THF were added to obtain a clear and transparent solution. Then 10. mu.l of polystyrene was added as an indicator. About 8ml of butyllithium (about 2.5M in hexane) was added dropwise until the solution just turned pale yellow, thus preparing a bifunctional initiator solution for use in the preparation of stretch-crystallizable elastomers.

Example 2

To produce an exemplary stretch-crystallizable elastomeric homopolymer, 10g (about 8ml) of F was added₃The monomer, poly (methyl (3,3, 3-trifluoropropyl) siloxane), was added to a 125ml reaction flask, dried under vacuum at 80 ℃ for 30 minutes, and then cooled to room temperature, wherein F was used₃The cis content of the monomer is about 60% and the trans content is about 40%. The cis/trans ratio was chosen to be 60/40 so that the melting point after stretch crystallization could be adjusted to a temperature close to normal body temperature. If a lower cis/trans ratio is chosen, the resulting material will have a melting point lower than the normal temperature of the human body.

1ml of THF and 7ml of Chloroform (CH) were added₂CL₂) And stirred for several minutes. 1ml of the bifunctional initiator prepared in example 1 was added to initiate the reaction under argon at room temperature. After 4 hours the reaction was stopped by adding 0.5ml of vinyldimethylchlorosilane and triethylamine. Washing with distilled water, dissolving THF, precipitating with methanol to obtain 8g F₃A polymer. The resulting homopolymer was clear, had an average molecular weight (M) of 40,000, and had a polydispersity of 1.1 and a refractive index of 1.383.

At 5g of F₃To the homopolymer were added 2. mu.l of a platinum (Pt) catalyst (Pt concentration of 2.5%), 8. mu.l of a polymerization inhibitor and 45. mu.l of tetrakis (dimethylsiloxy)Silane crosslinker and degassing the viscous fluid with a centrifuge to F₃The homopolymers are crosslinked together.

This gives F of crosslinked poly (methyl (3,3, 3-trifluoropropyl) siloxane)₃The copolymer, which has a cis/trans ratio of about 60/40, has a refractive index of 1.383. The silicone elastomer has optical transparency and good mechanical strength, and has an elongation in a certain direction of 600% or more. The polymer can be easily stretched and crystallized to form a stable shape at a temperature of less than 20 ℃. Heating the stretched crystalline material to about 35 c allows the material to recover its original shape in a few seconds. Disc-shaped intraocular lenses with an optical zone of 6mm can be made with this material. The lens is stretched into a thin rod shape of about 40mm in length and then the stretched lens is cooled in cold water at about 0-4 c to produce a stable, relatively hard rod shaped graft that is easy to handle by hand or forceps. The cooled rod graft is heated to a temperature between about 30℃ and about 40℃ to restore the original disc-shaped intraocular lens in less than about 5 seconds. The optical resolution of the lens remains unchanged during this process. Because of the low refractive index of this material, the maximum power of an intraocular lens made with this material having a 6mm optic zone is about 15.

Since most intraocular lens users require lenses of 20 diopters or greater, a higher refractive index stretch-crystallizable elastomeric material can be obtained by copolymerizing the homopolymer of example 2 with a monomer having a higher refractive index.

Example 3

To produce a stretch-crystallizable elastomer having a refractive index higher than that of the homopolymer described in example 2, 8g of F described in example 2 was used₃Monomer (cis/trans ratio 60/40) and 2g of biphenyl D₃Or hexaphenylcyclotrisiloxane, was added to a 125ml reaction flask, dried under vacuum at 110 deg.C for 30 minutes, and then cooled to 45 deg.C (oil bath temperature).2ml of THF and 14ml of methylene Chloride (CH)₂CL₂) Adding to the cooled solution and stirring for several minutes until biphenyl D₃And completely dissolving. 0.5ml of the bifunctional initiator prepared in example 1 was added to the reaction flask and the mixture was refluxed at 45 ℃ under argon. After 10 hours, the reaction was terminated by cooling, and then 0.2ml of vinyldimethylchlorosilane and triethylamine were added. 6g of the copolymer was collected by washing with distilled water and toluene and then precipitating with hexane. The resulting copolymer is clear and has a mean molecular mass (M)_n) 50,000 and a refractive index of 1.383. If desired, 5g of the co-homopolymer can be combined with 2. mu.l of platinum (Pt) catalyst (Pt concentration of 2.5%), 8. mu.l of inhibitor and 40. mu.l of tetrakis (dimethylsiloxane) silane crosslinker, and the mixture degassed with a centrifuge to crosslink the copolymers together.

As in example 2, an elastic strip was obtained by vulcanizing the copolymer obtained in example 3 at 100 ℃ to 140 ℃ for several minutes. The stretch-crystallizable elastomers thus produced have optical clarity and good mechanical strength, and can have elongations in one direction of more than 600%. The polymer can be easily stretched and crystallized to form a stable shape at a temperature of less than 4 ℃. Heating the stretched crystalline material to about 35 c allows the material to recover its original shape in a few seconds.

Intraocular lenses made with such optically clear, high refractive index, stretch-crystallizable elastomeric copolymers have diopters between 20 and 25. 6 disc-shaped intraocular lenses were molded from the copolymerized elastomer obtained in example 3 at 140 ℃ for 5 minutes. The optical resolution of the resulting lenses can be measured by conventional techniques and found to be comparable to that of commercially available intraocular lenses made from conventional, non-stretched crystalline materials. The lens obtained by stretch crystallization can be elongated 5 times longer than the original length and can stably maintain the shape after stretch deformation after cooling in an ice-water bath. The lens after the stretch crystallization is immersed in hot water at about 35 c, and the lens immediately recovers its original shape. After the lens is recovered, its optical resolution is measured and compared to the resolution before the stretching crystallization. As a result, it was found that the resolution after restoration was equal to or better than that of the lens before deformation. In addition, the difference in the size of the lens before and after the stretch crystallization was also measured to be less than 0.2%.

To demonstrate that the physical properties of stretch-crystallizable elastomers can be well adjusted by varying the preparation techniques, a number of copolymer formulation schemes have been implemented.

Example 4

The reaction described in example 3 was allowed to continue for 21 hours instead of only 10 hours as in example 3. The reaction was terminated by cooling to room temperature, as described in example 3, and then 0.2ml of vinyldimethylchlorosilane and triethylamine were added. 7g of the copolymer was collected by washing with distilled water and toluene and then precipitating with hexane. The resulting copolymer is clear and has a mean molecular mass (M)_n) 53,000 and a refractive index of 1.418.

The stretch-crystallizable copolymers obtained with this formulation have a higher refractive index, which allows lenses with smaller cross-sections and smaller volumes. However, the above-mentioned advantages are offset by the reduction in mechanical strength and elongation of the material. If the polymer in this example is crosslinked using the method described in example 3, the resulting polymer has an elongation of less than 200%. Thus, the advantage of the high refractive index of this material is offset by the disadvantage of not being able to achieve the elongation described in example 3. However, this material may be suitable for making other stretch-crystallizable implants than intraocular lenses.

The following describes a scheme for adjusting the physical properties of the stretch-crystallizable elastomer by changing the reaction temperature.

Example 5

The reaction described in example 3 was repeated, except that the temperature of the oil bath was changedThe temperature is increased from the original 45 ℃ to 70 ℃. After the reaction was continued for 10 hours, the reaction was terminated by cooling to room temperature, and then 0.2ml of vinyldimethylchlorosilane and triethylamine were added. 7g of the copolymer was collected by washing with distilled water and toluene and then precipitating with hexane. The resulting copolymer is clear and has a mean molecular mass (M)_n) 54,000 and a refractive index of 1.4. After crosslinking as described above, an elastomer is obtained which has the same mechanical strength as the product described in example 3. The elastomeric copolymers which are stretch-crystallizable have physical and mechanical properties suitable for use in making medical implants including intraocular lenses.

Additional variations of the preparation are described in the following non-limiting examples, which further illustrate the ability to adjust and optimize the physical and mechanical properties of the elastic materials of the present invention.

Example 6

The temperature of the reaction described in example 3 was lowered from 45 ℃ to room temperature, while the reaction time was extended from 10 hours to 21 hours. After 21 hours of reaction time, a small amount of material was removed and the refractive index was measured to be 1.390. After the reaction was carried out for 48 hours, the reaction was terminated by cooling to room temperature, and then 0.2ml of vinyldimethylchlorosilane and triethylamine were added. 7g of the copolymer was collected by washing with distilled water and toluene and then precipitating with hexane. The resulting copolymer is clear and has a mean molecular mass (M)_n) 36,000 and a refractive index of 1.392. The mechanical strength of the stretch-crystallizable elastomer obtained after crosslinking is lower than that of the material obtained in example 3. The reduction in refractive index and mechanical strength renders the intermediate material unsuitable for use in making intraocular lens implants. But such materials may be suitable for making other implants.

Example 7

The reaction described in example 4 was repeated, except that THF was used as the solvent instead of dichloromethane. The alkane dichloride of example 3 was replaced by 16ml of THF. After 2 hours of reaction, the solution viscosity decreased. The reaction was terminated by cooling to room temperature, and then 0.2ml of vinyldimethylchlorosilane and triethylamine were added. The polymer was substantially not collected by washing with distilled water and toluene and then precipitating with hexane.

Example 8

The reaction in example 9 above was repeated except that the reaction temperature was lowered to room temperature. After 2 hours of reaction, the solution viscosity decreased. The reaction was terminated by cooling to room temperature, and then 0.2ml of vinyldimethylaminosilane and triethylamine were added. The polymer was substantially not collected by washing with distilled water and toluene and then precipitating with hexane.

Example 9

A stretch-crystallizable elastomeric siloxane copolymer was prepared according to the protocol of example 3, except that benzyl D was used as in example 3₃Or 1,3, 5-benzene-2, 4, 6-methylcyclosiloxane as an alternative to the comonomer biphenyl D used in the examples₃. The procedure is as in example 3, 8g of F₃Monomer (cis/trans ratio 60/40) and 2g of benzyl D₃Or hexaphenylcyclotrisiloxane, was added to a 125ml reaction flask, dried under vacuum at 80 deg.C for 30 minutes, and then cooled to 45 deg.C (oil bath temperature). 2ml of THF and 8ml of methylene Chloride (CH)₂CL₂) Added to the cooled solution and the solution was stirred for a few minutes. 0.5ml of the dual initiator was added to the reaction flask and the mixture was refluxed at 45 ℃ under argon. After 10 hours of reaction, the solution became viscous, the reaction was terminated by cooling to room temperature, and then 0.2ml of vinyldimethylchlorosilane and triethylamine were added. The polymer collected, washed with distilled water and toluene and precipitated with methanol, had a refractive index of 1.383, indicating that no copolymerization had occurred.

Example 10

The reaction in example 9 was repeated except that the reaction temperature was increased to 110 deg.C (oil bath temperature). After 5 hours of reaction, the solution became viscous, the reaction was terminated by cooling to room temperature, and then 0.2ml of vinyldimethylchlorosilane and triethylamine were added. The polymer collected, washed with distilled water and toluene and precipitated with methanol, had a refractive index of 1.383, indicating that no copolymerization had occurred.

Those skilled in the art will appreciate that the foregoing embodiments provide many alternative variations. Other variations are also within the scope of the invention. By way of non-limiting example, it is seen that the stretch-crystallizable implants of the present invention may also be used as cosmetic implants for reconstructive or reinforcement purposes. Such implants include: artificial chin, cheekbones, nose, ears and other parts of the human body, and also includes implants of the chest and the penis. Other grafting devices may be used to effect grafting in accordance with the principles and teachings of the present invention. There are also a number of implants that can be implanted into the body through a small, relatively atraumatic surgical incision. The present invention is not limited to what is specifically described and illustrated in the present application.

Claims (25)

1. An improved medical implant made of a stretch-crystallizable, deformable elastomer.

2. The medical implant of claim 1 further comprising another portion made of a material that is not stretch crystallizable.

3. The medical implant of claim 1 wherein said elastomer is a stretch-crystallizable silicone.

4. The medical implant of claim 3 wherein said stretch crystallizable silicone is selected from the group consisting of homopolymers of methyl (3,3, 3-trifluoropropyl) siloxane and copolymers of methyl (3,3, 3-trifluoropropyl) siloxane and hexaphenylcyclotrisiloxane.

5. The medical implant of claim 4 wherein said methyl (3,3, 3-trifluoropropyl) siloxane has a cis/trans ratio ranging from about 40/60 to 100/0.

6. The medical implant of claim 5 wherein said stretch-crystallizable silicone has a crystallization temperature of between-100 ℃ and 50 ℃.

7. The medical implant of claim 5 wherein said stretch-crystallizable silicone has a crystallization temperature of between-20 ℃ and 50 ℃ and a recovery temperature of between 0 ℃ and 50 ℃.

8. The medical implant of claim 5 wherein said stretch-crystallizable silicone is optically clear and has a refractive index of between 1.38 and 1.46.

9. The medical implant of claim 5 wherein said stretch-crystallizable silicone has an elongation of from about 300% to about 600%.

10. The medical implant of claim 9 configured for use as an intraocular lens.

11. An intraocular implant configured to reduce implantation trauma, the light-focusing optical portion of which is made of a stretch-crystallizable silicone elastomer having a refractive index of between about 1.38 and 1.46.

12. The intraocular implant of claim 11 wherein said implant is an intraocular lens.

13. The intraocular implant of claim 12 wherein said intraocular lens comprises a balloon-type lens.

14. The intraocular implant of claim 12 further comprising a haptic portion.

15. The intraocular implant of claim 11 wherein said implant is an implantable contact lens.

16. The intraocular implant of claim 11 wherein said stretch crystallizable silicone is selected from the group consisting of homopolymers of methyl (3,3, 3-trifluoropropyl) siloxane and copolymers of methyl (3,3, 3-trifluoropropyl) siloxane and hexaphenylcyclotrisiloxane.

17. The intraocular implant of claim 16 wherein said methyl (3,3, 3-trifluoropropyl) siloxane has a cis/trans ratio ranging from about 40/60 to 100/0.

18. The intraocular implant of claim 16 wherein said stretch-crystallizable silicone has a crystallization temperature between-100 ℃ and 50 ℃.

19. The intraocular implant of claim 16 wherein said stretch-crystallizable silicone has a crystallization temperature between-20 ℃ and 50 ℃ and a recovery temperature between 0 ℃ and 50 ℃.

20. The intraocular implant of claim 16 wherein said stretch crystallizable silicone has an elongation of about 300% to 600%.

21. A method of surgical implantation with reduced trauma comprising the steps of:

providing a stretch-crystallizable, deformable implant;

subjecting said graft to stretch crystallization to become a stable shape suitable for small incision implantation;

the stretch-crystallized graft is implanted into the patient through a small incision.

22. The surgical implantation method of claim 21 further comprising the additional step of cooling said implant after said stretch crystallization step.

23. The surgical implantation method of claim 21 wherein said stable implant shape suitable for small incision implantation is an elongated or sheet-like shape.

24. The surgical implantation method of claim 23 further comprising the additional step of loading the stretch-crystallized, small-incision-compatible graft into an implantation device having a port prior to said implanting step.

25. A device for deforming a stretch-crystallizable medical implant into a shape suitable for small incisions, said device comprising:

a female die, the female die is provided with a longitudinal receiving groove, and the bottom of the receiving groove is provided with a die cavity; and

a male extrusion die having a longitudinally projecting guide member with a mating surface, the guide member being slidably engageable with the receiving slot to form the shape of the die cavity.