Abstract:
An intraocular lens ( 30 ) having focusing capabilities permitting focusing movement of the lens ( 30 ) in response to normal ciliary body ( 24 ) movement incident to changes in the distance between the eye and an object under observation is provided. The lens ( 30 ) is designed for surgical implantation within the capsule ( 20 ) of an eye ( 10 ) and includes an optic ( 32 ) and an optic positioning element ( 33 ) which cooperate to form the lens ( 30 ). Accommodation is achieved by relying upon the thickening and thinning of the optic ( 32 ) as a result of the normal retracting and contracting of the ciliary body ( 24 ) in response to the distance of an object from the viewer.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to accommodating intraocular lenses which can be surgically implanted as a replacement for the natural crystalline lens in the eyes of cataract patients.  
         [0003]     2. Description of the Prior Art  
         [0004]     Cataracts occur when the crystalline lens of the eye becomes opaque. The cataracts may be in both eyes and, being a progressive condition, may cause fading vision and eventual blindness. Cataracts were once surgically removed along with the anterior wall of the capsule of the eye. The patient then wore eyeglasses or contact lenses which restored vision but did not permit accommodation and gave only limited depth perception.  
         [0005]     The first implant of a replacement lens within the eye occurred in 1949 and attempted to locate the replacement lens in the posterior chamber of the eye behind the iris. Problems such as dislocation after implantation forced abandonment of this approach, and for some period thereafter intraocular lenses were implanted in the anterior chamber of the eye.  
         [0006]     Others returned to the practice of inserting the lens in the area of the eye posterior to the iris, known as the posterior chamber. This is the area where the patient&#39;s natural crystalline lens is located. When the intraocular lens is located in this natural location, substantially normal vision may be restored to the patient and the problems of forward displacement of vitreous humor and retina detachment encountered in anterior chamber intraocular lenses are less likely to occur. Lenses implanted in the posterior chamber are disclosed in U.S. Pat. Nos. 3,718,870, 3,866,249, 3,913,148, 3,925,825, 4,014,049, 4,041,552, 4,053,953, and 4,285,072. None of these lenses has focusing capability.  
         [0007]     Lenses capable of focusing offer the wearer the closest possible substitute to the crystalline lens. U.S. Pat. No. 4,254,509 to Tennant discloses a lens which moves in an anterior direction upon contraction of the ciliary body, and which is located anterior to the iris. Though providing focusing capabilities, it presents the same disadvantages as other anterior chamber lenses.  
         [0008]     U.S. Pat. No. 4,409,691 to Levy is asserted to provide a focusable intraocular lens positioned within the capsule. This lens is located in the posterior area of the capsule and is biased toward the fovea or rear of the eye. The &#39;691 lens is deficient because it requires the ciliary muscle to exert force through the zonules on the capsule in order to compress the haptics inward and drive the optic forward for near vision. However, the ciliary muscles do not exert any force during contraction because the zonules, being flexible filaments, exert only tension, not compression on the capsule. The natural elasticity of the lens causes the capsule to become more spherical upon contraction of the ciliary muscle. Thus, there is no inward force exerted on the capsule to compress the haptics of the Levy lens, and therefore accommodate for near vision.  
         [0009]     U.S. Pat. No. 5,674,282 to Cumming is directed towards an accommodating intraocular lens for implanting within the capsule of an eye. The Cumming lens comprises a central optic and two plate haptics which extend radially outward from diametrically opposite sides of the optic and are movable anteriorly and posteriorly relative to the optic. However, the Cumming lens suffers from the same shortcomings as the Levy lens in that the haptics are biased anteriorly by pressure from the ciliary bodies. This will eventually lead to pressure necrosis of the ciliary body.  
         [0010]     There is a need for an intraocular lens implant capable of focusing in a manner similar to the natural lens. This lens implant should be readily insertable into the capsule and should last for a substantial number of years without damaging any of the eye components.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention fills this need by providing an intraocular lens with focusing capabilities which is safe for long-term use in an eye.  
         [0012]     In more detail, the lens of the invention comprises an optic coupled to an optic positioning element. The optic positioning element is preferably balloon-shaped or preferably comprises an outwardly extending disc (optionally with thicker, radially extending “winged” portions separated by thin membranes). The optic is resilient and can be formed of a solid material (e.g., silicone) or can be gas-filled.  
         [0013]     As a result of the size and shape of the inventive lens and the material of which the optic is formed, the focusing action of the natural lens is simulated. That is, the ciliary body of the eye continues to exert a muscular force radially outward from the center of the capsule through the zonular fibers so as to alter the thickness of the optic, resulting in a decrease in light convergence as is necessary for viewing objects distant from the viewer. When viewing an object close to the viewer, the ciliary body contracts, thus releasing the outward pull on the zonular fibers. This alters the thickness of the optic to result in an increase in light convergence as is necessary for viewing nearby objects.  
         [0014]     The optic can be one of many shapes as described in more detail below. Furthermore, the optic can be formed of a solid, liquid, or gel refractive material, or the optic can be gas-filled (e.g., air) so long as the chosen materials are safe for use in the eye. The shape of the optic and the material of which the optic is formed are dependent upon one another. That is, the shape is chosen based upon the refractive index of the material used to form the optic, and this choice is made to result in an optic which will highly converge light upon contraction of the ciliary body. Thus, if the refractive index of the optic material is greater than about 1.33 (the refractive index of the fluids within the eye), then optic shapes such as meniscus, planoconvex, and biconvex would converge light. On the other hand, if the refractive index of the optic material is less than about 1.33, then optic shapes such as biconcave and planoconcave would converge light. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES  
       [0015]      FIG. 1  is a vertical sectional view showing placement of the lens of the invention within the capsule of an eye, with the eye focused on an object distant from the viewer;  
         [0016]      FIG. 2  is a vertical sectional view showing the change in shape of the lens of  FIG. 1  when focused on an object near the viewer;  
         [0017]      FIG. 3  is a perspective view of the lens of  FIGS. 1-2 , shown in its resting state;  
         [0018]      FIG. 4  is a vertical sectional view showing another embodiment of the inventive lens, with the lens being focused on an object distant from the viewer;  
         [0019]      FIG. 5  is a vertical sectional view showing the change in shape of the lens of  FIG. 4  when focused on an object near the viewer;  
         [0020]      FIG. 6  is a vertical sectional view showing another embodiment of the inventive lens, with the lens being focused on an object distant from the viewer;  
         [0021]      FIG. 7  is a vertical sectional view showing the change in shape of the lens of  FIG. 6  when focused on an object near the viewer;  
         [0022]      FIG. 8  is a vertical sectional view showing another embodiment of the inventive lens having a gas-filled optic, with the lens being focused on an object distant from the viewer;  
         [0023]      FIG. 9  is a vertical sectional view showing the change in shape of the lens of  FIG. 8  when focused on an object near the viewer;  
         [0024]      FIG. 10  is a vertical sectional view showing another embodiment of the inventive lens where the lens has a gas-filled optic;  
         [0025]      FIG. 11  is a vertical sectional view showing another inventive lens having a combination optic;  
         [0026]      FIG. 12  is an upper perspective view of another lens according to the invention utilizing a resilient optic with a different type of optic positioning element;  
         [0027]      FIG. 13  is a lower perspective view of the lens of  FIG. 12 ;  
         [0028]      FIG. 14  is a sectional view of the lens shown in  FIGS. 12-13 ; and  
         [0029]      FIG. 15  is a sectional view of another embodiment of the lens of  FIG. 12 , where the optic is a combination optic. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]     Referring now to the drawings, the present invention is in the form of an intraocular lens for surgical replacement of the human lens in the treatment of cataracts in the human eye.  FIG. 1  shows the various components of the human eye pertinent to this invention. Briefly, the eye  10  includes a frontal portion  12  and a rearward portion (not shown). The frontal portion  12  of the eye  10  is covered by a cornea  14  which encloses and forms an anterior chamber  16 . The anterior chamber  16  contains aqueous fluid and is bounded at the rear by an iris  18 . The iris  18  opens and closes to admit appropriate quantities of light into the inner portions of the eye  10 . The eye  10  includes a capsule  20  which ordinarily contains the natural crystalline lens. When the eye  10  focuses, the capsule  20  changes shape to appropriately distribute the light admitted through the cornea  14  and the iris  18  to the retina (not shown) at the rearward portion of the eye  10 .  
         [0031]     Although not shown in the accompanying figures, the retina is composed of rods and cones which act as light receptors. The retina includes a fovea which is a rodless portion which provides for acute vision. The outside of the rearward or posterior portion of the eye  10  is known as the sclera. The sclera joins with, and forms a portion of, the covering for the optic nerve. Images received by the retina are transmitted through the optic nerve to the brain. The area between the retina and the capsule  20  is occupied by vitreous fluid. Finally, the eye  10  includes a ciliary muscle or body  24  having zonular fibers  26  (also referred to as zonules) which are attached to the capsule  20 .  
         [0032]     Ocular adjustments for sharp focusing of objects viewed at different distances is accomplished by the action of the ciliary body  24  on the capsule  20  and crystalline lens (which would be located at numeral  28  in the natural, unmodified eye) through the zonular fibers  26 . The ciliary body  24  contracts, allowing the capsule  20  to return to a more spherical shape for viewing objects that are nearer the viewer. When the ciliary body  24  retracts and pulls on the zonular fibers  26  to make the capsule  20  more discoid, objects at a distance can be viewed in proper focus.  
       1. Lens Embodiment of FIGS.  1 - 3   
       [0033]     Referring to  FIGS. 1-3 , the inventive lens is an accommodating lens  30  which includes a biconvex optic  32  and an optic positioning element  33 . The optic  32  comprises a convex anterior surface  34  and a convex posterior surface  36 . The optic positioning element  33  comprises a resilient body  38 . Resilient body  38  comprises an outer wall  40  which extends radially from optic  32 . Resilient body  38  is preferably integral and essentially flush with optic  32  at optic perimeter  42  where wall  40  joins optic  32 . Wall  40  then curves to form a bight  44  and converges on the posterior side  46  of lens  30 . Wall  40  forms a chamber  48  and terminates at location  50  to form an opening  52  which communicates with the chamber  48 , allowing fluids to enter and fill the chamber  48 .  
         [0034]     Preferably, the overall shape of lens  30  in its original resting, non-deformed shape generally conforms to the shape of capsule  20  when capsule  20  is focused to view an object near the viewer ( FIGS. 1 and 3 ). Thus, outer wall  40  of the resilient body  38  cooperates with optic  32  to form a lens having an overall discoid or saucer-like shape as best shown in  FIG. 1 . The lens  30  is of sufficient size that optic  32  mildly urges against the posterior wall  54  of the capsule  20 , while the posterior side  46  of lens  30  urges against the anterior wall  56  of the capsule  20 . The optic  30  is formed of a resilient, bendable material which allows for changes in thickness of optic  30 .  
         [0035]     Intraocular lens  30  substitutes both locationally and functionally for the original, natural, crystalline lens (which would normally be at location  28 ). To insert the lens  30  into the capsule  20 , an ophthalmic surgeon would remove the natural lens (and thus the cataracts) by conventional methods, leaving an opening  58  in the anterior wall  56  of the capsule  20 . Lens  30  is then folded into a compact size for insertion into the capsule  20  through the opening  58 . Once inserted, the capsule  20  is filled with fluids (e.g., saline solution) which enter the chamber  48  of the lens  30 , causing the lens  30  to return to its original, non-deformed state as shown in  FIGS. 1 and 3 . There is no need to suture the lens  30  to the capsule  20  because, due to the size and shape of the lens  30  as described above, the lens  30  will not rotate or shift within the capsule  20 .  
         [0036]     Implantation of the inventive lens  30  restores normal vision because, not only does the lens  30  replace the patient&#39;s occluded natural lens, but the normal responses of the ciliary body  24  cooperate with the lens  30  during focusing. In  FIG. 1 , the capsule  20  is shaped for viewing an object distant from the eye  10 . That is, in order to view an object distant from the viewer, the ciliary body  24  has retracted, thus pulling on the zonular fibers  26 , making the capsule  20  (and thus the lens  30 ) more discoid in shape. This change in shape causes the optic  32  to become thinner (i.e., there is a decrease in the horizontal depth of the optic  32 ) so that it has a thickness T D . As used herein, the thickness of the optic is intended to be the thickness at approximately the center of the optic.  
         [0037]     Optic  32  is formed of a solid, liquid, or gel material (e.g., silicone) so it has a refractive index greater than that of the surrounding fluid in the eye (i.e., greater than 1.33). This refractive index, combined with the thinness of optic  32  as shown in  FIG. 1 , results in a less convergent lens which makes distance viewing possible.  
         [0038]     Referring to  FIG. 2 , the ciliary body  24  has contracted, making the capsule  20  more spheroid in shape. As a result, the optic  32  has had an increase in thickness to a thickness of T N  . The thickness increase should be such that T N  is at least about 1.1 times, preferably at least about 1.2 times, and more preferably from about 1.2-1.4 times that of T D  when a force of from about 1-9 grams, and preferably from about 6-9 grams, is applied to the optic positioning element (more specifically, to the outer edges of the optic positioning element or around the equatorial region of the optic positioning element). As used herein, the force is a measure of an inwardly directed force in the plane of the equator equally distributed over 360 degrees around the equator.  
         [0039]     This increase in optic thickness combined with the fact that the refractive index of the optic  32  is greater than 1.33 (and preferably at least about 1.36, more preferably at least about 1.4, and even more preferably at least about 1.5) results in an increased convergence of light, thus enabling the eye to see objects near the viewer. The lens  30  thus follows the eye&#39;s natural physiology for focusing to provide a substitute means of optical accommodation.  
       2. Embodiment of FIGS.  4 - 5   
       [0040]     While the anterior surface  34  and the posterior surface  36  of the lens  30  of  FIGS. 1-3  are both convex, the shapes of these surfaces can be varied depending upon the user&#39;s eyesight. One such variation is shown in  FIGS. 4-5 .  
         [0041]      FIGS. 4-5  show a lens  70  which is similar in construction to the lens  30  of  FIGS. 1-3  with the exception of the optic construction. That is, lens  70  includes a planoconvex optic  72 . The optic  72  comprises a planar anterior surface  74  and a convex posterior surface  76 . Lens  70  operates to provide accommodation in the same manner as discussed above with respect to lens  30 .  
       3. Embodiment of FIGS.  6 - 7   
       [0042]      FIGS. 6-7  show a lens  78  which is similar in construction to the lens  30  of  FIGS. 1-3  with the exception of the optic construction. Lens  78  includes an optic  80  whose cross-section is meniscus in shape. That is, the optic  80  comprises a concave anterior surface  82  and a convex posterior surface  84  so that the curves of surfaces  82 ,  84  follow the same general direction of curvature. Lens  78  operates to provide accommodation in the same manner as discussed above with respect to lens  30 .  
       4. Embodiment of FIGS.  8 - 9   
       [0043]      FIGS. 8-9  show a lens  86  which is also similar in construction to the lens  30  of  FIGS. 1-3  with the exception of the optic construction. Lens  86  includes an optic  88  whose cross-section is meniscus in shape. That is, the optic  88  comprises a concave anterior wall  90  and a convex posterior wall  92  so that the curves of walls  90 ,  92  follow the same general direction of curvature.  
         [0044]     While lens  86  includes a meniscus-shaped optic  88  like that of the embodiment of  FIGS. 6-7 , the optic  88  is very different from optic  80  of lens  78  in that optic  88  is gas-filled. That is, walls  90 ,  92  cooperate with endwalls  94   a,b  to form a chamber  96 . Chamber  96  is filled with a gas. While any biologically safe gas is acceptable, the preferred gas is simply air. Also, walls  90 ,  92  and endwalls  94   a,g  can be formed of the same materials described previously with respect to optic and optic positioning element materials.  
         [0045]     Although lens  86  has a gas-filled optic  88  rather than a solid optic, lens  86  still operates to provide accommodation in a somewhat similar manner as discussed above with respect to lens  30 . In more detail and referring to  FIG. 8 , the lens  86  is shaped for viewing an object distant from the viewer. That is, in order to view an object distant from the viewer, the ciliary body (not shown) has retracted, thus pulling on the zonular fibers and making the lens  86  more discoid in shape. This change in shape causes the optic  88  to become thicker (i.e., there is an increase in the horizontal depth of the optic  88  or there is an increase in the distance between wall  90  and wall  92 ) so that the optic  88  has a thickness T d . However, because optic  88  is filled with a gas, a thicker optic  88  results in a lesser convergence of light because the gas has a refractive index which is lower than the refractive index of the fluids in the eye (i.e., less than about 1.3, preferably less than about 1.2, and more preferably less than about 1.0), thus making optic  88  suitable for distance viewing.  
         [0046]     Referring to  FIG. 9 , the ciliary body (not shown) has contracted, making the lens  86  more spheroid in shape. As discussed with previous embodiments, a solid optic would incur an increase in thickness as a result of the contraction. However, due to the fact that optic  88  is gas-filled, the distance between wall  90  and wall  92  decreases, thus causing optic  88  to have a decrease in thickness to a thickness of T n . This decrease in optic thickness results in an increased convergence of light, thus enabling the eye to see objects near the viewer. Thus, the thickness decrease when a force of from about 1-9 grams, and preferably from about 6-9 grams, is applied to the optic positioning element (more specifically, to the outer edges of the optic positioning element or around the equatorial region of the optic positioning element) should be such that T d  is at least about 1.2 times, preferably at least about 1.3 times, and more preferably from about 1.3-1.35 times that of T n .  
       5. Embodiment of FIG.  10   
       [0047]      FIG. 10  shows a lens  100  which is similar in overall construction to the lens of  FIGS. 8-9  except that lens  100  includes a biconcave optic  102 . Optic  102  includes an anterior, concave wall  104 , a posterior concave wall  106 , and a pair of endwalls  108   a,b.  Walls  104  and  106  cooperate with endwalls  108   a,b  to form gas-filled chamber  110  which is filled with a biologically safe gas such as air. The lens  100  operates to provide accommodation in a manner similar to that described with respect to lens  86  of  FIGS. 8-9 .  
       6. Embodiment of FIG.  11   
       [0048]      FIG. 11  shows a lens  120  which is constructed in a manner similar to that of the preceding lens embodiments with the exception of the optic construction. Lens  120  includes a combination optic  122  which combines aspects of the optics shown in  FIGS. 1-7  with the type of optic disclosed in  FIGS. 8-10 . That is, the optic  122  comprises a biconvex, solid optic  124  and a gas-filled optic  126 . Optic  124  includes a convex, anterior surface  128  and a convex posterior surface  130 . Optic  126  includes a convex, posterior wall  132  and endwalls  134   a,b  which cooperate with convex posterior surface  130  of optic  124  to form a gas-filled chamber  136 . Again, any biologically safe gas is acceptable, although air is preferred.  
         [0049]     The lens  120  operates to provide accommodation in a manner similar to that described with respect to lens  86  of  FIGS. 8-10 . That is, the gas-filled optic  126  will become thinner, and the solid optic  124  may become thicker upon contraction of the ciliary body, thus causing an increased convergence of light to allow for near viewing. Upon retraction of the ciliary body, the opposite will occur. That is, the lens  120  will become more discoid in shape so that the gas-filled optic  126  will become thicker while the solid optic  124  will become thinner, thus causing a decreased convergence of light to allow for distance viewing.  
       7. Embodiment of FIGS.  12 - 14   
       [0050]      FIGS. 12-15  illustrate embodiments where a different type of optic positioning element is utilized. Referring to  FIGS. 12-13 , the lens includes an optic  142  and an optic positioning element  144 . Optic  142  can be of any known optic construction, or it can be any of the inventive optics disclosed herein.  
         [0051]     Optic positioning element  144  comprises a skirt  146  which includes a plurality of radially extending elements  148 . In the embodiment shown, elements  148  comprise respective openings  150 . The respective sizes and shapes of openings  150  are not critical so long as they are capable of allowing fibrosis of the tissue. Furthermore, openings  150  can be omitted if desired.  
         [0052]     Elements  148  are joined to one another by thin membranes  152 . Alternately, optic positioning element  144  can simply include a circular or disc-shaped haptic having a substantially uniform thickness (i.e., rather than thicker radially extending elements  148  and thinner membranes  152 ) extending from the optic.  
         [0053]     Elements  148  and membranes  152  are generally formed of the same material (e.g., silicones, acrylates) but with a difference in thicknesses, although the material can be different, and the selection of material is not critical so long as it is biologically safe and at least somewhat resilient. It will be appreciated that the respective thicknesses of elements  148  and membranes  152  can be adjusted as necessary by one of ordinary skill in the art. Ideally, the elements  148  will be of sufficient respective thicknesses to provide resistance to the force created on the outer edges  154  of the elements  148  by the contraction of the ciliary body. The respective thicknesses of the membranes  152  should be such that the flexibility of the overall skirt  146  is maintained while being resistant to tearing.  
         [0054]      FIG. 14  shows one type of possible optic construction for use with this type of optic positioning element  144 . In this embodiment, lens  160  is shown within a capsule  20  of an eye. The optic  142  includes a posterior convex surface  156  and an anterior convex surface  158 . In the embodiment shown, optic  142  is integrally formed with elements  148 , although this is not mandatory. Finally,  FIG. 14  demonstrates the formation of fibrin  160  (fibrosis) through openings  150 .  
         [0055]     Lens  140  would operate to provide accommodation in a manner similar to that described with respect to lens  30  of  FIGS. 1-3 . That is, the ciliary body (not shown) would retract or contract as necessary, thus either pulling on the zonular fibers  26  or releasing the pull on the zonular fibers  26 . Due to the fibrin  160  formed through openings  150 , this would necessarily result in an outward force on elements  148  (resulting in the thinning of optic  142 ) or the release of that outward force (resulting in the thickening of optic  142 ). Because optic  142  is formed of a material having a refractive index of greater than 1.33, thickening of optic  142  would result in increased convergence of light for near viewing and thinning of optic  142  would result in decreased convergence of light for distance viewing.  
       8. Embodiment of FIG.  15   
       [0056]      FIG. 15  shows another lens according to the invention. This lens is constructed similarly to that of  FIGS. 12-14  except that a different optic is utilized. Specifically, lens  170  comprises a combination optic  172  and an optic positioning element  174 . Optic positioning element  174  is similar to optic positioning element  144  of  FIGS. 12-14  in that it includes a plurality of radially extending elements  176  connected via thin membranes (not shown). Combination optic  172  comprises a biconvex optic  178  and a meniscus optic  180 . Biconvex optic  178  includes a convex, anterior surface  182  and a convex, posterior surface  184 . Optic  180  includes a concave, anterior wall  186  and a convex, posterior wall  188 .  
         [0057]     The lens  170  of  FIG. 15  is particularly unique in that each of the optics  178  and  180  of the combination optic  172  is prepared in a different state of accommodation. In the embodiment shown, optic  180  is formed in the disaccommodated state while the optic  178  is formed in the accommodated state. Due to strength differences, optic  180  has the greater influence when it is joined with optic  178 . Thus, the overall combination optic  172  will rest in, or default to (absent a counteracting external force), the disaccommodated state due to the fact that optic  180  will stretch optic  178  to the disaccommodated state.  
         [0058]     When the ciliary body (not shown) retracts or contracts as necessary (either pulling on the zonular fibers or releasing the pull on the zonular fibers), the fibrin (not shown) formed through openings  150  would result in a radially outward force on elements  176  (resulting in the thinning of optics  178 ,  180 ) or the release of that outward force (resulting in the thickening of optic  178 ,  180 ). Because optics  178 ,  180  are formed of materials (either the same or different) having respective refractive indices of greater than 1.33, thickening of optics  178 ,  180  would result in an increased convergence of light for near viewing, and thinning of optic  178 ,  180  would result in a decreased convergence of light for distance viewing.  
         [0059]     Each of the foregoing embodiments can be used to obtain an accommodation improvement of at least about 1.5 diopters, preferably at least about 3.0 diopters, and more preferably from about 4-8 diopters. “Diopter” is defined as the reciprocal of the focal length in meters: 
 
Diopter=1/focal length (m). 
 
 Focal length is the distance from the center of the lens to the object being viewed. 
 
         [0060]     Importantly, this accommodation can be achieved with very little force being required by the eye. That is, the typical eye exerts anywhere from about 6-9 grams of force on an intraocular lens. However, the inventive optic can be designed to change shape sufficiently to produce the desired accommodation with as little as 1 gram of force. Thus, lenses according to the present invention provide a further advantage in that they can be designed to respond to a force over the entire range of from about 1 to about 9 grams.  
         [0061]     For each of the foregoing embodiments illustrated in  FIGS. 1-15 , examples of suitable materials of which the lens and lens components (e.g., optic positioning elements, optics) can be constructed include any yieldable, synthetic resin material such as acrylates (e.g., polymethylmethacrylates), silicones, and mixtures of acrylates and silicones. It is particularly preferred that the optic positioning elements be constructed of a material having an elastic memory (i.e., the material should be capable of substantially recovering its original size and shape after a deforming force has been removed). An example of a preferred material having elastic memory is MEMORYLENS (available from Mentor Ophthalmics in California).  
         [0062]     Furthermore, the optics of each embodiment could be formed of a wide range of flexible, refractive materials so long as the necessary thickening or thinning thereof can be achieved. Suitable materials include gels, silicone, silicone blends, refractive liquids, elastomeric materials, rubbers, acrylates, gases such as air, and mixtures of the foregoing, so long as the material is flexible and resilient. The shape of the optic (e.g., meniscus, biconcave, biconvex) utilized will depend upon the refractive index of the material used to form the optic. That is, the combination of optic shape and optic material will need to be chosen so that the resulting lens will converge light when the ciliary body contracts for near viewing.  
         [0063]     While the foregoing description shows certain types of optic positioning elements with certain optics (both optic shapes and optic materials), it will be appreciated that this is for illustration purposes only, and the optic positioning elements and optic types can be switched. For example, the combination optic  172  of  FIG. 15  could be utilized with the optic positioning element  33  of  FIG. 1 , the optic  32  of  FIG. 1  could be utilized with the optic positioning element  144  of  FIG. 12 , etc.  
         [0064]     Although the invention has been described with reference to the preferred embodiments illustrated in the attached drawing figures, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims. For example, while the foregoing method of inserting the lens into the capsule presumed that a portion of the anterior wall of the capsule would be removed with the natural lens, it will be appreciated that it may be possible to insert the lens through an incision in the anterior wall. Furthermore, while the foregoing description discloses that the inventive lenses could be utilized in cataract patients, the lenses may be used in any situation where the natural lens needs to be replaced. For example, the inventive lenses may be used to correct myopia, hyperopia, presbyopia, cataracts, or a combination thereof.  
         [0065]     Finally, it will be appreciated that each of the foregoing lenses can be manufactured in either the accommodated or disaccommodated shape. That is, they can be manufactured in a default state of either an accommodated or disaccommodated shape, and the deformed state (i.e., the state caused by the forces within the eye during focusing) will be the other of the accommodated or disaccommodated shape.