Abstract:
An intraocular lens (IOL) device comprising a first lens, a second lens and a circumferential haptic. The first lens comprises a pair of opposing and deformable surfaces and a cavity defined therebetween. The first lens has a first lens diameter. The second lens has a second lens diameter. The circumferential haptic has an outer peripheral edge and couples the first lens and the second lens. A main IOL cavity is defined by the circumferential haptic, the first lens and the second lens. The IOL device is resiliently biased to an unaccommodated state, characterized by the IOL device having a first diameter d 1  in the absence of radial compressive forces exerted on the outer peripheral edge. The IOL device actuates to an accommodated state being characterized by a second diameter d 2  in response to radial compressive forces exerted on the outer peripheral edge, wherein d 1 &gt;d 2 .

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Patent Application No. PCT/US2014/063473 filed Oct. 31, 2014, which claims the benefit of Provisional Patent Application No. 61/899,106 filed Nov. 1, 2013, both of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates generally to an accommodating intraocular lens device and, more particularly, to an accommodating intraocular lens device configured for implantation in a lens chamber of a subject&#39;s eye. 
       BACKGROUND 
       [0003]    Surgical procedures on the eye have been on the rise as technological advances permit for sophisticated interventions to address a wide variety of ophthalmic conditions. Patient acceptance has increased over the last twenty years as such procedures have proven to be generally safe and to produce results that significantly improve patient quality of life. 
         [0004]    Cataract surgery remains one of the most common surgical procedures, with over 16 million cataract procedures being performed worldwide. It is expected that this number will continue to increase as average life expectancies continue to rise. Cataracts are typically treated by removing the crystalline lens from the eye and implanting an intraocular lens (“IOL”) in its place. As conventional IOL devices are primarily focused for distance visions, they fail to correct for presbyopia and reading glasses are still required. Thus, while patients who undergo a standard IOL implantation no longer experience clouding from cataracts, they are unable to accommodate, or change focus from near to far, from far to near, and to distances in between. 
         [0005]    Surgeries to correct refractive errors of the eye have also become extremely common, of which LASIK enjoys substantial popularity with over 700,000 procedures being performed per year. Given the high prevalence of refractive errors and the relative safety and effectiveness of this procedure, more and more people are expected to turn to LASIK or other surgical procedures over conventional eyeglasses or contact lens. Despite the success of LASIK in treating myopia, there remains an unmet need for an effective surgical intervention to correct for presbyopia, which cannot be treated by conventional LASIK procedures. 
         [0006]    As nearly every cataract patient also suffers from presbyopia, there is convergence of market demands for the treatment of both these conditions. While there is a general acceptance among physicians and patients of having implantable intraocular lens in the treatment of cataracts, similar procedures to correct for presbyopia represent only 5% of the U.S. cataract market. There is therefore a need to address both ophthalmic cataracts and/or presbyopia in the growing aging population. 
       BRIEF SUMMARY 
       [0007]    The intraocular lens (IOL) device described herein generally comprise two lens portions. In a preferred embodiment, a first lens portion provides most, if not all, of the accommodative power and a second base lens provides most, if not all, of the corrective refractive power that is needed by a particular patient. Because the first lens portion must provide an accommodative power, it must respond by either changing shape or by displacement along an optical axis in response to the contraction and relaxation of the ciliary muscles which control the eye&#39;s natural ability to accommodate. To that end, the first lens portion may be provided as an elastically deformable lens chamber that is filled with a fluid or gel. In contrast to the elastically deformable lens chamber, the base lens is configured to not readily deform or change its curvature in response to the radially compressive forces exerted on the circumferential edge. The transfer of the radially compressive forces onto the lens chamber may be accomplished by incorporating one or more of the following features in the IOL: (1) the opposing sides of the lens chamber having a reduced thickness as compared to the base lens, (2) a hinge disposed between the base lens and the peripheral portion, (3) the lens chamber being made of a material having a lower Young&#39;s modulus than the base lens, and/or (4) the base lens being made of a substantially rigid material. 
         [0008]    In one embodiment, an intraocular lens (IOL) device is provided. The IOL comprises a first lens comprising a pair of opposing and deformable surfaces and a cavity defined therebetween, the first lens having a first lens diameter, a second lens having a second lens diameter, and a circumferential haptic having an outer peripheral edge, the circumferential haptic coupling the first lens and the second lens. A main IOL cavity is defined by the circumferential haptic, the first lens and the second lens. The IOL device is resiliently biased to an unaccommodated state being characterized by the IOL device having a first diameter d 1  in the absence of radial compressive forces exerted on the outer peripheral edge. The IOL device actuates to an accommodated state characterized by a second diameter d 2  in response to radial compressive forces exerted on the outer peripheral edge, wherein d 1 &gt;d 2 . 
         [0009]    In accordance with a first aspect, the first lens is a biconvex lens. 
         [0010]    In accordance with a second aspect, the cavity is fully enclosed. 
         [0011]    In accordance with a third aspect, the IOL further comprises a gel in the cavity. The gel preferably has a refractive index of 1.46 or greater, preferably 1.48 or greater and most preferably 1.55 or greater. The gel preferably has a Young&#39;s modulus of 10 psi or less, preferably 5 psi or less, and more preferably 1 psi or less. In a particularly preferred embodiment, the gel has a Young&#39;s modulus of 0.5 psi or less, preferably 0.25 psi or less, and most preferably 0.01 psi or less. The gel preferably is a highly-branched polymer, preferably cross-linked silicone. 
         [0012]    In accordance with a fourth aspect, the second lens is a one of a plano-convex lens, a bi-convex lens and a positive meniscus lens. 
         [0013]    In accordance with a fifth aspect, the second lens is substantially more rigid than the first lens. 
         [0014]    In accordance with a sixth aspect, the IOL further comprises a hinge disposed between the circumferential haptic and the second lens. In a preferred embodiment, in the presence of the compressive forces on the peripheral edge, the hinge directs a substantial portion of the compressive forces onto the first lens to cause a greater proportionate reduction in the first lens diameter to be reduced proportionately than in the second lens diameter. 
         [0015]    In accordance with a seventh aspect, each of the opposing and deformable surfaces of the first lens has a thickness that is 50% or less of the second lens, preferably 25% or less of the second lens, and more preferably, 10% or less of the second lens. 
         [0016]    In accordance with an eighth aspect, the IOL further comprises one or both of a plurality of apertures disposed on the circumferential haptic and a circumferential channel defined within the circumferential haptic. The plurality of apertures may be in fluid communication with the main IOL cavity. The plurality of apertures may be in fluid communication with both the circumferential channel and the main IOL cavity. 
         [0017]    In accordance with a ninth aspect, the IOL device further comprises a plurality of raised bumps, wherein at least one of the plurality of raised bumps is positioned adjacent to each one of the plurality of apertures. 
         [0018]    In accordance with a tenth aspect, the IOL device further comprises a plurality of troughs, at least one of the plurality of troughs extending radially inward from each one of the plurality of apertures to facilitate fluid flow into the apertures. 
         [0019]    In accordance with an eleventh aspect, the circumferential haptic comprises a plurality of radial arms coupling the second lens, the plurality of radial arms defining apertures therebetween to permit fluid communication with the main cavity. 
         [0020]    In accordance with a twelfth aspect, the circumferential haptic comprises a third circumferential cavity disposed peripherally of the main IOL cavity. 
         [0021]    In accordance with a thirteenth aspect, the opposing surfaces of the first lens are displaced away from each other upon the application of a radial force along the circumferential haptic. The opposing surfaces comprises central and peripheral regions and a gradually increasing thickness profile from the peripheral to the central regions. 
         [0022]    In another embodiment, an IOL is provided. The IOL comprises a first lens made of an elastic and deformable material having a first Young&#39;s modulus, a second lens in spaced relation to the first lens along a central optical axis and a circumferential portion encircling the first and second lens, the circumferential portion comprising an outer peripheral edge. At least one of a portion of the second lens and a portion of the circumferential portion is made of a material having a second Young&#39;s modulus. The first Young&#39;s modulus is less than the second Young&#39;s modulus. 
         [0023]    In accordance with a first aspect, only the second lens is made of the material having the second Young&#39;s modulus. 
         [0024]    In accordance with a second aspect, only the portion of the circumferential portion is made of the material having the second Young&#39;s modulus. 
         [0025]    In accordance with a third aspect, the first Young&#39;s modulus is about 100 psi or less. 
         [0026]    In accordance with a fourth aspect, the second Young&#39;s modulus is about 100 psi or greater. 
         [0027]    In accordance with a fifth aspect, the second Young&#39;s modulus is about 150 psi or greater. 
         [0028]    In accordance with a sixth aspect, the first lens comprises a pair of opposing and deformable surfaces and a cavity defined therebetween, the first lens having a first lens diameter and wherein a main IOL cavity is defined between the first lens, the second lens and the circumferential portion. 
         [0029]    In accordance with a seventh aspect, the IOL further comprises a hinge disposed on the second lens outside of the active optical area. 
         [0030]    In accordance with an eighth aspect, the first lens is comprised of two opposing surfaces which are displaced away from each other upon the application of a radial force along a peripheral edge. The two opposing surfaces each having central and peripheral regions, wherein the central region has a thickness that is at least 2 times, preferably at least three times, and most preferably at least four times greater than a thickness of the peripheral region. 
         [0031]    In a further embodiment, an IOL is provided. The IOL comprises a first lens, a second lens in spaced relation to the first lens and a circumferential haptic coupling the first and second lens. The first lens comprises opposing sides and an enclosed cavity between the opposing sides. The opposing sides each have central and peripheral regions, the central region being disposed around an optical axis, the peripheral region being disposed around the central region. The central region is at least two times thicker than the peripheral region. The second lens in spaced relation to the first lens, the second lens having a thickness that is greater than either one of the opposing sides of the first lens. A circumferential haptic has an outer peripheral edge configured for engagement with a capsular bag of an eye when the IOL is implanted. A main IOL cavity is defined by the circumferential haptic, the first lens and the second lens. 
         [0032]    In accordance with a first aspect, the central region is at least three times thicker than the peripheral region. 
         [0033]    In accordance with a second aspect, the central region is at least four times thicker than the peripheral region. 
         [0034]    In accordance with a third aspect, the enclosed cavity of the first lens comprises a gel having a first refractive index. 
         [0035]    In accordance with a fourth aspect, the opposing sides of the first lens has a second refractive index that is less than the first refractive index of the gel. 
         [0036]    In accordance with a fifth aspect, the gel is a vinyl-terminated phenyl siloxane. 
         [0037]    In accordance with a sixth aspect, the gel has a Young&#39;s modulus of 0.25 psi or less, preferably 0.01 psi or less. 
         [0038]    Other objects, features and advantages of the described preferred embodiments will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]    Illustrative embodiments of the present disclosure are described herein with reference to the accompanying drawings, in which: 
           [0040]      FIGS. 1A-1B  are perspective and side cross-sectional views, respectively, of an embodiment of a dual-cavity IOL device. 
           [0041]      FIG. 2  is a perspective cross-sectional view of another embodiment of a dual-cavity IOL device having holes disposed on the top surface. 
           [0042]      FIGS. 3A-3B  are front and perspective cross-sectional views of another embodiment of a dual-cavity IOL device having through-holes disposed through the top and bottom surfaces in communication with the main cavity. 
           [0043]      FIG. 4  is a perspective cross-sectional view of another embodiment of a dual-cavity IOL device having through-holes disposed through the top and bottom surfaces and which are not in fluid communication with the main cavity. 
           [0044]      FIGS. 5A-5B  are perspective cross-sectional views of another embodiment of a dual-cavity IOL device comprising arc-shaped cutouts on the bottom surface to provide a fluid communication with the main cavity. 
           [0045]      FIGS. 6A-6B  are perspective cross-sectional and rear views of another embodiment of a dual-cavity IOL device comprising arch-shaped cutouts on the bottom surface and a plurality of peripheral through holes in communication with a circumferential channel. 
           [0046]      FIG. 7A-7B  are top perspective and cross-sectional views of another embodiment of a dual-cavity IOL device comprising a plurality of raised protrusions adjacent through-holes which are in communication with the main cavity and circumferential channel. 
           [0047]      FIG. 8A-8B  are top perspective and cross-sectional views of another embodiment of a dual-cavity IOL device comprising a plurality of troughs adjacent through-holes which are in communication with the main cavity and circumferential channel. 
           [0048]      FIG. 9  is a partial cross-sectional view of an embodiment of the IOL device, cut away along the optical axis A-A. 
           [0049]      FIGS. 10A-10B  are cross-sectional views of further embodiments of the IOL device. 
           [0050]      FIG. 11A  depicts the human eye with the lens material removed following a capsulorhexis. 
           [0051]      FIGS. 11B-11C  depict the implanted IOL device in the unaccommodated and accommodated states, respectively. 
       
    
    
       [0052]    Like numerals refer to like parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0053]    Specific, non-limiting embodiments of the present invention will now be described with reference to the drawings. It should be understood that such embodiments are by way of example and are merely illustrative of but a small number of embodiments within the scope of the present invention. Various changes and modifications obvious to one skilled in the art to which the present invention pertains are deemed to be within the spirit, scope and contemplation of the present invention as further defined in the appended claims. 
         [0054]      FIGS. 1A-1B  depicts a basic structure of an embodiment of the accommodating intraocular lens (IOL)  100 . The IOL  100  is depicted as comprising an elastically deformable lens chamber  110 , a base lens  150 , and a lens periphery  170  coupling the lens chamber  110  and the base lens  150 . The elastically deformable lens chamber  110  provides most, if not all, of the accommodative power by deforming or changing in curvature in response to the radially compressive forces that are exerted onto the IOL  100  during accommodation. The base lens  150  provides most, if not all, of the corrective refractive power that is required by a particular patient and is not required to deform or change in shape or curvature. Thus, the lens chamber  110  and the base lens  150  cooperate to restore both a patient&#39;s vision and natural range of accommodation. 
         [0055]    The lens chamber  110  is made of an elastically deformable material and comprises opposing sides  112  and  114  that are joined together at the periphery of the lens chamber  110  to define a bi-convex exterior shape and an internal enclosed cavity  120 . Each of the opposing sides  112  and  114  comprise a central region  112   a ,  114   a  and a peripheral region  112   b ,  114   b  and a gradient of thickness that increases radially from the peripheral region  112   b ,  114   b  to the central region  112   a ,  114   a . This thickness profile is intended to encourage deformation of the opposing sides  112 ,  114  away from one another and to permit the opposing sides to bulge and increase its curvature in opposing directions along an optical axis A-A without causing the membrane to buckle about the central region  112   a ,  114   a . Thus, while the conventional wisdom suggests that a greater degree of deformation and outward bulging would be achieved with the opposite thickness profile (e.g., a thickness profile that decreases radially from the peripheral region  112   b ,  114   b  to the central region  112   a ,  114   a ), such a thickness profile is more likely to cause the lens chamber  110  to buckle or collapse inwardly about the central region  112   a ,  114   a  upon the application of a radially compressive force once implanted in a patient&#39;s eye. During accommodation, the application of radially compressive forces may cause an internal vacuum to develop inside the lens chamber  110 , thereby causing the opposing sides  112 ,  114  to buckle inwardly. 
         [0056]    Thus, in a particularly preferred embodiment, the opposing sides have a gradually increasing thickness from the peripheral regions  112   b ,  114   b , to the central region  112   a ,  114   a . In a preferred embodiment, the central region  112   a ,  114   a , as measured along the optical axis A-A, has a thickness that is two times or more, preferably three times or more, and most preferably four times or more than the thickness of the peripheral region  112   b ,  114   b , as measured just adjacent to the area where the opposing sides  112 ,  114  join at the peripheral region. In another preferred embodiment, the point of greatest thickness in the central region  112   a ,  114   a  and the point of least thickness in the peripheral regions  112   b ,  114   b  is characterized as having a thickness ratio of 2:1 or greater, preferably 3:1 or greater, and most preferably 4:1 or greater. In one embodiment, the central region  112   a ,  114   a , as measured along the optical axis A-A, comprises an area of thickness that is about 100 microns, preferably about 200 microns, and the peripheral region  112   b ,  114   b  comprises an area of thickness that is about 50 microns as measured just adjacent to the area where the opposing sides  112 ,  114  join at the peripheral region. While the thickness profile is described in relation to  FIGS. 1A-1B , it is understood that the same or a substantially similar thickness profile may be provided for all of the IOL devices depicted and described herein. 
         [0057]    The base lens  150  is coupled to the lens chamber  110  via a lens periphery  170 . The base lens  150  may be a positive lens that provides convergent power, such as a bi-convex, plano-convex or a positive meniscus lens. Alternatively, the base lens  150  may be a negative lens that provides divergent power, such as a bi-concave, plano-concave or a negative meniscus lens. The base lens  150  depicted in  FIGS. 1A-1B  is a positive meniscus lens. 
         [0058]    The base lens  150  is preferably more rigid than the opposing sides  112 ,  114  of the lens chamber  110 . The greater rigidity may be imparted by providing a base lens  150  having a thickness that is significantly greater than the thicknesses of the opposing sides  112 ,  114  of the lens chamber  110 . Alternatively or in addition to providing a greater thickness, the base lens  150  may be made of a different or stiffer material having a higher elastic Young&#39;s modulus as compared to the lens chamber  110 . The base lens  150  preferably does not substantially change its shape and curvature in response to the radially-compressive accommodative force applied onto the peripheral edge  180  of the lens periphery  170 . Instead, the radially compressive accommodative forces are transferred onto the lens chamber  110  to cause the desired deforming changes. 
         [0059]    In a preferred embodiment, the base lens  150  is substantially thicker than one of the opposing sides  112 ,  114  of the lens chamber  110 , as measured along the optical axis A-A. In a preferred embodiment, the thickness of each one of the opposing sides  112 ,  114  of the lens chamber  110 , as along the optical axis A-A depicted in  FIGS. 1A-1B and 9 , is less than ½, preferably less than ⅓, preferably less than ¼, and most preferably less than ⅕ of the thickness of the base lens  150  at the central optical axis A-A. Because the base lens  150  is substantially thicker than either one of the opposing sides  112 ,  114  of the lens chamber  110 , the base lens  150  has an effective Young&#39;s modulus that is substantially greater than either one of the opposing sides  112 ,  114  of the lens chamber  110 . While  FIGS. 1A-1B and 9  depict the relative thickness of the opposing sides  112 ,  114  of the lens chamber  110  and the base lens  150  for IOL  100 , it is understood that all of the IOL devices disclosed herein may have the same or similar thickness profile with respect to the lens chamber  110  and the base lens  150 . 
         [0060]    The lens chamber  110  and the base lens  150  are coupled together by a lens periphery  170 . The lens periphery  170  comprises a circumferential edge  180  configured to engage a circumferential region of the capsular bag of the eye. As depicted in  FIGS. 11A-11C , the circumferential region  52  is where the capsular bag  40  is coupled to the zonules  50 , generally at a location where the density of the zonules  50  is the greatest. The zonules  50 , in turn, couple the capsular bag  40  to the ciliary muscles  60  which contract and relax to provide a range of accommodation. While  FIGS. 11B and 11C  depict a particularly preferred embodiment in which an IOL  100  is implanted with the lens chamber  110  being oriented anteriorly within the lens capsule  40  of the eye, it is understood that the IOL  100  may also be implanted with the lens chamber  110  being oriented posteriorly within the lens capsule  40  of the eye. 
         [0061]    The lens periphery  170  comprises a radial portion  172  and a circumferential hinge  174  that cooperate together to transmit a significant portion, if not most, of the radially compressive forces exerted onto the circumferential edge  180  onto the lens chamber  110  and away from the base lens  150 . Referring back to  FIGS. 1A-1B , the radial portion  172  extends radially inwardly from the lens periphery  170  to the lens chamber  110  and the hinge  174  is disposed between the lens periphery  170  and the base lens  150 . Both the radial portion  172  and the hinge  174  cooperate to maximize the extent to which the radially-compressive accommodative forces applied to the peripheral edge  180  are transmitted to the lens chamber  110 . The greater the force transmitted to the lens chamber  110 , the greater the deformation and change of curvature of the opposing sides  112 ,  114  of the lens chamber  110 . 
         [0062]    The lens periphery  170  may be solid and thickened as compared to the base lens  150 , as depicted in  FIGS. 1A-1B and 9 . Alternatively, the lens periphery  170  may comprise a hollow space or a circumferential channel to reduce the delivery profile of the IOL, as depicted in  FIGS. 2, 3A, 3B, 4, 6, 7, and 8 . Because the IOL  100  is implanted into a relatively small incision size, it must be rolled up to assume a delivery profile that is at least as small as the incision size. 
         [0063]    The circumferential hinge  174  is provided as a thinned or grooved area disposed in the lens periphery  170  and surrounding the base lens  150 . The circumferential hinge  174  permits the lens periphery  170  to pivot radially inwardly towards the lens chamber  110  such that the radially compressive forces applied to the circumferential edge  180  are directed substantially along the radial portion  172  and applied to the lens chamber  110 , as opposed to being applied to the base lens  150 , which is configured to generally resist deformation (See  FIG. 11C ). Thus, the radial portion  172  is itself preferably sufficiently rigid in order to substantially transmit the radial compressive force onto the lens chamber  110 . In a preferred embodiment, the hinge  174  is provided both peripherally and circumferentially around the base lens  150  as a thinned area or as a groove. 
         [0064]      FIGS. 11B and 11C  depicts the configuration of the IOL  100  in the absence of a radial compressive force applied to the circumferential peripheral edge  180  ( FIG. 11B , an unaccommodated eye) and in the presence of a radial compressive force applied to the circumferential peripheral edge  180  ( FIG. 11C , an accommodated eye) in which the peripheral edge  180  tilts in the direction C about the hinge  174 , transmitting the radial compressive forces onto the lens chamber  110 , and thereby causing the opposing sides  112 ,  114  of the lens chamber  110  to be displaced apart from one another and increase in curvature. 
         [0065]    The features described herein which are intended to maximize the extent to which the radially compressive forces are transmitted to a lens chamber  110  and thus provide a large range of accommodation. The IOLs described herein may further be made of a material that does not resist deformation or is characterized as having a low Young&#39;s modulus. The IOLs may be made of a single material or, alternatively, different portions of the IOL may be made of different materials having differing Young&#39;s modulus (see  FIGS. 10A-10B ). 
         [0066]    In one preferred embodiment, at least the opposing sides  112 ,  114  of the lens chamber  110  is made of a material of sufficient mechanical strength to withstand physical manipulation during implantation, but is of sufficiently low Young&#39;s modulus so as to minimize its resistance to deformation. In a preferred embodiment, the opposing sides  112 ,  114  of the lens chamber  110  is made of a polymer having a Young&#39;s modulus of 100 psi or less, preferably 75 psi or less, and most preferably 50 psi or less. In one preferred embodiment, the remaining portions of the IOL  100  (e.g., the base lens  150 , the peripheral portion  170 ) has a Young&#39;s modulus that is greater than the Young&#39;s modulus of the walls  112 ,  114 , of the lens chamber  110 . The walls  112 ,  114  of the lens chamber  110  may be a polymer, preferably a silicone polymer and, more preferably a phenyl siloxane, such as a vinyl-terminated phenyl siloxane or a vinyl-terminated diphenyl siloxane. In order to impart sufficient mechanical strength, the polymer may be crosslinked, reinforced with fillers, or both. The fillers may be a resin or silica that have been functionalized to react with the polymer. 
         [0067]    The opposing sides  112 ,  114  of the lens chamber  110  defines an enclosed cavity  120  that is filled with a fluid or gel having specific physical and chemical characteristics to enhance the range of refractive power provided by the IOL during accommodation. The fluid or gel is selected such that it cooperates with the walls  112 ,  114  of the lens chamber  110  in providing a sufficient range of accommodation of up to at least 3 diopters, preferably up to at least 5 diopters, preferably up to at least 10 diopters and most preferably up to at least 15 diopters. In a preferred embodiment, the enclosed cavity  120  is filled with the fluid or gel before implantation of the IOL  100  into the capsular bag  40  of the eye and, in a more preferred embodiment, the cavity  120  is filled with the fluid or gel in the manufacture of the IOL  100 . 
         [0068]    In one preferred embodiment the enclosed cavity  120  is filled with a fluid, such as a gas or a liquid, having low viscosity at room temperature and a high refractive index. In a preferred embodiment, the fluid is a liquid having a viscosity of 1,000 cP or less at 23° C. and a refractive index of at least 1.46, 1.47, 1.48, or 1.49. The fluid may be a polymer, preferably a silicone polymer, and more preferably a phenyl siloxane polymer, such as a vinyl-terminated phenyl siloxane polymer or a vinyl-terminated diphenyl siloxane polymer. Preferably, in embodiments where the fluid is made of a polymer, the polymer is preferably not crosslinked and that the polymer may be linear or branched. Where the fluid is a vinyl-terminated phenyl siloxane polymer or diphenyl siloxane polymer, the vinyl groups may be reacted to form other moieties that do not form crosslinkages. 
         [0069]    In accordance with one embodiment, fluid may be a polyphenyl ether (“PPE”), as described in U.S. Pat. No. 7,256,943, entitled “Variable Focus Liquid-Filled Lens Using Polyphenyl Ethers” to Teledyne Licensing, LLC, the entire contents of which are incorporated herein by reference as if set forth fully herein. 
         [0070]    In accordance with another embodiment, the fluid may be a fluorinated polyphenyl ether (“FPPE”). FPPE has the unique advantage of providing tunability of the refractive index while being a chemically inert, biocompatible fluid with low permeability in many polymers. The tunability is provided by the increasing or decreasing the phenyl and fluoro content of the polymer. Increasing the phenyl content will effectively increase the refractive index of the FPPE, whereas increasing the fluoro content will decrease the refractive index of the FPPE while decreasing the permeability of the FPPE fluid through the walls  112 ,  114  of the lens chamber  110 . 
         [0071]    In another preferred embodiment, the enclosed cavity  120  is filled with a gel. The gel preferably has a refractive index of at least 1.46, 1.47, 1.48, or 1.49. The gel may also preferably have a young&#39;s modulus of 20 psi or less, 10 psi or less, 4 psi or less, 1 psi or less, 0.5 psi or less, 0.25 psi or less and 0.01 psi or less. In a preferred embodiment, the gel is a crosslinked polymer, preferably a crosslinked silicone polymer, and more preferably a crosslinked phenyl siloxane polymer, such a crosslinked vinyl-terminated phenyl siloxane polymer or a vinyl-terminated diphenylsiloxane polymer. Other optically clear polymer liquids or gels, in addition to siloxane polymers, may be used to fill the cavity  120  and such polymers may be branched, unbranched, crosslinked or uncrosslinked or any combination of the foregoing. 
         [0072]    A gel has the advantages of being extended in molecular weight from being crosslinked, more self-adherent and also adherent to the walls or opposing sides or walls  112 ,  114  of the lens chamber  110  than most liquids. This makes a gel less likely to leak through the walls  112 ,  114  of the lens chamber  110 . In order to obtain the combination of accommodative power with relatively small deformations in the curvature of the walls  112 ,  114  of the lens chamber  110 , the gel is selected so as to have a high refractive index while being made of an optically clear material that is characterized as having a low Young&#39;s modulus. Thus, in a preferred embodiment, the gel has a refractive index of 1.46 or greater, preferably 1.47 or greater, 1.48 or greater and most preferably 1.49 or greater. At the same time, the gel preferably has a Young&#39;s modulus of 10 psi or less, preferably 5 psi or less, and more preferably 1 psi or less. In a particularly preferred embodiment, the gel has a Young&#39;s modulus of 0.5 psi or less, preferably 0.25 psi or less, and most preferably 0.01 psi or less. It is understood that at lower Young&#39;s modulus, the gel will present less resistance to deformation and thus the greater the deformation of the walls  112 ,  114  of the lens chamber  110  for a given unit of applied force. 
         [0073]    In particularly preferred embodiment, the gel is a vinyl-terminated phenyl siloxane that is produced based on one of the four formulas provided as follows: 
         [0074]    Formula 1:
       100 parts 20-25 mole % vinyl terminated diphenylsiloxane-dimethylsiloxane copolymer (Gelest PDV 2335).   3 ppm platinum complex catalyst   0.35 pph of phenyl siloxane hydride crosslinker (Nusil XL-106)   Young&#39;s modulus of elasticity=0.0033 psi       
 
         [0079]    Formula 2:
       100 parts 20-25 mole % vinyl terminated diphenylsiloxane-dimethylsiloxane copolymer (Gelest PDV 2335).   3 ppm platinum complex catalyst   0.4 pph of phenyl siloxane hydride crosslinker (Nusil XL-106)   Young&#39;s modulus of elasticity=0.0086 psi       
 
         [0084]    Formula 3:
       100 parts 20-25 mole % vinyl terminated diphenylsiloxane-dimethylsiloxane copolymer (Gelest PDV 2335).   3 ppm platinum complex catalyst   0.5 pph of phenyl siloxane hydride crosslinker (Nusil XL-106)   Young&#39;s modulus of elasticity=0.0840 psi       
 
         [0089]    Formula 4:
       100 parts 20-25 mole % vinyl terminated diphenylsiloxane-dimethylsiloxane copolymer (Gelest PDV 2335).   3 ppm platinum complex catalyst   0.6 pph of phenyl siloxane hydride crosslinker (Nusil XL-106)   Young&#39;s modulus of elasticity=2.6 psi       
 
         [0094]    The walls  112 ,  114  of the lens chamber  110  and the fluid or gel contained within the lens cavity  120  are preferably selected so as to prevent or reduce the likelihood of the fluid or gel migrating outside of the walls  112 ,  114  of the lens chamber  110 . Thus, in a preferred embodiment, one or both of the walls  112 ,  114  of the lens chamber  110  and the fluid or gel is/are selected from biocompatible materials that optimize the resistance to permeability of the fluid or gel across the walls  112 ,  114  of the lens chamber  110 . 
         [0095]    One method of decreasing the permeability of the gel contained inside the cavity  120  across the walls  112 ,  114  of the lens chamber  110  is to provide a gel that is cross-linked. The degree of cross-linking, however, must be selected and controlled such that, on the one hand, the walls  112 ,  114  of the lens chamber  110  and the gel have a sufficiently low Young&#39;s modulus to minimize the resistance of the walls  112 ,  114  of the lens chamber  110  to deformation and, on the other hand, to minimize the permeation of the gel across the walls  112 ,  114  of the lens chamber  110 . Thus, in a preferred embodiment, longer chain polymers that are lightly cross-linked, such as those used for silicone gels, starting with monomers having molecular weights that are greater than 35,000 daltons, preferably greater than 50,000 daltons and, most preferably, at least 70,000 daltons are desired. 
         [0096]    In another preferred embodiment, a gel is used having low permeability extractables. Such gels may be formulated by using long chain polymers that are branched. 
         [0097]    In a preferred embodiment, one or both of the lens chamber walls  112 ,  114  and the gel is made of homo- or co-polymers of phenyl-substituted silicones. 
         [0098]    For the lens chamber walls  112 ,  114 , the crosslinked homo- or co-polymers preferably have a diphenyl content of 5-25 mol %, preferably 10-20 mol % and more preferably 15-18 mol %. Alternatively, for the lens chamber walls  112 ,  114 , the homo- or co-polymers preferably have a phenyl content of 10-50 mol %, preferably 20-40 mol %, and more preferably 30-36 mol %. 
         [0099]    For the gel, the homo- or co-polymers preferably have a diphenyl content of 10-35 mol %, preferably 15-30 mol % and more preferably 20-25 mol %. Alternatively, for the gel, the homo- or co-polymers preferably have a phenyl content of 20-70 mol %, preferably 30-60 mol % and more preferably 40-50 mol %. 
         [0100]    In a particularly preferred embodiment, the lens chamber walls  112 ,  114  are made of a crosslinked phenyl siloxane having a diphenyl content of about 15-18 mol % or a phenyl content of about 30-36 mol % and the gel is made of a phenyl siloxane having a diphenyl content of about 20-25 mol % or a phenyl content of about 40-50 mol %. The lens chamber walls  112 ,  114  are understood to be more crosslinked than the gel. 
         [0101]    In a particularly preferred embodiment, the lens chamber walls  112 ,  114  are made of a vinyl-terminated phenyl siloxane, most preferably a crosslinked vinyl-terminated phenyl siloxane. Reinforcing agents, such as silica, may also be included in a range 10-70 mol %, preferably 20-60 mol % and most preferably 30-50 mol %. 
         [0102]    The walls  112 ,  114  of the lens chamber  110  and the fluid or gel contained within the lens cavity  120  are also preferably selected so as to increase the range of accommodative power that is provided by the lens chamber  110 . In one preferred embodiment, the walls  112 ,  114  of the lens chamber  110  are made of a material having a lower refractive index than the fluid or gel contained in the enclosed cavity. In one preferred embodiment, the refractive index of the lens walls  112 ,  114  of the chamber  110  is 1.38 and the refractive index of the gel or fluid is 1.49. 
         [0103]    The differential refractive indices provided by the lens chamber walls  112 ,  114  and the gel or liquid contained within the chamber  120  may be provided by the differences in the materials or the composition of the materials used for the lens chamber walls  112 ,  114  and the gel or liquid. 
         [0104]    In one embodiment, both the lens chamber walls  112 ,  114  and the gel or liquid is made of a phenyl siloxane having different diphenyl or phenyl content. In a preferred embodiment, the lens chamber walls  112 ,  114  has a diphenyl or phenyl content that is less than that for the gel or liquid. In another preferred embodiment, the walls  112 ,  114  of the lens chamber  110  may be made of a cross-linked vinyl-terminated phenyl siloxane having a diphenyl content of 15-18 mol % or a phenyl content of 30-36 mol % and the gel contained within the walls  112 ,  114  of the lens chamber  110  may be made of a vinyl-terminated phenyl-siloxane having a diphenyl content of 20-25 mol % or a phenyl content of 30-36 mol %. 
         [0105]    In another embodiment, the differential refractive indices may be provided by providing a dimethyl siloxane for the lens chamber walls  112 ,  114  and the gel may be a phenyl siloxane having a high diphenyl or phenyl content. In a preferred embodiment, the diphenyl content is at least 20 mol %, at least 25 mol %, at least 30 mol %, at least 35 mol %, and at least 40 mol %. Alternatively, the phenyl content is at least 40 mol %, at least 50 mol %, at least 60 mol %, at least 70 mol %, and at least 80 mol %. 
         [0106]    In a further embodiment, the differential refractive indices may be provided by a crosslinked fluoro siloxane, such as a 3,3,3-trifluoropropylmethyl siloxane and the gel may be a phenyl siloxane having a high diphenyl or phenyl content. In a preferred embodiment, the diphenyl content is at least 20 mol %, at least 25 mol %, at least 30 mol %, at least 35 mol %, and at least 40 mol %. Alternatively, the phenyl content is at least 40 mol %, at least 50 mol %, at least 60 mol %, at least 70 mol %, and at least 80 mol %. 
         [0107]    Now turning back to  FIGS. 1A-1B , a main cavity  130  is defined between the lens chamber  110 , the base lens  150  and the lens periphery  170 . The main cavity  130  is preferably filled with a fluid or gel. The fluid or gel in the main cavity  130  may be the same as the fluid or gel contained in the enclosed cavity  120 . In a preferred embodiment, the fluid is a saline solution and the main cavity  130  is filled with the saline solution after implantation of the IOL in the capsular bag of the eye. 
         [0108]    Filling the main cavity  130  after implantation of the IOL into the capsular bag will permit the IOL to take on a significantly smaller delivery profile such that the IOL may be rolled up and inserted through a relatively small incision. In a preferred embodiment, the incision size is less than 6 mm, preferably less than 5 mm, most preferably less than 4 mm and even most preferably less than 3 mm. 
         [0109]    In embodiments where the main cavity  130  is filled with a fluid or gel after implantation, a valve (not shown) is preferably disposed on the IOL to permit injection of the fluid or gel into the main cavity  130  after implantation. The valve may be a one-way valve that permits injection of fluid or gel into the main cavity  130  but prevents the fluid or gel from exiting the main cavity  130 . The valve is preferably disposed on the surface of the IOL that is facing in the anterior direction after it has been implanted in the eye. It is understood that the valve, however, is preferably not disposed on either one of the opposing sides  112 ,  114  so as to avoid disrupting the integrity of the lens chamber  110  which may house the same of different fluid or gel. 
         [0110]    In a preferred embodiment, the fluids or gels in the respective enclosed cavity  120  and the main cavity  130  are completely segregated from one another. In one preferred embodiment, the enclosed cavity  120  and the main cavity  130  may have a different fluid and/or gel. In another preferred embodiment, one of the enclosed cavity  120  and the main cavity  130  may comprise one of a fluid or gel and the other one of the enclosed cavity  120  and the main cavity  130  may comprise the other one of a fluid or gel. In a preferred embodiment, there is no fluid exchanged between the enclosed cavity  120  and the main cavity  130 . 
         [0111]    The IOL  100  is intended to be implanted in a capsular bag  40  of the eye and centered about an optical axis A-A (See  FIGS. 11A-11C ). The lens chamber  110  and the base lens  150  are dimensioned to extend to or beyond the effective optical zone B-B as defined about the optical axis A-A of a patient&#39;s eye. The effective optical zone B-B is generally the largest possible opening through which light can enter the eye and thus is controlled by the largest effective diameter of the pupil  30  when completely dilated. This diameter is typically about 4-9 mm. Therefore, in a preferred embodiment, the diameters of the lens chamber  110  and the base lens  150  is preferably at least 4 mm, at least 5 mm, at least 6 mm, at least 7 mm, at least 8 mm and at least 9 mm. 
         [0112]    As previously indicated, either one or both of the enclosed cavity  120  of the lens chamber  110  and/or the main cavity  130  is/are filled with a fluid or gel. The fluid may be a gas, a liquid. The fluid or gel preferably is characterized as having a sufficiently high refractive index such that the lens chamber  110  provides a range of accommodation in response to small changes in the curvature of the opposing sides  112 ,  114 . 
         [0113]    Because the IOL  100  is resiliently biased such that the opposing sides  112 ,  114  of the lens chamber  110  are substantially flat or have minimal curvature, small changes in the curvature of the opposing sides  112 ,  114  will lead to proportionately greater changes in the refractive power of the lens. Thus, the lens chamber  110 , in combination with the base lens  150 , can provide a change in the optical power of up to at least 3 diopters, preferably up to at least 5 diopters, preferably up to at least 10 diopters and most preferably up to 15 diopters in response to the accommodative forces (e.g., radially compressive forces) exerted on the implanted IOL. 
         [0114]      FIG. 2  depicts another embodiment of the IOL  200 . The IOL  200  is similar in many respects with the IOL  100  of  FIGS. 1A-1B  in that it comprises a lens chamber  210 , a base lens  250  and a lens periphery  270  joining the lens chamber  210  and the base lens  250 . The lens periphery  270  further comprises a circumferential edge  280 . The IOL  200  differs from IOL  100  in that IOL  200  comprises a plurality of holes  202  disposed circumferentially along the top surface of the IOL  200  and externally around the lens chamber  210  and a circumferential channel  240  disposed within the lens periphery  270 . The holes  202  are intended to provide a fluid exchange channel between the circumferential channel  240 , the main cavity  230  and the exterior of the IOL  200 . The accommodative forces of the eye&#39;s capsular bag will cause the IOL  200  to radially expand and compress which, in turn, will cause the aqueous fluid to enter and exit the main cavity  230  through the holes  202 . In a preferred embodiment, the holes  202  are disposed symmetrically about the top surface of the IOL  200 . 
         [0115]      FIGS. 3A-3B  depict another embodiment of the IOL  300  which comprises a plurality of through-holes  302  around the circumferential periphery of the IOL  300 . The through-holes  302  differ from the holes  202  in  FIG. 2  in that the through-holes are provided through both sides of the IOL  300  and the IOL  300  does not comprise a circumferential channel, whereas the holes  202  of the IOL  200  of  FIG. 2  are only provided on the top surface of the IOL  200 . The provision of through-holes  302  increase the efficiency with which the aqueous fluid fills and exits the main cavity  330 . 
         [0116]    Moreover, the through-holes  302  are dimensioned to be as large as can fit between the space between the circumferential edge  380  and the lens chamber  310 . One advantage in the provision of numerous large through-holes  302  about the circumferential periphery is that it reduces the material bulk of the IOL  300  and permits it to take on a smaller delivery profile when it is folded and inserted into the capsular bag of the eye during implantation surgery. Thus, the IOL  300  will require a smaller incision for implantation into the capsular bag of the eye. It is understood, however, that the spacing  301  between the through-holes  302  must be sufficient to permit the transfer of force applied to the circumferential edge  380  onto the lens chamber  310 . In a preferred embodiment, the spacing  301  is no more than ¼, preferably no more than ½, and most preferably no more than ¾ of the diameter of the through-holes  302 . 
         [0117]      FIG. 4  depicts another embodiment of the IOL  400  also comprising through-holes  402 , except that the through-holes  402  do not provide a fluid exchange between the main cavity  430  and the exterior of the IOL  400 . The IOL  400  is thus similar to the IOL  100  of  FIGS. 1A-1B  in that a valve is required such that the main cavity  430  of the IOL  400  may be filled after implantation into the capsular bag of the eye. The main function of the through-holes  402  in this embodiment is to reduce the bulk of the IOL  400  so as to provide a smaller delivery profile. Thus, once implanted, the fluid or gel in the lens cavity  420  and the main cavity  430  remain contained and the IOL  400  does not permit for fluid exchange between the fluid in the exterior of the IOL  400  and the fluid or gel in the main cavity  430 .  FIG. 4  differs from the IOLs depicted in the preceding figures ( FIGS. 1-3 ) in that it depicts the shape of the IOL  400  when a radial force is applied to the peripheral edge so as to cause a the opposing sides of the cavity  420  to bulge apart from one another. It is noted that the IOL  400  must be dimensioned such that the lower wall of the lens cavity  420  does not contact the base lens  450  within a range of the radial force that would be expected during the accommodation of the eye. 
         [0118]      FIGS. 5A-5B  depict yet a further embodiment of the IOL  500  which comprises a plurality of arc-shaped cutouts  502 . The arc-shaped cutouts  502  are configured to function to provide a fluid exchange between the main cavity  530  and the exterior of the IOL  500 . The IOL  500  comprises radial arms  504  between the arc-shaped cutouts  502  to couple and support the base lens  550  to the lens periphery  570 . In a preferred embodiment, the radial arms  504  comprise a hinge between the peripheral portion  570  and the base lens  550  that permits the radial arms  504  to bend or rock inwardly upon application of a force upon the circumferential edge  580  so that the force is transferred to radially compressing the lens chamber  510 . The hinge may simply be a groove or an area of reduced material thickness that is disposed either on the internal, external or both internal and external surfaces of the radial arms  504 . As with the other IOLs described herein, the IOL  500  returns to a radially-expanded state in the absence of a force applied upon the circumferential edge  580 . The IOL  500  is resiliently biased to a flatter configuration as shown in  FIG. 5A  in the absence of radially-compressive forces being exerted on the circumferential edge  580 , as when the eye is unaccommodated. The IOL  500  is radially compressible to reduce the overall diameter of the lens chamber  110  and thus cause opposing sides  512 ,  514  of the lens chamber  510  to increase its curvature upon the application of a radially compressing force onto the circumferential edge  580 , as when the eye is accommodated. See, e.g.,  FIG. 4 . 
         [0119]      FIGS. 6A-6B  depicts yet a further embodiment of the IOL  600  which comprises an internal circumferential channel  640  in addition to the enclosed cavity  620  and the main cavity  630 . The circumferential through-holes  602  permit aqueous fluid flow into and out of the circumferential channel  640  and the arc-shaped cutouts  604  permit aqueous fluid flow into and out of the main cavity  630 . Radial arms  606  couple the base lens  650  to the peripheral portion  670  and a hinge is disposed on the radial arm between the base lens  650  and the peripheral portion  670 . Again, the presence of the internal circumferential channel  640  is intended to reduce the material bulk and thus to permit insertion of the IOL  600  through relatively smaller incisions. 
         [0120]    The IOLs described herein are intended for implantation in a capsular bag of a patient&#39;s eye following performance of a capsulorhexis, in which a circular portion is removed from the anterior portion of the capsular bag. 
         [0121]      FIG. 11A  depicts the eye  10  following performance of a capsulhorexis and before implantation of an IOL. The eye  10  is depicted as comprising a cornea  20  through which the surgical incision is made to access the capsular bag  40 . The diameter of the circular portion B-B removed from the capsular bag  40  depends upon each person&#39;s individual anatomy is typically in the range of from about 4 mm to about 9 mm. Here, the diameter  32  of the circular portion B-B removed from the capsular bag  40  corresponds roughly to the diameter of the pupil  30 . Preferably, as much of the capsular bag  40  and its zonular connections  50  are maintained as possible. The zonules  50  couple the capsular bag  40  with the ciliary muscle  60  and transmit the accommodative forces to effectuate the curvature or shape changes of the capsular bag  40 . Once the crystalline lens material is removed from the capsular bag  40 , the IOL may be inserted and implanted such that the circumferential edge substantially engages the zonules  50  attached to the capsular bag  40 . Additionally, the IOL is substantially centered along the optical axis A-A and engagement of the IOL with the zonules  50  is preferred to reduce the likelihood of decentration. In embodiments of the IOL comprising holes and through-holes, it is preferable that the holes and through-holes be located outside of the optical zone B-B. Moreover, the holes and through-holes should have rounded edges so as to prevent the perception of glare by the recipient. 
         [0122]      FIGS. 7A-7B and 8A-8B  depict an IOL  700  which is configured with raised protrusions  790  or troughs  795  adjacent to the through-holes  702  to create a space between the capsular bag and the through-holes  702  and to thereby ensure the free flow of the aqueous fluid in and out of the main cavity  730  and the circumferential channel  740 . 
         [0123]    The IOL  700  comprises three enclosed chambers: an enclosed lens chamber  720 , a main cavity  730  and an internal circumferential channel  740 . A plurality of circumferentially disposed through-holes  702  are sized to provide fluid exchange between both the main cavity  730  and the internal circumferential channel  740 , on the one hand, and the exterior of the IOL  700 , on the other hand. The fluid or gel in the lens chamber  720  remains contained within the lens chamber  720 . 
         [0124]    The IOL  700  further comprises arc-shaped cut-outs  704  and radial arms  706  disposed to couple the base lens  750  to the peripheral portion  770 , in the same manner as depicted in  FIGS. 6A-6B . The significant feature of IOL  700  is the presence of raised protrusions  790  ( FIGS. 7A-7B ) or troughs  795  ( FIGS. 8A-8B ) adjacent the through-holes  702 . The raised protrusions  790  or troughs  795  are configured to ensure that the capsular bag does not form a seal over the through-holes  702  so as to impede or prevent the aqueous fluid from flowing freely in and out of the main cavity  730  and the circumferential channel  740 . 
         [0125]    As discussed above, the IOLs described herein are configured to transmit most, if not all, of the radially compressive forces exerted on the circumferential edge onto the lens chamber. In contrast to the elastically deformable lens chamber, the base lens is not configured to deform or change its curvature in response to the radially compressive forces exerted on the circumferential edge. The transfer of the radially compressive forces onto the lens chamber may be accomplished by incorporating one or more of the following features in the IOL: (1) the opposing sides of the lens chamber having a reduced thickness as compared to the base lens, (2) a hinge disposed between the base lens and the peripheral portion, (3) utilizing materials having different elastic moduli for the lens chamber and the base lens; and (4) the variation of refractive indices provided for the opposing sides of the lens chamber and the fluid or gel contained therein. 
         [0126]      FIGS. 10A and 10B  depict an IOL  800  which is constructed of at least two different elastomeric materials having different Young&#39;s modulus of elasticity, with at least the base lens  850  being made of a material having a higher Young&#39;s modulus than the lens chamber  810 . 
         [0127]      FIG. 10A  depicts the IOL  800  as being constructed by assembling at least five (5) separately molded pieces,  801 A,  802 A,  803 A,  804 A, and  850 . Thus, in addition to the two halves  801 A,  803 A of the lens chamber  810 , The peripheral portion of the IOL  800  is provided in two ring portions  802 A,  804 A. The first ring portion  802 A surrounding the lens chamber  810  has a higher elastic Young&#39;s modulus than the second ring portion  804 A surrounding the base lens  850 . In a preferred embodiment, the two halves  801 A,  803 A of the lens chamber  810  and the second ring portion  803 A has a Young&#39;s modulus of 100 psi or less, preferably 75 psi or less, and most preferably 50 psi or less and the base lens  850  and the first ring portion  802  has a Young&#39;s modulus of more than 100 psi, preferably more than 250 psi, and most preferably more than 350 psi. In a particularly preferred embodiment, the Young&#39;s modulus of the first ring portion  802 A may be up to 500 psi. 
         [0128]      FIG. 10B  depicts the IOL  800  as being constructed by assembling at least three (3) separately molded pieces  801 B,  802 B and  803 B. The first lens chamber  810  and the surrounding peripheral portion is provided by assembling  801 B and  802 B and the base lens portion  850  and the surrounding peripheral portion is provided by assembling  803 B to the underside of  802 B. The assembled first lens chamber  810  and surrounding peripheral portion ( 801 B,  802 B) has a lower elastic Young&#39;s modulus than the base lens portion  850  and the surrounding peripheral portion ( 803 B). In a preferred embodiment, portions  801 B,  802 B has a Young&#39;s modulus of 100 psi or less, preferably 75 psi or less, and most preferably 50 psi or less and the base lens portion  803 B has a Young&#39;s modulus of more than 100 psi, preferably more than 250 psi and, most preferably, more than 350 psi. In a particularly preferred embodiment, the Young&#39;s modulus of the base lens portion  803 B may be up to 500 psi. 
         [0129]    The invention described and claimed herein is not to be limited in scope by the specific preferred embodiments disclosed herein, as these embodiments are intended as illustrations of several aspects of the invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims.