Abstract:
An accommodating intraocular lens (AIOL) including a biasing mechanism for elastically deforming an elastically deformable shape memory disk-like optical element for affording the AIOL a natural positive diopter strength for near vision. The AIOL is intended to be implanted in a human eye such that relaxation of its ciliary body causes its capsular diaphragm to apply an accommodation force for overcoming the biasing mechanism to reduce the AIOL&#39;s natural positive diopter strength for distance vision.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Domestic priority claim is made to U.S. Provisional Patent Application Ser. No. 60/617,738 filed on Oct. 13, 2004 and International priority claim is made to World Intellectual Property Organization (WIPO) PCT/IL2005/001069 filed on Oct. 9, 2005, assigned the International Publication Number WO 2006/040759 A1, published Apr. 20, 2006. 
     
    
     TECHNICAL FIELD  
       [0002]     The invention pertains to accommodating intraocular lenses (AIOLs), and AIOL assemblies including same.  
       BACKGROUND OF THE INVENTION  
       [0003]     Commonly owned PCT International Application No. PCT/IL02/00693 entitled Accommodating Lens Assembly and published under PCT International Publication No. WO 03/015669 illustrates and describes accommodating intraocular lens (hereinafter AIOL) assemblies, the contents of which are incorporated herein by reference. The AIOL assemblies include a haptics system adapted to be securely fixed in a human eye&#39;s annular ciliary sulcus at at least two spaced apart stationary anchor points so that it may act as a reference plane for an AIOL of continuously variable diopter strength affected by a human eye&#39;s capsular diaphragm acting thereagainst from a posterior direction and under the control of its sphincter-like ciliary body. WO 03/015669&#39;s FIGS. 1 and 2 show an AIOL assembly 2 designed to replicate a human eye&#39;s natural crystalline lens. The AIOL assembly 2 has a lens 6 made of a rigid material and a natural spherical shaped silicone ball 10 both having a refractive index greater than that of water. A human eye&#39;s capsular diaphragm directly bears against the silicone ball 10 from a posterior direction for resiliently elastically deforming it to a compressed flattened shape on relaxation of a human eye&#39;s ciliary body for decreasing its natural positive diopter strength for distance vision in a similar fashion to a human eye&#39;s natural crystalline lens. However, a human eye, and particularly an aging human eye, may be too weak to apply sufficient force to overcome such a silicone ball&#39;s inherent tendency to retain its natural shape thereby precluding accommodation.  
         [0004]     Exemplary AIOLs are illustrated and described in U.S. Pat. No. 4,254,509 to Tennant, U.S. Pat. No. 4,409,691 to Levy, U.S. Pat. No. 4,888,012 to Horn et al., U.S. Pat. No. 4,892,543 to Turley, U.S. Pat. No. 4,932,966 to Christie et al., U.S. Pat. No. 5,476,514 to Cumming, U.S. Pat. No. 5,489,302 to Skottun, U.S. Pat. No. 5,496,366 to Cumming, U.S. Pat. No. 5,522,891 to Klaas, U.S. Pat. No. 5,674,282 to Cumming, U.S. Pat. No. 6,117,171 to Skottun, U.S. Pat. No. 6,197,059 to Cumming, U.S. Pat. No. 6,299,641 to Woods, U.S. Pat. No. 6,342,073 to Cumming et al., U.S. Pat. No. 6,387,126 to Cumming, U.S. Pat. No. 6,406,494 to Laguette et al., U.S. Pat. No. 6,423,094 to Sarfarazi, U.S. Pat. No. 6,443,985 to Woods, U.S. Pat. No. 6,464,725 to Skotton, U.S. Pat. No. 6,494,911 to Cumming, U.S. Pat. No. 6,503,276 to Lang et al., U.S. Pat. No. 6,638,306 to Cumming, U.S. Pat. No. 6,645,245 to Preussner, and US Patent Application Publication No. US 2004/0169816 to Esch.  
       BRIEF SUMMARY OF THE INVENTION  
       [0005]     The present invention is for a novel AIOL including a biasing mechanism for elastically deforming an elastically deformable shape memory optical element for affording the AIOL with a natural positive diopter strength for near vision. The biasing mechanism is designed to apply a deforming force F BM  bounded on its lower side to be marginally greater than a minimum deformation force F OE  required to deform the optical element and on its upper side by the sum of the deformation force F OE  and an accommodation force F CD  effected by a human eye&#39;s capsular diaphragm in an anterior direction on relaxation of the human eye&#39;s ciliary body for enabling the optical element to revert to its natural shape to decrease the AIOL&#39;s natural positive diopter strength for distance vision. The forces acting on the optical element of the AIOL of the present invention can be mathematically expressed as F OE +F CD &gt;F BM &gt;F OE . By virtue of this arrangement, the AIOL of the present invention facilitates accommodation even in the case of an aging eye capable of applying an accommodation force F CD  which may be considerably less than that of a healthy eye.  
         [0006]     The AIOL forms part of an AIOL assembly intended for self-anchoring implantation in a human eye&#39;s ciliary sulcus at least two spaced apart stationary anchoring points. The AIOL can be mounted in a discrete haptics system enabling in situ displacement of the AIOL along a human eye&#39;s visual axis for enabling accurate eyesight correction in general, and for compensating for capsular contraction in particular. Alternatively, the AIOL can be integrally formed with a haptics system including plastically deformable haptics also enabling in situ AIOL displacement. Commonly owned PCT International Application No. PCT/IL2005/000456 entitled Accommodating Intraocular Lens Assemblies and Accommodation Measurement Implant illustrates and describes such a discrete haptics system, and a unitary construction including a haptics system with plastically deformable haptics and integrally formed with an AIOL both enabling in situ AIOL displacement, the contents of which are incorporated herein by reference.  
         [0007]     The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     In order to understand the invention and to see how it can be carried out in practice, preferred embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings in which similar parts are likewise numbered, and in which:  
         [0009]      FIG. 1  is a cross section view of an anterior part of a human eye in its natural near vision condition in an axial plane of the human body;  
         [0010]      FIG. 2  is a cross section view of an anterior part of a human eye in its natural distance vision condition in an axial plane of the human body;  
         [0011]      FIG. 3  is a perspective view of a dissembled two component AIOL assembly including a first preferred embodiment of an AIOL in accordance with the present invention;  
         [0012]      FIG. 4  is a perspective view of a unitary AIOL assembly integrally formed with a first preferred embodiment of an AIOL in accordance with the present invention;  
         [0013]      FIG. 5  is an exploded view of  FIG. 3 &#39;s AIOL;  
         [0014]      FIG. 6  is a longitudinal cross section of  FIG. 3 &#39;s AIOL in its near vision state;  
         [0015]      FIG. 7  is a longitudinal cross section of  FIG. 3 &#39;s AIOL in its distance vision state;  
         [0016]      FIG. 8  is a cross section view of an anterior part of a human eye implanted with  FIG. 3 &#39;s AIOL in its near vision state in an axial plane of the human body;  
         [0017]      FIG. 9  is a cross section view of an anterior part of a human eye implanted with  FIG. 3 &#39;s AIOL in its distance vision state in an axial plane of the human body;  
         [0018]      FIG. 10  is a perspective view of a second preferred embodiment of an AIOL in accordance with the present invention; and  
         [0019]      FIG. 11  is a perspective view of a third preferred embodiment of an AIOL in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]      FIGS. 1 and 2  are cross sections of an anterior part of a human eye  10  having a visual axis VA in its natural near and distance vision conditions, respectively, in an axial plane of the human body. The human eye  10  has a cornea  11  peripherally connected to a spherical exterior body made of tough connective tissue known as the sclera  12  at an annular sclero-corneal juncture  13 . An iris  14  inwardly extends into the human eye  10  from its root  16  at the sclero-corneal juncture  13  to divide the human eye&#39;s anterior part into an anterior chamber  17  and a posterior chamber  18 . A sphincter-like peripheral structure known as the ciliary body  19  includes ciliary processes housing ciliary muscles  21  fired by parasympathetic nerves. The ciliary muscles  21  are connected to zonular fibers  22  which in turn are peripherally connected to the equatorial edge of a membrane known as the capsular bag  23  with an anterior capsule  24  and a posterior capsule  26  enrobing a natural crystalline lens  27 . The iris&#39;s root  16  and the ciliary body  19  delimit a portion of the interior surface of the sclera  12  at the sclero-corneal juncture  13  known as the ciliary sulcus  28 . Remnants of the anterior capsule  24  which may remain after extraction of the natural crystalline lens  27  and the intact posterior capsule  26  are referred to hereinafter as the capsular diaphragm  29 . Contraction of the ciliary body  19  allows the lens  27  to thicken to its natural thickness T 1  along the visual axis VA for greater positive optical power for near vision (see  FIG. 1 ). Relaxation of the ciliary body  19  tensions the zonular fibers  22  which draws the capsular bag  23  radially outward as shown by arrows A for compressing the lens  27  to shorten its thickness along the visual axis VA to T 2 &lt;T 1  for lower positive optical power for distance vision (see  FIG. 2 ).  
         [0021]      FIG. 3  shows an AIOL assembly  31  for self-anchoring implantation in a human eye&#39;s ciliary sulcus  28  for enabling spectacle free vision over the nominal range of human vision. The AIOL assembly  31  includes a discrete haptics system  32  for selectively retaining a discrete AIOL  33  therein. The haptics system  32  is made from suitable bio-compatible material such as PMMA, and the like. The haptics system  32  includes a tubular main body  34  with a longitudinal axis  36  and an axial length L 1  (see  FIG. 6 ), and a pair of diametrically opposite haptics  37  tangentially extending therefrom in opposite directions in a front view of the haptics system  32 . The haptics  37  have a pair of parallel and opposite attachment plates  38  with pointed penetrating members  39  of sufficient strength for forced penetration into the tough connective tissue of a human eye&#39;s sclera  12 . The penetrating members  39  are preferably dimensioned so as to penetrate slightly more than half of a sclera&#39;s thickness of about 1 mm. Further details regarding the haptics system  32  are illustrated and described in the aforementioned PCT International Application No. PCT/IL2005/000456 in general, and  FIGS. 3-5  in particular.  
         [0022]      FIG. 4  shows an AIOL assembly  41  for self-anchoring implantation in a human eye&#39;s ciliary sulcus  28  for enabling spectacle free vision over the nominal range of human vision. The AIOL assembly  41  includes a haptics system  42  integrally formed with an AIOL  43  similar in construction and operation as the discrete AIOL  33 . The haptics system  42  is similar in construction as the haptics system  32  but differs therefrom insofar that it includes plastically deformable haptics  44  with regions  46  impregnated with radiation sensitive bio-compatible chemicals, for example, Infra Red (IR) sensitive indocyanine green (ICG), and the like, such that the haptics  44  are plastically deformable on heating to a so-called glass transition temperature. Further details regarding the haptics system  42  are illustrated and described in the aforementioned PCT International Application No. PCT/IL2005/000456 in general, and  FIGS. 12-16  in particular.  
         [0023]      FIGS. 5-7  show the AIOL  33  includes a cup shaped casing  51  made from a suitable rigid bio-compatible material such as PMMA, and the like, and having an axial length L 2  along a longitudinal axis  52 , a leading surface  53 , a stepped external surface  54  with a wide diameter leading portion  56  for secure clamping in the main body  34  and a narrow diameter trailing portion  57 , a right cylindrical internal surface  58 , and a trailing surface  59  formed with an annular flange  61  defining an aperture  62 . The casing&#39;s axial length L 2  is longer than the main body&#39;s axial length L 1  such that the main body  34  is capable of contacting the casing  51  along an adjustment stroke longer than the main body&#39;s axial length L 1 . The leading portion  56  is formed with three peripherally disposed longitudinally directed grooves  63  formed with cutouts  64  in the leading surface  53 . The casing  51  has a natural disc-like shape optical element  66  made of suitable elastically deformable bio-compatible material, such as, polymeric gel, hydrogel, and the like, having a refractive index greater than that of water. Suitable polymeric gels include silicone gel commercially available from NuSil Technology LLC., USA (www.nusil.com). The optical element  66  begins to undergo elastic deformation along its longitudinal axis on application of a minimum deformation force F OE .  
         [0024]     A rigid carriage  67  is slidingly mounted on the casing  51  from the exterior and includes an annular base plate  68  formed with an aperture  69  and three longitudinally directed struts  71  having free ends  72  each formed with an aperture  73 , and an aperture lens  74  having a leading portion  76  and a trailing portion  77  formed with three equispaced radially directed protrusions  78  for snap fitting into the apertures  73 . The base plate  68  is preferably formed from a suitable rigid bio-compatible material such as PMMA, and the like. The aperture lens  74  is preferably formed from a suitable rigid bio-compatible material such as PMMA, and the like. The aperture lens  74  preferably has sufficient positive diopter strength, say, in the range of between about +10 to about +30, for basic eyesight correction. The struts  71  are slidingly received in the grooves  63  such that the aperture lens  74  is lateral to the leading surface  53  and the base plate  68  is lateral to the trailing surface  59 . The carriage  67  reciprocates through a stroke S between a first extreme position in which the base plate  68  is adjacent the trailing surface  59  and a second extreme position in which the base plate  68  is distanced from the trailing surface  59  relative to the first extreme position. A biasing mechanism  79  constituted by a compression spring is disposed between the trailing portion  57  and the struts  71  for urging the carriage  67  to its second extreme position. The biasing mechanism  79  applies a deforming force F BM  where F BM =F OE +Δ for deforming the optical element  66  to bulge through the aperture  62  to afford the AIOL  33  with a positive diopter strength for near vision (see  FIG. 6 ). The biasing mechanism  79  is designed such that an accommodation force F CD  applied against the base plate  68  in an anterior direction on relaxation of the ciliary body  19  satisfies the condition that F OE +F CD &gt;F BM  such that the carriage  67  assumes its first extreme position for allowing the optical element  66  to revert to its natural disc-like shape to decrease the AIOL&#39;s natural positive diopter strength for distance vision (see  FIG. 7 ).  
         [0025]      FIGS. 8 and 9  show the AIOL assembly  31  self-anchored in a human eye&#39;s ciliary sulcus at peripherally disposed stationary anchor points AP in its near vision and far distance states, respectively. The AIOL assembly  31  is implanted in a human eye  10  such that the capsular diaphragm  29  lightly bears against the base plate  68  in the contracted state of the human eye&#39;s ciliary body  19  such that on its relaxation, the capsular diaphragm  29  urges the AIOL  33  from its near vision state to its distance vision state.  
         [0026]     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, the biasing mechanism  79  can be implemented by longitudinally compressible flex elements  81  (see  FIG. 10 ), leaf springs  82  (see  FIG. 11 ), and the like. Also, basic eyesight correction can be effected by a base plate instead of the aperture lens  74 . Furthermore, the carriage can be assembled using non-mechanical techniques, for example, gluing, welding, and the like.  
         [0027]     Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.