Patent Publication Number: US-2011071628-A1

Title: Accommodative intraocular lens

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to implantable medical devices, and specifically to intraocular lenses. 
     BACKGROUND OF THE INVENTION 
     Accommodating intraocular lenses (AIOLs) allow the eye to focus at different distances. The Crystalens® (Bausch &amp; Lomb, Rochester, N.Y., USA) is an AIOL that has received FDA approval in the United States. 
     The following references may be of interest: 
     U.S. Pat. No. 7,416,562 to Gross McLeod SD et al., “Synchrony dual-optic accommodating intraocular lens Part 1: Optical and biomechanical principles and design considerations,” J Cataract Refract Surg. 2007; 33:37-46 Ossma IL et al., “Synchrony Dual-Optic Accommodating Intraocular Lens Part 2: Pilot Clinical Evaluation,” J Cataract Refract Surg. 2007; 33:47-52. 
     SUMMARY OF THE INVENTION 
     In embodiments of the present invention, an accommodative intraocular lens (AIOL) implant comprises posterior and anterior lens complexes coupled to a frame. The AIOL implant is configured such that the width (in the anterior-posterior direction) of the frame changes in response to the natural accommodation mechanism of the eye. This change in width changes the distance between the anterior lens complex and the posterior lens complex, thereby adjusting the focal length of the AIOL implant. The frame comprises one or more levers, which magnify the relatively small change in the width of the frame caused by the natural change in the shape of the capsular bag, in order to move the anterior lens complex a greater distance with respect to the posterior lens complex. Because of this distance magnification, the AIOL implant provides a high level of accommodation that mimics that of the natural eye. 
     The AIOL implant&#39;s accommodation typically provides a continuous range of focus, including near, distance, and intermediate distances. The AIOL implant exploits the natural accommodation mechanism of the eye, which reacts in order to sharpen the image on the retina. The AIOL implant thus typically reduces the need for glasses, which are generally required by patients with conventional IOLs. The AIOL implant is typically implanted in the eye after natural lens removal because of cataract, or for Refractive Lens Exchange (RLE), using well-known IOL implantation techniques, including making a small incision. 
     For some applications, the frame of the AIOL implant is configured to stretch the natural capsular bag of the eye toward its natural, fully functional shape. Assuming this reduced-diameter natural shape increases the tension of the zonular fibers, and thus allows the zonular fibers and ciliary muscle to function normally, and interact with the AIOL implant as they would with the natural lens. As a result, the AIOL implant to a large extent restores the eye&#39;s natural accommodation mechanism. For some applications, the frame comprises a plurality of wings, which extend radially outward from the interior of the AIOL implant, and are configured to help restore the natural, fully functional shape of the capsular bag. 
     There is therefore provided, in accordance with an embodiment of the present invention, apparatus including an accommodating intraocular lens (AIOL) implant, which includes: 
     at least an anterior floating lens complex and a posterior lens complex, each of which includes one or more optical elements; and 
     a frame including one or more levers, which are coupled to the frame and the anterior floating lens complex, and are configured to leverage motion of the frame to move the anterior floating lens complex with respect to the posterior lens complex. 
     Typically, the levers are coupled to the frame and the anterior floating lens complex such that the levers move the anterior floating lens complex by a first distance with respect to the posterior lens complex, when an anterior-posterior width of the frame increases by a second distance, the first distance greater than the second distance. 
     For some applications, the AIOL implant is configured to decrease a diameter of a natural capsular bag of an eye in which the AIOL implant is implanted. For example, the frame may include a plurality of wings, which are configured to decrease the diameter of the natural capsular bag. 
     For some applications, the frame includes an accommodating lens holder, arranged such that the levers are coupled to the anterior floating lens complex indirectly via the accommodating lens holder. Alternatively, the levers are coupled directly to the anterior floating lens complex. 
     For some applications, the frame includes an anterior support structure; a posterior support structure, to which the posterior lens complex is coupled; and one or more links, which couple the anterior support structure to the posterior support structure, and provide a variable distance between the support structures. For some applications, the levers are coupled to respective ones of the links. Typically, the levers are coupled to the frame and the anterior floating lens complex such that the levers move the anterior floating lens complex by a first distance with respect to the posterior support structure, when the anterior support structure moves a second distance with respect to the posterior support structure, the first distance greater than the second distance. For some applications, the links are configured to provide spring functionality that tends to push the anterior support structure away from the posterior support structure. 
     For some applications, the frame is configured to assume locked and unlocked states. For some applications, the frame is configured to automatically transition from the locked state to the unlocked state after a period of time after implantation of the AIOL implant in an eye. 
     The present invention will be more fully understood from the following detailed description of embodiments thereof, taken together with the drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-B  are schematic isometric views of an accommodative intraocular lens (AIOL) implant, in non-accommodated and fully-accommodated states, respectively, in accordance with an embodiment of the present invention; 
         FIGS. 2A-B  are schematic side views showing the AIOL implant of  FIGS. 1A-B  implanted in a natural capsular bag of the eye, in non-accommodated and fully-accommodated states, respectively; 
         FIGS. 3A-B  are simplified side views showing only a portion of the AIOL implant of  FIGS. 1A-B , for clarity of illustration; 
         FIGS. 4A-B  are schematic side views of another configuration of the AIOL implant of  FIGS. 1A-B  implanted in the natural capsular bag, in non-accommodated and fully-accommodated states, respectively, in accordance with an application of the present invention; 
         FIGS. 5A-B  are schematic side views of yet another configuration of the AIOL implant of  FIGS. 1A-B  implanted in the natural capsular bag, in non-accommodated and fully-accommodated states, respectively, in accordance with an application of the present invention; 
         FIGS. 6A-B  are schematic isometric views of still another configuration of the AIOL implant of  FIGS. 1A-B , in non-accommodated and fully-accommodated states, respectively, in accordance with an application of the present invention; 
         FIGS. 7A-B  are schematic side views of another configuration of the AIOL implant of  FIGS. 1A-B , in non-accommodated and fully-accommodated states, respectively, in accordance with an application of the present invention; and 
         FIGS. 8A-B  are schematic side views of yet another configuration of the AIOL implant of  FIGS. 1A-B  implanted in the natural capsular bag, in non-accommodated and fully-accommodated states, respectively, in accordance with an application of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       FIGS. 1A-B ,  2 A-B, and  3 A-B are schematic illustrations of an accommodative intraocular lens (AIOL) implant  10 , in accordance with an embodiment of the present invention.  FIGS. 1A-B  are isometric views of the AIOL implant.  FIGS. 2A-B  are side views showing the AIOL implant implanted in a natural capsular bag  12  of the eye.  FIGS. 3A-B  are simplified side views showing only a portion of the AIOL implant for clarity of illustration. 
       FIGS. 1A ,  2 A, and  3 A show AIOL implant  10  in a non-accommodated state, while  FIGS. 1B ,  2 B, and  3 B show the AIOL implant in a fully-accommodated state. Although only these two states are shown in these and the other figures, AIOL implant  10  is typically configured to assume a continuous range of accommodation between the non-accommodated state and the fully-accommodated state. The fully-accommodated state provides near vision, the non-accommodated state provides distance vision, and partially-accommodated states therebetween provide intermediate vision. The AIOL implant is configured to reach the fully-accommodated state responsively to the natural accommodation mechanism of the eye, without the need for external power. 
     AIOL implant  10  comprises a frame  20 , which typically comprises anterior and posterior support structures  30  and  32 . For some applications, both of the support structures are shaped as rings, which are typically concentric. Support structures  30  and  32  are coupled together by one or more links  34  (e.g., one to three, or four or more), which are coupled to the support structures typically such that the links articulate with the support structures. The links are configured to provide a variable distance between the two support structures, as described hereinbelow. To this end, the links are flexible, include flexible portions, and/or include hinges. 
     AIOL implant  10  further comprises at least an anterior floating lens complex  40  and a posterior lens complex  42 . (The lens complexes are shown in  FIGS. 2A-B  and  3 A-B, but are omitted in  FIGS. 1A-B  for clarity of illustration.) Posterior lens complex  42  is coupled to posterior support structure  32 , and remains generally fixed with respect to the posterior of the eye during accommodation of the AIOL implant. For some applications, as shown in  FIGS. 1A-B ,  2 A-B, and  3 A-B, anterior floating lens complex  40  is coupled to an accommodating lens holder  44 , which may be shaped as a ring. 
     The AIOL implant is configured such that anterior floating lens complex  40  (and accommodating lens holder  44 , if provided) moves with respect to posterior lens complex  42  (and posterior support structure  32 ) in response to the natural accommodation mechanism of the eye. The natural accommodation mechanism of the eye changes the shape of capsular bag  12 , as shown in  FIGS. 2A-B . In the non-accommodated state shown in  FIG. 2A , the ciliary muscle is relaxed and the zonular fibers are thus tensed, causing the capsular bag to assume a relatively narrow width (in the anterior-posterior direction) and relatively large diameter. As used herein, including in the claims, the diameter of the capsular bag means the greatest diameter of the capsular bag when viewed from its posterior aspect. This shape of the capsular bag squeezes the AIOL implant in the anterior-posterior direction. In contrast, in the fully-accommodated state shown in  FIG. 2B , the ciliary muscle contracts, thereby releasing the tension of the zonular fibers on the capsular bag, causing the capsular bag to assume a relatively large width and relative small diameter. This shape of the capsular bag allows the AIOL implant to expand in the anterior-posterior direction. 
     As the width of the capsular bag changes, as described above, anterior support structure  30  moves with respect to posterior support structure  32 , thereby changing the distance between the support structures. As described above, frame  20  typically comprises one or more links  34 , which couple anterior support structure  30  to posterior support structure  32 . Links  34  flex and assume a straighter, longer shape, as the support structures move away from each other. For some applications, links  34  are configured to function as springs that tend to push anterior support structure  30  away from posterior support structure  32  when the natural capsular bag is not applying a force that squeezes the support structures together. Alternatively or additionally, frame  20  comprises one or more separate springs that are configured to widen the AIOL implant (configuration not shown). 
     When the width of AIOL implant  10  changes, one or more elements of frame  20  move anterior floating lens complex  40  (and accommodating lens holder  44 , if provided) with respect to posterior lens complex  42  (and posterior support structure  32 ). The elements of frame  20  that cause this relative motion typically include one or more levers  52  (e.g., between one and three, or four or more). Typically, one end of each of the levers is attached to one of links  34 , and the other end is attached to anterior floating lens complex  40  (either directly or via accommodating lens holder  44 , if provided). The levers magnify the relatively small change in the width of the frame and in the distance between support structures  30  and  32 , in order to move accommodating lens holder  44  by a greater distance with respect to posterior support structure  32 . Because of this distance magnification, the AIOL implant provides a high level of accommodation that mimics that of the natural eye. The levers are typically attached to the links at respective points along the links that result in optimal angular change due to the straightening of the links, and a resulting optimal shifting of the anterior floating lens complex. 
     Typically, anterior floating lens complex  40  (and accommodating lens holder  44 , if provided) moves a first distance with respect to posterior support structure  32 , when anterior support structure  30  moves a second distance with respect to posterior support structure  32 , which first distance is greater than the second distance. 
     For some applications, as shown in  FIGS. 1A-B ,  2 A-B, and  3 A-B, each of levers  52  is defined by an arm  54  and an anterior portion of one of links  34 . The arm and the anterior portion of the link are coupled together at a fixed angle α. For some applications, the levers are coupled to accommodating lens holder  44 , such that the levers are indirectly coupled to anterior floating lens complex  40 . For other applications, the levers are coupled to anterior floating lens complex  40  directly or via a small joining mechanism. In these latter applications, frame  20  does not necessarily comprise accommodating lens holder  44 . Typically, the levers are coupled to lens holder  44  or lens complex  40  such that the levers articulate with the holder or lens complex. The points of connection of the levers with the holder or lens complex are optimized to provide an adequate shift of the floating lens complex in response to the natural accommodation of the eye. 
     The anterior and posterior movement of anterior floating lens complex  40  changes the distance between the lens complexes, thereby adjusting the focal length of the AIOL implant. In the fully-accommodated state, which provides near vision, frame  20  is relatively wide (in the anterior-posterior direction), with a large separation between the anterior and posterior lens complexes, creating a large free space between the complexes. In the non-accommodated state, which provides distance vision, the frame is relatively narrow, with a small separation between anterior and posterior complexes. Anterior floating lens complex  40  typically shifts at least 1 mm between the non-accommodated and fully-accommodated states. 
     Anterior floating lens complex  40  moves within an interior space of frame  20 , which is typically open to the natural fluid within the eye. The floating lens complex is configured to create minimum drag during movement, while maintaining the optical performance of the combined lens structure. For example, the floating lens complex may have a smooth shape, and/or may be coated with a hydrophobic coating such as silicone. 
     Typically, the lens complexes are configured to together create an optical structure having a total power that varies between +15 D and +25 D, as selected by the physician implanting the AIOL implant. For some applications, the shift of anterior floating lens complex changes the optical power of the combined optical structure in accordance with the following equation: 
         ΔDc ≈( Dm /13)Δ s   (1)
 
     in which ΔDc is the change in conjugation power of the eye, Dm is the dioptric power of the moving lens complex, and As is the change in lens complex position expressed in millimeters. Thus, the greater the optical power of anterior floating lens complex  40 , the greater the change in optical power of the combined optical structure. 
     Each of lens complexes  40  and  42  comprises one or more optical elements, such as lenses, fixed power optics, convex lenses, concave lenses, biconvex lenses, biconcave lenses, spherical lenses, aspheric lenses, astigmatic lenses, deformable optics, aberration free optics, doublets, triplets, filtered optics, or combinations of these lenses, as is known in the optical arts. Typically, each of lens complexes  40  and  42  comprises at least one lens. For some applications, each of the lens complexes comprises exactly one lens element. For some applications, one or more of lens complexes  40  are attached to frame  20  during manufacture. Alternatively or additionally, one or more of the lens complexes may be attached by a healthcare worker either prior to or during the implantation procedure, such as to provide the lens complex most appropriate for the particular patient. 
     For some applications, frame  20  further comprises a plurality of wings  60 , which extend radially outward from the interior of AIOL implant  10 . (The wings are shown in  FIGS. 1A-B  and  2 A-B, but omitted in  FIGS. 3A-B  for clarity of illustration.) Wings  60  are configured to help stretch capsular bag  12  toward its natural, fully functional shape. Assuming this reduced-diameter natural shape increases the tension of the zonular fibers, and thus allows the zonular fibers and ciliary muscle to function normally, and interact with AIOL implant  10  as they would with the natural lens. Alternatively or additionally, the AIOL implant increases the width (in the anterior-posterior direction) of the capsular bag, which reduces the diameter of the capsular bag, and increases the tension of the zonular fibers. As a result, AIOL implant  10  to a large extent restores the eye&#39;s natural accommodation mechanism. Wings  60  function as haptics, which hold AIOL implant  10  in place within the capsular bag. 
     For some applications, a first portion of wings  60  are coupled to anterior support structure  30 , and a second portion of the wings are coupled to posterior support structure  32 . The wings coupled to the anterior support structure typically extend radially outward in a posterior direction, while the wings coupled to the posterior support structure typically extend radially outward in an anterior direction. For some applications, the wings are provided in pairs, each of which includes one wing coupled to anterior support structure  30 , and one wing coupled to posterior support structure  32 , generally aligned with each other, as shown in  FIG. 1A-B ,  2 A-B, and  3 A-B. Alternatively, the wings are offset from one another around frame  20 . For some applications, the wings are generally shaped as tabs. 
     For some applications, frame  20  is configured to have locked and non-locked states. For example, in the locked state, the frame may be held in the non-accommodated state, or close thereto. Alternatively, the frame is held in a different position in the locked state. AIOL implant  10  is implanted in the locked state, in order to control the capability of accommodation and/or to optimize the span of accommodation and/or tense the zonular fibers. After implantation, the lock is disengaged, allowing the AIOL implant to accommodate by exploiting the eye&#39;s natural accommodation mechanism. For some applications, the locking mechanism is configured to automatically disengage a short time after implantation, e.g., between a few minutes and a few weeks, or longer, after implantation, in order to allow time for the eye to become accommodated to the implant. For some applications, the locking mechanism is implemented using absorbable sutures and/or biodegradable medical adhesives, or by the structure of frame  20 . Alternatively, for example, laser energy can be applied to the implant to release the lock. 
     For some applications, AIOL implant  10  is fully pre-assembled or modularly assembled prior to, during, or after implantation. AIOL implant  10  typically comprises biocompatible materials, such as silicone, acrylic, Poly(methyl methacrylate) (PMMA), Nitinol, or platinum. 
     Upon implantation of some IOLs, the eye&#39;s natural accommodation may be lost over time, with a resultant loss in tension of the zonules, thereby affecting the ability of the zonules to focus the lens. For some applications, AIOL implant  10  comprises mechanical means for reducing or preventing this slackening of the zonules. For some applications, AIOL implant  10  implements one or more of the techniques described in U.S. Pat. No. 7,416,562 to Gross, which is incorporated herein by reference. 
       FIGS. 4A-B  are schematic side views of another configuration of AIOL implant  10  implanted in natural capsular bag  12 , in non-accommodated and fully-accommodated states, respectively, in accordance with an application of the present invention. For some applications, as shown in  FIGS. 4A-B , links  34  are hinged. Alternatively or additionally, for some applications, a single bent wing  60  serves in place of a pair of wings  60  described hereinabove with reference to  FIGS. 1A-B ,  2 A-B, and  3 A-B. 
       FIGS. 5A-B  are schematic side views of yet another configuration of AIOL implant  10  implanted in natural capsular bag  12 , in non-accommodated and fully-accommodated states, respectively, in accordance with an application of the present invention. 
       FIGS. 6A-B  are schematic isometric views of still another configuration of AIOL implant  10 , in non-accommodated and fully-accommodated states, respectively, in accordance with an application of the present invention. For clarity of illustration, lens complexes  40  and  42  are not shown. In this configuration, levers  52  are directly coupled to anterior floating lens complex  40 . Each lever is shaped so as to define two arms  54 , which are curved to generally match the shape of the circumference of anterior floating lens complex  40 , so as to hold the floating lens complex. 
       FIGS. 7A-B  are schematic side views of another configuration of AIOL implant  10 , in non-accommodated and fully-accommodated states, respectively, in accordance with an application of the present invention. 
       FIGS. 8A-B  are schematic side views of yet another configuration of AIOL implant  10  implanted in natural capsular bag  12 , in non-accommodated and fully-accommodated states, respectively, in accordance with an application of the present invention. The figures show the floating lens complex shift caused by the reshaping of capsular bag  12  during accommodation. 
     In this configuration, frame  20  comprises one or more (e.g., two) wings  70 , which are configured to help stretch capsular bag  12  toward its natural, fully functional shape. Assuming this reduced-diameter natural shape increases the tension of the zonular fibers, and thus allows the zonular fibers and ciliary muscle to function normally, and interact with AIOL implant  10  as they would with the natural lens. For some applications, each of wings  70  extends in both anterior and posterior directions. Alternatively, the wings extend in only the anterior direction, or only the posterior direction (configuration not shown). For some applications, the wings comprise curved rods (as shown). For applications in which the wings at least in part cover the anterior aspect of capsular bag  12 , the wings are typically forked so as to not interfere with vision (e.g., so as not to substantially block the opening in the anterior aspect of the capsular bag). 
     It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description.