Abstract:
A two-optic accommodative lens system. The first lens has a negative power and is located posteriorly against the posterior capsule. The periphery of the first optic contains a pair of clasps. The second optic is located anteriorly to the first optic and is of a positive power. The peripheral edge of the second optic contains a pair of locking arms that fit into the clasps contained on the periphery of the first optic to lock the second optic onto the first optic, but allow for rotation of the arms within the clasps. Hinge structures on the locking arms allow the second optic to move relative to the first optic along the optical axis of the lens system in reaction to movement of the ciliary muscle.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to the field of intraocular lenses (IOL) and, more particularly, to accommodative IOLs. 
     The human eye in its simplest terms functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of a crystalline lens onto a retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and the lens. 
     When age or disease causes the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. An accepted treatment for this condition is surgical removal of the lens and replacement of the lens function by an artificial intraocular lens (IOL). 
     In the United States, the majority of cataractous lenses are removed by a surgical technique called phacoemulsification. During this procedure, an opening is made in the anterior capsule and a thin phacoemulsification cutting tip is inserted into the diseased lens and vibrated ultrasonically. The vibrating cutting tip liquifies or emulsifies the lens so that the lens may be aspirated out of the eye. The diseased lens, once removed, is replaced by an artificial lens. 
     In the natural lens, bifocality of distance and near vision is provided by a mechanism known as accommodation. The natural lens, early in life, is soft and contained within the capsular bag. The bag is suspended from the ciliary muscle by the zonules. Relaxation of the ciliary muscle tightens the zonules, and stretches the capsular bag. As a result, the natural lens tends to flatten. Tightening of the ciliary muscle relaxes the tension on the zonules, allowing the capsular bag and the natural lens to assume a more rounded shape. In the way, the natural lens can be focus alternatively on near and far objects. 
     As the lens ages, it becomes harder and is less able to change shape in reaction to the tightening of the ciliary muscle. This makes it harder for the lens to focus on near objects, a medical condition known as presbyopia. Presbyopia affects nearly all adults over the age of 45 or 50. 
     Prior to the present invention, when a cataract or other disease required the removal of the natural lens and replacement with an artificial IOL, the IOL was a monofocal lens, requiring that the patient use a pair of spectacles or contact lenses for near vision. Allergan has been selling an bifocal IOL, the Array lens, for several years, but due to quality of issues, this lens has not been widely accepted. 
     Several designs for accommodative IOLs are being studied. For example, several designs manufactured by C&amp;C Vision are currently undergoing clinical trials. See U.S. Pat. Nos. 6,197,059, 5,674,282, 5,496,366 and 5,476,514 (Cumming), the entire contents of which being incorporated herein by reference. The lens described in these patents is a single optic lens having flexible haptics that allows the optic to move forward and backward in reaction to movement of the ciliary muscle. A similar designs are described in U.S. Pat. No. 6,302,911 B1 (Hanna), U.S. Pat. Nos. 6,261,321 B1 and 6,241,777 B1 (both to Kellan), the entire contents of which being incorporated herein by reference. The amount of movement of the optic in these single-lens systems, however, may be insufficient to allow for a useful range of accommodation. In addition, as described in U.S. Pat. Nos. 6,197,059, 5,674,282, 5,496,366 and 5,476,514, the eye must be paralyzed for one to two weeks in order for capsular fibrosis to entrap the lens that thereby provide for a rigid association between the lens and the capsular bag. In addition, the commercial models of these lenses are made from a hydrogel or silicone material. Such materials are not inherently resistive to the formation of posterior capsule opacification (“PCO”). The only treatment for PCO is a capsulotomy using a Nd:YAG laser that vaporizes a portion of the posterior capsule. Such destruction of the posterior capsule may destroy the mechanism of accommodation of these lenses. 
     There have been some attempts to make a two-optic accommodative lens system. For example, U.S. Pat. No. 5,275,623 (Sarfarazi), WIPO Publication No. 00/66037 (Glick, et al.) and WO 01/34067 A1 (Bandhauer, et al), the entire contents of which being incorporated herein by reference, all disclose a two-optic lens system with one optic having a positive power and the other optic having a negative power. The optics are connected by a hinge mechanism that reacts to movement of the ciliary muscle to move the optics closer together or further apart, thereby providing accommodation. In order to provide this “zoom lens” effect, movement of the ciliary muscle must be adequately transmitted to the lens system through the capsular bag, and none of these references disclose a mechanism for ensuring that there is a tight connection between the capsular bag and the lens system. In addition, none of these lenses designs have addressed the problem with PCO noted above. 
     Therefore, a need continues to exist for a safe and stable accommodative intraocular lens system that provides accommodation over a broad and useful range. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention improves upon the prior art by providing a two-optic accommodative lens system. The first lens has a negative power and is located posteriorly against the posterior capsule. The periphery of the first optic contains a pair of clasps. The second optic is located anteriorly to the first optic and is of a positive power. The peripheral edge of the second optic contains a pair of locking arms that fit into the clasps contained on the periphery of the first optic to lock the second optic onto the first optic, but allow for rotation of the arms within the clasps. Hinge structures on the locking arms allow the second optic to move relative to the first optic along the optical axis of the lens system in reaction to movement of the ciliary muscle. 
     Accordingly, one objective of the present invention is to provide a safe and biocompatible intraocular lens. 
     Another objective of the present invention is to provide a safe and biocompatible intraocular lens that is easily implanted in the posterior chamber. 
     Still another objective of the present invention is to provide a safe and biocompatible intraocular lens that is stable in the posterior chamber. 
     Still another objective of the present invention is to provide a safe and biocompatible accommodative lens system. 
     These and other advantages and objectives of the present invention will become apparent from the detailed description and claims that follow. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is an enlarged top plan view of the first optic of a first embodiment of the lens system of the present invention. 
     FIG. 2 is an enlarged cross-sectional view of the first optic of a first embodiment of the lens system of the present invention taken at line  2 — 2  in FIG.  1 . 
     FIG. 3 is an enlarged top plan view of the second optic of a first embodiment of the lens system of the present invention. 
     FIG. 4 is an enlarged cross-sectional view of the second optic of a first embodiment of the lens system of the present invention taken at line  4 — 4  in FIG.  3 . 
     FIG. 5 is an enlarged partial cross-sectional view taken at circle  5  in FIG.  4 . 
     FIG. 6 is an enlarged top plan view of the first optic of a second embodiment of the lens system of the present invention. 
     FIG. 7 is an enlarged cross-sectional view of the first optic of a second embodiment of the lens system of the present invention taken at line  7 — 7  in FIG.  6 . 
     FIG. 8 is an enlarged top plan view of the second optic of a second embodiment of the lens system of the present invention. 
     FIG. 9 is an enlarged cross-sectional view of the second optic of a second embodiment of the lens system of the present invention taken at line  9 — 9  in FIG.  8 . 
     FIG. 10 is a cross-sectional view of the first embodiment of the lens system of the present invention illustrated in FIGS. 1-5. 
     FIG. 11 is a cross-sectional view of the second embodiment of the lens system of the present invention illustrated in FIGS. 6-9. 
     FIG. 12 is a cross-sectional view of the first embodiment of the lens system of the present invention illustrated in FIGS. 1-5 and illustrating the lens system implanted within a capsular bag. 
     FIG. 13 is a cross-sectional view of the second embodiment of the lens system of the present invention illustrated in FIGS. 6-9 and illustrating the lens system implanted within a capsular bag. 
     FIG. 14 is an enlarged top plan view of the first optic of a third embodiment of the lens system of the present invention. 
     FIG. 15 is an enlarged cross-sectional view of the first optic of a third embodiment of the lens system of the present invention taken at line  15 — 15  in FIG.  14 . 
     FIG. 16 is an enlarged partial cross-sectional view taken at circle  16  in FIG.  15 . 
     FIG. 17 is an enlarged top plan view of the second optic of a third embodiment of the lens system of the present invention. 
     FIG. 18 is an enlarged cross-sectional view of the second optic of a third embodiment of the lens system of the present invention taken at line  18 — 18  in FIG.  17 . 
     FIG. 19 is an enlarged partial cross-sectional view taken at circle  19  in FIG.  18 . 
     FIG. 20 is an enlarged top plan view of the third embodiment of the lens system of the present invention illustrated in FIGS. 14-19. 
     FIG. 21 is a cross-sectional view of the third embodiment of the lens system of the present invention taken at line  21 — 21  in FIG.  20 . 
     FIG. 22 is an enlarged top plan view of the first optic of a fourth embodiment of the lens system of the present invention. 
     FIG. 23 is an enlarged cross-sectional view of the first optic of a third embodiment of the lens system of the present invention taken at line  23 — 23  in FIG.  22 . 
     FIG. 24 is an enlarged top plan view of the second optic of a fourth embodiment of the lens system of the present invention. 
     FIG. 25 is an enlarged cross-sectional view of the second optic of a third embodiment of the lens system of the present invention taken at line  25 — 25  in FIG.  24 . 
     FIG. 26 is an enlarged partial cross-sectional view taken at circle  26  in FIG.  25 . 
     FIG. 27 is an enlarged top plan view of the fourth embodiment of the lens system of the present invention illustrated in FIGS.  26 — 26 . 
     FIG. 28 is a cross-sectional view of the fourth embodiment of the lens system of the present invention taken at line  28 — 28  in FIG.  27 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As best seen in FIGS. 1-5 and  10 , lens system  10  of the present invention generally consists of posterior optic  12  and anterior optic  14 . Optic  12  is preferably formed in any suitable overall diameter or length, for example, around 12 millimeters, for implantation in the posterior chamber. Optic  12  preferably is made from a soft, foldable material that is inherently resistive to the formation of PCO, such as a soft acrylic. Optic  14  preferable is made from a soft, foldable material such as a hydrogel, silicone or soft acrylic. Optic  12  may be any suitable power, but preferably has a negative power. Optic  14  may also be any suitable power but preferably has a positive power. The relative powers of optics  12  and  14  should be such that the axial movement of optic  14  toward or away from optic  12  should be sufficient to adjust the overall power of lens system  10  at least one diopter and preferably, at least three to four diopters, calculation of such powers of optics  12  and  14  being within the capabilities of one skilled in the art of designing ophthalmic lenses by, for example, using the following equations: 
     
       
           P=P   1   +P   2   −T/n*P   1   P   2   (1) 
       
     
     
       
           δP=δT/n*P   1   P   2   (2) 
       
     
     As best seen in FIGS. 1 and 2, optic  12  is generally symmetrical about optical axis  22  and contains a pair of opposing clasps  16  that are shaped to stretch and fill equatorial region  210  of capsular bag  200 . Clasps  16  contain sockets  18  generally defined by latch  20 . As best seen in FIGS. 3-5, optic  14  contains a pair of haptics  24  that are connected to optic  14  by hinge regions  26  and contain locking pins  28  distally from hinge regions  26 . As seen in FIG. 10, locking pins  28  are sized and shaped to fit within sockets  18  on optic  12 , thereby holding optic  14  firmly within optic  12  while still permitting rotation of locking pins  28  within sockets  18 . One skilled in the art will recognize that sockets  18  may be located on hinge regions  26  and that locking pins  28  may be located on optic  12 . In order to insert locking pins  28  within sockets  18 , sockets  18  may be spread apart slightly, thereby preloading haptics  24 . Once implanted in an eye, as one skilled in the art will recognize, contraction of capsular bag  200  will cause clasps  16  to collapse slightly, thereby causing compression of optic  14 . As optic  14  is compressed, hinge regions  26  allow optic  14  to vault anteriorly away from optic  12 , with locking pins  28  pivoting within sockets  18 . One skilled in the art will recognize that no specific feature needs to be used to form hinge regions  26  as haptics  24  may be formed from a material and/or in such a configuration that haptics naturally flex in the manner of a hinge. 
     As best seen in FIGS. 6-9 and  11 , lens system  110  of the present invention generally consisting of posterior optic  112  and anterior optic  114 . Optic  112  is preferably formed in any suitable overall diameter or length, for example, around 12 millimeters, for implantation in the posterior chamber. Optic  112  preferably is made from a soft, foldable material that is inherently resistive to the formation of PCO, such as a soft acrylic. Optic  114  preferable is made from a soft, foldable material such as a hydrogel, silicone or soft acrylic. Optic  112  may be any suitable power, but preferably has a negative power. Optic  114  may also be any suitable power but preferably has a positive power. The relative powers of optics  112  and  114  should be such that the axial movement of optic  114  toward or away from optic  112  should be sufficient to adjust the overall power of lens system  10  at least one diopter and preferably, at least three to four diopters, calculation of such powers of optics  112  and  114  being within the capabilities of one skilled in the art. One skilled in the art will also recognize that the axial movement of optic  114  relative to optic  112  is greater in this embodiment as opposed to the embodiment illustrated in FIGS. 1-5 due to the longer length of haptic  124  versus haptic  24 . 
     As best seen in FIGS. 6,  7  and  13 , optic  112  is generally symmetrical about optical axis  122  and contains a pair of opposing clasps  116  that are shaped to stretch and fill equatorial region  310  of capsular bag  300 . Clasps  116  contain sockets  118  generally defined by latch  120 . As best seen in FIGS. 8 and 9, optic  114  contains circumferential haptic  124  that are connected to optic  114  by hinge regions  126  and contain locking pins  128  distally on the periphery of haptics  124 . One skilled in the art will recognize that sockets  118  may be located on clasps  116  and that locking pins  128  may be located on haptics  124 . As seen in FIG. 11, locking pins  128  are sized and shaped to fit within sockets  118  on optic  112 , thereby holding optic  114  firmly within optic  112  while still permitting rotation of locking pins  128  within sockets  118 . Preferably, locking pins  128  are located approximately 90° from hinge regions  126  around the circumference of optic  114 . In order to insert locking pins  128  within sockets  118 , sockets  118  may be spread apart slightly, thereby preloading haptics  124 . One skilled in the art will recognize that no specific feature needs to be used to form hinge regions  126  as haptics  124  may be formed from a material and/or in such a configuration that haptics naturally flex in the manner of a hinge. 
     Once implanted in an eye, as one skilled in the art will recognize, contraction of capsular bag  300  will cause clasps  116  to collapse slightly, thereby causing compression of optic  114 . As optic  114  is compressed, hinge regions  126  allow optic  114  to vault anteriorly away from optic  112 , with locking pins  128  pivoting within sockets  118 . 
     As best seen in FIGS. 12 and 13, lens system  10  and  110  fills capsular bag  200  and  300 , respectively, following removal of the natural lens. In order to remove the natural lens, an opening or rhexis is normally made in the anterior side of capsule  200  or  300 . The opening contains rim or margin  212  or  312  During implantation of system  10  or  110 , rim or margin  212  or  312  is inserted into socket  18  or  118  prior to the introduction of optic  14  or  114 , respectively. Once optic  14  or  114  is installed in optic  12  or  112 , locking pins  28  and  128  help to contain rim  212  or  312  within sockets  18  or  118 , respectively, thereby maintaining a positive mechanical connection between capsular bag  200  and  300  and lens system  10  and  110 , respectively. Contraction of capsular bag  200  or  300  will therefore be more directly translated into contraction of optics  12  and  112 , respectively. In addition, the self-locking design of sockets  18  and  118  prevent capsular bag  200  and  300  from slipping out of sockets  18  or  118 , respectively. 
     As best seen in FIGS. 15-21, lens system  410  of the present invention of the present invention generally consists of posterior optic  412  and anterior optic  414 . Optic  412  is preferably formed in any suitable overall diameter or length, for example, around 12 millimeters, for implantation in the posterior chamber. Optic  412  preferably is made from a soft, foldable material that is inherently resistive to the formation of PCO, such as a soft acrylic. Optic  414  preferable is made from a soft, foldable material such as a hydrogel, silicone or soft acrylic. Optic  412  may be any suitable power, but preferably has a negative power. Optic  414  may also be any suitable power but preferably has a positive power. The relative powers of optics  412  and  414  should be such that the axial movement of optic  414  toward or away from optic  412  should be sufficient to adjust the overall power of lens system  410  at least one diopter and preferably, at least three to four diopters, calculation of such powers of optics  412  and  414  being within the capabilities of one skilled in the art as described above. 
     As best seen in FIGS. 15 and 16, optic  412  is generally symmetrical about optical axis  422  and contains a circumferential socket  418 . As best seen in FIGS. 17-19, optic  414  contains a pair of hemispherical haptics  424  that are connected to optic  414  by hinge regions  426  and contain circumferential locking rib  428 . As seen in FIG. 21, locking rib  428  is sized and shaped to fit within socket  418  on optic  412 , thereby holding optic  414  firmly within optic  412  while allowing rotation of locking rib  428  within socket  418 . Once implanted in an eye, as one skilled in the art will recognize, contraction of the capsular bag will cause compression of optic  414 . As optic  414  is compressed, hinge regions  426  allow optic  414  to vault anteriorly away from optic  412 , with locking rib  428  pivoting within socket  418 . 
     As best seen in FIGS. 22-28, lens system  510  of the present invention of the present invention is similar to system  510  and generally consists of posterior optic  512  and anterior optic  514 . Optic  512  is preferably formed in any suitable overall diameter or length, for example, around 12 millimeters, for implantation in the posterior chamber. Optic  512  preferably is made from a soft, foldable material that is inherently resistive to the formation of PCO, such as a soft acrylic. Optic  514  preferable is made from a soft, foldable material such as a hydrogel, silicone or soft acrylic. Optic  512  may be any suitable power, but preferably has a negative power. Optic  514  may also be any suitable power but preferably has a positive power. The relative powers of optics  512  and  514  should be such that the axial movement of optic  514  toward or away from optic  512  should be sufficient to adjust the overall power of lens system  510  at least one diopter and preferably, at least three to four diopters, calculation of such powers of optics  512  and  514  being within the capabilities of one skilled in the art as described above. 
     As best seen in FIGS. 22 and 23, optic  512  is generally symmetrical about optical axis  522  and contains a circumferential rib  528 , which is similar to rib  428  in system  410 . As best seen in FIGS. 24-26, optic  514  contains a pair of hemispherical haptics  524  that are connected to optic  514  by hinge regions  526  and contain circumferential socket  518 . As seen in FIG. 28, locking rib  528  is sized and shaped to fit within socket  518  on optic  514 , thereby holding optic  514  firmly within optic  512  while allowing rotation of locking rib  528  within socket  518 . Once implanted in an eye, as one skilled in the art will recognize, contraction of the capsular bag will cause compression of optic  514 . As optic  514  is compressed, hinge regions  526  allow optic  514  to vault anteriorly away from optic  512 , with locking rib  528  pivoting within socket  518 . 
     This description is given for purposes of illustration and explanation. It will be apparent to those skilled in the relevant art that changes and modifications may be made to the invention described above without departing from its scope or spirit.