Abstract:
The invention relates to a novel phakic intraocular lens. The positioning arms or haptics of the lens are designed to hold the lens in position and proper orientation without engaging structures within the eye.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This Application is a Non-Provisional of Provisional (35 USC 119(e)) application 60/853,100 filed on Oct. 20, 2006. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable.  
       REFERENCE TO A COMPACT DISK APPENDIX  
       [0003]     Not applicable.  
       TECHNICAL FIELD  
       [0004]     This invention generally relates to an intraocular lens and, more particularly, to a posterior chamber, phakic intraocular lens. One configuration of the present invention is directed to a phakic intraocular lens having a lens positioning arm having a platform. An exemplary lens having the platform includes three positioning arms.  
       BACKGROUND OF THE INVENTION  
       [0005]     Various posterior chamber, phakic intraocular lenses are known in the art. These lenses are implanted directly behind the iris in front of the eye&#39;s natural lens. One drawback with these lenses is the need for an iridotomy that allows fluid to flow from the posterior chamber to the anterior chamber of the eye. The art desires an implant that may be used without an iridotomy. Another drawback with known lenses is the limitation on the size of the optical portion of the lens. The art desires a lens with a large optical portion. The art also desires a lens having a configuration that does not interfere with the fluid flow patterns in the eye while having a structure that maintains a desired location within the eye. Typical known lenses use haptics that span the eye chamber and engage opposed portions of the ciliary bodies to wedge the lens in place. Other lenses use the iris to create centering forces on the lens. The art desires a phakic lens that does not relay on as much contact with the eye to remain in a desired position as known lenses.  
         [0006]     The advantages of these lenses are that the flat front surface of the lens can have a larger diameter than lenses with curved front surfaces. The large diameter and large radius of the posterior optical surface allow the lens to be formed in a wide range of optical powers such as those that are needed by patients who are ineligible for corneal laser surgery. The large diameter optical portion also minimizes halos. The large flat surface minimizes pressure on the iris so as to avoid iris chafing. Further, the channels of the invention allow fluid flow even when the joint of the lens contacts the iris. The lens may thus be implanted without an iridotomy. The thick rim disposed about the optical portion of the lens maintains the lens in the desired location.  
         [0007]     There remains, however, a need for an improved phakic intraocular lens which provides improved positioning stability.  
       BRIEF SUMMARY OF THE INVENTION  
       [0008]     The present invention relates to an intraocular lens with improved positioning stability.  
         [0009]     In one configuration, the invention provides a phakic intraocular lens having a flat front surface and a curved rear optical surface to define the optical power of the lens. The lens may be used with or without an iridotomy. The lens has positioning arms that help maintain the position of the lens within the eye. Different configurations for the positioning arms are disclosed. In one configuration, the invention provides a platformed positioning arm that allows more aqueous to be disposed behind the lens adjacent the anterior surface of the crystalline lens. The platformed positioning arm may be incorporated into two arm lens designs and three arm lens designs.  
         [0010]     In a further configuration, the invention provides a three-positioning arm lens design for a posterior chamber, phakic intraocular lens. The three-positioning arm lens is designed to be easy to insert behind the iris. The positioning arms are configured to allows the lens to float behind the iris in front of the crystalline lens without the need to vault the lens or fixate the ends of the positioning arms. On configuration of the three-arm lens is configured to maintain a predictable position within the eye.  
         [0011]     Another aspect of the invention is the method of designing the lens based on the measurements of the eye.  
         [0012]     When properly sized and implanted in the eye, different lens configurations of the invention will accommodate when the zonular fibers engage the ends of the positioning arms to drive the optical body forward or cause the positioning arms to flex the optical body. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a sectional view of the eye having a phakic intraocular lens implanted next to the natural lens;  
         [0014]      FIG. 2  is a top plan view of an alternative lens configuration having two platformed positioning arms or haptics;  
         [0015]      FIG. 3  is a section view taken along line  12 - 12  of  FIG. 2 ;  
         [0016]      FIG. 4  is a section view taken along line  13 - 13  of  FIG. 2 ;  
         [0017]      FIG. 5  is a top plan view of another lens configuration;  
         [0018]      FIG. 6  is a section view taken along line  17 - 17  of  FIG. 5 ;  
         [0019]      FIG. 7  is an enlarged section view of the end of the positioning arm of  FIG. 5 ;  
         [0020]      FIG. 8  is a top plan view of another lens configuration;  
         [0021]      FIG. 9  is a section view of an arm of the lens in  FIG. 8 ;  
         [0022]      FIG. 10  is an enlarged section view of the end of the positioning arm of  FIG. 9 ;  
         [0023]      FIG. 11  is a top plan view of another lens configuration having three positioning arms;  
         [0024]      FIG. 12  is an end view of the lens shown in  FIG. 11 ;  
         [0025]      FIG. 13  shows various arm configurations. 
     
    
       [0026]     Similar numbers refer to similar elements throughout the specification.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0027]     The lens described below may be implanted in the eye by folding the lens and slipping the folded lens through the pupil of the eye. As shown in  FIG. 1 , once implanted in the posterior chamber of the eye, lens  100  provides accommodation when the outer ends of positioning arms  120  are manipulated by the ciliary body or the zonular fibers that connect lens  18  to the ciliary body of the eye. The ciliary body and zonular fibers expand into the posterior chamber of the eye when eye accommodates. Lens  100  is able to take advantage of this movement by having the floating outer ends of arms  120  closely positioned adjacent the ciliary body and zonular fibers when lens  100  is floating. During accommodation, the ciliary body and/or zonular fibers engage arms  120  and push lens  100  toward iris  16  causing accommodation. The ciliary body and/or zonular fibers may also force arms  120  toward each other (radially inwardly) to flex the optical body of lens  100  thus decreasing radius  36 . Arms or haptics  120  are relatively stiff compared with many prior art haptics so that the arms  120  effectively transmit the force of the zonular fibers to the optical portion of lens  100  because of the relatively thick rim  41  and the cupped configuration of arms  120  and the body of the lens  100 . The ends of the haptics or arms should have a radius of curvature equal to the radius of curvature of the ciliary suculus. This helps ensure that the haptics do not contain any of the internal ocular structures.  
         [0028]     A lens is indicated generally by the numeral  100  in  FIGS. 11 and 12 . Lens  100  is designed to be a posterior chamber, phakic intraocular lens that may be inserted behind iris  16  but in front of lens  18 . Lens  100  includes at least a pair of two-part positioning arms  120  but may also include three (as shown in  FIG. 3 ) or more two-part positioning arms  120 . Each positioning arm  120  is platformed to provide a lens configuration that may be designed with a large optical radius  36  while also providing a relatively deep pocket  102  that receives aqueous from the eye. Platformed arms  120  and pocket  102  allow a larger volume of aqueous to be disposed between the anterior surface of lens  18  and the posterior surface of lens  100 . When lens  100  is formed with an opening  104  at the optical portion of lens  100 , the fluid of the eye flows behind arms  120  along the anterior surface of lens  18  and through opening  104 . This allows the flow of aqueous between anterior and posterior chambers using adequate flow of nutrients to the lesser in the two regions. It also eliminates the need for an iridotomy.  
         [0029]     Platformed arms or haptics  120  also allow the lens designer to position the ends of arms  120  close to the ciliary body and zonular fibers so that lens  100  will accommodate when the body and fibers engage arms  120 . This positioning may be accomplished because platformed arms  120  allow the depth of lens to be increased without increasing the overall diameter of the lens to a degree that would wedge the lens within the eye. Lens  100  may thus remain floating within the eye.  
         [0030]     One method of sizing the overall outer diameter is to measure (such as with ultrasound) the outer diameter  98  of lens  18  and the outer diameter of posterior chamber  99 . The outer diameter of lens may be designed to be half of the sum of these two measurements. Such an outer diameter allows lens  100  to float within the eye after implantation as long as the depth of lens  100  is designed to prevent lens  100  from becoming wedged between the crystalline lens  18  and the iris  16 . The ultrasound measurements may be used to define this depth and the angles of the arms  120  described below.  
         [0031]     In one embodiment of the invention, lens  100  is customer manufactured for a patient by measuring the eye and the posterior chamber and then cutting lens  100  from a material (such as by a lathe and a material such as acrylic) instead of molding lens  100 . Cutting lens  100  provides for an efficient manner of manufacturing lens for a particular patient. Once the lens is manufactured, the lens may be heated to a temperature that matches the eye before implantation. Heating helps the lens be folded for implantation and helps the lens to unfold once implanted. Another method is to load the lens into a sterile injection cartridge before it is shipped to the surgeon. This method prevents the surgeon from loading the lens in the injector. This method, however, requires the lens to be manufactured form a material that allows the lens to immediate regain its desired shaped after implantation.  
         [0032]     To aid the surgeon in positioning the lens after insertion, various structures can be created in the arms. For example, a small indentation may be placed in one arm of the lens. This allows the surgeon to insert a probe or similar instrument to the indentation and move the lens accordingly. Alternatively, a revised structure can be used. The shape of the structures can vary and includes, but is not limited to, squares, circles, crescents and the like.  
         [0033]     In one embodiment, a central operation  104  is provided which allows fluid communication from the anterior to the posterior portions of the lens and between the anterior and posterior chambers. The presence of the application permits the free flow of fluid between the two chambers, eliminating the need for an iridotomy.  
         [0034]     In an alternate embodiment, ridges are cut into the outer edge of the lens rim again allowing free flow of fluid to both chambers.  
         [0035]     Each two-part platformed arm or haptic  120  includes an inner arm portion  121  and an outer arm portion  122 . The inner arm portion  121  integrally extends posteriorly and radially outwardly from rim  41  to the inner end of outer arm portion  122 . Outer arm portion  122  extends posteriorly and radially outwardly from the outer end of inner arm portion  121 . Outer arm portion  122  extends, however, at an angle that is more shallow with respect to the flat front surface  130  of the optical body of lens  100 . Arm portion  122  is not, however, disposed parallel to anterior surface  130 . Reference plane  133  is parallel to anterior surface  130  while reference plane  134  is parallel to anterior surface  135  (disposed along the same radius of lens  100  as shown in  FIG. 3 ). Reference plane  136  is parallel to anterior surface  137 . The acute angle between reference plane  133  and  134  falls in a broad range to allow the lens to fit to a variety of eye sizes. Angle  138  must be greater than the acute angle between plane  136  and plane  133  and may be greater than this angle by at least 10 degrees to define the platform of arm  120 .  
         [0036]     In one configuration, angle  138  may be between 75 degrees and 15 degrees and more specifically between 30 and 50 degrees. In one particular configuration, angle  138  is 45 degrees and angle  139  is 165 degrees. The acute angle between plane  136  and plane  133  should always be greater than 15 degrees.  
         [0037]     The posterior surface of inner arm portion  121  may be substantially parallel to surface  135  such that arm portion  121  has a constant thickness. In other embodiments, the arm portion  121  may taper slightly down from rim  41  toward arm portion  122 .  
         [0038]     In the lens depicted in  FIGS. 2 and 3 , the anterior surface  130  of the optical body is flat as described above with the posterior surface  132  providing the optical curvature  36  of lens  100 . The optical radius  36  may be in the range of 12 mm to 24 mm. The posterior surface of arm portion  122  may have a radius described above and may be 10 mm. The platformed arms  120  allow radius  36  to be increased without increasing the overall diameter of lens  100  thus allows the outer ends of arms  120  to be designed to be disposed radially outwardly of lens  18 . The exemplary diameter  34  of the flat optical portion is 6 mm with an optical radius  36  of 13.43 mm. The center of the optical body defines the thinnest portion of the optical body which is limited by the material properties of lens  100 . The center of the lens may optionally define an opening  104  to allow fluid to flow through lens  100 . Opening  104  may have a diameter from about 0.1 mm to 0.6 mm. As also was described above, a rim  41  surrounds the outer periphery of the optical body. The platformed arms  120  decrease the thickness of rim  41  while maintaining the relative position of the anterior surface of rim  41  with the posterior surface of the outer ends of arms  120 .  
         [0039]     In one configuration, the transition between arm portions  121  and  122  has a diameter  141  of 9 mm with the overall diameter  142  of lens  100  being 11.3 mm. The outer diameter  140  of posterior surface  132  is 7 mm. Diameter  34  is 6 mm. Arm portions  122  are 0.2 mm thick. Radius  36  is 13.43 mm while radius  42  is 10 mm.  
         [0040]     In another configuration having the same outer diameter  142  of 11.3 mm, transition diameter  141  is 9 mm while optical radius  36  is 23.43 mm. Diameter  34  is 5.5 mm. Arm portions  122  are 0.2 mm thick. Radius  42  is 10 mm.  
         [0041]     These configurations are exemplary and the dimensions change based on such factors as the desired optical power of lens  100 .  
         [0042]      FIGS. 4-7  depict an alternative lens  100  wherein the ends of arm portions  122  are stepped to provide two spaced apart and distinct posterior ends  150  and  152  for lens  100 . Ends  150  and  152  are created by extending a tip  154  from the outer end of arm portion  122 . Tip  154  may have a thickness less than the thickness of arm portion  122  and may be on the order of 0.10 mm. End  152  is the point that is most posterior on lens  100 . The posterior spacing between ends  150  and  152  is defined by the length of tip  154  and the angle which tip  154  is disposed with respect to arm portion  122 . Angle  156  may be similar or less than angle  139  and may be about 170 degrees. Ends  150  and  152  provide two different locations on lens  100  for the eye to engage and move lens  100  after lens  100  is implanted. In this configuration, each arm  120  has three arm sections  121 ,  122 , and tip  154  that are each disposed at a different angle with respect to anterior surface  130 . In  FIG. 19-21 , angle  156  is 180 degrees thus spacing end  150  further anteriorly with respect to end  152  than in  FIG. 18 . These thin arm tips minimize contact between lens  100  and the eye or the structure supporting the eye while maintaining pockets  102 .  
         [0043]      FIG. 11  depicts a configuration for lens  100  wherein three positioning arms  120  are used to position lens  100  within the eye. This arrangement is sometimes called a tripod configuration. This lens may be designed to accommodate as described above. The three arm configuration may be used to relatively fix the orientation of lens  100  within the eye. In some situations, the eye is non-symmetric such that lens  100  may be implanted with arm  120 A disposed aligned with the long dimension of the eye. This configuration will prevent lens  100  from freely rotating within eye  100  even though lens  100  is floating within the posterior chamber. In another embodiment, arms  120 B and  120 C may be made heavier to cause lens  100  to return to a configuration with arm  120 A disposed upwardly. Arms  120 B and  120 C may be made heavier by making them twice as thick as arm  120 A.  
         [0044]     In one configuration, diameter  34  is 6 mm with diameter  142  being 11.5 mm. The optical radius  36  is 13.43 mm. Each arm  120  has one of the structures described above. The two arms  120 B and  120 C that are closest together are angled from centerline  170  by an angle  171  of 35 degrees while the other arm  120 A is disposed on centerline  170 . The outer sidewall  172  of each of these arms  120  is angled from the centerline at an angle  173  of 12.46 degrees. Walls  172  are tangent to rim  41  while the outer walls  174  of the center arm  120  are inset from tangent to reduce the size of center arm  120 A. Reducing the size of centered arm  120 A allows the mass of the center arm  120 A to be reduced with respect to the combined masses of the offset arms  120 B and  120 C. Inset walls  174  also allow lens  100  to rolled or folded into the shape of a dart for easier insertion into the eye or an injector. The notch  180  defined between arms  120 B and  120 C has an inner end disposed at the thick rim  41  so that the injector plunger will push directly against the thick rim  41  when lens  100  is being injected into the eye. The size of notch  180  may be varied by varying the width  181  of arms  120 B and  120 C. Widths  181  may be varied so that the combined length of the tips  182  of arms  120 B and  120 C are equal to the length of the tip  183  of arm  120 A. Widths  181  may also be varied to make the area of combined arms  120 B and  120 C equal to arm  120 A.  
         [0045]     Another manner of maintaining the position of a lens within an eye is to provide fingers  200  projecting posteriorly from the posterior surface of arm portion  122  as shown in  FIG. 24 . These fingers may interact with the zonular fibers to prevent the lens from freely rotating. Different configurations are depicted in  FIG. 24 .  
         [0046]     Lens embodiments may be manufactured from a silicone material although some extremely thin members described herein may not be able to be manufactured from silicone. Any of the lens embodiments of the invention may be fabricated from an acrylic. A hydrophobic acrylic having a UV inhibitor and a blue blocker may be used. The material may have an index of refraction of 1.499 and allows portions of the lens to be formed as thin as 40 microns. However, various lens materials are known in the art. For instance, it is know that the optical portions of intraocular lenses may be fabricated from polymethyl methacrylate, poly-2-hydroxyethyl methacrylate, methyl methacrylate copolymers, siloxanylalkyl, fluoroalkyl and aryl methacrylate, silicone, silicone elastomers, polysulfones, polyvinyl alcohols, polyethylene oxides, copolymers of fluoroacrylates and methacrylate, and polymers and copolymers of hydroxyalkyl methacrylate, such as 2-hydroxyethyl methacrylate, as well as methacrylic acid, acrylic acid, acrylamide methacrylamide, N,N-dimethylacrylamide, and N-vinylpryrrolidone. Additionally, compounds that absorb ultraviolet or other short wavelength (e.g. below about 400 nm) radiation, such compounds derived from benzotriazole groups, benzophenone groups, or mixtures thereof may be added to the monomers and/or polymers that constitute the implant.  
         [0047]     In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.  
         [0048]     Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.