Abstract:
An intraocular lens includes an optic adapted to focus light toward a retina of an eye, and at least one fixation member configured to at least assist in supporting the optic in the eye. The fixation member includes a proximal portion coupled to the optic and a distal portion configured to be in contact with eye tissue when the intraocular lens is in use in the eye. The proximal portion of the fixation member includes at least one first area formed of a first, substantially rigid material, and at least one second area formed of a second material which is more flexible than the first material.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to intraocular lenses (IOLs). More particularly, the invention relates to deformable, e.g., foldable, IOLs for placement in eyes, e.g., in the anterior chambers of eyes, and to methods of making and using such IOLs.  
           [0002]    The human eye is susceptible to numerous disorders and diseases, a number of which attack the crystalline lens. For example, cataracts mar vision through cloudy or opaque discoloration of the lens of the eye, and can result in partial or complete blindness. When this happens, the crystalline lens can be removed and replaced with an intraocular lens, or IOL. In certain other circumstances, an IOL can be placed in an eye containing the natural crystalline lens, for example, to provide for enhanced vision in the phakic eye. A typical IOL comprises an optic body, or lens, adapted to focus light toward the retina of the eye, and one or more fixation members, or haptics, adapted to at least assist in supporting or fixating the IOL in a suitable location in the eye, such as the anterior chamber, iris, or capsular bag of the eye.  
           [0003]    The optic and haptics may be formed as an integral unit from a single material, but in recent years the trend has been toward composite IOLs which use different materials for the various components, so that the properties of these components can be separately optimized. Examples of such composite IOLs are shown in Barrett U.S. Pat. No. 4,997,442 and Vanderbilt U.S. Pat. No. 5,217,491, both of which employ relatively flexible materials in the optic portion and more rigid materials in the haptics. The disclosure of each of these patents is incorporated in its entirety herein by reference. In both the Barrett composite IOL and the Vanderbilt composite IOL, the flexible material of the optic enables the IOL to be deformed, e.g., folded, rolled and the like, for insertion through a small surgical incision in the eye, while the relatively rigid material of the haptics enhances the stability of the optic in the eye.  
           [0004]    In most, if not all, prior art composite IOLs, such as those disclosed by Vanderbilt and Barrett, the haptics have been configured as extremely thin, filament or loop-type members suitable for securing the optic in the posterior chamber, or capsular bag, of the eye. The slenderness of these types of fixation members to some degree compensates for the rigidity of the material from which they are made, and enables such fixation members to be curled, folded, or wound up inside a conventional inserter cartridge, without significantly interfering with the folding of the optic. However, such filament or loop type fixation members are generally not recommended for use in the anterior chamber of the eye.  
           [0005]    More particularly, anterior chamber IOLs are subject to different conditions than posterior chamber IOLs, and thus differ significantly in their design. For instance, anterior chamber IOLs must be able to withstand the relatively high compressive forces exerted by the surrounding structure of the anterior chamber without allowing significant movement of the optic. In addition, anterior chamber IOLs should be structured to reduce the potential for complications such as pupil ovalling, endothelial cell loss and the like.  
           [0006]    Various designs for anterior chamber IOLs are disclosed in Nigam U.S. Pat. No. 5,982,282. Other designs are disclosed in Laguette et al. co-pending U.S. patent application Ser. No. 09/908,515, Nguyen et al. co-pending U.S. patent application Ser. No. 09/847,957, Laguette co-pending U.S. patent application Ser. No. 09/847,958 and Paul co-pending patent application Ser. No. 10/225,990. Each of these co-pending applications and the present application are commonly owned. The disclosure of each of the Nigam patent and the above co-pending U.S. patent applications is hereby incorporated in its entirety by reference herein.  
           [0007]    Although the anterior chamber IOLs disclosed in the above patent applications perform satisfactorily in most respects, they all include relatively large fixation members which, if made entirely of rigid material such as poly methylmethacrylate (PMMA), might interfere with the ability of the IOLs to be deformed for insertion into eyes through small incisions. It is advantageous to insert in an IOL though such a small incision to obtain benefits, for example, reduced surgical trauma, reduced recovery time and the like.  
           [0008]    Accordingly, it would be advantageous to provide foldable IOLs, for example, anterior chamber IOLs, with fixation members having sufficient rigidity to maintain optic stability in the eye, while still being flexible or deformable enough to allow the IOL to be folded or otherwise deformed for insertion through a small, or even a very small, incision in the eye. In addition, it would be advantageous to provide such IOLs with configurations that are compatible for use with conventional insertion apparatus. It would also be advantageous to devise methods of manufacturing such IOLs that are relatively simple and cost-effective.  
         SUMMARY OF THE INVENTION  
         [0009]    New IOLs for implantation in eyes, for example in anterior chambers of the eyes, as well as methods of making and using such IOLs have been discovered. The present IOLs are sized and structured to reduce the incidence of one or more known complications in the eye caused by prior IOLS, and to be foldable for effective and safe insertion through small or very small incisions in the eye using, for example, conventional insertion apparatus.  
           [0010]    In accordance with one aspect of the present invention, an intraocular lens comprises an optic adapted to focus light toward a retina of an eye, and at least one fixation member configured to secure the optic in the eye. The fixation member includes a proximal portion coupled to the optic and a distal contact portion configured to be in contact with eye tissue when the intraocular lens is in use in the eye. The proximal portion of the fixation member includes at least one first area formed of a first, substantially rigid material, and at least one second area formed of a second material which is less rigid or more flexible than the first material.  
           [0011]    In one embodiment, the fixation member is configured to secure the optic in an anterior chamber of an eye. The proximal portion of the fixation member includes at least two segments formed of the first, substantially rigid, material, preferably extending generally in a first direction and a different second direction, respectively, relative to the optic. In one useful version of this embodiment, the first segment extends generally radially with respect to the optic, and the second segment extends generally circumferentially with respect to the optic. An area between the two segments is formed of the second, more flexible material.  
           [0012]    In a particularly useful embodiment, the optic is formed of a deformable, e.g., resiliently deformable, or foldable material, preferably a material allowing the optic to be folded or rolled for insertion through an incision measuring about 3.5 mm or less. Preferably this material is the same as the second material. In one version of this embodiment, the first and second materials are acrylic-based polymeric materials. For instance, the first material may be poly methylmethacrylate (PMMA), and the second material may be an acrylic-based polymeric material compatible with PMMA.  
           [0013]    A method of producing an IOL according to the present invention comprises a step of forming a composite member into an intraocular lens having an optic adapted to focus light toward the retina of an eye and at least one fixation member configured to secure the optic in the eye, wherein the fixation member includes a proximal portion coupled to the optic, and a distal contact portion configured to be in contact with eye tissue when the intraocular lens is in use in the eye, and wherein the proximal portion includes at least one first area formed of a first, substantially rigid material and at least one second area formed of a second material less rigid or more flexible than the first material.  
           [0014]    In one useful embodiment, the method further comprises a step of producing the composite member, preferably by polymerizing a first monomeric component to obtain the first material, and polymerizing a second monomeric component to obtain the second material.  
           [0015]    In an especially useful embodiment, the step of polymerizing a first monomeric component comprises polymerizing a first acrylic-based polymeric precursor material within a mold, and the step of polymerizing a second monomeric component comprises polymerizing a second acrylic-based polymeric precursor material, compatible with the first material, within a cavity formed in the polymerized first material.  
           [0016]    A method of correcting vision according to the present invention comprises providing an intraocular lens in a compressed configuration. The intraocular lens includes an optic adapted to focus light toward a retina of an eye, and at least one fixation member configured to at least assist in supporting the optic in an eye. The fixation member includes a proximal portion coupled to the optic and a distal portion configured to be in contact with eye tissue when the intraocular lens is in use in the eye. The proximal portion includes at least one first area formed of a first, substantially rigid material and a second area formed of a second material less rigid or more flexible than the first material. The compressed intraocular lens is inserted through a small incision in the eye, and preferably positioned within the anterior chamber, for use.  
           [0017]    Each and every feature described herein, and each and every combination of two or more of such features, is included within the scope of the present invention provided that the features included in such a combination are not mutually inconsistent.  
           [0018]    Additional aspects and advantages of the present invention are set forth in the following description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is a vertical sectional view of an eye and an exemplary anterior intraocular lens of the present invention implanted therein;  
         [0020]    [0020]FIG. 2 is a top plan view of an intraocular lens according to the present invention;  
         [0021]    [0021]FIG. 3 is a top plan view of a composite button from which the intraocular lens of FIG. 2 may be fabricated;  
         [0022]    [0022]FIG. 4 is a perspective view of a precursor button created during a first step of a method of manufacturing an intraocular lens according to the present invention;  
         [0023]    [0023]FIG. 5 is a vertical sectional view taken through the precursor button of FIG. 4;  
         [0024]    [0024]FIG. 6 is a front side view, in perspective, showing an IOL according to the present invention positioned in an open loading cartridge of an insertion apparatus;  
         [0025]    [0025]FIG. 7 is a front side view, in perspective, showing the loading cartridge of FIG. 6 is a closed position; and  
         [0026]    [0026]FIG. 8 is a somewhat schematic illustration showing an IOL according to the present invention being inserted in an anterior chamber of an eye. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    Referring now to FIG. 1, an anterior chamber IOL  10  according to the present invention is shown implanted in an eye. For ease of illustration, the illustrated eye is aphakic; that is, the natural crystalline lens has been removed. It will be apparent to one of ordinary skill in the art, however, that an anterior chamber IOL  10  according to the present invention may also, and often will, be used in an eye having the natural crystalline lens in place—in other words, a phakic eye.  
         [0028]    The eye  12  comprises a cornea shown to the left and an iris  16  shown in the middle of the eye. It is to be understood that the cornea  14  is at the front of the eye  12 . The iris  16  divides the eye into an anterior chamber  18  at the front of the eye and a posterior chamber  20  in front of the iris  16 . The iris  16  also defines the pupil  22 , which is an opening in the middle of the iris  16 . In front of the iris  16  is the scleral spur  24 . The scleral spur and the iris  18  delimit the ciliary band  26 .  
         [0029]    The IOL  10 , shown in greater detail in FIG. 2, includes a central optic  28  and a pair of fixation members  30   a, b . The illustrated number and structure of the fixation members is merely exemplary, as the principles of the present invention may be applied to a large variety of anterior chamber IOLs including, but not limited to, the IOLs disclosed in Laguette et al. co-pending U.S. patent application Ser. No. 09/908,515, Nguyen et al. co-pending U.S. patent application Ser. No. 09/847,957, Laguette co-pending U.S. patent application Ser. No. 09/847,958 and Paul co-pending patent application Ser. No. 10/225,990, the contents of all of which are incorporated by reference herein.  
         [0030]    As illustrated, each fixation member  30   a, b  is sinuous in structure, and includes a proximal portion  31  and distal contact portion  40 . Each proximal portion  31  has several regions, or segments, including a proximal connector segment  32  that extends radially outwardly from the optic, an elongated intermediate segment  34  that extends generally circumferentially from a distal end of the connector portion  32 , and a distal segment or elongated member  36  that is configured to extend generally along a chordal line with respect to the ciliary band  26  when the IOL  10  is positioned in the anterior chamber  18  of eye  12 . A bridge segment  38  extends generally perpendicularly between a distal end of the intermediate segment  34  and a proximal end of the distal segment  36 . The distal contact portion  40 , also called a pod or footplate, is enlarged and somewhat bulbous, to minimize contact stress on, and reduce the potential for trauma to, the ocular tissue in the anterior chamber of the eye.  
         [0031]    The optic  28  of the IOL  10  is advantageously made from a sufficiently flexible material to enable the IOL  10  to be resiliently deformed, e.g., folded or rolled, for insertion through a small incision, for example an incision of about 3.5 mm long or less, such as about 3.2 mm or less, or about 3.0 mm or less, and preferably no more than about 2.8 mm long. One preferred optic material meeting these requirements is the acrylic polymeric material from which the optic of an IOL marketed under the trademark SENSAR® by Advanced Medical Optics, Inc. is made. The optic of the SENSAR® IOL is made of a cross-linked acrylic polymeric material formed of copolymers of methacrylate and acrylate esters, cross-linked with a diacrylate ester to produce the cross-linked acrylic copolymer. Useful deformable cross-linked acrylic polymeric materials are disclosed in Gupta U.S. Reissue Pat. No. RE36,150, the disclosure of which is incorporated in its entirety herein by reference.  
         [0032]    The proximal portion  31  of each of the fixation members  30   a  and  b  includes at least one area made of a substantially rigid first material, for instance poly methylmethacrylate (PMMA), and at least one area made of a second material which is more flexible than the first material. In the illustrated embodiment, proximal connector segment  32 , intermediate segment  34 , distal segment  36 , and bridge segment  38  are all made of the first material, and regions or areas  44 ,  46 , and  42  are made of the second material. The number and location of flexible areas may vary, depending on the structure of the fixation members  30   a, b . In one useful embodiment, the flexible areas are located at areas of the fixation members subject to increased stress, for example, areas where the possibility of breakage would be increased or even highest if the fixation members were made entirely of the first material. In sinuous fixation members, such high stress areas often exist at each bend or substantially sharp change in direction along the length of the fixation member. In the illustrated embodiment, there are three such bends in each fixation member  30   a, b : a first bend at the intersection between proximal portion  32  and intermediate portion  34 ; a second bend at the intersection between intermediate portion  34  and bridge portion  38 ; and a third bend at the intersection between bridge portion  38  and distal segment  36 . Thus, flexible areas  44 ,  46 , and  42  are advantageously located at the first, second and third bends, respectively. These flexible areas  44 ,  46 , and  42 , which also may be thought of as joints or elbows, allow the fixation members  30   a  and  b  to be resiliently deformed, i.e. folded, thus greatly facilitating the insertion of the IOL  10  through a small incision.  
         [0033]    In addition to being less rigid or more flexible than the first material, the second material advantageously is resilient so that the fixation members  30   a  and  b  return quickly to substantially their original, uncompressed configurations after insertion into the eye. Advantageously, the second material is the same as the material used in the optic. It is also preferred that the second material is compatible with the first material, for example, so that the two materials can easily be co-processed and/or used effectively and safely together. For instance, the first material may be poly methylmethacrylate (PMMA), and the second material may be a deformable cross-linked acrylic material similar to the materials described in the aforementioned Gupta patent.  
         [0034]    In the illustrated embodiment, the flexible area  42  between bridge portion  38  and distal segment  36  is bulbous and serves as a pod or footplate similar to distal contact portion  40 . Thus, in addition to facilitating folding, the flexible material in this area  42  reduces contact stresses on the surrounding ocular tissues.  
         [0035]    Distal contact portion  40  is shown in FIG. 2 as being formed of the same material as flexible areas  44 ,  46  and  42 . However, in some IOL designs, it may be preferable to make the contact portions of a more rigid material, for instance the same material as proximal connector segment  32 , intermediate segment  34 , bridge segment  38 , and distal segment  36 . Alternatively, the bridge segment  38  may be formed of the same flexible material as one or both of the distal contact portions  40 ,  42 .  
         [0036]    A method of manufacturing IOL  10  will now be described with reference to FIGS.  3 - 5 .  
         [0037]    Initially, a first monomeric component, for instance methylmethacrylate precursor material, is poured or otherwise placed in a cylindrical mold (not shown) and polymerized to form a button  48  of substantially rigid material, such as PMMA. A cavity or hole  50  is formed in the central region of the button  48 . In the illustrated embodiment, the button  48  has a depth or axial thickness of about 5 mm, and the central cavity has a depth of about 3 to 4 mm. Several smaller, annular cavities or holes  52 ,  54 ,  56  are formed radially outwardly of the central cavity  50 , at the locations where flexible segments  44 ,  46  and  42  are desired. These cavities  52 ,  54 ,  56  are illustrated herein as being continuous, concentric annular cavities, each having a radial thickness of about 0.5 to 1.0 mm, depending on the desired size of the fixation members and pods. Alternatively, the cavities  52  or  54  could be formed as discrete circular spots or holes (about 0.5 to 1.0 mm in diameter) at the desired locations.  
         [0038]    Once the cavities  50 ,  52 ,  54 ,  56  are formed, a second monomeric component, for instance a precursor component of a flexible or deformable cross-linked acrylic polymeric material similar to the materials described in the aforementioned Gupta patent, is polymerized within the cavities  50 ,  52 ,  54  and  56  to form flexible rings or spots in the button  48 . Finally, the button  48 , now having a composite composition, is processed, for example, lathed, cut or otherwise shaped, for instance along the outline  58  shown in FIG. 3, to form the optic  28  and fixation members  30   a, b  of the IOL  10 . In the embodiment shown, the relatively flexible material in the cavities  50 ,  52 ,  54 ,  56  is shaped to form the optic  28 , the joints  44 ,  46  and the contact portions  42 ,  40 , while the stiffer or substantially rigid material of the remainder of the button  48  is shaped to form the proximal connector segments  32 , elongated intermediate segments  34 , distal segments  36  and bridge segments  38  of the fixation members.  
         [0039]    The IOL  10  can be effectively inserted into an anterior chamber of an eye and used to provide vision correction, for example, vision enhancement. As shown in FIG. 6, an anterior chamber IOL  10  is placed in the load chamber  60  of an IOL insertion cartridge  62  having folding leaves  64   a, b  and a hollow distal tip  65 . The leaves of the cartridge  62  are then moved from their open position, shown in FIG. 6, to their closed position, shown in FIG. 7, bringing both the optic and fixation members into a folded or rolled configuration (not shown). The cartridge  62  is then placed in a suitable insertion apparatus  66  such that the distal tip  65  of the cartridge projects through an distal opening in the insertion apparatus  66 . The distal tip  65  of the cartridge is then placed in or near a very small incision  68  in the sclera or cornea of an eye  12 , and a plunger  68  or the like is advanced through the insertion apparatus, causing the IOL  10  to be passed through the outlet of the distal tip  65  into the anterior chamber  18  of the eye. Once placed in the anterior chamber  10 , the IOL may, if necessary, be repositioned using a needle or the like to obtain optimum stability and centration.  
         [0040]    The illustrated insertion apparatus  66  is similar to an apparatus disclosed in Makker U.S. Pat. No. 5,735,858, the disclosure of which is incorporated herein by reference. However, the IOL  10  of the present invention is not limited to use with any particular insertion apparatus, and may in fact be inserted using surgical forceps or other similar devices.  
         [0041]    While this invention has been described with respect to various specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.