Patent Publication Number: US-2007123981-A1

Title: Bag-in-the-lens intraocular lens with removable optic and capsular accommodation ring

Description:
RELATED US PATENTS AND APPLICATIONS  
      This application is a continuation in part of U.S. application Ser. No. 11/110,463 filed on Apr. 20, 2005. The background of the invention is in the general field of intra-ocular lenses, in particular lenses with accommodative properties. 
    
    
     BACKGROUND OF THE INVENTION  
      In our U.S. Pat. No. 6,027,531 a description is made of a new concept of intraocular lens, implantable in the eye to replace the natural crystalline lens. This IOL is inserted in a calibrated, circular and continuous anterior and posterior capsulorhexis, of which the diameters are slightly smaller than the optical diameter of the lens in order to fit tightly in the groove defined at the periphery of the optical part by two flanges (one flange is the continuation of the anterior part of the optic and the other flange is the continuation of the posterior part of the optic). The perpendicularly oriented axes of the flanges facilitate the insertion of both anterior and posterior capsule into the groove by the surgeon and stabilize and avoid tilting of the IOL.  
      The IOL as described in U.S. Pat. No. 6,027,531 is being manufactured by the company Morcher, Germany. The intraocular lens has been implanted in children (7 months of age to 15 years), in young adults (16 to 21 years) and in about 200 adult eyes at this moment with a follow-up period of at least 5 years. The results of the clinical work and experience have been published and those publications are herewith incorporated by reference: 
          Tassignon M. J., De Groot V., Vrensen G. F. J. M. (2002). Bag-in-the-lens implantation of intraocular lenses. J. Cataract Refract. Surg. 28 (7), 1182-1188     De Groot V., Tassignon M. J., Vrensen G. F. J. M. (2005). Effect of bag-in-the-lens implantation on posterior capsule opacification in human donor eyes and rabbit eyes. J. Cataract Refract. Surg. 31 (2), 398-405        

      These publications corroborate our hypothesis as stated in the U.S. Pat. No. 6,027,531 that secondary cataract is avoided in 100% of the cases. Secondary cataract is the most frequent complication corresponding to posterior capsule opacification (PCO) in eyes operated with the traditional lens-in-the-bag implantation technique.  
      Besides the long-lasting excellent optical results of 100% transparency and besides the excellent stability of the lens within the eye, the bag-in-the-lens presents the additional option to be positioned electively within the eye by the surgeon. The idea of elective positioning or centration according to a visual axis of the eye of an intraocular lens has not yet been described.  
      Since the publication of the U.S. Pat. No. 6,027,531, other authors have used the idea to fixate the IOL using the posterior capsule (Okada Kiyashi, U.S. Pat. No. 6,881,225), but the design is very complicated an the implantation is based on the lens-in-the-bag technique having the permanent risk that lens epithelial cells will encapsulate the IOL with proliferative tissue.  
      Furthermore, a large number of proposals have been made to correct the eye optics for far and for near at the time of cataract surgery. A binocular lens system was proposed by Robert Steinert (U.S. Pat. No. 6,537,317) and Lang Alan (U.S. Pat. No. 6,576,012), aiming at allowing far and near vision simultaneously. However, these IOLs are composed of two optic portions that still have the risk of cellular deposits and proliferation between the parts.  
      Additionally, in order to correct the optical aberrations of the eye, Theodore Weblin (U.S. Pat. No. 6,413,276) proposed a three-part IOL of which at least one part can be removed and adapted according to the ocular aberrations and repositioned in a second surgical step. This elaborated IOL also has the risk of cellular deposits at the level of the interfaces causing visual impairment with over time.  
     OBJECTS AND ADVANTAGES OF THE INVENTION  
      This invention concerns an improvement of the U.S. Pat. No. 6,027,531 in two major aspects: a new device is proposed to perform easily a calibrated, circular and continuous anterior capsulorhexis, and an intraocular lens is proposed with a removable optic. Some additional minor improvements in embodiments and surgical technique are also described.  
     I. Device for Anterior and Posterior Capsulorhexis Size Calibration and Positioning  
      To do so, a ring of 0.25 mm diameter, made of PMMA, or of any other biomaterial with memory, has been designed ( FIG. 1 ). This ring can be inserted within the eye through a very small corneal or limbal incision (3 mm or less). Because of its memory, the ring will unfold within the eye as soon as inserted in the anterior chamber. It then will be gently applied on top of the anterior lens capsule and fixed with viscoelastics. The capsulorhexis can subsequently be initiated and the surgeon will take care to follow the internal border of the ring caliper. This ring caliper has two functions: (1) to determine a precise diameter of the anterior capsulorhexis. This can be achieved by manufacturing a ring with a precise internal diameter. (2) The ring is also to be used in order to centre the position of the anterior capsulorhexis according to the pupillary area, or to the limbus or to any other reference used to optimize centration of the anterior capsulorhexis along an optical axis of the eye (line of sight, visual axis or other axis). The optical axis can be determined according to well-established techniques described in clinical psychophysics handbooks.  
     II. Intraocular Lens with a Removable Optic  
      Starting from the initial concept of a one piece IOL ( FIG. 1 A , B and C of the Prior Art), the haptic device can be separated from the optic part ( FIG. 2 A , B and C). This removable and replaceable optic can be versatile in design construction and incorporate spherical, astigmatic or prismatic powers as well as customized adaptive optics correction. In addition electro-optical constructions for artificial vision or low vision purposed can be incorporated. In general such optic part can be made to resemble more the natural lens of the eye, including its GRIN properties and furthermore such design is easier for the manufacturer to produce.  
      Additional advantages of such removable optic include (1) intraocular correction of ametropia repeatable over time in case the axial length or corneal optical parameters have changed due to disease, age or trauma or miscalculated previous IOL power, (2) to introduce new biomaterials in the future with additional characteristics, (3) easy access for the retinal surgeon in case of complex repeat posterior segment surgeries.  
      The haptic device can be constructed from an opaque material to minimize intraocular scattering and glare.  
     III. Capsular Accommodation Ring  
      This invention describes a capsular accommodation ring to be used in combination with either the bag-in-the-lens (BIL) intraocular lens (IOL) of which the IOL and surgical procedure has been described in U.S. Pat. No. 6,027,531, or with the BIL-IOL with removable optic as described in this application. Both concepts will be further referred to as BIL-IOL.  
      The capsular accommodation ring is meant to be inserted into the capsular bag once the crystalline lens has been removed. This accommodation ring should be positioned at the level of the capsular equator. The shape of the accommodation ring is an open, U-shaped flexible ring, which is made of a biomaterial presenting similar mechanical properties compare to the human lens capsule. The mechanical properties of the lens capsule have been studied in length by Susanne Krag et al.: 
          Krag S., Andreassen T. T. (2003). Mechanical properties of the human posterior lens capsule. Invest. Ophthalmol. Vis. Sci. 44, 691-696     Krag S., Andreassen T. T. (2003). Mechanical properties of the human lens capsule. Prog. Retin. Eye Res. 22 (6), 749-767        

      It is not the intention to exert any tension on the equator of the capsular bag by this accommodation ring but to restore its natural curvature. The anterior and posterior lips of this accommodation ring will support that part of the capsular equator where the anterior and posterior zonular fibres have their insertion. As a result, the physiological relationship and impact of the zonular fibres on the equatorial part of the capsular bag will be re-established. The antero-posterior movement of the BIL-IOL/capsular bag will again be possible and optimized during accommodation or relaxation of the ciliary&#39;s muscle. It should be understood that during accommodation the zonular fibres will release all tension on the equatorial capsular bag, allowing the capsular accommodation ring to take its original shape, designed to mimic the physiological curvature of the equatorial part of the capsular bag of a young adult lens during accommodation. The BIL-IOL will move forward and correct the eye for a certain degree of accommodation. In case of relaxation of the ciliary&#39;s muscle, the zonular fibres will be stretched and exert tension on the equatorial part of the capsular bag. The accommodation ring will follow this movement and the BIL-IOL will move backward, allowing optimal correction of the eye for distance. Because the mechanical properties of the accommodation ring are similar to that of the capsular bag, it is expected that the changes in physiological curvatures of the capsular equator, at the accommodation or relaxation position, will be released in comparable speed as in physiological conditions. 
    
    
     DESCRIPTION OF THE DRAWINGS  
       FIG. 1 A , B, C correspond to the prior art as described in U.S. Pat. No. 6,027,531. These figures illustrate the bag-in-the-lens in one piece comprising the optical part  14 , the haptic parts  18  and  20  and the groove  16  to accommodate both the anterior and posterior capsule.  
       FIG. 2  illustrates the ring caliper device.  
       FIG. 3 A , B, C illustrates the removable optic and the haptic device as two separate parts of the new IOL. The haptic device still consists of the outer flanges ( 18  and  20 ) defining the external lens groove ( 16 ) to accommodate the anterior and posterior capsule, but in addition presents internal flanges ( 24  and  26 ) defining an internal groove ( 28 ) in order to accommodate the removable optic part of the lens ( 14 ). This modification of the original lens will allow the removal of the optic part of the lens without removing the haptic device. The external outer flanges ( 18 - 20 ) can be angulated posteriorly ( 30 ) compared to the straight insertion of the internal flanges of the haptic device ( 24 - 26 ). The posterior internal flanges ( 26 ) can extend further to create an additional closed transparent and thin barrier ( 32 ) between the removable optic and the vitreous in case posterior dislocation of the removable optic is feared.  
       FIG. 4 A , B and C show an alternative to the embodiment of the intraocular lens with removable optic as illustrated on  FIG. 3 A , B and C. This second version differs with the previous one in the fixation of the optic part  14  into the haptic part ( 16 - 18 - 20 ). Instead of having internal haptics ( 24 - 26 ) defining the internal groove  28  in which the optic  14  will take place, the external haptics ( 18 - 20 ) define a sharp arc at the internal side  34  in which the groove  36 , positioned at the equator of the optic  14 , will take place. This second embodiment may be easier to manufacture and will avoid the possible posterior dislocation of the optic  14  as described in the previous embodiment.  
       FIG. 5 A  illustrates the U-shape accommodation ring  42  of which the anterior lip  38  may be slightly shorter than the posterior lip  40 . The curvature of the ring correspond to the physiological curvature of a young adult crystalline lens  
       FIG. 5 B  and C illustrate the accommodation ring  42  positioned at the equatorial part of the capsular bag. The relationship with the anterior zonular fibre  44 , the equatorial zonular fibre  46  and the posterior zonular fibre  46  is schematized. In case the ciliary&#39;s muscle is relaxed, as illustrated in  FIG. 5 B , the zonular fibres  44 - 46  and  48  are stretched as well as the anterior  50  and posterior  52  capsules. In this situation, both lips  38  and  40  of the accommodation ring  42 , define a sharp angle. The capsular bag together with the BIL-IOL  14  in which it is inserted at the level of the lens groove  16 , will move backward. In case the ciliary&#39;s muscle is contracted, as illustrated in  FIG. 5 C , the zonular fibres  44 - 46  and  48  will become loose as will relax the anterior  50  and posterior capsule  52 , allowing the lips  38  and  40  of the accommodation ring  42  to take their original angle. The capsular bag and the BIL-IOL will move forward 
    
    
     REFERENCE NUMERALS IN DRAWINGS  
       14  removable optic part of the intraocular lens. This part is joined with the haptic device in one piece in  FIG. 1 A , B, C; and it is a separate part, removable and replaceable in  FIG. 3 A , B, C  
       16  external groove in the haptic device to accommodate both capsules  
       18  anterior flange of the external part of the haptic device  
       20  posterior flange of the external part of the haptic device  
       22  perforation within the anterior flange for purpose of rotation during surgery  
       24  anterior flange of the internal part of the haptic device  
       26  posterior flange of the internal part of the haptic device  
       28  internal groove in the haptic device to accommodate the optic  
       30  angulation of the external flanges of the haptic device  
       32  extension of the posterior internal flange of the internal haptic device, create a membrane like barrier between vitreous and removable optic part  
       34  internal arc of the lens groove  
       36  equatorial groove of the lens optic  
       38  anterior lip of accommodation ring  
       40  posterior lip of accommodation ring  
       42  accommodation ring with specific angle  
       44  anterior zonular fibres  
       46  equatorial zonular fibres  
       48  posterior zonular fibres  
       50  anterior lens capsule  
       52  posterior lens capsule  
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       FIG. 1 A , B, C shows the preferred embodiment of the prior art. This preferred embodiment could be slightly adapted by introducing a posterior angulation  30  of the external flanges of the haptic device. This is done in order to prevent capture of the iris into the groove immediately postoperatively. The posterior angulation will optimally vary from 5 degrees to 10 degrees. Other angulations are possible.  
       FIG. 2  shows the preferred embodiment of the ring caliper that permits a precise sizing and centration of the anterior capsulorhexis. This ring caliper may be constructed of any biomaterial allowing its insertion within the eye in a folded condition after which it will unfold in the eye to its original shape because of its material memory. The diameter of the cross section of this ring is optimally 0.25 mm but can be made thinner or thicker depending on the biomaterial used. It can be transparent or coloured to enhance visibility once put in place in the eye. When used in relation with an IOL of 5 mm diameter optic part size, as described in the U.S. Pat. No. 6,027,531 or in current application, a diameter of 5 mm is optimal ( FIG. 2 ). Though this ring can also be used when implanting of the more traditionally lens-in-the-bag IOLs is intended.  
       FIG. 3 A , B and C show the preferred embodiment of the new intraocular lens design consisting of two separate parts: a haptic device and a removable and replaceable optic part. The haptic device is preferably made of one piece and can be made of rigid or deformable biomaterials such as silicone polymeric materials, acrylic polymeric materials, hydrogel forming polymeric materials and mixture of these materials or the like. This hatpic device can be made opaque by coloration or using mechanical techniques. The aim of making the haptic part partially or totally opaque is avoiding stray light effects and glare.  
      The haptic device consists of an external anterior flange  18  and an external posterior flange  20 , defining an external groove  16  in between. Both external flanges are made oval in shape to promote a good insertion and fixation of the intraocular lens, but can have any shape that may improve IOL fixation or insertion. Both flanges can have a variety of functional extensions or perforations  22  to promote the stability of the lens or to prevent any type of luxation or inadvertent capture of the iris.  
      On the internal side, the haptic device has an anterior internal flange  24  and a posterior internal flange  26  defining an internal groove  28  to accommodate the removable optic part. The diameter of the internal groove can be variable but should not be less than 5 mm for reasons of optical quality and for ease of centration. The internal flanges are preferably transparent but can also be made opaque. In case a posterior luxation of the optic part into the vitreous would be an issue, the posterior internal flanges can be made continuous  32 , defining a membrane like transparent barrier between the optic part and the vitreous. The distance between the internal groove and the external groove will determine the thickness and therefore the stability and rigidity of the haptic device. This parameter can vary depending on the biomaterials used in constructing the haptic device.  
      The preferred embodiment of the optic part  14  is circular but of variable shape depending on the intended optical errors to be corrected, including the ocular aberrations, in particular spherical aberration or chromatic aberration. It can be made of the same biomaterial as the haptic device as specified above or can be made of another biomaterial. It can be made of one biomaterial, can use a combination of different layered biomaterials, or be made of a GRIN substance. Each construction has specific optical and mechanical properties in order to correct the spherical, the cylindrical or the toric refractive errors of the eye, and to permit accommodation (mechanically or optically mediated accommodation). Prismatic effects could be of use in relocating the preferential retinal locus of fixation in magnification of the image on the retina for low vision purposes. These additions can be fitted on the anterior surface of the optic part, within the optic part or on the posterior surface of the optic part. The final result is a customized optic part of one piece, containing all optical adaptations needed to correct the optical errors of the eye as measured preoperatively. This one piece optic part  14  may have the same diameter as the diameter of the internal groove  28  or it can be slightly larger or it can be slightly smaller. For the purpose of stability, a slightly larger diameter of the optic part  14  could be beneficial, though a slightly smaller diameter of the optic part  14  might increase an accommodative effect in the eye.  
      An alternative for the fixation of the removable optic part  14  is to add an equatorial groove  36  to the optic part  14  of which size matches the internal arc  34  defined by both the external haptic parts  18  and  20 . The capsular accommodation ring is preferentially manufactured of a biocompatible biomaterial which has similar biomechanical properties than the capsular bag. The biomechanical properties of the capsular bag have been studied in the literature and are well known.  
      The most appropriate shape for the accommodation ring is U-shaped. The width of the angle of the U-shape ring is variable, depending on the physiological angle of eyes presenting the same optical properties e.g.: corneal curvature, white to white measurements, sulcus to sulcus measurements and axial length.  
      The diameter of the accommodation ring is also variable, depending on the physiological diameter of the natural crystalline lenses of young adult eyes of which their optical parameters have been measured as mentioned earlier.  
      The variation in physiological parameters of the diameter and equatorial angle of young adult lenses is expected to be important. It is therefore mandatory to match the parameters of the accommodation ring to these measurements.  
      The accommodation ring may be open in order to facilitate its insertion and positioning into the capsular bag.  
      The anterior lip of the accommodation ring may be slightly shorter than the posterior lip. The length of the lips is defined by the anatomical insertion of the anterior and posterior zonular fibres on the anterior and posterior capsules respectively. This can be measured in post mortem donor eyes. A longer posterior lip will also promote a better support of the posterior capsule which is slightly larger than the anterior capsule (the natural crystalline lens in non equiconvex).  
     Description of a Preferred Surgical Procedure  
      The surgical procedure consists of a number of steps that are currently used in conventional extracapsular cataract extraction, some of which have to be modified, and some new steps are necessary to insert the new intraocular lens in the most optimal fashion.  
      The opening of the anterior chamber and the filling of the anterior chamber with viscoelastics are well known steps in the prior art. The anterior curvilinear continuous capsulorhexis must be calibrated in such way that its diameter is slightly smaller (about 1 mm) than the diameter of the optic part  14 .  
      For this purpose, the ring caliper is inserted, either by means of two forceps or by means of a lens manipulator. After insertion the ring is gently pushed on top of the anterior capsule by means of additional viscoelastics. A small opening is made in the centre of the anterior capsule, which serves as the starting point for the capsulorhexis. The surgeon will take care to follow the internal border of the ring caliper.  
      The centration of the capsulorhexis with respect to such landmarks as the pupil edge or the limbal edge can be done using well-known techniques for documenting the optic, visual axis or line of sight. To reference the centre of positioning of the ring during surgery, a standard fiduciary reticule can be used with the operating microscope.  
      After the anterior capsulorhexis is performed, the lens consisting of nucleus and cortical material is removed in the usual manner for an extracapsular cataract extraction technique. The capsular accommodation ring can then be positioned at the level of the capsular equator. The posterior curvilinear continuous capsulorhexis must then be executed in such way that its diameter is the same as the diameter of the anterior capsulorhexis. The openings of both anterior and posterior capsulorhexis should match each other as close as possible in size, location and centration. The technique of making the posterior capsulorhexis is the same as the one that is currently used in conventional extracapsular cataract extraction. A puncture is made in the centre of the posterior capsule. The posterior capsule is then separated from the anterior hyaloid of the vitreous by injecting viscoelastic material through the puncture in the space of Berger. After this step a calibrated posterior curvilinear continuous capsulorhexis is performed by following the edge of the anterior capsulorhexis resulting in a posterior capsulorhexis of the same size than the diameter of the anterior capsulorhexis.  
      The insertion of the foldable haptic device of the intraocular lens using the bag-in-the-lens technique can then be applied. It is different from the conventional lens-in-the-bag insertion technique. First, the haptic is introduced into the anterior chamber of the eye. Then the posterior flange  20  of the haptic device is placed behind the rim of the opening of the posterior capsule in the space of Berger and the anterior flange  18  of the haptic device of the intraocular lens is placed before the rim of the opening of the anterior capsulorhexis.  
      Because the diameters of both the anterior and posterior capsulorhexis are identical but slightly smaller than the diameter of the lens groove  16 , the capsular openings will be stretched when inserting the lens, thus providing a tight junction around the intraocular lens and a closed space or environment that contains the remaining proliferating epithelial cells of the lens bag.  
      Once the haptic device is put in place, the removable optic part which has been chosen preoperatively in such way that it will correct the optics of the eye in the most optimal way (spherical correction, astigmatism, aberrations, accommodation) can be inserted in the anterior chamber in a foldable condition and once unfolded in the eye, put in place in the empty central space of the haptic device. The viscoelastic is then removed from the anterior chamber and the anterior chamber is then closed water tight. In case the short-term postoperative refractive or optical results are not satisfactory for the patient or in case the optical properties of the eye have changed as a function of time, the optic part can be removed from the haptic and changed by an optic part matching better the optical needs of the eye. In case the visual acuity of the patient would drop dramatically over time because of irreversible retinal or optic nerve problems, the optic can be removed from the haptic and replaced by a new optic containing or consisting of magnification elements or opto-electronic elements for the purpose of magnification or artificial vision.  
     SUMMARY AND SCOPE  
      The clinical results obtained after implantation of the intraocular lens as described in the U.S. Pat. No. 6,027,531, are excellent, and even exceptional because of an incidence of zero percent Nd-Yag laser treatments after five years of implantation. The current continuing application describes new developments as a result of our experience gained over this period.  
      Firstly, a ring caliper is positioned in order to facilitate the surgical procedure by improving the precision of the size and centration of the anterior and posterior capsulorhexis.  
      Secondly, we implemented the following modifications to the bag-in-the-lens design: 
          Posterior angulations of the external haptic flanges     Converting the intraocular lens to a two component system comprising a haptic device and an optic part, which is removable and replaceable over time     The haptic device can be rendered partially or totally opaque     The optic part can be customized to correct various optical aberrations, permit artificial vision or low vision rehabilitation     The curvature of the capsular equatorial zone is restored by inserting a U-shaped ring which has the same biomechanical properties than the capsular bag in order to optimize the relationship between the zonular fibres and the capsular bag and to enhance the backward or forward movement of the BIL-IOL depending whether the ciliary&#39;s muscle is in relaxation or accommodation mode.        

      Although the above description contains many specifications, these should not be considered as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Other embodiments on the invention, including additions, subtractions, deletions or modifications of the disclosed embodiment will be obvious to those skilled in the art and are within the scope of the following claims. As such, the scope of the invention should be determined by the appended claims and their legal equivalents.