Bag-in-the-lens intraocular lens with removable optic and capsular accommodation ring
This invention describes an intraocular lens (IOL) design with a removable optic, which can be inserted in and removed from a haptic device. In this haptic the anterior and posterior capsules are sealed in order to have a perfect control over the lens epithelial cell proliferation which is thereby restricted to the peripheral part of the capsular bag. Additionally, a ring caliper is described as new surgical device to allow a precise sizing and centration of the anterior capsulorhexis. The removable optic allows repeatable correction of the eye focusing over time in case the optical parameters of the eye have changed due to a variety of factors. By separating the optic part from the haptic part, the optic part can easily be manufactured in any shape matching the optical errors of the eye, including the optical aberrations. The optic part can be manufactured out of any biomaterial restoring ocular accommodation. The optic part may include prismatic, astigmatic or magnification correction to improve visual performance. The optic part may consist of or include an electronic device for the purpose of artificial vision. In order to further assist the accommodative capabilities of the implant a capsular accommodation ring of specific biomechanical properties is inserted in the capsular equator.
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 INVENTIONIn 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:
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- 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 INVENTIONThis 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 (
Starting from the initial concept of a one piece IOL (
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 RingThis 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.:
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- 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'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'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
14 removable optic part of the intraocular lens. This part is joined with the haptic device in one piece in
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
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 ProcedureThe 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 SCOPEThe 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:
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- 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'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.
Claims
1. An intraocular lens for bag-in-the-lens implantation in the eye to replace the natural crystalline lens, comprising of:
- A. a haptic part further comprising (a) two external haptic flanges to delineate an external groove, and (b) two internal haptic flanges to delineate an internal groove;
- B. an optic part;
- whereby said external groove will accommodate matched anterior and posterior capsules of the lens bag after anterior and posterior capsulorhexis and said internal groove will accommodate said optic part allowing a removal or replacement of said optic part.
2. An intraocular lens according to claim 1 wherein said haptic part and said optic part are made of deformable biomaterials so as to allow insertion of the intraocular lens in a folded condition.
3. An intraocular lens according to claim 1 wherein said haptic part is sufficiently opaque so as to reduce optical edge effects and glare.
4. An intraocular lens according to claim 1 wherein said external flanges of said haptic part are posteriorly angulated with respect to said internal flanges of said haptic part.
5. An intraocular lens according to claim 1 further comprising a transparent barrier, said transparent barrier continuous with the posterior flange of said two internal haptic flanges so as to eliminate the chance of posterior luxation into the vitreous of said optic part.
6. An intraocular lens according to claim 1 wherein said optic part is made of a combination of biomaterials, said combination permitting a better correction of the various optical aberrations of the human eye and magnification for enhanced vision.
7. An intraocular lens according to claim 1 wherein said optic part is made of a combination of optical components, said combination permitting a better correction of the various optical aberrations of the eye and magnification for enhanced vision.
8. An intraocular lens according to claim 1 wherein said optic part contains electro-optic means for the purpose of artificial and enhanced vision.
9. An intraocular lens according to claim 1 wherein said optic part contains at least one doped biomaterial, so as to give said optic part a graded index of refraction or medical properties.
10. A calibrating ring for assisting in intraocular lens implantation, said calibrating ring made of flexible biomaterial of sufficient memory so as to permit unfolding of said ring to its original shape after introduction into the eye.
11. A capsular accommodation ring to be inserted at the capsular equator and made of a biomaterial having the same biomechanical properties than the said capsular bag so that accommodation can be optimally restored after cataract surgery and insertion of the said bag-in-the-lens intraocular lens or intraocular lens according to claim 1.
12. The capsular accommodation ring according to claim 11 can only be implanted in combination with the bag-in-the-lens intraocular lens or with the intraocular lens according to claim 1 since said intraocular lenses do not exert any pressure by haptics or any lens adds at the level of the capsular equator.
13. The capsular accommodation ring according to claim 11 aims at restoring the physiological curvature of the capsular equator after cataract extraction from which it is understood that the angle of said ring may vary depending on the optical parameters of the eye.
14. The capsular accommodation ring according to claim 11 is a U-shaped ring of which the diameter may vary based on the physiological diameter of the natural crystalline lens.
15. The capsular accommodation ring according to claim 11 may be open in order to facilitate its insertion and positioning into the capsular bag.
Type: Application
Filed: Jan 20, 2007
Publication Date: May 31, 2007
Inventor: Marie-Jose Tassignon (Berchem-Antwerpen)
Application Number: 11/656,136
International Classification: A61F 2/16 (20060101);