FR2797177A1 - PRECRYSTALLINE INTRAOCULAR IMPLANT - Google Patents

Abstract

The precrystalline intraocular implant, adapted to be housed in the sulcus of the eye, comprises a central optical part (10) and a haptic part (20), at least the optical element being made of flexible material. The haptic portion includes a plurality of haptic tabs (21, 22). The diameter of the haptic part being at least equal to the diameter of the ciliary sulcus of the eye, the curvature of the posterior surface corresponding to that of the lens in the state of rest, and capable of remaining slightly spaced from the anterior surface of the lens at rest.

Description

1i 2797177 The present invention relates to an intraocular implant intended

for

  the phakic eye and more particularly a precrystalline intraocular implant.

  Such an implant is positioned in the posterior chamber of the phake eye between the iris and the anterior capsule of the lens sac, and therefore housed in the ciliary sulcus of the eye. Such an implant is intended for the correction of

  ametropia of an intact and healthy lens.

  Pre-crystalline implants have been known for a number of years, but so far the number of such implantations has been limited. Such implants have advantages over keratotomy or keratomileusis since the correction is reversible by replacing the implant with a modified correction and do not have the disadvantages of contact lenses and

  glasses, since they require no manipulation or maintenance by the user.

  Precrystalline intraocular implants, like other intraocular implants, moreover, have a central optical part and a peripheral haptic part. In order to allow the introduction of the implant through a corneal or sclerocorneal incision, of minimum size,

  the optics are made of flexible material capable of being folded or rolled.

  It goes without saying that the implantation of a precrystalline lens must be free of risks for the patient's eye, both at the level of the crystalloid of the anterior capsule and at the level of the iris. Indeed, untimely friction between the posterior surface of the implant and the crystalloid can cause cataracts. Likewise, the friction between the lens and the posterior surface of the iris

  can cause depigmentation, or even pupillary blockage.

  The object of the present invention is therefore a precrystalline intraocular implant ensuring good correction of ametropia with good

  stability and a minimum risk of cataracts and iridian depigmentation.

  According to the invention, the diameter of the haptic part is at least equal to the diameter of the ciliary sulcus of the eye for which it is intended; the curvature of the posterior surface corresponds to that of the anterior surface of the lens in the state of rest, so that the posterior surface of the implant remains

  slightly spaced from the anterior surface of the lens in its resting state

this.

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  Such an implant therefore allows the flow of aqueous humor between the anterior surface of the lens and the implant, and consequently good irrigation of the lens and avoiding undesirable friction between the implant and the lens. The geometry of the implant is such that during the accommodation of the lens for near vision, under the control of the ciliary muscle, the modification of its curvature takes place normally and the implant tends to move towards the anterior , while keeping the gap between its posterior face and the crystal, thus avoiding any undesirable friction during

accommodation.

  Preferably, the implant is at least partially made of hydrophilic acrylic material and a roughness not exceeding one nanometer. It will be understood that, thanks to such a hydrophilic material and the smoothness of its surfaces, in particular the posterior surface and of the parts likely to come into contact with the iris, reduces the risk for the lens or iris even less case of

untimely contact.

  Preferably, the posterior face of the implant is the same for any implant of the same series, that is to say whatever the correction, whether the optics are positive or negative, for example concave-convex, concaveplan

or biconcave.

  Preferably, the haptic part includes a ring surrounding the optical part of the implant and forms a transition with the haptic elements.

  able to cooperate with the ciliary sulcus.

  Preferably, the haptic part comprises three haptic legs called "flat" haptics extending radially from the periphery of

the haptic ring.

  According to the preferred embodiment of the invention, two of the flat haptic elements are narrower (in the circumferential direction) and closer to each other and the third arranged on the line of symmetry than the first two and more wide (in the circumferential direction). Three flat haptic elements ensure excellent stability and centering of the optics without risk of decentering or expulsion of the implant through the

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  pupil towards the anterior chamber. Reducing the width of two of the three flat elements and bringing them together makes it possible to reduce the effective width of the implant folded along its axis of symmetry and therefore to reduce the risk of damaging the corneal endothelial cells at the time of Introduction into the posterior chamber of the eye. In addition, bringing two of the three flat haptic elements together also makes it easier to manipulate the implant with a micromanipulator.

  after positioning in the ciliary sulcus.

  In practice, the radius of the posterior surface of the optic will be approximately 10 mm, which corresponds to the physiological curvature of the capsule.

  anterior lens at rest.

  The radial haptic elements have, in practice, a posterior angulation of about 10 in order to ensure the minimum spacing between the crystalloid and the implant and the translation of the implant during the accommodation of the lens for near vision. . In other words, the optic remains parallel

  to himself in the positions of rest and accommodation.

  Other characteristics and advantages of the invention will appear

  in the following description, with reference to the accompanying drawings, given as

  non-limiting examples, in which: - Figure 1 is a front view of the precrystalline intraocular implant, according to the embodiments of Figures 2 to 5; - Figure 2 is a sectional view along the broken line I-I of Figure 1 for a converging optic of meniscus shape; - Figure 3 is a sectional view along the broken line I-I of Figure 2 for a biconcave optic; - Figure 4 is a sectional view along the broken line I-I for a plano-concave optic; - Figure 5 is a sectional view along the broken line I-I of Figure 1 for a diverging optic of meniscus shape; - Figure 6 is a similar view of the implant according to Figure 2 implanted in the eye, the lens being in the rest position;

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  - Figure 7 is a similar view of the implant according to Figure 3 implanted in the eye, the lens being in the rest position; - Figure 8 is a similar view of the implant according to Figure 4 implanted in the eye, the lens being in the rest position; - Figure 9 is a similar view of Figure 5; - Figure 10 is a view similar to that of Figure 1 to illustrate

  the implant when folded along its axis of symmetry.

  We will first describe a first embodiment of the present invention, the optical element of which is convergent for the correction of

  Hyperopia, with reference to Figures 1, 2 and 6.

  The precrystalline intraocular implant normally made entirely of flexible material, preferably a hydrophilic acrylic, such as

  than a copolymer of polymethylmethacrylate and polyhydroxyethyl-

  methacrylate, comprises a central optical part 10, a peripheral haptic part 20. Being an optical element of the meniscus type, the anterior face 11 is convex and the posterior face 12 is concave. The radius of

  curvature of the posterior surface of the optic is approximately 10 mm and invariable.

  The radius of curvature of the anterior face is smaller than that of the posterior face. Depending on the desired diopter, between 0 and +10, the radius of curvature of the anterior face is chosen accordingly. Preferably, the optical part has

a diameter of about 6 mm.

  In order to have the smallest possible axial thickness of the optical element in the center, the thickness at the periphery of the optical element is

preferably 0.05 mm.

  The haptic part 20 comprises a haptic crown 15 and a plurality of radial haptic lugs 21, 22. The haptic crown 15A has the shape of a previously convex bead. This bead surrounding the optical part ensures the mechanical resistance of the assembly, notwithstanding the minimal thickness at the periphery of the optical part, up to about 0.05 mm. In the example illustrated, the haptic crown has a radial width of approximately 0.5 mm

  and an outside diameter of about 7 mm.

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  The haptic part also comprises in the preferred embodiment three radial haptic legs 21, 22 extending radially outward from the haptic crown and the peripheral edge of the three haptic legs 21, 22 extends over a radial circumference corresponding to that of the ciliary sulcus and, in practice, between 10 mm and 12 mm. The radial lug 21 is wider at its root and at its periphery than the lugs 22 which are preferably identical by approximately 50%. The midline of the tab 21 is on the axis of symmetry of the implant; the radial lugs 22 are located on either side of this same axis of symmetry of the implant. The two tabs 22 are closer to each other than to the radial tab 21. They form an acute angle at the center between 70 and 90 and preferably about 80. Consequently, each tab 22 forms an obtuse angle with the tab 21 between and 145 and preferably 140. Each of the radial legs has an angulation of about 10 towards the posterior, so that, when the haptic part is housed in the ciliary sulcus, as illustrated in FIG. 6, the radially anterior part of the optical part is also slightly spaced from the anterior lens capsule thus allowing the aqueous humor to flow uninterruptedly over the entire surface of the crystalloid to ensure proper irrigation of the lens. Preferably, the legs have a

  constant thickness of about 0.1 mm.

  Thanks in particular to the haptic crown 15A of reinforcement, the implant has sufficient rigidity to oppose any deformation of the optics and any flexion of the radial legs, so that the force transmitted by the ciliary muscle has the consequence of displacing (very slightly) towards the front the entire implant parallel to itself, thus ensuring the maintenance of the interstitial space between the posterior face of the implant and the crystalline lens, and therefore the good flow of the watery mood even during accommodation

of the lens.

  The second embodiment illustrated in Figures 1, 3 and 7 has the same general architecture as the first embodiment, with the exception of the front face 1 B of the optical part which is concave. Such a biconcave optic thus ensures a correction of myopia for diopters between

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  -12 (excluded) and -20 (included). Therefore, only the optical part and the crown

  haptics of this second embodiment will be described in detail.

  The posterior face of the implant 12 has a radius of curvature of approximately 10 mm, like that of the first embodiment, and a concave anterior face 11B having a radius of curvature between approximately 200 and 20 mm for the range of diopters negative above. To have an optical part of minimum thickness, the thickness in the center has a value of approximately 0.05 mm and

  the thickness at the peripheral edge varies as a consequence of the given diopter.

  The annular crown 15B is also convex towards the front but has a much larger axial dimension than the bead of the first embodiment since the haptic crown 15B provides the junction between the periphery of the optical part having a significant axial thickness and the root of the radial legs 21, 22. The haptic crown 15B thus rounded ensures the best possible contact with the posterior surface of the iris thus avoiding any risk of injury. As seen in Figure 7, the part

  peripheral optics causes minimal deformation of the iris.

  The position of the posterior surface of the implant relative to the lens in the rest position and the displacement of the implant parallel to itself during the accommodation of the lens is the same as

  that described with respect to the first embodiment.

  The third embodiment of FIGS. 4 and 8 differs from the second embodiment only by the fact that the front face 11C of the optics is flat and not concave. It will be understood that this is the limiting case of the second embodiment, when the radius of curvature of the anterior face is infinite. As a result, the shape of the anterior surface of the haptic crown 15C is more flattened since the thickness of the optics at its periphery is smaller. The mechanical operation of the third embodiment is therefore substantially identical to the first two embodiments. The minimum thickness in the center of the optical part in the center is preferably 0.05 mm. The maximum thickness of the haptic part at its junction with the haptic crown 15C being smaller than the axial thickness of the second embodiment, the optics will hardly be in contact with the

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  posterior surface of the iris. Finally, the diopter of this implant is approximately -12.

  The fourth embodiment of Figures 5 and 9 completes the range of diopters of the implant according to the present invention. The optical part D of meniscus shape and its front face 11 D is convex, like that of the first embodiment of FIGS. 2 and 6. But, unlike the first embodiment, the radius of curvature of the front face 11 D of the optic is larger than the radius of curvature of the rear face and, therefore, the optic is divergent. The curvature of the posterior concave face

  of the optical part 12 is identical to that of the other embodiments.

  For this configuration of the optical part, the thickness in the center is constant and minimum and, in practice, 0.05 mm. This optic meniscus and

  divergent is suitable for a range of diopters from 0 to -12 excluded.

  To ensure its implantation, this intraocular lens can be folded on the axis of symmetry AA of FIG. 1, as illustrated in FIG. 8. The bringing together of the two lateral tabs and their width of peripheral contact smaller than that of the front tab makes it possible to significantly reduce the overall width of the folded implant. This width is close to the half-diameter of the implant. We minimize any unwanted contact

  between the endothelial cells of the cornea upon introduction through the incision.

  Similarly, the approximation of the haptic legs 22 facilitates the modification of the orientation when the implant is released behind the iris and deployed in the sulcus

ciliary with a micromanipulator.

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Claims (11)

  1. A precrystalline intraocular implant adapted to be housed in the sulcus of the eye comprising a central optical part (10) and a haptic part (20) comprising a plurality of peripheral haptic elements, at least the optical element being made of material flexible, characterized in that the peripheral haptic elements comprise a plurality of haptic legs (21, 22), the diameter of the haptic part being at least equal to the diameter of the ciliary sulcus of the eye, the curvature of the posterior face corresponding to that of the crystalline lens at rest, and able to remain slightly   spaced from the anterior surface of the lens in the resting state.   2. precrystalline implant according to claim 1, characterized in   that it is at least partially made of a hydrophilic acrylic material.   3. precrystalline implant according to claim 1, characterized in that   that it is in one piece and entirely made of a hydrophilic acrylic material.   4. Pre-crystalline implant according to any one of the claims   previous, characterized in that the optical element has a convex anterior face and the haptic part (20) comprises a haptic crown (15A, 15B,   C, 15D) of reinforcement surrounding the optical part (10).   5. Pre-crystalline implant according to any one of the claims   previous, characterized in that the plurality of haptic tabs extends radially from a haptic ring (15A, 15B, 15C, 15D) surrounding the optical part, the axial thickness of the haptic crown being substantially   larger than that of haptic legs.   6. Pre-crystalline implant according to any one of claims   previous, characterized in that the radius of the rear face of the optic is about 10 mm.   7. Pre-crystalline implant according to any one of the claims   previous, characterized in that the haptic legs have a   posterior angulation of about 10.   8. Pre-crystalline implant according to any one of claims   previous, characterized in that the haptic part (20) comprises a haptic crown (15A, 15B, 15C, 15D) of reinforcement surrounding the optical part 9 2797177   and imparting rigidity to the implant, such that the optical part is able to move parallel to itself between the rest position and the position lens adaptation.   9. Pre-crystalline implant according to any one of claims   previous, characterized in that the haptic part comprises three radial haptic legs (21, 22), one of the radial parts having a greater circumferential extent (21) than that of the other haptic elements radial (22).   10. precrystalline implant according to claim 9, characterized in that the two other radial haptic legs are substantially closer to each other than the haptic element has a most circumferential extent great possible.   11. precrystalline implant according to one of claims 5 to 10,   characterized in that the radial haptic elements (21, 22) are devoid of window.