Improved endocapsular tension ring

Abstract: An improved endocapsular tension ring is provided which is particularly adapted to provide long-term stabilization and centralization of the capsular bag during and after intraocular surgery in patients having missing or damaged zonules. In one embodiment, the improved endocapsular tension ring includes an open-ended loop formed of biocompatible material that is constructed to be resilient to compression in the radial direction within the capsular bag to prevent shrinkage of the capsular bag during and after intraocular surgery. The improved endocapsular tension ring includes a fixation element joined to the open-ended loop that is adapted to be attached to the scleral wall of the eye and thereby stabilize and centralize the capsular bag within the posterior chamber of the eye without passing sutures through the capsular bag. Methods for implanting the improved endocapsular tension ring in the capsular bag of a human eye are also disclosed.

Description: The present invention relates generally to eye implants for human eyes and, more particularly, to a capsular bag implant for stabilizing the capsular bag of a human eye during and after intraocular surgery. The human eye is susceptible to various diseases and abnormalities that can lead to impaired vision in the eye. In severe cases of ocular disease or abnormality, near or total loss of functional vision may result which can only be restored through intraocular surgery. For example, cataracts are caused by a gradual clouding of the lens and its surrounding material which, over an extended period, may result in complete loss of functional sight in the cataractous eye. Intracapsular cataract extraction includes complete removal of the lens, the capsular bag enveloping the lens, and the zonules connecting the capsular bag to the scleral wall of the eye. Following their removal, an artificial intraocular lens (IOL) is then implanted in the anterior chamber of the eye, with the haptics of the IOL being received in the anterior chamber angle region between the iris and the cornea. Alternatively, the IOL can be sutured to the iris or scleral wall in the posterior chamber, with the haptics of the IOL resting between the iris and the ciliary body. Extracapsular cataract extraction is performed to remove the cataractous lens while leaving the capsular bag and zonules intact within the posterior chamber of the eye. In this procedure, a capsulorhexis incision is performed to remove a generally circular mid-portion of the anterior capsule of the capsular bag, thereby leaving the posterior capsule, an annular anterior capsular flap and a generally circular anterior capsulorhexis edge. The cataractous lens is removed from the residual capsular bag and replaced with an artificial IOL. The IOL has haptics to engage an inner peripheral surface of the residual capsular bag and centralize the IOL within the capsular bag. Those skilled in the art of ophthalmic surgical procedures will appreciate that the capsular bag is a delicate elastic membrane that envelops the lens. The capsular bag is connected to the scleral wall of the eye through zonule fibers that function to centralize the lens behind the iris and in alignment with the pupil. In eye patients with missing or damaged zonules from trauma or disease, the position of the capsular bag within the posterior chamber of the eye is unstable, making removal of the enclosed cataractous lens difficult and implantation of the IOL challenging. In the past, capsular bag implants have been developed to stabilize the capsular bag during the extracapsular cataract extraction procedure and to generally centralize the capsular bag within the posterior chamber of the eye in patients having limited damaged or missing zonules. One known capsular bag implant, commercially available from Morcher GmbH of Stuttgart, Germany, under model designations Type 14, 14A and 14C, has been found to be successful in preventing shrinkage of the elastic capsular bag during the cataract extraction procedure and to improve stabilization of the intraocular environment in some patients with limited zonular dialysis or zonular weakness. The Morcher capsular bag implant (endocapsular tension ring) comprises an open-ended loop of polymethyl methacrylate (PMMA) which is resilient to compression in the radial direction within the capsular bag. The Morcher capsular bag implant is adapted to be implanted in the residual capsular bag before or after the cataractous lens is removed, and to engage the inner peripheral surface of the residual capsular bag to prevent shrinkage. The general circular expansion of the capsular bag as provided by the Morcher capsular bag implant improves stabilization of the intraocular environment and lens centration during intraocular surgery in patients with limited zonular dialysis or generalized zonular weakness. The Morcher capsular bag implant may be sutured to the scleral wall of the eye by passing a loop around the endocapsular tension ring and then passing the suture through the annular anterior capsulorhexis flap or the peripheral edge of the capsular bag. However, passing a suture through the residual capsular bag jeopardizes the residual capsular bag's integrity and therefore jeopardizes long-term IOL centration and stabilization. An endocapsular tension ring according to the preambles of claims 1 and 2 is known from document EP-A-0 478 929. Notwithstanding the advancements made in the prior art in the field of capsular bag implants, there is a need for a capsular bag implant which improves stabilization of the intraocular environment during and after intraocular surgery. There is also a need for an improved capsular bag implant that provides long-term intraocular lens centration and stabilization in patients having more significant zonular dialysis or generalized progressive zonular weakness. To these ends, the present invention sets forth an improved endocapsular tension ring and which is particularly adapted to provide long-term stabilization and centralization of the capsular bag in patients during and after intraocular surgery. In one embodiment of the invention, the improved endocapsular tension ring includes an open-ended loop formed of bicompatible material. The open-ended loop is constructed to be resilient to compression in the radial direction within the capsular bag to prevent shrinkage of the capsular bag during and after intraocular surgery. The invention includes a fixation element having one end fixed to the open-ended loop and a free end which preferably terminates in an eyelet. The eyelet of the fixation element is operable to receive a suture for attachment of the fixation element to the scleral wall of the eye and thereby stabilize and centralize the capsular bag within the posterior chamber of the eye. The open-ended loop of the improved endocapsular tension ring generally lies in a plane, and the fixation element preferably extends from the loop outside of the plane. In one aspect of the invention, the fixation element is curved from the fixed end to the free end, and includes a portion that lies in a second plane offset from and generally parallel to the plane defined by the open-ended loop. The fixation element has one portion that extends from the fixed end inwardly from the loop. A second portion of the fixation element extends from the first portion outwardly toward the loop to define a curved "hook" or haptic member between the fixed end and the free end. Preferably, the fixation element lies within the circumference of the open-end loop. During an extracapsular cataract extraction, the improved endocapsular tension ring is implanted in the capsular bag with its fixed end joined to the loop within the capsular bag, and its free end extending past the capsulorhexis edge and positioned anterior to the annular anterior capsular flap. A suture is passed through the eyelet of the fixation element and sutured to the scleral wall of the eye anterior to the capsular bag and posterior to the iris. The placement of the suture is chosen preferably near the location of the missing or damaged zonules to reduce or eliminate shifting of the capsular bag within the posterior chamber of the eye. Positioning of the eyelet anterior to the annular anterior capsular flap eliminates the need to pass a suture through the fragile capsular bag which, over time, might jeopardize or disrupt the integrity of the capsular bag. The improved endocapsular tension ring prevents shrinkage of the capsular bag and stabilizes and centralizes the implanted IOL in alignment with the pupil. A method of implanting an endocapsular tension ring in accordance with the invention in a capsular bag of an eye therefore comprises providing a loop of biocompatible material, the loop being operable to generally prevent shrinkage of the capsular bag following implantation therein, providing an elongated fixation element joined to the loop and formed of biocompatible material, the fixation element having a first end fixed to the loop and a second free end,removing a mid-portion of the anterior capsule of the capsular bag, thereby leaving the posterior capsule, an annular anterior capsular flap and an anterior capsulorhexis edge, implanting the loop in the capsular bag between the posterior capsule and the annular anterior capsular flap, positioning the fixation element having its first end fixed to said loop and its second free end extending past the capsulorhexis edge and positioned anterior to the capsular bag with the annular anterior capsular flap positioned therebetween, and attaching the second free end of the fixation element to the scleral wall of the eye, whereby the endocapsular tension ring generally stabilizes and centralizes the capsular bag in the posterior chamber of the eye during and after intraocular surgery following attachment of the fixation element to the scleral wall. Preferably, the method further comprises positioning the second free end of the fixation element posterior to the iris of the eye. The attaching step may comprise suturing the second free end of said fixation element to the scleral wall of the eye. The attaching step may further comprise positioning the suture anterior to the annular anterior capsular flap and posterior to the iris of the eye. The invention will now be described by way of example and with reference to the accompanying drawings in which: Fig. 1 is an illustration of a human eye, partially in cross-section, showing implantation of an improved endocapsular tension ring in a residual capsular bag in accordance with the principles of the present invention; Fig. 2 is a top plan view of the improved endocapsular tension ring shown in Fig. 1; Fig. 3 is a side view of the improved endocapsular tension ring shown in Fig. 2; Fig. 4 is a fragmentary top view of a residual capsular bag following a capsulohexis procedure, showing implantation of the improved endocapsular tension ring of the present invention and an artificial intraocular lens in the capsular bag; and Fig. 5 is an alternative embodiment of the improved endocapsular tension ring shown in Fig. 2. With reference to the figures, and to Fig. 1 in particular, an improved endocapsular tension ring 10 in accordance with one embodiment of the present invention is shown implanted in a capsular bag 12 of a human eye 14. As will be described in more detail below, the improved endocapsual tension ring 10 of the present invention is particularly adapted to stabilize and centralize the capsular bag 12 within the posterior chamber 16 of the eye 14 during and after intraocular surgery, particularly in patients that suffer from missing or damaged zonules from trauma or disease (zonular dialysis or weakness) or lens decentration. In a normal human eye, the lens of the eye (not shown) is enveloped in the capsular bag 12 which is positioned centrally in the posterior chamber 16 of the eye behind the iris 18 and aligned with the pupil 20. The capsular bag 12 is an elastic membrane or pouch having a generally circular cross-section taken along a horizontal plane, and is attached to the ciliary body 22 of the eye through a series of zonules 24. The ciliary body 22 is attached to the scleral wall 25 of the eye. The zonules 24 are thin fibers that function to centralize the capsular bag 12 and its enveloped lens in a normal anatomic position within the posterior chamber 16 of the eye. In patients suffering from missing or damaged zonules 24 from trauma or disease, as illustrated by the fewer zonules 24 on the left side of the capsular bag 12 shown in Fig. 1, the normal anatomic position of the capsular bag 12 may become unstable or decentralized in the posterior chamber 16 of the eye. The weakened or missing zonules 24 may allow the capsular bag 12 to shift or drift within the posterior chamber 16 of the eye, thereby resulting in general decentration of the lens and an unstable intraocular environment. As shown in Fig. 1, the improved endocapsular tension ring 10 of the present invention is particulary adapted to be implanted in the capsular bag 12, and further to be attached to the scleral wall 25 of eye 14 for long-term stabilization of the capsular bag 12 in a normal anatomic position during and after intraocular surgery. The capsular bag 12 of Fig. 1 is illustrated as a residual capsular bag which remains following a capsulorhexis procedure commonly performed during intraocular surgery to remove a cataractous lens. During the capsulorhexis surgical procedure, an incision is made in the anterior capsule 26 of the capsular bag 12 to remove a generally circular mid-portion of the anterior capsule 26. Following this procedure, the residual capsular bag 12 includes a posterior capsule 28, an annular anterior capsular flap 30, and a generally circular capsulorhexis edge 32 as shown most clearly in Fig. 1. As described in detail below, the residual capsular bag 12 is able to retain the improved endocapsular tension ring 10 and an artificial intraocular lens (IOL) 34 (Fig. 4) within the capsular bag 12 following the capsulorhexis procedure. Referring now to Figs. 1-4, the improved endocapsular tension ring 10 according to one embodiment of the present invention includes an open-ended loop 36 of biocompatible material having spaced ends 38, 38 terminating in respective eyelets 40, 40. The open-ended loop 36 is adapted to be implanted in the residual capsular bag 12 of eye 14 to prevent shrinkage of the capsular bag 12 during and after intraocular surgery. More particularly, the open-ended loop 36 is implanted between the posterior capsule 28 and the annular anterior capsular flap 30 to engage an inner peripheral surface 42 (Figs. 1 and 4) of the capsular bag 12 and to maintain a predetermined diameter of the capsular bag 12. The open-ended loop 36 is generally flexible to resist compression in a radial direction within the capsular bag 12. Preferably, the open-ended loop 36 has an unflexed diameter (not shown) of about 12 mm and a radially inward flexed diameter (Fig. 2) of about 10 mm, although other diameters of open-ended loops 36 are possible without departing from the spirit or scope of the present invention. The open-ended loop 36 is preferably made of polymethyl methacrylate (PMMA), although those skilled in the art will appreciate that other biocompatible materials suitable for implantation in a capsular bag 12 are also available. The open-ended loop 36 further includes at least one fixation element 44 joined to the loop 36 which is adapted to be attached to the scleral wall 25 of eye 14 through a suture 46 (Fig. 1). The fixation element 44, also preferably made of PMMA or other suitable biocompatible material, has one end 48 integrally formed or fixed to the open-ended loop 36 and a free end 50 terminating in an eyelet 52 for receiving the suture 46 during attachment of the fixation element 44 to the scleral wall 25. As shown most clearly in Fig. 3, the open-ended loop 36 lies in a plane "A", while the fixation element 44 extends from the loop 36 outside of the plane "A". Preferably, as shown most clearly in Fig. 3, the fixation element 44 has a portion 54 lying in a second plane "B" offset from and generally parallel to plane "A" of the open-ended loop 36 for purposes to be discussed in more detail below. Fixation element 44 preferably has a first portion 56 extending from the fixed end 48 inwardly from the loop 36, and a second portion 58 extending from the first portion 56 outwardly toward the loop 36 to form a curved "hook" or haptic member between the fixed end 48 and the free end 50. As shown in Fig. 2, the fixation element 44 preferably lies within the circumference of the open-ended loop 36. Aternatively, as shown in Fig. 5, the improved endocapsular tension ring 10 may include a pair of fixation elements 44 spaced on the open-ended loop 36 about 180° apart for attaching the improved endocapsular tension ring 10 to the scleral wall 25 of eye 14 at a pair of locations. The embodiment of the improved endocapsular tension ring 10 illustrated in Fig. 5 is particularly useful in cases of severe zonular damage or zonular weakness where more than one attachment point of the improved endocapsular tension ring 10 to the scleral wall 25 is required to stabilize and centralize the capsular bag 12 in the posterior chamber 16. During intraocular surgery to remove a cataractous lens or to correct IOL lens centration, and in accordance with a preferred implantation method of the present invention, a capsulorhexis procedure is first performed to form the residual capsular bag 12 having the posterior capsule 28, annular anterior capsular flap 30 and capsulorhexis edge 32. A 10.0 PROLENE® suture 46 and needle (not shown) are thread through the eyelet 52 of fixation element 44 prior to implantation, and the needle and suture 46 are then passed through the scleral wall 25 anterior to the capsulorhexis edge 32 and posterior to the iris 18. It will be appreciated that other suture diameters and materials are possible without departing from the spirit or scope of the present invention. The improved endocapsular tension ring 10 is implanted in the residual capsular bag 12 of eye 14 between the posterior capsule 28 and the annular anterior capsular flap 30. The open-ended loop 36 is operable to generally prevent shrinkage of the capsular bag 12 as the loop 36 engages the inner peripheral surface 42 of the capsular bag 12. The fixation element 44 is positioned having its fixed end 48 joined to the loop 36 within the capsular bag 12, and its free end 50 extending past the capsulorhexis edge 32 and positioned anterior to the annular anterior capsular flap 30 and posterior to the iris 18. The suture 46 through eyelet 52 of fixation element 44 is sutured to the scleral wall 25 to thereby stabilize and centralize the capsular bag 12 in the posterior chamber 16 of the eye 14 during and after intraocular surgery. The placement of the suture 46 is chosen preferably near the location of the missing or damaged zonules to reduce or eliminate shifting of the capsular bag within the posterior chamber 16 of eye 14. Where the natural lens (not shown) is to be replaced by an IOL, the IOL 34 shown in Fig. 4 is implanted in the capsular bag 12 which is stabilized by the improved endocapsular tension ring 10. The IOL 34 typically includes haptic members 60 which engage the inner peripheral surface 42 of the capsular bag 12. Those skilled in the art will readily appreciate that the improved endocapsular tension ring 10 of the present invention advantageously prevents shrinkage of the capsular bag 12 during and after intraocular surgery. The fixation element 44 that is joined to the open-ended loop 36 and attached to the scleral wall 25 of eye 14 provides long-term stabilization and centralization of the capsular bag 12 during and after intraocular surgery in patients having missing or damaged zonules through zonular dialysis or weakness. With the eyelet 52 of fixation element 44 positioned anterior to the capsular bag, the suture 46 may be attached to the scleral wall 25 without passing through the fragile capsular bag 12. Through attachment of the fixation element 44 to the scleral wall 25 of the eye, the improved endocapsular tension ring 10 of the present invention also provides improved IOL centration and stabilization in patients having pre-existing or future zonular dialysis or zonular weakness.

Claims: An endocapsular tension ring (10) for implantation into a residual capsular bag of an eye following a capsulorhexis procedure, comprising a loop (36) informed of biocompatible material, the loop (36) being operable to generally prevent shrinkage of the capsular bag following implantation therein, characterised in that the ring comprises an elongated fixation element (44) associated with the loop and formed of biocompatible material, the fixation element having a first end (48) fixed to the loop (36) end a second free end (50) adapted to be positioned anterior to the capsular bag, the fixation element (44) being operable to receive a suture (46) for attachment to the scleral wall of the eye without passing the suture (46) through a wall of the capsular bag, whereby the endocapsular tension ring (10) generally stabilizes and centralizes the capsular bag in the posterior chamber of the eye during and after intraocular surgery following attachment of the fixation element (44) to the scleral wall. An endocapsular tension ring, comprising a generally flexible open-ended loop (36) free of attachment to an intraocular lens, the loop (36) having first and second ends (38), characterised in that the ring comprises a first elongated fixation element (44) having a first portion (56) projecting inwardly from the loop and a second portion (58) extending outwardly from the first portion (56), the first fixation element (44) being open-ended with one end (48) fixed to the loop (36) and the other end (50) tree. An endocapsular tension ring as claimed in Claim 2 wherein each of the first and second ends (38) of the loop (36) includes an eyelet (40). An endocapsular tension ring as claimed in any preceding claim wherein the loop (36) lies in a planet (A) and the fixation element (44) extends from the loop outside of the plane (A). An endocapsular tension ring (10) as claimed in any preceding claim wherein the loop (36) lies in a first plane (A) and the fixation element (44) has a portion (54) lying in a second plane (B) generally parallel to the first plane (A). An endocapsular tension ring (10) as claimed in any preceding claim wherein the second free (50) end of the fixation element (44) includes an eyelet (52). An endocapsular tension ring (10) as claimed in any preceding claim wherein the fixation element (44) is generally curved from the first fixed end (48) to the second free end(50). An endocapsular tension ring (10) as claimed in any preceding claim wherein the second free end (50) of the fixation element (44) lies within the circumference of the loop (36). An endocapsular tension ring (10) as claimed in any one of Claims 1 and 4 to 8 as dependent on Claim 1 wherein the ring is adapted to be implanted in a residual capsular bag having a posterior capsule, an annular anterior capsular flap and an anterior capsulorhexis edge and the loop (36) is adapted to be impanted in the capsular bag between the posterior capsule and the annular anterior capsular flap, and wherein the fixation element (44) is joined to the loop (36) and the second free end thereof is adapted to extend past the anterior capsulorhexis edge and is operable to receive a suture (46) for attachment to the scleral wall of the eye without passing the suture (46) through a wall of the capsular bag. An endocapsular tension ring (10) is claimed in Claim 9 further comprising a second fixation element (44), wherein the second fixation elements (44) has a first end (48) fixed to the loop (36) and a second free end (50) adapted to extend past the anterior capsulorhexis edge and adapted to be positioned anterior to the capsular bag, the second free end (50) of the second fixation element (44) being operable to receive a suture (46) for attachment to the scleral wall of the eye without passing the suture (46) through a wall of the capsular bag. An endocapsular ring (10) as claimed in either Claim 2 or Claim 3 further comprising a second fixation element (44) projecting from the loop (36), the second fixation element (44) being open-ended with one ends (48) fixed to the loop (36) and the other end (50) free. An endocapsular ring as claimed in either Claim 10 or Claim 11 wherein the first and second fixation elements (44) are spaced on said loop (36) about 180° apart.

Inventors: CIONNI ROBERT J, CIONNI, ROBERT J.
Applicants: MORCHER GMBH
Application year: 1998
Main classification: A61F2
IPC codes: A61F2