Patent ID: 12208258

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure relate to electrical apparatus for applying stimulation to any eye of a patient and/or monitoring the eye of the patient. The electrical apparatus may provide a “visual prosthesis apparatus” for improving a patient's vision (or at least giving improved “perception” of vision), and will be understood to include devices otherwise known as bionic eyes, artificial eyes, retinal prostheses and retinal stimulators or similar. However, features of the present disclosure may be useable with any type of device implanted in the eye, whether for sight restoration or otherwise, or with entirely different types of implantable devices, including devices adapted to stimulate or monitor brain activity. In general, monitoring as described herein may include, for example, measuring of a signal, e.g. from an eye, recording of signal data, processing of signal data and/or analysing of the signal data.

FIG.1shows a top view of electrical apparatus according to an embodiment of the present disclosure, the apparatus including an implantable device1, an anchor device2and a lead3.

The implantable device has a flexible substrate10with a distal end11, a proximal end12, a first side13, and a second side14. The substrate10, when viewed from above, is substantially rectangular, with curved corners to minimise surgical trauma. The longitudinal direction (length) of the substrate extends between the distal and proximal ends11,12and the transverse direction (width) of the substrate extends between the first and second sides13,14. The substrate10includes first and second opposite surfaces15,16that each extend between the distal and proximal ends11,12and between the first and second sides13,14(see alsoFIG.3a). Electrodes17are partially embedded in the substrate, which electrodes17are used to apply electrical current to tissue of the eye for the purposes of eliciting a visual percept to a subject, and/or are used to monitor properties of the eye by receiving electrical current from tissue of the eye. In this embodiment, 44 electrodes17are provided, the electrodes being arranged in a staggered pattern with electrodes17offset in rows extending in the longitudinal direction of the substrate but aligned in the transverse direction of the substrate. The electrodes17are exposed at the second surface16of the substrate.

The length of the substrate10is between about 16 mm and 20 mm, e.g. about 17 mm, 18 mm or 19 mm, although other lengths are possible. The width of the substrate10is between about 6 and 10 mm, e.g. about 8 mm, although other widths are possible. The electrodes17are disc-shaped electrodes with circular peripheries, although other shapes are possible. The diameters of the electrodes17are between about 0.4 mm and 2.5 mm, e.g., about 1.05 mm in this embodiment for stimulation electrodes17band about 2.1 mm for current return electrodes17a(i.e. having a first surface area of about 0.13 mm2and 4.91 mm2, i.e. about 0.87 mm2). However, as discussed in more detail below, a lip101surrounds the electrodes17such that only a portion of each electrode, e.g., having a diameter of about 1.00 mm (i.e., an area of about 0.79 mm2) for the stimulation electrodes17band 2.0 mm (i.e., an area of about 3.14 mm2) for the current return electrodes17a, is exposed from the substrate.

In addition to covering a relatively large area of the substrate10, the electrodes17are sized and distributed to retain flexibility of the implantable device1.

Each electrode17is connected to one or more separate electrical conductors33, e.g., biocompatible metal wires such as platinum wires. The conductors33extend through the substrate, and extend out of the substrate and through the lead3. Although only a basic representation of the conductors33is provided inFIG.1, in practice the conductors33may be configured in a helical configuration, enabling the conductors to adjust to flexing of the implantable device1and/or lead3.

The substrate10of the implantable device includes one or more navigation markers1011,1012to assist in the implantation of the implantable device1. The navigation markers1011,1012can serve as an indicator of the depth of insertion of the implantable device1through an incision in the eye and/or as an indicator of the orientation of the implantable device1relative to the incision. In this embodiment, at least two navigation markers1011,1012are provided, each on the first (rear) surface15of the substrate10. In this embodiment, the navigation markers1011,1012are provided in the form of lines. The lines are printed on the rear surface15of the substrate10, although in alternative embodiments they may be etched or moulded into the substrate, for example. The lines15are straight lines that extend in a transverse (width) direction of the substrate10, perpendicularly to the longitudinal (length) direction of the substrate10.

A first one of the navigation markers1011is provided to mark the position at which the implantable device1, when fully implanted, is to align with the incision in the eye. The first marker1011when positioned at the incision not only indicates that the implantable device1has been inserted to the full implantation depth through the incision, but also provides a means of ensuring that the implantable device1is oriented appropriately relative to the incision at the full implantation depth. In this embodiment, appropriate orientation at the full implantation depth is achieved when the first marker is positioned directly underneath, and extends parallel to, the incision. Notably, the first marker is positioned slightly distally of the proximal end of the substrate10, since the implantable device1, when fully implanted, is configured to extend either side of the incision. A major portion (distal side) of the implantable device1is to be located to one side of the incision with a remaining minor portion (proximal side) of the implantable device1being tucked to the opposite side of the incision (see e.g.FIGS.6ato6c). The lead3extends from the implantable device1at a position that is aligned with the first marker1011, since it is arranged to extend from the implantable device1immediately through the incision.

A second one of the navigation markers1012, which is located distally of the first navigation marker, provides an intermediate marker. It provides an indication, for example, that the implantable device1has been inserted to a predetermined intermediate implantation depth through the incision, e.g. at least half of the full implantation depth. Moreover, it provides an indication that the implantable device1is being inserted at the appropriate orientation relative to the incision at the intermediate implantation depth. In this embodiment, appropriate orientation is achieved at the intermediate implantation depth when the second marker1012is positioned directly underneath and extends parallel to the incision. Additional markers, e.g. lines, may be provided to provide additional indications of the depth of insertion of the implantable device and/or to ensure suitable orientation of the implantable device1at those different depths.

An example method of implanting the implantable device1in an eye5is now discussed with respect toFIGS.2aand2b. An incision50is made in the sclera51of the eye5with a scalpel52, the incision50being slightly wider than the width of the substrate10of the implantable device1. For example, the incision may have a width of about 7 to 12 mm. The incision50is made between the superior rectus muscle53and the lateral rectus muscle54of the eye5. The incision is positioned about 4 to 5 mm posterior from the intramuscular septum. The distal end11of the substrate10is pushed into the incision50, using soft-tipped forceps53, through the sclera51and into a pocket between the sclera51and the choroid56(SeeFIG.2b). Once fully inserted, the opening of the incision50is closed using sutures. When implanted, the implantable device1of the present embodiment is located entirely between the superior and lateral rectus muscles53,54of the eye5, in a superior anterior temporal position of the eye (e.g., in the superior anterior temporal octant of the eye). In alternative embodiments, a part of the implantable device may be located between the superior and lateral rectus muscles of the eye and a part of the implantable device may be located under one or both of the superior and lateral rectus muscles of the eye.

Stimulation provided by the implanted device1may restore visual function through eliciting the perception of light as a direct result of the stimulation.

By implanting the implantable device1suprachoroidally and at a superior anterior temporal position of the eye (e.g., in the superior anterior temporal octant of the eye), efficacious stimulation and/or monitoring of tissue of the eye can be achieved. Positioning of the implantable device1suprachoroidally can provide an approach that is safe and stable and requires minimally-invasive surgery.

In addition or as an alternative to providing electrical stimulation, the implantable device1may be used to monitor electrical properties, such as voltages, impedances or otherwise, of the eye. In one embodiment, the implantable device1is used to perform electroretinography monitoring (ERG).

In addition to the positioning of the implantable device1in the eye, safety, stability and the need for only minimally invasive surgery is provided in part through the shaping of the substrate10of the implantable device. A side view, an end view and an oblique view of the substrate10are provided inFIGS.3a,3band3c, respectively. As can be seen, the first surface15of the substrate is curved. When positioned suprachoroidally, the first surface15is designed to rest against the inner surface of the sclera51, as illustrated inFIG.2b.

With reference toFIG.3a, the degree of curvature of the first surface15increases in the longitudinal direction from a central region151of the first surface15of the substrate10towards the distal end11of the substrate10. The curvature of the first surface15also increases in the longitudinal direction from the central region151towards the proximal end12of the substrate10. Similarly, with reference toFIG.3b, the degree of curvature of the first surface15increases in the transverse direction from the central region151of the first surface15of the substrate10towards the first side13the substrate10. The curvature the first surface15also increases in the longitudinal direction from the central region151towards the second side14of the substrate10. The curvature of the first substrate15of the substrate10is such that the substrate10tapers in thickness from a central region of the substrate10towards the ends and sides of the substrate10.

The degree of curvature of the first surface15changes in steps in this embodiment, although a continuous change may be provided in alternative embodiments. By increasing in steps, the first surface15has discrete regions, each region having a constant radius of curvature, but with the radius of curvature changing from one region to the next. In particular, at least three curved regions are provided in the present embodiment, the central region151, a first outer region152and a second outer region153, wherein the first outer region151is located between the central region151and the second outer region152. The central region151has a first radius of curvature R1, the first outer region152has a second radius of curvature R2and the second outer region153has a third radius of curvature R3, where R1>R2>R3.

The curvature of any one or more of the curved regions151,152,153can be part-spherical. In this embodiment, the curvature at the central region151is part-spherical and substantially follows the spherical curvature of the eye. The first surface15is configured to lie against the inside of the scleral. The relatively low, part-spherical curvature of at least the central region151of the first surface15reduces the amount of static pressure exerted against the sclera when the implantable device1is in the implantation position between the sclera and choroid. Nevertheless, the relatively high curvature of the outer regions152,153of the first surface can assist in the insertion of the substrate10between the tissue layers of the eye. The substrate10can be pushed into place between the tissue layers, causing separation of the tissue layers. The relatively high curvature can assist in separating the tissue layers, essentially opening up a pocket in which the implantable device locates. The curvature of the substrate10may ease surgical placement and forces. Moreover, the curvature may help support the incision50in the eye5through which the implantable device1is implanted in the eye5.

With reference toFIGS.4aand4b, the lead3is arranged to extend from the implantable device1, through the incision in the sclera51of the eye5, from the eye5to the adjacent orbital bone61, around the orbital bone61and along the side of the patient's skull62to a communications interface (an implantable stimulator63in this embodiment). A return electrode64is connected to the stimulator63. The communications interface can allow for connection between the implantable device and an electrical component such as a signal generator, signal monitor or otherwise.

Referring also toFIG.5, the lead3includes first and second lead sections31,32that locate externally to the eye when the implantable device1is implanted in position. The second lead section32is configured to extend around the orbital bone61and the first lead section31is configured to locate between the implantable device1and the second lead section32. The first lead section31has a pre-formed bend and specifically a pre-formed U-shaped bend, in this embodiment. The pre-formed bend provides a change in direction of the lead at the first lead section of about 180 degrees, although other angles may be utilised. The pre-formed bend has a radius of about 1.5 mm to 3 mm, although other radii may be utilised. Moreover, more than one pre-formed bend may be provided at the first lead section31.

The pre-formed bend of the first lead section31bends in a posterior direction when the implantable device is implanted in the eye, as shown inFIG.4a. Thus, ends311,313of the U-shaped bend locate anteriorly of a middle-section312of the U-shape.

The first lead section31is flexible and has a length that is greater than the distance between the eye5and the orbital bone61and, more specifically, a length that is greater than the distance between the incision50of the eye5at which the lead3exits the eye, when the eye is in a forward-facing position, and a point on the orbital bone61to which the lead3makes contact as it extends around the orbital bone61.

During use of the electrical apparatus, the eye5can rotate. To allow relatively unhindered rotation of the eye5when the implantable device1is implanted in the eye5, the lead flexes and moves. Without the flexing and moving of the lead3, the lead3would hinder or prevent movement of the eye5in one or more rotational directions. Essentially it might fix the position of the eye5relative to the orbital bone61. By providing a first lead section31that is flexible and that has a length that is greater than the distance between the eye5and the orbital bone61, the eye can move substantially in all rotational directions. As the eye rotates, depending on the direction of rotation, regions of the first lead section31collect together (concertina) or extend apart (straighten). By providing the first lead section31with the pre-formed bend, the amount of force required to cause the first lead section31to concertina or straighten is significantly lower, reducing discomfort to the patient and/or potential eye damage.

The pre-formed bend of the first lead section31in the present embodiment is formed subsequent to moulding of the first lead section31. The first lead section31comprises the conductors33embedded in a surrounding cladding layer. The cladding layer is formed of silicone or other polymeric material, such as polyurethane, that is cured during the moulding process. The pre-formed bend is formed using a post-curing technique and specifically by rolling or holding the first lead section about a curved or angled surface while subjecting the first lead section to heating for a period of time. The curved or angled surface is at least part-cylindrical surface and has a radius of curvature of about 1.5 mm to 3 mm in this embodiment. The heating is conducted at a temperature of about 135° C. for a period of time of about 120 minutes, although other curvatures, temperatures and timings can be employed.

In the present embodiment, the second lead section32includes a reinforcement device4that provides for a thickening of the second lead section. The reinforcement device4directs the lead around the orbital bone61of the eye socket, as shown inFIGS.4aand4b, and provides protection for the lead and its conductors61against high stresses at this region. The reinforcement device4has a bend region402, a first section401on the implantable device side of the bend region402, and a second section403on the communications interface side of the bend region402.

The reinforcement device4is arranged to be attached to the orbital bone61. For example, the reinforcement device can be located in a notch formed in the orbital bone61to assist with attachment to the orbital bone61. The notch can include a recessed groove to receive the reinforcement device4and an access opening through which the reinforcement device4is locatable in the recessed groove. The access opening may be narrower than the recessed groove. The reinforcement device may be squeezed through the access opening into the recessed groove where it remains substantially trapped in position at the orbital bone. The point at which the lead extends around the orbital bone61, at which the notch is located, is higher than a transverse plane extending through the centre of the eye. In a posterior direction, the groove of the notch is angled superiorly, by about 15 degrees.

The reinforcement device4is formed integrally with the second lead section32in this embodiment, e.g. by a moulding technique or otherwise, but may be a discrete component in alternative embodiment. For example, in alternative embodiments, the reinforcement device may be clipped to and/or glued in position at the second lead section32.

The second lead section32and the reinforcement device4at the second lead section32has at least one pre-formed bend configured to conform to the angle of the orbital bone61such as to navigate the second lead section32around the orbital bone61. The pre-formed bend at the second lead section32is formed through a post-curing technique, e.g., in the same manner that the pre-formed bend of the first lead section31is formed.

The pre-formed bend of the second lead section32has a sharper angle than the pre-formed bend of the first lead section31. In particular, the pre-formed bend of the second lead section32is a V-shaped bend. In combination, the bends at the first and second lead sections31,32provide the lead3with an S-shaped configuration or more specifically a 2-shaped configuration (i.e. a configuration shaped substantially like the number 2). The bends at the first and second lead sections bend in opposite directions. The bend at the first lead section31bends in a posterior direction as described above and the bend at the second lead section32bends in an anterior direction.

With reference toFIG.5, the lead3has one or more stripes331,332extending along the lead3. The one or more stripes331,332assist with placement of the lead3during implantation of the implantable device1. Specifically, the stripes331provide a visual indication to the surgeon implanting the device regarding whether or not the lead3is twisted. The one or more strips331,332extend along at least the first lead section as shown inFIG.5, although they may extend along the entire length of the lead3. The stripes331,332can be formed from a layer of titanium dioxide or other material that has a contrasting colour to adjacent parts of the lead. Two of the stripes331,332can be provided, each stripe331,332being located at substantially opposite sides of the lead3.

As indicated above, the electrical apparatus includes an anchor device2. The anchor device2is provided to anchor the lead3at the outer surface of the eye5, at or adjacent the incision50in the eye5through which the lead3extends, and to route the lead3away from the eye. The anchor device2is flexible and formed of polymeric material such a medical grade silicone or polyurethane with a stiffening element embedded at one or more portions therein, such as a mesh, e.g. polyethylene terephthalate mesh (Dacron™ mesh). The anchor device2is in the form of a patch or flap with a preformed shape, e.g. channel23, that is adapted to receive a portion of the lead3when it secures the lead3to the outer surface of the eye5.

The anchor device2includes a proximal end portion21fixed to the lead3and a distal end portion22connected to the proximal end portion. Prior to implantation of the implantable device1, e.g. during the manufacturing process, the anchor device2is releasably secured in a folded configuration in which the distal end portion22projects towards the proximal end portion21, as illustrated inFIG.6a. The releasable securing of the anchor device2in the folded configuration is achieved by providing at least one suture241to suture the distal end portion22to the proximal end portion21, although other releasable fixation means may be employed such as adhesive.

While the anchor device2is in the folded configuration, the proximal end portion21may be secured to the outer surface of the eye5, e.g., using one or more sutures242.

By releasably securing the anchor device2in the folded configuration, the distal end portion22of the anchor device2can be temporarily held away from the incision50in the outer surface of the eye5through which the lead3exits the eye. Accordingly, the distal end portion22does not block or obstruct access to the incision50in the outer surface of the eye5. By maintaining such access to the incision50, sutures243can be applied more easily at the incision50in the outer surface of the eye5, e.g. to close up the incision50(seeFIG.6b), and/or other treatment can be more easily applied at or adjacent the incision. Once such steps have been completed, the suture241securing the distal end portion22to the proximal end portion21can be released, whereupon the distal end portion22automatically, or through manipulation, projects away from the proximal end portion21(seeFIG.6c). The distal end portion22can then at least partly cover the incision50in the outer surface of the eye5. In general, the anchor device2can extend over the lead3and cover at least part or all of the incision50in the outer surface of the eye5.

The proximal and/or distal end portions21,22of the anchor device2can be secured to the outer surface of the eye5using one or more sutures242,244or other fixation means. In some embodiments, alternatively or additionally, one or more side portions of the anchor device2may be securable to the outer surface of the eye5using one or more sutures or other fixation means.

With reference toFIGS.11a,11b,12aand12b, any anchor device2′,2″ according to the present disclosure, whether it is folded or otherwise, may include one or more recesses25′,25″, each configured to receive a respective suture knot246′,246″ of sutures242′,242″ used to secure the device to the surface of an eye5. The recesses25′,25″ may be discrete recesses as shown in the Figures, or otherwise connected together. In the embodiment ofFIGS.11aand11b, for example, the recesses25′ are each provided as depressed portions on the top surface of the anchor device2′, e.g. at side portions of the anchor device2′. In an alternative embodiment, shown inFIGS.12aand12b, the recesses25″ are provided on the underside of the anchor device2″, e.g. at side portions of the anchor device2″, to create pockets between the anchor device2″ and the outer surface of the eye5. In use, once each suture242′,242″ has been tied off, the suture may be rotated to position the suture knot246′,246″ in the respective recess25′,25″. In the embodiment ofFIGS.11aand11b, the suture knot246′ may be pulled through the material of the anchor device to access the pocket.

In general, when secured to the outer surface of the eye5, the anchor device2,2′,2″ provide supports and stabilisation for the lead as it extends out of the incision50in the outer surface of the eye5. Furthermore, the anchor device shields the incision50in the outer surface of the eye5. The anchor device2also serves to route the lead3in an appropriate direction away from the anchor device2and the eye5, e.g., past extraocular muscles of the eye and towards the lateral orbital rim61. To achieve this routing, the lead3at the anchor device follows a bent path.

As discussed above, the implantable device1according to the present disclosure includes a substrate10and electrodes17partially embedded in the substrate10. The substrate10is formed primarily of a first, non-conductive material; and the electrodes are formed of a second, conductive material. As will now be described with reference toFIGS.7ato7d, each electrode17includes apertures171through which the first material of the substrate10at least partially extends to anchor the electrode17to the substrate10.

Each electrode17is substantially flat and with a first surface172and an opposite second surface. Each electrode17has a circular disk shape. The first surface172of the electrode faces away from the substrate10and is partially exposed from the substrate10to enable electrical contact with tissue of the eye5. The second surface of the electrode17is buried within the substrate10and specifically the first, non-conductive material of the substrate10. Each aperture171of the electrode17has open ends at the first and second surfaces of the electrode17.

In this embodiment, a plurality of the apertures171are provided in each electrode17, adjacent a peripheral edge of the electrode17. The apertures171are uniformly spaced and positioned in a ring pattern adjacent the peripheral edge of the electrode17and positioned within the outer 10 or 15% of the diameter of the electrode17. Each aperture171has a diameter that is less than 15% of the diameter of the electrode17. For example, each aperture may have a diameter of between 100 μm and 800 μm. Each aperture may be circular, although other aperture shapes can be used.

The first, non-conductive material is a flowable polymeric material such as a silicone elastomer or polyurethane that is set during the manufacturing process to form the substrate10. While in the flowable state, and prior to setting, the first material can flow into each aperture171to fill the aperture, generally as represented by arrows102inFIG.7d. The first material can extend out of the aperture171via the open ends of the aperture171, whereupon the first material can extend transversely to the aperture171across surfaces of the electrode17. The first material can form a continuous loop that extends through each aperture171and around a periphery of the electrode17and through other apertures171. Thus, each electrode17is trapped between portions of the first material, assisting in the anchoring of the electrode17to the substrate10.

As shown inFIGS.7band7d, the substrate10provides a lip101of the first material that extends around the periphery of the first surface172of each of the electrodes17to assist with anchoring the electrodes17to the substrate, while leaving a central region173of the first surface172of each electrode17exposed. In this embodiment, the first material extends through the apertures171underneath the lip101. Thus, the apertures171enhance the function of the lip101as a means of assisting anchoring of the electrode17to the substrate10.

In addition to or as an alternative to providing apertures171that extend between the first and second opposite surfaces of the electrode17, at least one aperture may be defined by a projection on the second surface of the electrode. For example, with reference toFIGS.8ato8c, the second surface1701of an electrode1700can include a projection such a loop, handle and/or hoop1702, the centre of which provides the aperture1703through which first material of the substrate10extends. The second surface1701of the electrode170is buried within the substrate. By providing the projection1702at the second surface that defines the aperture1703, the first material of the substrate can extend through the aperture1703when the second surface is buried within the substrate during manufacturing of the device, e.g., while the first material of the substrate is in a flowable state as discussed above. In some embodiments, as illustrated inFIGS.9ato9c, a plurality of the projections1702can be provided, each defining at least one aperture1703. With reference toFIG.10, the plurality of projections1702may be provided on relatively large electrodes, e.g. on current return electrodes17a, whereas the single (or fewer) projection1702may be provided on relatively small electrodes, e.g. on stimulation electrodes17b. As electrodes adjacent the outer edges of the substrate may be more susceptible to dislocation or popping out of the substrate, only outer electrodes17bmay be provided with the projections1702for the purpose of assisting anchoring of the electrodes17bto the substrate10.

The implantable devices of the present disclosure include a plurality of electrodes that can be used to electrically stimulate the eye. In some embodiments, electrical current may be applied to a plurality of the electrodes simultaneously. For example, two or more of the electrodes17, shown inFIG.1, for example, can be electrically grouped. Electrical current can be applied simultaneously to electrodes of the group. The electrodes of the group can be electrically addressed in parallel or can be ganged together. The simultaneous addressing of the electrodes17can provide an increased penetration of the electric field into tissue, leading to better efficacy. Moreover, reduced power consumption may be achieved as a result of lower impedances and lower charge required per electrode.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.