WO2011106781A1 - Apparatus for enhancement of aqueous humor drainage from the eye - Google Patents

Methods and apparatus for treatment of glaucoma. Excess eye pressure is relieved by producing a fistula between Schlemm's canal and the suprachoroidal space, allowing for drainage of aqueous humor. The device is formed of a handle with a hollow shaft. A deployable element (19) located in the shaft is used to create the fistula. The deployable element may be a wire, blade, loop or ablation element.

Apparatus for Enhancement of Aqueous Humor Drainage from the Eye

Cross-Reference to Other Applications

This application claims priority of US Provisional Application Serial Number 61/308,679, filed February 26, 2010 which is hereby incorporated by reference in its entirety.

Field of the Invention

The present invention relates to methods and instruments for performing ocular surgery. More specifically, treatment of glaucoma by creation of an opening between Schlemm's canal and the suprachoroidal space.

Background of Invention:

Glaucoma is a disease condition of the eye in which increased intraocular pressure (IOP) is created by blockage of the drainage mechanism for the aqueous fluid produced in the anterior portion of the eye. Such conditions are usually treated by topical drugs in the form of eye drops, but may result in surgical treatment if drug treatment becomes ineffective or if patient compliance is an issue. Traditional glaucoma surgery, known as a trabeculectomy, involves dissection of the eye and the forming of a fistula or hole, from the anterior chamber to the subconjunctival space. Trabeculectomy is associated with a high incidence of postoperative complications.

Recently developed surgical treatments for glaucoma have focused on the natural drainage system and are approached through intrascleral incisions with access to the main drainage passageway, Schlemm's canal. These procedures are known as "non-penetrating" procedures because they do not access or penetrate into the anterior chamber.

Viscocanalostomy, deep sclerectomy and canaloplasty are such procedures. Nonpenetrating procedures are associated with fewer complications than traditional surgical methods.

Schlemm's canal based non-penetrating surgeries allow drainage from the anterior chamber through the trabecular meshwork and a surgically created trabeculo-descemetic "window" which is an exposure of Descemet's membrane to the surgical site. In the cases of viscocanalostomy and canaloplasty, the aqueous humor is directed into Schlemm's canal and then exits the canal through the collector channels in the outer wall of the canal. In situations where there may be a reduction in drainage capacity from the collector channels and associated aqueous veins, it is desired to provide a pathway from Schlemm's canal to the suprachoroidal space. The suprachoroidal space is a potential space between the sclera, or outer shell of the eye and the choroid, the next innermost layer of the eye. The suprachoroidal space is associated with the secondary or alternate outflow path for aqueous humor. This uveoscleral outflow pathway has the capacity to drain significant amounts of aqueous humor from the eye. Although the uveoscleral pathway may only account for 10- 20% of aqueous outflow in the normal state, there is evidence that it can accommodate a significantly greater percentage of outflow.

This invention is directed to an apparatus to surgically effect the connection of Schlemm's canal to the suprachoroidal space in an eye.

Brief Description of the FIGURES:

Figure 1 is an illustration of the cross section of the human eye.

Figure 1 a is a detail section showing the anterior angle structures.

Figure 2, 2a and 2b show the apparatus with a semi flexible curve distal shaft, sliding actuation, offset deployment window, and wire loop active element.

Figure 3 and 3a illustrate the ophthalmic apparatus procedural orientation.

Figure 4, 4a and 4b illustrate the ophthalmic apparatus with plastic flexible shaft with distal curve, push button actuation, rotating wheel actuation, fiber optic feature(s) and viscoelastic injection feature.

Figure 5 illustrates the ophthalmic apparatus in Schlemm's canal and deploying an implant from the hole or fenestration at the distal end.

Description of Invention:

Figure 1 is an illustration of the cross section of the human eye, including the cornea 1 , sclera 2, choroid 3, retina 4, suprachoroida space 5, anterior angle 6, lens 7 and optic nerve 8. Figure 1 a is a detail section showing the anterior angle structures including Schlemm's canal 9, sclera 10, choroid 1 1 , ciliary body 12, suprachoroidal space 13, scleral spur 14, fistula 15 and cornea 16.

The present invention is a surgical apparatus to create an opening between Schlemm's canal 9 and the suprachoroidal space 5, 13 in the eye, for the treatment of open-angle glaucoma. The apparatus is designed to be placed into Schlemm's canal 9 and to be advanced within the canal to a target location. The apparatus is designed to fit within Schlemm's canal 9 and be appropriately curved so as to be able to advance easily within the canal. Once at the target location, a mechanism is activated which deploys an element to create an opening, or fistula, between the canal and suprachoroidal space. The fistula may be maintained by fluid pressure, or an implant device may be placed through the fistula to maintain the flow path.

As seen in Figure 2, 2a and 2b, the apparatus includes of a proximal handle 17 containing an deployment mechanism 20, a distal shaft 18 sized and shaped appropriately for access to and advancement within Schlemm's canal and a deployable element 19 disposed inside the handle 17 and shaft 18, which, when actuated, deploys from the shaft 18 and creates the opening between the canal and the suprachoroidal space.

In a cross-section through the eye, Schlemm's canal presents as a flattened, narrow channel disposed at approximately 45° to the ocular axis. The suprachoroidal space begins above the ciliary body 12 and is separated from Schlemm's canal by the scleral spur 14, 24, a region of circumferential scleral fibers which forms the posterior base of the canal. The invention is designed to create a fistula 15 through the region of the scleral spur 14, 24 and therefore effect the connection of Schlemm's canal 9 to the suprachoroidal space 5, 13 in an atraumatic manner. The deployable element 19 of the device exits the distal shaft 18 from an opening 22 disposed at a downward angle, toward the scleral spur 14, 24. As the distal shaft 18 is curved to accommodate the curvature of the canal, two versions of the apparatus may be created, a left-handed or clockwise and a right-handed or counter-clockwise version. In each version, the opening 22 in the distal shaft 18 is directed posteriorly towards the scleral spur 14, 24 to accommodate the anatomic morphology of the eye. The shaft 18 within Schlemm's canal is designed to have sufficient length to stabilize the device during creation of the fistula and assure proper orientation of the active mechanism 20 in relation to the scleral spur 14, 24. A length sufficient to be advanced between 60° and 120° from the entry point is preferred. When mechanical means are used to blunt dissect or cut the scleral spur, the device requires sufficient length to distribute any reactive force that may cause the device to penetrate through the trabecular meshwork into the anterior chamber. Typically a length of at least approximately 3 mm to 5 mm beyond the deployed element is preferred.

Figure 3 and 3a illustrate the ophthalmic apparatus procedural orientation, including the apparatus handle 17, a hollow shaft with a curvature or cannula 18, an active element 19such as a wire in the deployed position at a 45 degree offset, an actuation mechanism 20 such as a sliding element, the eye globe 23 and Schlemm's canal scleral spur 24. The fistula 15 between Schlemm's canal 9 and the suprachoroidal space 5, 13 may be created by dissection through the scleral spur 14, 24 or the ablation or removal of tissue to create an open tract. In a preferred embodiment, blunt dissection is used to create the fistula 15 so as to not create a wound in the tissue which can lead to bleeding and fibrotic scar formation. In an active device, energy, in the form of light or thermal energy, may be delivered by the deployable element 19 to destructively remove tissue. In another embodiment, a sharpened deployable element 26 may be employed to remove tissue by cutting or coring.

The deployable element 19 of the apparatus may be manually advanced (actuated) or advanced through either electromechanical, hydraulic or pneumatic means. The apparatus may be terminally sterilized in a suitable package, or may be sterilized prior to use. The apparatus may be a single use, disposable device, or may be re-usable upon cleaning and re-sterilization. The apparatus may incorporate means to illuminate the distal tip 30 for surgical guidance and to determine the location of the distal tip. The apparatus may further comprise the means to deliver an implant device to maintain the fistula 15.

The deployable element 19 resides within or along the body of the apparatus within

Schlemm's canal. The deployable element 19 may be configured to cut or blunt dissect through the scleral spur by orientation of the apparatus within Schlemm's canal such that the element is deployed in a manner as to be directed outward away from the trabecular meshwork and posterior toward the scleral spur. The deployable element may be attached to the actuating mechanism at one end of the apparatus. The deployable element may comprise an elongated member with a distal tip to perform cutting or blunt dissection. The deployable element may be rigid and formed in a curved geometry to reside within the apparatus. The deployable element may alternatively be flexible but with sufficient stiffness to cut or blunt dissect through the scleral spur. The deployable element must extend a sufficient distance from the shaft to dissect or cut through the scleral spur, a distance of at least 2 mm is preferred. Furthermore, a sufficient length of the deployable element acting on the scleral spur is also desired to provide an adequate flow path for aqueous humor.

Typically a length of 2.5 mm to 4mm is preferred.

An implant may also be placed in the fistula 15 created between Schlemm's canal and the suprachoroidal space to maintain the flow path. The implant may be formed of a conduit, tubular mesh or porous wick to allow aqueous humor to flow through the implant, or a solid member to allow aqueous humor to flow along the surface. The implant may comprise any biocompatible material suitable for implantation. The implant may be permanent or biodegradable to keep the flow path open during the critical acute healing period. Some examples of suitable implants include conduits made of nickel-titanium alloy, polyethylene, polysiloxane, polyglycolic or lactic acid, polyester, polyimide or a sponge formed of collagen, polyethylene, polytetrafluoroethylene or a filament of polypropylene, polyimide, or collagen.

Embodiments:

Figure 4, 4a and 4b illustrate the ophthalmic apparatus with plastic flexible shaft with distal curve, push button actuation, rotating wheel actuation, fiber optic feature(s) and viscoelastic injection feature for injecting a biocompatible viscoelastic material , such as sodium hyaluronate. Figures 4, 4a and 4b include the hollow flexible plastic shaft or cannula 25, the active element 26 (in this case a tubular blade) in the deployed position, a push button actuation mechanism 27, a rotating wheel actuation mechanism 28, vsicoelastic injection port 29, fiber optic beacon tip 30 and fiber optic filament coupler 31.

The embodiments of the device share common features which include a proximal handle portion 17 and a distal shaft portion 18 configured to fit within Schlemm's canal. The handle portion 17 contains a mechanism 20, 27, 28 to actuate a deployable element 19, 26 which resides within the device wherein the deployable element exits at a point along the distal shaft 18.

The handle portion 17 is sized to fit comfortably in an adult hand and may have a cross- sectional aspect that is round, square, rectangular or similar shape. The handle 17 may be solid or hollow and may be comprised of a metal such as stainless steel or titanium or a rigid polymer such as polycarbonate, polyetherimide or similar material.

In one embodiment, the deployment mechanism utilizes a linearly sliding component which is manually activated. The sliding component is formed of an element to allow finger pressure to advance and retract the deployable element, such as a thumb button or sliding ring disposed on the outside of the handle portion. The sliding component is connected at the device axis either directly or through an intermediary assembly to the deployable element. In another embodiment, the manual sliding element is spring loaded to return to its non-activated state.

The distal shaft 18 is configured to fit within and to be advanced along Schlemm's canal. In the preferred embodiment, the distal shaft is sized between 100 and 300 microns diameter and is curved with a radius of curvature between 6 and 14 mm, so as to conform to the dimensions and curvature of the canal. In one embodiment, the distal shaft 18 includes a secondary curvature proximal to the primary curvature in the range of 80 - 120 degrees to allow for easier placement of the distal tip into the surgical ostia of Schlemm's canal. The distal shaft 18 preferably incorporates a fenestration or opening 22 along the curve of the shaft, near to the distal tip. The fenestration 22 can be a hole or slot and is disposed at an angle from the plane of the curvature, the angle being in the range of 30 to 60 degrees. In the preferred embodiment, the angle of the fenestration is 45 degrees below the plane of the shaft curvature in order to direct the deployable element downwards toward the posterior end of Schlemm's canal and directed at the scleral spur.

The distal shaft 18 may be fabricated from metals such as stainless steel, titanium or preferably nickel-titanium alloy (Nitinol). The shaft may alternatively be fabricated from a rigid polymer such as polyimide, polycarbonate, nylon or similar material. In one embodiment, the distal shaft also incorporates a fiber optic which transmits light to the distal tip to provide transcleral illumination of the distal tip in Schlemm's canal to provide surgical guidance of the tip location.

The deployable element 19, 26 is comprised of a rigid or semi-rigid linear structure such as a wire or ribbon. In the preferred embodiment, the deployable element 19 is a wire with a diameter of 50 - 250 microns. The wire element is attached at its proximal end to the deployment mechanism and attached at its distal end to the distal end of the shaft portion. Upon activation of the deployment mechanism 20, 27, 28 in the handle portion 17, the proximal end of the deployable element 19 is advanced and due to the fixation at the distal tip, a loop of the element 19 is translated out of the shaft fenestration 22. In another embodiment, the deployable element 26 is attached to the deployment mechanism 27, 28 only at the proximal end, such that upon activation of the mechanism, the distal end of the deployable element 26 is advanced out of the shaft fenestration to penetrate the tissues.

The deployable element 19, 26 may comprise a metal such as stainless steel, titanium, nickel-titanium alloy (Nitinol), or a high modulus polymer such as nylon, polyimide, poly paraphenylene terephthalamide, or a ceramic such as alumina, silicon carbide, fused silica or a combination of materials.

Figure 5 illustrates the ophthalmic apparatus 32 placed into and partially around Schlemm's canal 33 of an eye, deploying an implant 34 device from the hole or fenestration at the distal end of the apparatus 35. Said implant forms a connection between Schlemm's canal and the suprachoroidal space 36. Examples:

Example 1

An experiment was performed to evaluate one embodiment of the invention for its ability to successfully cannulate and advance into Schlemm's canal in a human cadaver eye. The device was comprised of a handle portion containing a linear actuating mechanism that deployed a straight, 100 micron diameter nitinol wire out of a side window, 2.0 to 3.0 mm length x 100 - 120 microns wide, 40° - 45° below horizontal axis along the outside of cannula radius positioned along a distal semi-flexible micro-cannula fabricated from superelastic Nitinol with an outer diameter of 250 microns, a radius of curvature of 6 mm and a length of 3 cm. The micro-cannula was placed through an access incision into Schlemm's Canal and advanced 4 to 5 clock hours around the canal. Upon positioning the micro-cannula, ultrasound imaging confirmed the cannula location and the straight tip wire was deployed via actuator control. The straight tip wire was then retracted and the device removed from Schlemm's Canal. The eye was then dissected and the scleral tissue examined to confirm dissection of the scleral spur adjacent to Schlemm's Canal leaving the trabecular meshwork intact.

Example 2

A second embodiment of the device was tested in the same manner as Example 1 above. The device comprised a handle with linearly sliding actuator, and semi-flexible "J" shaped cannula of 250 microns outer diameter by 3 cm in length. The j-tip Nitinol cannula contained a window of 4 mm length and 125 micron width at the outside apex of the curvature that was slightly offset from the horizontal plane by approximately 45°. The actuator was attached to a Nitinol wire of 100 microns diameter, the wire was also welded to the distal end of the cannula portion. Forward movement of the sliding actuator caused a loop of the Nitinol wire to protrude a distance of 3 mm out of the window in the cannula. The experiment was monitored in real time with ultrasound imaging. The wire loop deployment and scleral dissection through the scleral spur was observed and confirmed using ultrasound imaging.

Example 3

An experiment in human cadaver eyes was performed using a device as described in Example 2 above. An incision was made into sclera tissue exposing Schlemm's Canal. The device micro-cannula was inserted and advanced around the canal to approximately 3 clock hours from the incision site. The instrument was inserted into the canal such that the distal window was facing the posterior portion of the canal and the scleral spur, due to its location at 45° off axis. The actuator was engaged, forcing the wire loop out of the window. The wire loop dissected the scleral spur and opened up a fistula, forming a flow path into the suprachoroidal space. The wire loop was retracted and the instrument removed from Schlemm's Canal. An ultrasound imaging system was used to confirm placement of the instrument and to record the procedure. The eyes were then dissected and creation of a fistula between Schlemm's canal and the suprachoroidal space, through the scleral spur was confirmed and photographed.

Many features have been listed with particular configurations, options, and embodiments. Any one or more of the features described may be added to or combined with any of the other embodiments or other standard devices to create alternate combinations and embodiments.

The preferred embodiments described herein are illustrative only, and although the examples given include many specifics, they are illustrative of only a few possible embodiments of the invention. Other embodiments and modifications will no doubt occur to those skilled in the art. The examples given should only be interpreted as illustrations of some of the preferred embodiments of the invention.

Claims:

1. An apparatus adapted for use in an eye to relieve excess eye pressure by producing a fistula between Schlemm's canal and a suprachoroidal space to drain aqueous humor, the apparatus comprising:

a proximal handle,

a distal hollow shaft extending from said proximal handle,

and a deployable element in a distal section of said hollow shaft.

2. The apparatus of claim 1 , wherein said proximal handle contains a mechanism to affect deployment of said deployable element.

3. The apparatus of claim 2, wherein said mechanism includes an axially moveable element.

4. The apparatus of claim 3, wherein said moveable element utilizes a sliding mechanism.

5. The apparatus of claim 4, wherein said sliding mechanism is activated by a mechanism selected from the group consisting of a sliding element, a rotating wheel and a push button.

6. The apparatus of claims 5, wherein said sliding mechanism is actuated by in a manner selected from the group consisting of manual actuation, electromechanical actuation and pneumatic actuation.

7. The apparatus of claim 1 , wherein said handle is formed of a material selected from the group of material consisting of stainless steel, titanium and nickel-titanium, polyetherimide, acrylonitrile butadiene styrene, high density polyethylene and polyamide.

8. The apparatus of claim 1 , wherein said handle is formed of a material capable of withstanding multiple sterilizations.

9. The apparatus of claim 1 , wherein said distal shaft is sized to fit into Schlemm's canal in the eye.

10. The apparatus of claim 9, wherein said shaft is sized between 50 and 500 microns in diameter.

11. The apparatus of claim 2, wherein said distal shaft is flexible and has a curved tip to fit into Schlemm's canal in the eye.

12. The apparatus of claim 1 1 , wherein said shaft is curved in a radius between 8 and 16 mm.

13. The apparatus of claim 12, wherein said shaft curvature is between 60 and 120 degrees.

14. The apparatus of claim 1 , wherein said distal shaft has a compound curvature.

15. The apparatus of claim 14, wherein said compound curvature includes a first curve in the range of 60 to 120 degrees and a radius of 5 and 12 mm, and a second curvature to fit into Schlemm's canal with curvature between 60 and 120 degrees and a radius between 8 and 12 mm.

16. The apparatus of claim 1 , wherein said distal shaft is shaped and configured for insertion into Schlemm's canal in a direction selected from the group consisting of a clockwise or counter-clockwise.

17. The apparatus of claim 1 , wherein said distal shaft has a closed distal tip.

18. The apparatus of claim 1 , wherein said distal shaft has an opening located close to a distal tip.

19. The apparatus of claim 18, wherein said opening is disposed between 30 and 60 degrees away from a plane of curvature of said shaft.

20. The apparatus of claim 18, wherein said opening is sized to allow said deployable element to exit said shaft.

21. The apparatus of claim 1 , wherein said distal shaft is formed of a material selected from the group of materials consisting of stainless steel, titanium, tungsten, nickel-titanium alloy, polyimide, polyamide, fluoropolymer and polyamide block-copolymer.

22. The apparatus of claim 1 , wherein said distal shaft incorporates a fiber optic element to provide for an illuminated beacon at a distal tip for surgical guidance.

23. The apparatus of claim 1 , wherein said distal shaft incorporates a lubricious coating.

24. The apparatus of claim 1 , wherein said deployable element comprises a wire.

25. The apparatus of claim 24, wherein said wire has a proximal end and a distal end and is permanently attached at said proximal end to a mechanical activating element in said handle and attached at said distal end to a distal end of said shaft, such that actuation of said mechanical activating element results in a loop of said wire exiting an opening in said distal shaft.

26. The apparatus of claim 24, wherein said wire is a metal selected from the group consisting of nickel-titanium alloy, stainless steel and tungsten.

27. The apparatus of claim 1 , wherein said deployable element comprises a hollow element with a distal edge sharpened and suitable for tissue cutting.

28. The apparatus of claim 1 , wherein said deployable element comprises a blade.

29. The apparatus of claim 1 , further comprising means for delivering viscoelastic to maintain a flow path between Schlemm's canal and the suprachoroidal space.

30. The apparatus of claim 1 , further comprising means for delivering an implant to maintain a flow path between Schlemm's canal and the suprachoroidal space.

31. The apparatus of claim 30, wherein said implant is formed of one selected from the group consisting of a filament, a tube and a wicking element.

32. The apparatus of claim 1 , wherein energy is directed from said distal shaft to a scleral spur to form a flow path from Schlemm's canal to the suprachoroidal space.

33. A method of relieving excess eye pressure by draining aqueous humor, the method comprising the steps of:

a) entering Schlemm's canal with a shaft;

b) and actuating an element of the device to create a fistula between Schlemm's canal and a suprachoroidal space.

34. The method of claim 33, further comprising the step of deploying an implant into the fistula.

35. The method of claim 33, wherein said fistula is created by a wire.

36. The method of claim 33, wherein said fistula is created by cutting blade.

37. A method of relieving excess eye pressure by draining aqueous humor, the method comprising the steps of:

a) creating an incision into sclera tissue thereby exposing Schlemm's canal;

b) entering Schlemm's canal with a shaft;

c) advancing the shaft around at least a portion of Schlemm's canal;

d) and actuating an element of the device to create a fistula between Schlemm's canal and a suprachoroidal space;

e) retracting the element;

f) deploying an implant into the fistula;

g) and withdrawing the shaft.