Improved method and apparatus for treating glaucoma and other ophthalmic conditions

Abstract

Disclosed herein are methods and apparatus for treating glaucoma and other ophthalmic conditions. A microcatheter apparatus for use in ophthalmic surgery is disclosed, comprising a handpiece and an end configured to cannulate Schlemm's canal within the eye. The apparatus comprises a fluid flow path configured to deliver a viscoelastic fluid into desired areas of the eye during or after cannulation. The apparatus may comprise a pump to provide the viscoelastic fluid into the apparatus. Cascading microcatheter sections having a decreasing cross-sectional area, internal baffles, transducers, interwoven cable-like members, and / or internal helixes are provided along the flow path of the viscoelastic fluid so as to induce turbulence into the viscoelastic fluid. These means of inducing turbulence thereby induce shear thinning in the viscoelastic fluid as it travels through the flow path, decreasing the viscosity of the viscoelastic fluid as it travels through the flow path.

Description

IMPROVED METHOD AND APPARATUS FOR TREATING GLAUCOMA AND OTHER OPHTHALMIC CONDITIONSFIELD OF THE INVENTION

[0001] The present invention relates to a method and apparatus that uses a microcatheter device and viscoelastic fluid known as ophthalmic viscosurgical devices (OVDs), for the treatment of glaucoma, a disease commonly suffered by humans with a hereditary disposition to glaucoma as they age. The condition is usually characterised by the elevation of intra-ocular pressure (IOP) through impaired drainage of intraocular fluid that is continuously produced within the eye and outflow restriction results in over inflation and pressure build up resulting in optical nerve damage and the consequence being progressive vision loss leading to blindness.

[0002] This invention addresses the treatment of the conventional outflow pathway with OVD, a fluid that changes its properties under pressure (a nonNewtonian fluid). It is extensively used in ophthalmic surgery for its unique mechanical properties. These are well described in engineering literature. The many types of OVD’s are formulated to deliver different characteristics for specific surgical outcomes.BACKGROUND TO THE INVENTION

[0003] About two percent of the adult population in the United States suffer from glaucoma, a group of eye diseases that causes pathological changes in the optic disk and corresponding visual field loss resulting in blindness if untreated. Raised intraocular pressure elevation is a common factor in most glaucoma however some patients develop symptoms at normal pressures. Nevertheless, treatment endeavours to improve the outflow of aqueous humour from the patient’s conventional trabecular outflow pathway with a variety of interventions.

[0004] An eye comprises many components, the three key being the lens, retina and transparent vitreous humour fluid between them that provides structure to aneye. Further components at the front of the eye include a cornea acting as an external fixed lens, an iris and pupil for regulating the light striking the retina and an adjustable internal lens that facilitates focus. Between the cornea and the lens, a transparent fluid fills the void. This fluid is called the aqueous humour (AH). The AH serves to nourish the eye with vital nutrients and to keep the eye inflated to maintain its shape. The eye is not in a sealed system and the AH is constantly secreted to make space for fresh AH. Drainage is needed and is achieved primarily through the conventional trabecular outflow pathway. The AH flows into a filter-like tissue known as the trabecular meshwork (TM), then to a tubular structure known as Schlemm’s Canal (SC), discharging through collector channels (CC) and aqueous veins into the vascular system of the body. Obstruction of drainage can either occur through flow resistance within the TM, collapse of the SC or blockages in the CC’s and aqueous veins. A secondary pathway known as the uveo-scleral pathway, facilitates the direct absorption of the AH through other ocular structures.

[0005] The primary cause of outflow resistance is often within the TM, the SC and CC. The eye's pressure is determined by a balance between the rate of production of AH and its exit rate through to the episcleral veins providing the final pathway for return of aqueous to the general circulation (the conventional pathway) or via uveoscleral outflow (minor route). The TM is located between the outer rim of the iris and the internal periphery of the cornea.

[0006] The healthy outflow pathway is an active system that senses pressure changes to regulate AH outflow.

[0007] Patients with glaucoma disease exhibit a TM that is clogged with cellular debris and collapsed or stenosed SC and CC interfering with outflow resulting in diminished outflow resulting in increased pressure.

[0008] Glaucoma is generally classified into two categories: closed-angle glaucoma and open-angle glaucoma. The closed-angle glaucoma is caused by closure of the anterior angle by contact between the iris and the inner surface of the TM. Closure of this anatomical angle prevents normal drainage of AH from the anterior chamber of the eye. Open-angle glaucoma is any glaucoma in which the angle of the anterior chamber remains open, but the exit of aqueous through the TMis diminished.

[0009] Current therapies for glaucoma are usually directed at decreasing intraocular pressure. This is traditionally treated with topically administered eye drops including beta-blockers, prostaglandin analogues and angiotensin-converting enzyme (ACE) inhibitors some of which reduce the production of aqueous humour, others change the frequency of the heart rate or increase the outflow of AH.However, drug therapies for glaucoma are frequently associated with significant side effects, such as headache, blurred vision, allergic reactions, irritated and inflamed eyes, atrophy of the components of the conventional outflow system and adverse interactions with other drugs. Patient compliance is a major hurdle for management with less than 50% of patients maintaining consistent self-administration. When drug therapy fails, a range of surgical solutions are used. Surgical treatment for openangle glaucoma consists of laser trabeculoplasty, trabeculotomy, shunting implants or trabeculectomy.

[0010] Trabeculectomy is a surgical procedure used in the treatment of glaucoma to relieve intraocular pressure by creating a pathway for AH from the anterior chamber to the sub-conjunctival space. It is the most common glaucoma surgery performed and creates a bypass route for the aqueous humour to drain from within the eye to the conjunctiva where it is absorbed. Trabeculectomy is associated with a high incidence of failure after a few years due to scar tissue formation.

[0011] Glaucoma drainage devices are frequently used for the treatment of glaucoma as an alternative to trabeculectomy. These devices typically are composed of a tube that shunts aqueous humour from the anterior chamber of the eye to the conjunctiva. Both trabeculectomy and drainage device implantation requires dissection of the external sclera and conjunctiva of the eye.

[0012] All the currently known and performed embodiments and variations of glaucoma surgery have numerous disadvantages. Most devices have a limited service-life as they are prone to failure due to fibrotic activity and wound healing processes and scarring at the site of surgery and surrounding the implanted device.

[0013] The wound healing and scarring process associated with glaucomasurgery involving the conjunctiva and sclera also limits the ability to perform subsequent glaucoma surgery at the same location. Therefore, there is a great clinical need for the treatment of glaucoma by a method that would be minimally invasive, faster, safer and less expensive than currently available modalities.

[0014] A more recently developed, keyhole like, minimally invasive technique termed ab-interno canaloplasty does not require a conjunctival or scleral dissection and clears the canal and TM, or downstream structures such as feeder vessels by injection of fluid into the canal via a self-closing clear corneal incision, hence minimising trauma and speeding recovery time. This procedure also spares tissues, allowing for more surgical options later if needed.

[0015] MIGS (Minimally Invasive Glaucoma Surgery) Canaloplasty was initially developed as a minimally invasive glaucoma surgical procedure to exploit the benefit of infusing a viscous OVD to dilate Schlemm’s Canal (SC) to enhance aqueous humour outflow thus reducing intraocular pressure caused by collapsed canals.

[0016] OVD can be directly injected to dilate the SC that has collapsed due to Glaucoma disease, via a rigid canula in a surgical procedure termed viscocanalostomy This approach has a limited efficacy as it can only achieve a localised dilation of SC in the immediate vicinity of the injection.

[0017] Canaloplasty is described in US Patent no. 10,918,521 and comprises inserting into SC, a flexible and hollow micro catheter containing an integral fluid communication channel and optical communication channel, preferably an optical fibre, permitting the transmission of light as well as the advancement of the fluid or fluids through the microcatheter. Insertion of the microcatheter and its subsequent placement into the canal may be by means of a separate instrument, such as ocular micro-forceps, requires the surgeon to grip and advance, release, regrip and advance in a hand over hand fashion requiring great skill, training and agility. This method of propulsion can take significant time and varies materially depending on surgical skill.

[0018] Delivery of OVD through a microcatheter permits the delivery of aliquots of OVD along the total length of SC permitting complete SC dilation. This surgicaltreatment is effective in dilating the SC and shows some pressure reducing effect but does not achieve comprehensive treatment of the CC if the viscosity of the OVD is too high to efficiently penetrate the CC.

[0019] SC in a diseased eye can be quite asymmetric in cross section measuring in a meridional diameter from 20 to 500 microns in two orthogonal axes. The canal has a length of between 30 to about 40 mm due to variations in human anatomy, the size of the eye, or from disease. For cannulating SC, a microcatheter is used having a diameter of 100 to 500 microns with 250 microns preferred and an active length of at least 30 mm with 50 mm preferred. To minimise trauma to surrounding tissue and facilitate advancement of the microcatheter in the SC, the distal tip may be spherically shaped, and the device may have a lubricious coating on at least the most distal 50 mm from tip.

[0020] With the invention of a microcatheter applicator in the form of an ergonomic handpiece containing a canula and catheter propulsion mechanism, the microcatheter may be advanced along the SC efficiently. This product is named iTrack Advance and described in US Patent 20230119521 A1. The surgical treatment of the intubation of the full length of SC followed by the injection of OVD to dilate the SC. Surgery iTrack Advance can be accomplished in a timely and repeatable manner requiring less surgical skill and achieving timing consistency.

[0021] During the procedure, for navigation safety, it is important for a surgeon to know the location of the catheter tip and preferably to know the immediate environment around the tip. To help identify the distal tip location, light is directed down an optical fibre inside the microcatheter to illuminate the spherical tip and to project light into the up-stream volume of SC. This illumination and resultant scattering glow from the tip allow the tip location to be visualized through the TM, the walls of SC as well as through the sclera and conjunctiva.

[0022] The Composite Ophthalmic Microcatheter as described in US Patent No.7,207,980 consists of a flexible and hollow tube containing an integral fluid communication channel and optical fibre, permitting the transmission of light as well as the advancement of the fluid or fluids through the microcatheter.

[0023] The preferred fluid for injection into the canal to clear the outflow system of the eye is a viscoelastic fluid commonly described as an Ophthalmic Viscosurgical Device (OVD) that exhibits non-linear mechanical properties, well described in engineering literature. OVD an non-Newtonian fluid changes its properties under pressure. At rest OVD has a gel-like consistency but when subjected to pressure and shear thinning, it reduces in viscosity permitting injection through a narrow cannula. On removal of pressure post injection, the OVD recoils to the original gel-like state exhibiting a repeatable recoil relaxation time constant.

[0024] Differing OVD’s can be engineered to exhibit a specific recoil relaxation time constant.

[0025] The preferred OVD type for expanding the SC is a cohesive type of OVD. Commercially available OVD’s include Healon (J&J), Healon GV (J&J) and ProVisc (Alcon).

[0026] Healon exhibits a typical recoil relaxation time of about 20 seconds and Healon GV exhibits a recoil relaxation time of about 80 seconds.

[0027] The OVD may be delivered by an infusion pump or Injector for Viscous Materials as described in US Patent No 7,967,772. Differing types of OVD’s are formulated to deliver a range of characteristics for specific surgical outcomes such as protecting corneal endothelium from mechanical damage during a cataract surgery.

[0028] A Surgical Handpiece with Rotatable Head US Patent Application 17 / 506,579, whose contents are herein incorporated in full by reference herein, describes an enhanced method of guiding a microcatheter into the eye through a rotatable canula that facilitates surgeon adjustable configuration to suit the ergonomic requirements of a left-handed or a right handed surgeon operating on either left eye or right eye.

[0029] The present application relates to improvements in a canaloplasty method and microcatheter delivery device to fully exploit the properties of high viscosity OVDs to improve the effectiveness and persistence of the canaloplasty procedure to fully dilate the SC as well as clear and flush the total conventional outflow pathway,inclusive of the TM and CC of cellular debris, or downstream structures such as feeder vessels.

[0030] Derivatives of this device have direct utility for treating other structures in the eye including the drug delivery to other segments in the eye including the retina.SUMMARY OF THE INVENTION

[0031] In a first aspect of the invention, there is provided an apparatus for delivering a viscoelastic fluid to a target location, the apparatus comprising:a handpiece body having a microcatheter with an output configured to deliver a viscoelastic fluid to a target location;wherein the viscoelastic fluid is configured to flow along a flow path through the microcatheter; andwherein at least a portion of the flow path is configured to induce shear thinning of the viscoelastic fluid, such that the viscosity of the viscoelastic fluid is decreased.

[0032] In a preferred embodiment, a cross-sectional area of the microcatheter changes along the flow path of the viscoelastic fluid.

[0033] In a preferred embodiment, the microcatheter comprises a plurality of cascading sections such that the cross-sectional area of the microcatheter changes along the flow path of the viscoelastic fluid.

[0034] In a preferred embodiment, the cross-sectional area of the microcatheter decreases along the flow path of the viscoelastic fluid.

[0035] In a preferred embodiment, the apparatus comprises one or more baffles along the flow path of the viscoelastic fluid, the one or more baffles configured to induce turbulence in the viscoelastic fluid, thereby causing shear thinning and a decrease in viscosity of the viscoelastic fluid.

[0036] In a preferred embodiment, the apparatus comprises a first member and a second member extending through a length of the flow path.

[0037] In a preferred embodiment, the first member and the second member are wires, filaments, fibres, strands, or cables.

[0038] In a preferred embodiment, the first member is wrapped around the second member to induce shear thinning of the viscoelastic fluid.

[0039] In a preferred embodiment, either member has a cross-section to induce turbulence.

[0040] In a preferred embodiment, the cross-section of either member is cylindrical, square, hexagonal, woven, pleated, or spiralled.

[0041] In a preferred embodiment, the first member is an optical fibre configured to illuminate any or all portions of the microcatheter.

[0042] In a preferred embodiment, the flow path comprises a helical structure configured to induce shear thinning in the viscoelastic fluid.

[0043] In a preferred embodiment, the helical structure is rotatable.

[0044] In a preferred embodiment, the helical structure is a helical screw.

[0045] In a preferred embodiment, a diameter of the microcatheter is 250 microns or less.

[0046] In a preferred embodiment, an interior of the handpiece body comprises a plurality of transducers configured to vibrate the handpiece body, thereby inducing turbulence in the viscoelastic fluid.

[0047] In a preferred embodiment, a surface of the flow path comprises a rough inner surface configured to induce shear thinning in the viscoelastic fluid.

[0048] In a preferred embodiment, an input tube is configured to deliver a viscoelastic fluid into the handpiece body or directly into the microcatheter.

[0049] In a preferred embodiment, a pump is connected to the input tube to pump the viscoelastic fluid into the handpiece body or directly into the microcatheter.

[0050] In a preferred embodiment, the pump is configured to deliver theviscoelastic fluid at selectable frequencies.

[0051] In a preferred embodiment, the pump is configured to periodically pulsate when delivering the viscoelastic fluid.

[0052] In a preferred embodiment, the apparatus is configured to deliver about 100 microlitres of viscoelastic fluid within about 60 seconds.

[0053] In a preferred embodiment, the cross-sectional area of the microcatheter is substantially circular.

[0054] In a second aspect of the invention, there is provided a method of delivering a viscoelastic through the apparatus of a preferred embodiment of the invention, the method comprising:making an incision into an eye;cannulating Schlemm’s canal;delivering a viscoelastic fluid to dilate an eye structure from the group consisting of Schlemm’s canal, the trabecular meshwork, or feeder vessels;removing the microcatheter from the eye;wherein a viscosity of the viscoelastic fluid increases over time after being delivered into the eye; andwherein the increase in viscosity releases a force to surrounding structures, from a stored elastic potential energy of the viscoelastic fluid, thereby scrubbing cellular debris from the surrounding structures.BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a numberof drawings as follows.

[0056] Figure 1 demonstrates the non-linear properties of OVD with the significant reduction in viscosity with increased shear rate;

[0057] Figure 2 is a cross-sectional view of a section of the device embodying the invention;

[0058] Figure 3 is a cross-sectional view of the microcatheter used in the device of Figure 2;

[0059] Figure 4 is a schematic diagram of a passive turbulent helix to be used in the device; and

[0060] Figure 5 is a schematic diagram of an active turbulent helix to be used in the device.LIST OF COMPONENTS

[0061] The drawings include the following integers.1 handpiece body2 internal barrel3 input tube4 member5 chamber6 baffles7 member8 microcatheter9 ultrasonic transducer10 ultrasonic transducer11 tube12 tube13 distal shaft14 optical fibre15 nitinol Wire16 roughened internal tube surface finish17 distal tip18 helical screwDETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0062] Figure 1 demonstrates the non-linear properties of OVD. From the transfer curve it can be seen that more significant reduction in viscosity can be achieved with increased shear rate so that the OVD will penetrate deeper past the SC to reach the total outflow structure of the eye.

[0063] It is to be appreciated that ophthalmic viscosurgical devices (OVDs) are alternatively referred to as viscoelastic substances, viscoelastics, or viscoelastic fluids, and refer to fluid-like substances that exhibits well-known non-linear mechanical properties. OVDs are non-Newtonian fluids, and its properties change under pressure. At rest OVDs have a gel-like consistency but when subjected to pressure and shear thinning, it reduces in viscosity permitting injection through a narrow cannula. On removal of pressure post injection, the OVD recoils to the original gel-like state exhibiting a repeatable recoil relaxation time constant.

[0064] As illustrated in Figure 2, there is illustrated an apparatus having a handpiece body 1 including an internal barrel 2. An input tube 3 allows for viscous fluid to be injected into the barrel of the handpiece body. In embodiments, the input tube allows for viscous fluid to be directly injected into the microcatheter. The OVD flows out of the infusion pump device via a high pressure coupling into the input tube 3. A member 4 also passes through the body 1. The barrel includes a chamber 5 including baffles 6 that extend into the chamber and causes turbulence in the fluid. The baffles can be of any appropriate shape and number. In an embodiment, the member 4 may be an optical fibre configured to illuminate a portion or all of the apparatus, including its handpiece and / or microcatheter.

[0065] A second member 7, preferably formed from nitinol, also extends from the barrel out of the body and can wrap around the optical fibre also providing for a shape that ensures the turbidity of the fluid. It is to be appreciated that the first and / or second member may be wires, or alternative referred to as filaments, fibres, strands, or cables. Both the optical fibre 4 and the nitinol wire extends through microcatheter 8 extending out of the body 1. Microcatheter 8 also extends into and through thehandpiece body, and forms part of the flow path of the viscoelastic fluid through the apparatus.

[0066] The cross-section of the first and second members may be a typical shape such as circular or elliptical. However, in embodiments the cross-section may be alternate shapes so as to further induce turbulence in the viscoelastic fluid as it travels through the microcatheter, such as for example cylindrical, square, hexagonal, woven, pleated, or spiralled. The first and second members may also be tapered, thereby further inducing turbulence in the viscoelastic fluid.

[0067] Transducers 9 and 10 can also cause turbulence in the fluid. The transducers introduce lateral vibrations to the delivery pathway at discrete points to further optimise the shear-thinning process. Thus, the baffles, the optical fibre and wire combination as well as the transducers all help to maximise the shear thinning forces prior to the OVD entering the delivery microcatheter.

[0068] Figure 3 is an alternate embodiment of the microcatheters including cascading tubes 11, 12 and 13. Optical fibre is illustrated as 14 and the wire as 15. Tube 11 may include a rough inner surface 16 that also aids in hampering laminar flow. The microcatheter ends in a distal tip 17. The tubes that the fluid traverses on its path to the distal tip utilise the shear thinning measures described earlier to maximise the shear thinning forces on the OVD during this final journey to the delivery tip of the microcatheter. The cascading tubes are of decreasing cross-sectional area, or diameter, with each junction designed as a shear thinning ports and the joints with structured pipe ends enhance turbulent fluid flow all designed to incrementally decrease the viscosity of the OVD at each interface element. In some embodiments, microcatheter may be asymmetric in its cross-sectional shape. In other embodiments, the microcatheter may comprise a more common cross-sectional shape, such as circular or elliptical.

[0069] A further way of increasing or maintaining turbulence of the fluid is illustrated in Figures 4 and 5 where an internal helix 18 causes the fluid to swirl. Figure 4 illustrates where the internal helix is passive, that is, does not rotate, whereas in Figure 5 the internal helix is active and can be driven to rotate by external means. The internal helix can be placed anywhere in the apparatus including insidethe microcatheter.

[0070] With sufficient shear thinning of the OVD achieved by a range of features and turbulence elements described, matched to the relaxation time constant of the specific OVD, comprehensive penetration of the outflow system can be achieved. Maintaining the OVD in a sufficiently low viscous state until final delivery to the target ocular structure is a key objective. This must be achieved within the optimal delivery time of the OVD, typically of the order of 60 seconds.

[0071] To satisfy the delivery time constraint required by this intervention, the microcatheter must utilise the capabilities available with the iTrack Advance handpiece (Fig 3). The iTrack system can deliver around 100 microlitres of OVD within the optimal time. In this embodiment, this period is chosen to deliver a comprehensive flush of both the canal and the outflow system as the molecules transform back to their original viscous state.

[0072] To further facilitate timely delivery the control mechanism should be under surgeon control enabling control of dosimetry and delivery characteristics from within the sterile area as appropriate.

[0073] With the advent of synthetically produced rather than fermented OVD’s there is an opportunity to engineer a broader range of OVD characteristics to optimise both the shear thinning properties as well as the relaxation time constant to achieve the optimal performance to directly expand the SC as well as penetrating the CC and the channels to the TM, and downstream structures such as the feeder vessels. The ability to provide the required timely delivery of OVD in a low viscosity state, means only the iTrack Advance system can achieve the necessary penetration into all the channels not just the core of the SC.

[0074] Once delivered, the OVD begins its relaxation stage during which long chain molecules, that have been linearised via shear thinning, start to bunch up into clumps, much like a ball of string. As this occurs the OVD becomes more viscous and as each molecule changes shape the coalescence of molecules expand and apply force to the walls of the SC, CC and TM anatomy that they flow through, stretching, expanding the structures and scrubbing cellular debris from the walls. It isto be appreciated that this force applied by the OVD to surrounding structures is derived from a stored potential energy of the OVD during its more viscous state.

[0075] A specific type of OVD for expanding the structures can be a cross-linked type that provides a three-dimensional scaffold within the hollow structure and with sufficient porosity not to impede aqueous drainage. The cross-linking bonds should be sufficiently spaced to bind the linear chains but not too dense to prevent the flow of aqueous through the scaffold.

[0076] Some specific OVD molecules can bind to molecular receptors found in human tissue with affinity for the OVD molecules, typically CD-44 receptors typically found inside the SC. Such binding is useful to provide persistence of effect.

[0077] Removal of cellular debris can be additionally assisted by the introduction of intermittent pulses of turbulent flow by adding a frequency component to OVD flow to enable a secondary hydrostatic pressure cleaning effect on these structures. The use of a variable frequency pumping device will enable matching of this frequency to the features of individuals eyes or the optimal frequency for the debris to fragment. The pump and its remote control can be under surgeon control with appropriate ergonomic remote controls of all parameters. The removal of cellular debris could also be assisted by applying ultrasonic vibrations to the distal tip through a transducer to the guide wire included therein. (10)

[0078] This combination of factors means that the effect of canaloplasty utilising this device is optimised to act far beyond dilation of the SC by expanding and scrubbing the whole outflow channel to provide maximum benefit from the treatment. This surgical approach importantly preserves and supports the normal anatomy of the eye and unlike other more radical surgical interventions does not undermine the healthy, natural pulsatile action of the outflow pathway and is not susceptible to fibrotic activity or scarring.

[0079] The reader should now understand that present application relates to transforming the viscosity of the OVD in a timely manner. This is achieved through a novel system of flow management measures which may include some or all of:

[0080] A series of cascading tubes of decreasing diameter to amplify the shearrate.

[0081] A chicane of baffles that introduces turbulent flow into the fluid column.

[0082] A plaited wire core inside the delivery tube to increase the OVD turbulence.

[0083] A means of vibrating the delivery tube with a transducer to further increase turbulence.

[0084] An infusion pump that can, by manual or automatic means apply bursts of pressure at a predetermined rate to induce high shear into the OVD.

[0085] Use of constricting stepped catheter stages to optimise shear thinning of OVD.

[0086] Use of internally roughened tubes for transporting the OVD.

[0087] Inclusion of a labyrinth in the delivery system.

[0088] Use of specially patterned pipe ends to make convoluted joints within the delivery system.

[0089] Applying pressure to the OVD as a series of pulses from the pump device.

[0090] Use of a turbulence generating element that adds lateral vibration to the delivery pipework.

[0091] Use of a transducer to impart ultrasonic vibration to distal tip.

[0092] Use of helix formed with the guide wire and fibre optic to optimise shear thinning.

[0093] Use of extremely small aperture distal shaft bore diameter 200-micron or less (in combination with Helix) to maintain pressure post priming and pre delivery.

[0094] Use of iT rack Advance delivery system to synchronise delivery of the OVD within the relaxation time of the OVD.

[0095] Use of electronically controlled pump to deliver OVD bolus at a selectable frequency.

[0096] A means of monitoring and regulating dosimetry and frequency of each delivered dose.

[0097] Remote control of pumping system by a surgeon with foot pedal or similar.

[0098] In preference, the OVD used is a highly viscous OVD comprising hyaluronic acid. It is to be appreciated that hyaluronic acid is commonly used as an OVD in ophthalmic surgery, particularly in procedures for treating glaucoma. Given its relatively high viscosity due to its high molecular weight, allowing it for example amongst other advantages to maintain volume in the anterior chamber and protect surrounding tissue from damage.

[0099] Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus. Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in this field.

[0100] In this specification, unless the context clearly indicates otherwise, the word "comprising" is not intended to have the exclusive meaning of the word such as "consisting only of", but rather has the non-exclusive meaning, in the sense of "including at least". The same applies, with corresponding grammatical changes, to other forms of the word such as "comprise", etc.

[0101] Other definitions for selected terms used herein may be found within the detailed description of the invention and apply throughout. Unless otherwise defined, all other scientific and technical terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the invention belongs.

[0102] Any promises made in the present document should be understood to relate to some embodiments of the invention and are not intended to be promises made about the invention in all embodiments. Where there are promises that are deemed to apply to all embodiments of the invention, the applicant / patentee reserves the right to later delete them from the description and they do not rely on these promises for the acceptance or subsequent grant of a patent in any country.

[0103] Although specific embodiments of the invention are illustrated and described herein, it will be appreciated by persons of ordinary skill in the art that a variety of alternative and / or equivalent implementations exist. It should be appreciated that each exemplary embodiment is an example only and is not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents. Generally, this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

[0104] It will also be appreciated that, unless the context requires otherwise, the terms "comprise", "comprising", "include", "including", "contain", "containing", "have", "having", and any variations thereof, used in this document are intended to be understood in an inclusive (i.e. non-exclusive) sense, such that the process, method, device, apparatus, or system described herein is not limited to the features, integers, parts, elements, or steps recited but may include other features, integers, parts, elements, or steps not expressly listed and / or inherent to such process, method, device, apparatus, or system. Further, the terms "a" and "an" used herein are intended to be understood as meaning one or more unless explicitly stated otherwise. Moreover, the terms "first", "second", "third", etc. are used merely as labels, and are not intended to impose numerical requirements on or to establish a certain ranking of importance of their objects. In addition, any reference to positional terms, such as “lower” and “upper”, used in the above description are to be taken in context of the embodiments depicted in the figures, and are not to be taken aslimiting the invention to the literal interpretation of the term but rather as would be understood by the skilled addressee in the appropriate context.

[0105] The phrase “and / or”, as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e. , elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

Claims

CLAIMS1. An apparatus for delivering a viscoelastic fluid to a target location, the apparatus comprising:a handpiece body having a microcatheter with an output configured to deliver a viscoelastic fluid to a target location;wherein the viscoelastic fluid is configured to flow along a flow path through the microcatheter; andwherein at least a portion of the flow path is configured to induce shear thinning of the viscoelastic fluid, such that the viscosity of the viscoelastic fluid is decreased.

2. The apparatus as in claim 1, wherein a cross-sectional area of the microcatheter changes along the flow path of the viscoelastic fluid.

3. The apparatus as in claim 2, wherein the microcatheter comprises a plurality of cascading sections such that the cross-sectional area of the microcatheter changes along the flow path of the viscoelastic fluid.

4. The apparatus as in claim 3, wherein the cross-sectional area of the microcatheter decreases along the flow path of the viscoelastic fluid.

5. The apparatus as in claim 1, comprising one or more baffles along the flow path of the viscoelastic fluid, the one or more baffles configured to induce turbulence in the viscoelastic fluid, thereby causing shear thinning and a decrease in viscosity of the viscoelastic fluid.

6. The apparatus as in claim 1, comprising a first member and a second member extending through a length of the flow path.

7. The apparatus as in claim 1, wherein the first member and the second member are wires, filaments, fibres, strands, or cables.

8. The apparatus as in claim 6, wherein the first member is wrapped around the second member to induce shear thinning of the viscoelastic fluid.

9. The apparatus as in claim 6, wherein either member has a cross-section to induce turbulence.

10. The apparatus as in claim 9, wherein the cross-section of either member is cylindrical, square, hexagonal, woven, pleated, or spiralled.

11. The apparatus as in claim 8, wherein the first member is an optical fibre configured to illuminate any or all portions of the microcatheter.

12. The apparatus as in claim 1, wherein the flow path comprises a helical structure configured to induce shear thinning in the viscoelastic fluid.

13. The apparatus as in claim 12, wherein the helical structure is rotatable.

14. The apparatus as in claim 1, wherein a diameter of the microcatheter is 250 microns or less.

15. The apparatus as in claim 1, wherein an interior of the handpiece body comprises a plurality of transducers configured to vibrate the handpiece body, thereby inducing turbulence in the viscoelastic fluid.

16. The apparatus as in claim 1, wherein a surface of the flow path comprises a rough inner surface configured to induce shear thinning in the viscoelastic fluid.

17. The apparatus as in claim 1, comprising an input tube configured to deliver the viscoelastic fluid into the handpiece body or directly into the microcatheter.

18. The apparatus as in claim 17, comprising a pump connected to the input tube to pump the viscoelastic fluid into or directly into the microcatheter.

19. The apparatus as in claim 18, wherein the pump is configured to deliver the viscoelastic fluid at selectable frequencies.

20. The apparatus as in claim 18, wherein the pump is configured to periodically pulsate when delivering the viscoelastic fluid.

21. The apparatus as in claim 1, configured to deliver about 100 microlitres ofviscoelastic fluid within about 60 seconds.

22. The apparatus as in claim 2, wherein the cross-sectional area of the microcatheter is substantially circular.

23. A method of delivering a viscoelastic fluid through the apparatus of claim 1 in ophthalmic surgery, the method comprising:making an incision in an eye;cannulating Schlemm’s canal;delivering a viscoelastic fluid to dilate an eye structure from the group consisting of Schlemm’s canal, the trabecular meshwork, or feeder vesselsremoving the microcatheter from the eye;wherein a viscosity of the viscoelastic fluid increases over time after being delivered into the eye; and .wherein the increase in viscosity releases a force to surrounding structures, from a stored elastic potential energy of the viscoelastic fluid, thereby scrubbing cellular debris from the surrounding structures.

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