Improved method and apparatus for performing glaucoma treatment

Abstract

This invention relates to an ophthalmic method and apparatus for the treatment of glaucoma. It provides an apparatus and method of illuminating a microcatheter tip either by using green light for optimised visualisation, blue light to stimulate fluorescence or IR light in conjunction with a dye for angiography of vascular structures the light produced by an LED coupled to an optical fibre. Laser focussing optics is used and back scatter through the fibre is monitored. The backscatter information is used to automatically signify priming of the microcatheter with a fluid or signal changes in a fluid pump function or multiple fluid deliveries through a single microcatheter. Furthermore, the backscatter information offers the potential for automatic dispensation of fluids with or without operator intervention.

Description

IMPROVED METHOD AND APPARATUS FOR PERFORMING GLAUCOMA TREATMENTField of the Invention

[0001] This invention relates to an ophthalmic method and apparatus 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 pressure in the eye because of impaired drainage of intraocular fluid that is continuously produced within the eye and outflow restriction results in over inflation and pressure build up resulting optical nerve damage and the consequence being progressive vision loss leading to blindness.

[0002] 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 major common factor in most of the glaucoma however some patients develop symptoms at normal pressures. Nevertheless, treatment endeavours to lower the patient’s pressure by a variety of interventions.

[0003] An eye comprises many components, with three key being the lens, retina and transparent vitreous humor fluid between them that provides structure to an eye. 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 aqueous is constantly secreted to make space for fresh AH. Drainage is needed and is achieved primarily through the 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.

[0004] 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 and the SC. The eye's pressure is determined by a balance between the rate of production of aqueous fluid and itsexit rate through the TM (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. The portion of the TM adjacent to SC (juxtacanalicular meshwork) provides most of the resistance to aqueous outflow in the conventional pathway.

[0006] 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 TM is diminished.

[0007] Current therapies for glaucoma are usually directed at decreasing intraocular pressure. This is traditionally treated with topically administered eye drops that reduce the production of aqueous humor, change the frequency of the heart rate or increase the outflow of aqueous. However, drug therapies for glaucoma are frequently associated with significant side effects, such as headache, blurred vision, allergic reactions, and adverse interactions with other drugs. Patient compliance is a major hurdle for management with less than 50% of patients maintaining consistent administration. When drug therapy fails, a range of surgical solutions are used. Surgical treatment for open-angle glaucoma consists of laser (trabeculoplasty), trabeculectomy with final resort to aqueous shunting implants after failure of trabeculectomy or if trabeculectomy is unlikely to succeed.

[0008] 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 subconjunctival space. It is the most common glaucoma surgery performed and creates a bypass route for the aqueous humor 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.

[0009] Glaucoma drainage devices are frequently used for the treatment of glaucoma as an alternative to trabeculectomy. These devices typically are composed of a tube to shunt aqueous humor 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.

[0010] All the currently known and performed embodiments and variations of glaucoma surgery have numerous disadvantages and moderate success rates. These involve either substantial risk, trauma to the eye and / or require good surgical skill. Corneal-scleral surgery to create a flow pathway requires the use of antimetabolites to inhibit fibroblast activity and to limit wound closure. Trabeculectomy is implant device free but subjects the patient to future infection risk. Other strategies include the placement of permanent outflow devices such as stents, shunts and drainage valves, in different structures, including the subconjunctival space, to enhance outflow. 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.

[0011] The wound healing and scarring process associated with glaucoma surgery 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.

[0012] A more recently developed, minimally invasive technique termed ab-interno canaloplasty does not require a conjunctival and scleral dissection and clears the canal and TM by injection of fluid into the canal and leaves no device behind, hence minimises trauma and speeds recovery time. This procedure also spares tissues, allowing for more surgical options later if needed.

[0013] Canaloplasty is described in US Patent no. 10918521 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, permittingthe 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, that grip and advance the microcatheter along the canal or integrated into a disposable injector that can be used to advance the microcatheter along the SC. Both the insertion and consequent retraction can be aided by using a lubricous coating on the microcatheter to reduce friction. The injection of a fluid during retraction serves to dilate the diameter of the SC, disturb stenotic adhesions and to flush cellular debris from SC. This surgical treatment has a sustained pressure reducing effect and does not negate the use of appropriate drugs or devices if required for additional benefit.

[0014] 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 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. The microcatheter may comprise a flexible metal, polymer, or biocompatible material, but preferably is made from a PEBA such as PEBAX* or Vestamid*.

[0015] Any reference to background or related art, including to any documents, herein is intended to facilitate an understanding of the present disclosure only and shall not be considered as an admission that such background or related art forms part of the prior art, or that such background or related art is widely known or forms part of the common general knowledge in the relevant field in Australia or in any other country.Summary of the Invention

[0016] The invention in one form can be summarised as an improved method of illuminating a microcatheter tip either by using green light for optimised visualisation, or blue light to stimulate fluorescence or IR light in conjunction with a dye for angiography of vascular structures.

[0017] In another form the invention uses modulated green light and an ability to integrate the light source and power supply in a handpiece.

[0018] In another form the invention uses an optical fibre directly coupled to a light emitting diode.

[0019] In another form of the invention, laser focussing optics is used and back scatter through the fibre is monitored. The backscatter information is used to automatically signify priming of the microcatheter with a fluid or signal changes in a fluid pump function or multiple fluid deliveries through a single microcatheter. Furthermore, the backscatter information offers the potential for automatic dispensation of fluids with or without operator intervention.

[0020] Fluids that are differently coloured to that fluid that fills the SC and the CC can be injected to provide flow pattern visualisation in order to better understand the deficiencies in anindividual patient’s disease, providing visualisation of blockages and canal topology to aid in assessment of canal health.

[0021] By way of example a biocompatible dye contrast media may be used to aid visualisation directly or a fluorescence dye may be used to enhance visualisation either directly or via a CCD camera.

[0022] In a further form of the invention there is proposed a micro-catheter for use in an eye including a sheath having a having a tip and an aperture to permit the injection of fluid into eye; an optical fibre having a core extending though the sheath enabling light to be transmitted therethrough to illuminate the tip wherein the light then passes into the eye.

[0023] Advantageously the optical fibre is coupled to a LED mounted within a container and sealed from external environments by a window, the optical fibre including a core and a sheath held within a ferule.

[0024] Advantageously the micro-catheter includes a sheath having a having a tip and an aperture to permit the injection of fluid into eye; an optical fibre having a core extending though the sheath enabling light to be transmitted therethrough to illuminate the tip wherein the light then passes into the eye.

[0025] Advantageously the optical fibre is coupled to a LED mounted within a container and sealed from external environments by a window the optical fibre including a core and a sheath.

[0026] Advantageously the core of the optical fibre has the sheath held within a ferrule.

[0027] Advantageously the ferrule has an end profile that couples concentrically to the container and may include a bayonet or magnetic engagement with an outer housing.

[0028] Advantageously the fluid is injected into the Schlemm’s canal.

[0029] Advantageously the tip is a ball end.

[0030] In a further form of the invention there is proposed a system to enable delivery of light from a laser diode into an optical fibre and detect light backscattered through the fibre including a laser diode emittingthe light collimated by a lens to produce a collimated beam, the collimated beam transmitted through a beam-splitter mirror to strike the lens focusing the collimated beam onto the end of the optical fibre wherein the light returning through the opticalfibre collimated by the lens and partially reflected by the beam-splitter mirror, the partially reflected light focused by a second lens onto a photodetector.

[0031] Advantageously to observe fluorescence, a high pass filter removes wavelengths corresponding to the laser light.

[0032] Advantageously the light is green light for optimised visualisation, blue light to stimulate fluorescence or IR light in conjunction with a dye for angiography of vascular structures.

[0033] Advantageously the green light is modulated.

[0034] Advantageously the method uses a handpiece with an integral light source and power supply.

[0035] Advantageously laser focussing optics is used and back scatter through the fibre is monitored.Brief Description of the Drawings

[0036] Figure 1 shows a cross-section of the distal end of a microcatheter featuring a ball end and internal optical fibre.

[0037] Figure 2 shows the output light power of a semiconductor diode light source as a function of current.

[0038] Figure 3 shows a method of coupling an optical fibre to a light source.

[0039] Figure 4 shows the optical arrangement for a system that can analyses backscatter from the tip of an optical fibre.

[0040] The accompanying drawing figures are included to provide further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate particular embodiments of the disclosure and together with the description serve to explain the principles and operation thereof. Other embodiments of the disclosure and many of the attendant advantages will be readily appreciated as they become better understood with reference to the following detailed description.

[0041] It will be appreciated that common and / or well understood elements that may be useful or necessary in a commercially feasible embodiment are not necessarily depicted in order to facilitate a more abstracted view of the embodiments. It will also be understood that certain actions and / or steps in an embodiment of a method may be described or depicted in a particular order of occurrences while those skilled in the art will understand that such specificity with respect to sequence may not actually be required.Detailed Description of Preferred Embodiments

[0042] Previous inventions have suggested light be directed down the fibre and commonly red light from a semiconductor diode has been used. However, we have found that other colours offer distinct advantages, both on account of the light sources used, their interaction with structures in a patient’s eye, potential interaction with new drugs and its visibility by the practitioner. Initially, red light was chosen for the beacon because of its general use in surgical procedures on the basis that red colour transmits through blood. During eye surgery, the presence of blood is not very significant so does not represent an obstruction through which the light beacon has to penetrate. Consequently, other colours can now be considered that will now be discussed with reference to their merits.

[0043] Green light offers several advantages over red light, because the human eye is most sensitive to green in both scotopic and photopic response to the extent that the same power of light is almost 10 times visually brighter than red light. While a greater intensity is not required by a surgeon, the greater sensitivity to green light enables a lower power source to be used. Lower power consumption permits a more compact instrument enabling batteries to be used as the power source. These batteries can be incorporated in a separate housing together with the light source that is delivered to the surgical site via an optical fibre. Further power savings can be achieved by using a light emitting diode or a laser diode as a light source and driving it with a repetitive pulse train. Because of the non-linear relationship between light output and input current in a light emitting diode, a higher drive current can produce a much higher power output but because of the knee voltage non-linearity a duty cycle limited drive signal running the diode at a high peak power with low average power is more energy efficient than running the diode at an equivalent constant current driven power. The aim is not the higher intensity of emission, but the ability to lower the input power demand to increase the life of a battery powering the diode. With such an arrangement the intensity of the light can be controlled by adjusting the duty cycle of the drive current.

[0044] Referring to Figure 1 it shows the distal end of a micro-catheter. A sheath 1 has been processed to produce a ball end 2 with an aperture to permit the injection of fluids through the SC with the distal tip. An optical fibre 3 through which light is transmitted is located within the microcatheter sheath.

[0045] 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.

[0046] Figure 2 shows the response of the output of a semiconductor diode light source such as semiconductor laser diode as a function of current. From the plot it can be seen that above a threshold (30 mA) the intensity increases linearly with current, whereas below the threshold there is no significant emission. In the example response curve, it can be seen that increasing the current by 50% from 40 mA to 60 mA results in a 260% increase in output intensity from 5 to 13 mW. So, a steady output (5 mW) from a 40 mA current can be equivalent to the average output from a 60 mA current with a pulse modulation of 38% representing a power saving 43%. These aforementioned values are purely for illustrative purposes.

[0047] By having a lower power demand, the possibility of having the light source and associated drive electronics and batteries housed in a microcatheter injector handpiece becomes a possibility, offering ergonomic advantages for the surgeon. The coupling of the light from the laser to the fibre becomes integral to the hand piece eliminating the need for a separate light source.

[0048] Other colours that can be used to advantage to illuminate the distal tip of a microcatheter, not limited to but including, by way of example, blue or near infra-red (I ). Both UV and blue light are known to excite auto-fluorescence of diseased tissue. UV is generally used for exciting fluorescence but not preferred as these shorter wavelengths are phototoxic to the eye and should be avoided. However longer wavelengths within the blue visible light spectrum can be tolerated. To see fluorescence while viewing an eye undergoing treatment through a microscope, a long-pass filter will be necessary to filter the excitation light. For example, a 405 nm laser diode excitation source with a long pass cutoff filter at 410 nm could be used, passing all longer wavelengths thereby not impairing the general view of the eye under white light. Tobetter see any fluorescence the ambient light can be extinguished or otherwise dimmed.Alternatively, a band pass filter can be included within the optics to suppress any wavelengths that do not correspond to those of any fluorescence of interest to improve signal to noise ratio.

[0049] As previously mentioned, transmitting IR through an inter-canula fibre could also be used to advantage. The eye is relatively unaffected by near-IR light, as this wavelength is not photo toxic and not well absorbed by ocular pigments so the illumination can have a relatively high intensity without thermally induced damage. The IR spectrum is also efficient at exciting a dye such as indocyanine green (ICG) dye. ICG dye is approved for in vitro use and can be used for angiography of the vascular system of the eye. Peak excitation occurs at 789 nm and fluorescence is at 815 nm which matches the spectral response of silicon-based CCD cameras.

[0050] In a more sophisticated embodiment, one or more colours can be directed through the intra-catheter fibre, either selectively or in combination. For example, green light could be used to guide the microcatheter and potentially visualise any upstream features such as blockages, while blue light can then be used to inspect the region around the distal end of the catheter.

[0051] Another consideration when coupling an optical fibre to a laser diode light source is howto achieve an efficient coupling while also satisfying the requirement that the optical fibre be disposable after each operation. The attachment must be simple and not require complex alignment or positioning. Laser diodes typically have a small light emitting chip in the order of 100 microns diameter, but to prevent moisture induced degradation of the chip, a glass window is placed immediately adjacent the chip inside a hermetically sealed metal can. This window prevents the direct butting of an optical fibre end to the chip and the separation space between the fibre to the chip is typically about 1 mm. Because of the asymmetric divergence of the light emanating from the chip geometry, the typically emission is 10 by 20 degrees full angle with the beam dimensions at the exit window around 200 by 400 microns. An efficient and low cost means of coupling is to locate the fibre directly on the window concentric with the chip. The preferred fibre core dimension to maximise brightness is 200 microns in diameter.

[0052] Figure 3 shows a schematic of an optical fibre coupled to a LED 11 mounted on a housed within a can or container 13, preferably metal, and sealed from external environments by a window 12. The core 14 of an optical fibre has a sheath 15 that is held within a ferrule 16. The ferrule has an end profile that couples concentrically to the can and may include a bayonet or magnetic engagement with an outer housing (not shown).

[0053] If a greater brightness or more coupling power is required, focusing optics are required to aid diode-fibre coupling. This more efficient means of coupling a laser beam into a fibre requires a lens or lenses to focus the beam, preferably to a spot size smaller than the fibre core that is positioned at the focus of the beam. This will increase the system cost. While such an arrangement is more complex the optical scheme permits the use of a beamsplitter that can be used to detect backscattered light from the distal end of the fibre. The backscattered light signal will be affected by the media at the distal end of the fibre. As the distal end encounters differing materials of differing reflectivity, the backscatter will change and can be monitored at the sensor. Such signals can be interpreted to give the surgeon a better understanding of the location and nature of the obstructions or other features within Schlemm’s Canal during treatment. Additional information can be gained by using different light sources or a combination of light sources such as excitation light sources to detect fluorescence as described above.

[0054] This information can also be beneficial when delivering a reagent through the microcatheter for example Ophthalmic Viscosurgical Device (OVD), saline an organic dye or a drug. Such reagents are used to flush or expand Schlemm’s canal.

[0055] Figure 4 is an optical schematic illustrating a system that would enable delivery of light from a laser diode into an optical fibre and detection of light backscattered through the fibre. Referring to the figure, the light output from a laser diode 21 is collimated by a lens 22. The collimated beam is transmitted through a beam-splitter 23 and strikes a lens 24 that focuses the beam onto the end of an optical fibre 25. Light returning through the fibre is collimated by lens 24 and partially reflected of the beam-splitter mirror 23. The reflected beam is focused by lens 27 onto a photodetector 28. Where desirable for example if observing fluorescence, a high pass filter 26 may be introduced to remove wavelengths corresponding to the laser. The optical fibre 25 can be coupled to a connector such as an SMA connector commonly used in the industry.

[0056] For laser diodes that include a lens to collimate the output light, lens 22 may be omitted and for greater efficiency the beam splitter can comprise a mirror with a central hole to allow passage of the laser beam.

[0057] The appropriate diameters and focal lengths of the lenses would be rudimentary to those skilled in the art of optical design, with the key factor being the numerical aperture of the optical fibre that is typically 0.22.

[0058] It is anticipated that with a backscattering monitor it will be possible to detect when a micro-catheter has been primed with a fluid like OVD. Priming is usually performed manually by a surgeon’s assistant operating a manual infusion pump and visually monitoring the catheter for egress of a fluid from the distal tip. However, with a backscatter monitoring system as described above, a surgeon could control the fluid delivery with an electrically driven infusion pump preferably driven by a stepper motor in a semi-automated manner not requiring the services of a surgical assistant to operate the infusion pump.

[0059] The infusion pump can be driven in various modes to accommodate the characteristics of infusion fluids. For example, OVD fluids driven with a pulsatile injection manner can be shear thinned by inducing a series of pressure bursts by modulating the pump drive with a digital pulse train to create a high shear rate known to alter the viscosity of nonNewtonian fluids such as OVD.

[0060] The electrically driven infusion pump system can also be used to deliver one or more fluids by cascading multiple infusion pumps coupled in parallel to single or multiple infusion lines that converge at the microcatheter. The electrically driven infusion pumps with a microcatheter can be used with or without the backscatter system to achieve several control objectives.Establish if the catheter is dry of fluidAdvance the injection to prime the lineSense that the pump is delivering fluid in the required mannerTitrating volume of deliveryControlling fluid delivery rateControlling OVD shear rate. The preferred point of convergence of the fluid lines from multiple pumps should be as distal as practical to reduce the latent lag time and fluid volume.

[0061] The use of an electrically driven infusion pump offers consistency in delivery by permitting preselection of the dosimetry preferred by the surgeon.

[0062] There may be occasions when the delivery of more than one fluid is beneficial, for example a reagent and a dye for revealing blocked vessels. This can be accomplished by bifurcating two or more fluid feed lines to the microcatheter and driving one at a time,sequentially or in unison. The illumination and detection scheme described above can be used to monitor the delivery of the fluid at the distal tip by interrogating the sensor.

[0063] With the ability to illuminate the distal tip as well as to electrically drive infusion pumps, the light signal can be used to indicate changes in fluid pump function. For example, a change in illumination by way of flicker or colour can signify the initiation of injection or cessation of injection or change of reagent. As the OVD is a non-Newtonian fluid that takes finite time to settle post pressurisation, the injection process and settling time can be preprogrammed and indicated to the surgeon to guide the viscodilation process.

[0064] This scheme places the surgeon in direct control, with prompt feedback and the minimising of lag time and errors introduced by another human in the control chain. The preferred means of control by the surgeon can be a wired or wireless foot pedal or voice command for hands-free operation or by finger switch if that is desired.

[0065] The fibre optic communication channel integral to the microcatheter can be used to deliver therapeutic doses of light to the canal to stimulate cells directly or via a chemical enhancer. By way of example some wavelengths of light in the visible and near-IR wavelengths exhibit photo biomodulation properties that are considered beneficial for treating compromised cells. Delivering energy to the mitochondria can be used to stimulate healing of compromised cells. Photodynamic therapy using a photosensitive chemical can also be used to treat compromised cells. Light can be used to selectively damage cells to trigger regeneration such as treating the trabecular meshwork with a process termed Selective Laser Trabeculoplasty (SLT).

[0066] The intra-catheter fibre can be composed of polymer rather than glass as it is disposable with the preferred diameter of the fibre at about 80 microns enabling it to fit inside the preferred 250-micron OD sized micro-catheter while allowing space around it for fluids to pass.

[0067] It will be appreciated that the above description and preferred embodiments allow for improved ocular surgery and while specific details have not been discussed, operational systems could be constructed by those skilled in the art of engineering and optical science.Variations and Modifications

[0068] 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 / orequivalent 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.

[0069] 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 as limiting the invention to the literal interpretation of the term but rather as would be understood by the skilled addressee in the appropriate context.

[0070] 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 . A micro-catheter for use in an eye including; a sheath having a having a tip and an aperture to permit the injection of fluid into eye; an optical fibre having a core extending through the sheath enabling light to be transmitted therethrough to illuminate the tip wherein the light then passes into the eye.

2. The micro-catheter as in claim 1 wherein the optical fibre is coupled to a LED mounted within a container and sealed from external environments by a window; the optical fibre including a core and a sheath.

3. The micro-catheter as in claim 2 wherein the sheath is held within a ferrule.

4. The micro-catheter as in claim 1 wherein the ferrule has an end profile that couples concentrically to the container and may include a bayonet or magnetic engagement with an outer housing.

5. The micro-catheter as in claim 1 wherein the fluid is injected into the Schlemm’s canal.

6. The micro-catheter as in claim 1 wherein the tip is a ball end.

7. A system to enable delivery of light from a laser diode into an optical fibre and detect light backscattered through the fibre including: a laser diode emitting the light collimated by a lens to produce a collimated beam, the collimated beam transmitted through a beam-splitter mirror to strike the lens focusing the collimated beam onto the end of the optical fibre; wherein the light returning through the optical fibre collimated by the lens and partially reflected by the beam-splitter mirror, the partially reflected light focused by a second lens onto a photodetector.

8. The system as in claim 7 wherein to observe fluorescence, a high pass filter removes wavelengths corresponding to the laser light.

9. A method of illuminating a microcatheter tip either by using green light for optimised visualisation, or blue light to stimulate fluorescence or IR light in conjunction with a dye for angiography of vascular structures.

10. The method of illuminating a microcatheter tip as in claim 9 where the green light is modulated.11 . The method of illuminating a microcatheter tip as in claim 9 where a handpiece has an integral light source and power supply.

12. The method of illuminating a microcatheter tip as in claim 9 where laser focussing optics is used and back scatter through the fibre is monitored.

13. The microcatheter as in claim 1 used for the treatment of glaucoma in the eye.

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