WO2008030951A2

WO2008030951A2 - Glaucoma implant device

Info

Publication number: WO2008030951A2
Application number: PCT/US2007/077748
Authority: WO
Inventors: Leonard Pinchuk; Jean-Marie Parel; Francisco Fantes
Original assignee: Innfocus, Llc
Priority date: 2006-09-06
Filing date: 2007-09-06
Publication date: 2008-03-13
Also published as: WO2008030951A3

Abstract

An aqueous humour drainage device includes a structure realized from a porous polymeric matrix that allows for regulated outflow of aqueous humour through the structure and also serves to prevent bacteria from entering the eye. In one embodiment, the structure is located in the stroma of the cornea and simply shunts fluid from the anterior chamber to the exterior of the cornea. In another embodiment, the structure is located in the conjunctiva and allows fluid from the anterior chamber to flow to the exterior of the conjunctiva by means of duct work implanted within the conjunctiva and sclera. In yet another embodiment, the structure is implanted just below the conjunctiva to further protect the structure from bacteria infestation. In the preferred embodiment, the porous polymeric matrix of the device includes polyisobutylene.

Description

GLAUCOMA IMPLANT DEVICE

CROSS REFERENCED RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial Nos. 60/824,632 filed September 6, 2006 and 60/825,595 filed on September 14, 2006 and is related to International Patent Appl. No. PCT/US07/77731, entitled "Porous Polymeric Material For Medical Applications," filed concurrently herewith (Attorney Docket No. INN- 025 PCT), all of which are herein incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0002] This invention relates broadly to medical devices and materials for reducing intraocular pressure. More particularly, this invention relates to medical devices and materials for diverting aqueous humor out of the anterior chamber of the eye.

2. State of the Art

[0003] Glaucoma is a disorder of the optic nerve that frequently occurs in the setting of an elevated intraocular pressure (typically referred to as "IOP"). The pressure within the eye increases causing changes in the appearance ("cupping") and function ("blind spots" in the visual field) of the optic nerve. High pressure develops in an eye because of impaired outflow of aqueous. In open-angle glaucoma, the impaired outflow is caused by abnormalities of the drainage system of the anterior chamber. In closed-angle glaucoma, the impaired outflow is caused by impaired access of aqueous to the drainage system. If the pressure within the eye remains sufficiently high for a long enough period of time, total vision loss occurs. Thus, glaucoma is a leading cause of preventable blindness.

[0004] As shown in Figure 1, the eye 1 is a hollow structure that contains a clear fluid called "aqueous humor." Aqueous humor is formed by the ciliary body 2 adjacent to the posterior chamber 3 of the eye. The fluid, which is made at a fairly constant rate, then passes around the lens 4, through the pupillary opening 5 in the iris 6 and into the anterior chamber 7. Once in the anterior chamber 7, the fluid drains out of the eye 1 through two different routes. In the "uveoscleral" route, the fluid percolates between muscle fibers of the ciliary body 8. This route accounts for approximately ten percent of the aqueous outflow in humans. The primary pathway for aqueous outflow in humans is through the "canalicular" route that involves the trabecular meshwork 9 and Schlemm's canal 10.

[0005] The trabecular meshwork 9 and Schlemm's canal 10 are located at the junction between the iris 6 and the sclera 11. This junction is typically referred to as the "angle". The trabecular meshwork is a wedge-shaped structure that runs around the circumference of the eye. It is composed of collagen beams arranged in a three-dimensional sieve-like structure. The beams are lined with a monolayer of cells called trabecular cells. The spaces between the collagen beams are partially filled with an extracellular substance that is produced by the trabecular cells. These cells also produce enzymes that degrade the extraneous material. Schlemm's canal 10 is disposed adjacent to the trabecular meshwork. The outer wall of the trabecular meshwork coincides with the inner wall of Schlemm's canal 10. Schlemm's canal 10 is a tube-like structure that runs around the circumference of the cornea. In human adults, Schlemm's Canal 10 is believed to be divided by septa into a series of autonomous, dead-end canals. The aqueous fluid travels through the spaces between the trabecular beams of the trabecular meshwork, across the inner wall of Schlemm's canal 10 into the canal, through a series of collecting channels that drain from Schlemm's canal 10 and into the episcleral venous system (not shown).

[0006] The tough outer membrane known as the sclera 11 covers all of the eye 1 except that portion covered by the cornea 12, which is the thin, transparent membrane which covers the pupillary opening 5 and the iris 6. The sclera is composed of many natural layers of collagenous tissue. The cornea is composed of many layers called the corneal stroma 13. The cornea 12 merges into the sclera 11 at a juncture referred to as the limbus 14. A portion of the sclera 11 is covered by a thin tissue called Tenon's membrane 15, which envelopes the bulb of the eye from the optic nerve (not shown) to the ciliary region, and separates the eye from the orbital fat and forms a socket in which the eye moves. Near its front, Tenon's membrane 15 blends into the conjunctiva 16 where it is attached to the ciliary region of the eye as shown.

[0007] In a normal patient, aqueous production is equal to aqueous outflow and intraocular pressure remains fairly constant (typically in the 15 to 21 mmHg range). In glaucoma, there is abnormal resistance to aqueous outflow, which manifests itself as increased IOP. Tonometry is the measurement of IOP. In primary open angle glaucoma, which is the most common form of glaucoma, the abnormal resistance is believed to be along the outer aspect of trabecular meshwork and the inner wall of Schlemm's canal 10. Primary open angle glaucoma accounts for approximately eighty-five percent of all glaucoma in the U.S. Other forms of glaucoma (such as angle closure glaucoma and secondary glaucomas) also involve decreased outflow through the canalicular pathway but the increased resistance is from other causes such as mechanical blockage, inflammatory debris, cellular blockage, etc.

[0008] With the increased resistance, the aqueous fluid builds up because it cannot exit fast enough. As the fluid builds up, the IOP within the eye increases. The increased IOP compresses the axons in the optic nerve and also may compromise the vascular supply to the optic nerve. The optic nerve carries vision from the eye to the brain. Some eyes seem more susceptible to elevated IOP than other eyes. While research is investigating ways to protect the nerve from an elevated pressure, the therapeutic approach currently available in glaucoma is to reduce the intraocular pressure.

[0009] The clinical treatment of glaucoma is typically carried out in a step-wise manner. Medication often is the first treatment option. Administered either topically or orally, these medications work to either reduce aqueous production or they act to increase outflow. Currently available medications have many serious side effects including: congestive heart failure, respiratory distress, hypertension, depression, renal stones, aplastic anemia, sexual dysfunction and death. Compliance with medication is a major problem, with estimates that over half of glaucoma patients do not follow their correct dosing schedules.

[0010] When medication fails to adequately reduce the pressure, laser trabeculoplasty often is performed. In laser trabeculoplasty, thermal energy from a laser is applied to a number of noncontiguous spots in the trabecular meshwork. It is believed that the laser energy stimulates the metabolism of the trabecular cells in some way, and reactivates the phagocytosis activity of the trabecular meshwork cells. In a large percent of patients, aqueous outflow is enhanced and IOP decreases. However, the effect often is not long lasting and a significant percentage of patients develop an elevated pressure within the years that follow the treatment. The laser trabeculoplasty treatment is typically not repeatable. In addition, laser trabeculoplasty is not an effective treatment for primary open angle glaucoma in patients less than fifty years of age, nor is it effective for angle closure glaucoma and many secondary glaucomas. [0011] If laser trabeculoplasty does not reduce the pressure sufficiently, then incisional surgery (typically referred to as filtering surgery) is performed. With incisional surgery, a hole is made in the sclera 11 adjacent the angle region. This hole allows the aqueous fluid to leave the eye through an alternate route.

[0012] The most commonly performed incisional procedure is a trabeculectomy. In a trabeculectomy, a posterior or anterior incision is made in the conjunctiva 16. The conjunctiva 16 is rolled forward or backward, depending upon whether it was an anterior or posterior incision, thereby exposing the sclera 11 at the limbus 14. A partial scleral flap is made and dissected into the cornea. The anterior chamber 7 is entered beneath the scleral flap, and a section of deep sclera and trabecular meshwork is excised and an iridectomy is performed to prevent the iris from blocking the egress path. The scleral flap is loosely sewn back into place. The conjunctiva incision is tightly closed. Post-operatively, the aqueous fluid passes through the hole, beneath the scleral flap and collects in a bleb formed beneath the conjunctiva 16. The fluid then is either absorbed through blood vessels in the conjunctiva 16 or traverses across the conjunctiva 16 into the tear film or both. Trabeculectomy surgery of this nature is extremely difficult and only a small fraction of well qualified ophthalmologists , perform this procedure successfully. In addition, in private clinics it is very time consuming and physicians are not reimbursed for the time it takes to perform the surgery and it is therefore rarely performed.

[0013] When trabeculectomy doesn't successfully lower the eye pressure, the next step, and usually the last prior to cyclo-destruction of the cilliary body, is a surgical procedure that implants a device that shunts aqueous humor to control the IOP. One such implant device, as shown in U.S. Patent 6,050,970 to Baerveldt, is a drainage tube that is attached at one end to a plastic plate. The drainage tube is a flow tube between 1.0 and 3.0 French (and preferably with an inner diameter of 0.3 mm and an outer diameter of 0.6 mm). An incision is made in the conjunctiva 16, exposing the sclera 11. The plastic plate is sewn to the surface of the sclera posteriorly, usually over the equator. A full thickness hole is made into the eye at the limbus 14, usually with a needle. The tube is inserted into the anterior chamber through this hole. The external portion of the tube is covered with either sclera, cornea or other preserved donor tissues to prevent tube extrusion through the delicate overlaying conjunctiva. The conjunctiva 16 is replaced and the incision is closed tightly. With this shunt device, aqueous drains out of the anterior chamber through the silicone tube to the bleb, which is a thin layer of connective tissue which forms with time that encapsulates the plate and tube distal end and then to the tear network or venous network of the eye. The plate typically has a large surface area in order to wick and disperse fluid, which facilitates absorption of fluid in the surrounding tissue. These disks are generally made of silicone rubber, which serves to inhibit tissue adhesion as the plate becomes encapsulated by the connective tissue of the bleb. The disks can be as large as 10 to 15 mm in diameter and are irritating to some patients and may cause hindering of eye movement in others.

[0014] Other implant devices are shown in U.S. Patent 6,468,283 to Richter et al. and U.S. Patent 6,626,858 to Lynch et al., respectively. The Richter implant device is a tubular structure that shunts aqueous humor from the anterior chamber to a space between the conjunctiva 16 and the sclera 11. The Lynch implant device is a tubular structure that shunts aqueous humor from the anterior chamber through the trabecular meshwork and into Schlemm's canal 10. These implant devices are described as being formed from silicone, Teflon, polypropylene, stainless steel, etc. These implant devices also typically require precise placement away from the angle and the iris in order to prevent interference with the iris and/or to avoid occlusion of the drainage lumen by ocular tissue (for example, the fibrous tissue of the iris and/or the sclera that may plug the drainage lumen). In addition, some implant devices include a unidirectional valve to minimize hypotony (low IOP) in the anterior chamber of the eye. However, the desired flow control provided by such valves is difficult to maintain and are prone to failure. Lastly, these shunt devices are relatively stiff and have been shown to erode through the ocular tissue wall adjacent thereto over time.

[0015] As described above, trabeculectomies, drainage tubes such as the Baerveldt, the Richter device and the device described by Pinchuk et al in U.S. Application No. 60/741,514, filed on December 1, 2005, which is a continuation- in-part of U.S. Patent Application No. 11/004,539 filed on December 3, 2004, require that the fluid drain into and sustain a bleb. As mentioned above, a bleb is formed in the conjunctiva where fluid within the bleb diffuses into the tissues encompassing the bleb with eventual drainage in the venous system or tear system of the eye. In very severe patients who have undergone numerous operations in the eye, more often than not the conjunctiva and sclera are highly scarred thus making it difficult for the bleb to filter aqueous into the normal networks surrounding the bleb. Devices that do not drain into a bleb, such as the Lynch device, which drain into Schlemm's canal as well as other devices which drain into the sub-choroidal space (such as those described in US Patent Publication Nos. 2006/0069340, 2005/0165385, and 2004/0254521 (the Gold Shunt®)) are difficult to place and therefore limited in practice.

[0016] Thus, there remains a need in the art to provide an implant device for the treatment of glaucoma that is realized from a biocompatible material, that enables control over IOP without the need for a bleb or for large surface area plates and possibly without the need for unidirectional flow control valves, and that is easy to place.

SUMMARY OF THE INVENTION

[0017] It is therefore an object of the invention to provide an implant device for the treatment of glaucoma that is realized from a biocompatible material that will not form a thick and dense capsule in the eye, thereby avoiding occlusion of the implant device by ocular tissue and enabling control over IOP without the need for a bleb.

[0018] It is a further object of the invention to provide an implant device for the treatment of dry eye syndrome where fluid from the anterior chamber is filtered to the external surface of the cornea.

[0019] In accord with these objects, which will be discussed in detail below, a surgical implant device for treating glaucoma includes a structure realized from a porous polymeric matrix that allows aqueous humor of the eye to flow through the matrix in a regulated manner. The matrix also serves to prevent bacteria from entering the eye. In one embodiment, the device is located in the stroma of the cornea and simply shunts fluid from the anterior chamber to the exterior of the cornea. In another embodiment, the device is located in the conjunctiva and allows fluid from the anterior chamber to filter to the exterior of the conjunctiva by means of duct work implanted within the conjunctiva and sclera. In yet another embodiment, the device is implanted just below the conjunctiva to further protect the device from bacteria infestation. In still another embodiment, the device includes a biological component that helps heal it to the tissues of the eye. In all these structures, antimicrobials can be added to the porous polymeric matrix to kill bacteria and thereby prevent microbial infections such as keratitis or endophthalmitis.

[0020] In the preferred embodiment, the porous polymeric matrix includes polyisobutylene and a glassy segment. Such material is advantageous in that it will not encapsulate within the ocular environment and thus provides an unobstructed flow path that diverts aqueous humor from the anterior chamber. Such material also allows for smaller, simpler designs and thus promotes quicker healing.

[0021] According to the preferred embodiment of the invention, the porous polymeric matrix is realized from a soft polymeric material with a hardness less than Shore 9OA but greater than Shore 5 A and with pore sizes in a range from 0.01 μm to 10 μm.

[0022] Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a prior art illustration showing anatomic details of the human eye.

[0024] Figure 2A is a 3-dimentional view of an all-polymeric porous aqueous drainage device in accordance with the present invention.

[0025] Figure 2B is a 3-dimentional view of an all-polymeric porous aqueous drainage device in accordance with the present invention with a plurality of fixation holes in the skirt to allow permanent fixation via biointegration (tissue ingrowth through the holes).

[0026] Figure 3 is a scanning electron micrograph of a cross-section of the porous structure of the present invention.

[0027] Figure 4A is a schematic of the eye showing a delamination tract formed between the layers of the sclera and cornea with a blunt spatula.

[0028] Figure 4B shows the trephined hole through the cornea intersecting the delaminated tract.

[0029] Figure 4C shows the drainage device of the present invention located in the tract and trephined hole in the cornea.

[0030] Figure 5 shows a frontal photograph of a rabbit's eye with the drainage device in place. [0031] Figure 6 is a schematic of an aqueous drainage device connected to ductwork that ducts fluid from the anterior chamber to the porous filter device and out the surface of the conjunctiva.

[0032] Figure 7 A is a top view of a polymeric/tissue aqueous drainage device construct in accordance with the present invention.

[0033] Figure 7B is a side view of a polymeric/tissue aqueous drainage device construct in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] As used herein, the term "porous" refers to a material or structure that has a plurality of holes, perforations, openings, or void spaces (collectively, "pores").

[0035] As used herein, the term "microporous" refers to a material or structure that has a plurality of pores with an average pore size of less than 200 microns. For purposes of this application, pore size shall mean the largest dimension of the pore.

[0036] As used herein, the term "porosity" refers to the ratio of non-solid volume to the total volume of a porous material.

[0037] Turning now to Figures 2A and 2B, there is shown an aqueous drainage device 20 for treating glaucoma in accordance with the present invention. The aqueous drainage device 20 includes a generally disk-shaped skirt 21 with a central peg 22 that extends equidistantly from both the upper and lower planes of the skirt. Both the skirt 21 and the peg 22 are porous with porosity such that aqueous humor can flow through the peg or skirt in a regulated manner (without inducing hypotony of the eye) yet bacteria cannot penetrate same. Figure 2B shows a similar device but with a plurality of holes 25 punched into the skirt 21 to better fixate the device in the eye by means of tissue ingrowth.

[0038] The skirt 21 and the peg 22 of the aqueous drainage device 20 are preferably formed from a porous polyolefinic copolymer material having a triblock polymer backbone comprising poly(styrene-ό/øcA:-isobutylene-ό/øcA:-styrene), which is herein referred to as "SIBS". High molecular weight polyisobutylene (PIB) is a soft elastomeric material with a Shore hardness of approximately 1OA to 30A. When copolymerized with polystyrene, it can be made at hardnesses ranging up to the hardness of polystyrene, which has a Shore hardness of 10OD. Thus, depending on the relative amounts of styrene and isobutylene, the SIBS material can have a range of hardnesses from as soft as Shore 1OA to as hard as Shore 10OD. In this manner, the SIBS material can be adapted to have the desired elastomeric and hardness qualities. In the preferred embodiment, the SIBS material of the aqueous drainage tube 100 has a hardness less than Shore 9OA. Details of the SIBS material is set forth in U.S. Patent Nos. 5,741,331; 6,102,939; 6,197,240; 6,545,097, which are hereby incorporated by reference in their entirety. The SIBS material of the aqueous drainage device 20 may be polymerized under control means using carbocationic polymerization techniques such as those described in U.S. Patent Nos. 4,276,394; 4,316,973; 4,342,849; 4,910,321; 4,929,683; 4,946,899; 5,066,730; 5,122,572; and Re 34,640, each herein incorporated by reference in its entirety. The amount of styrene in the copolymer material is preferably between about 2 mole % to 30 mole % and most preferably between 5 mole % and 25 mole%. The styrene and isobutylene copolymer materials are preferably copolymerized in solvents. The preferred SIBS material of the aqueous drainage device 20 provides superb biocompatibility and biostability characteristics. Moreover, animal tests have shown that surprisingly it will not significantly encapsulate in the eye, and thus can be used to provide unobstructed drainage from the anterior chamber of the eye.

[0039] It is expected that the skirt 21 and the peg 22 of the aqueous drainage device 20 can be realized from alternative porous polymeric materials. Such alternative polymeric materials preferably include polyisobutylene-based material capped with a glassy segment. The glassy segment provides a hardener component for the elastomeric polyisobutylene. The glassy segment preferably does not contain any cleavable group which will release in the presence of body fluid inside the human eye and cause toxic side effects and cell encapsulation. The glassy segment can be a vinyl aromatic polymer (such as styrene, α-methylstyrene, or a mixture thereof), or a methacrylate polymer (such as methylmethacrylate, ethylmethacrylate, hydroxymethalcrylate, or a mixture thereof). Such materials preferably have a general block structure with a central elastomeric polyolefϊnic block and thermoplastic end blocks. Even more preferably, such materials have a general structure:

BAB or ABA (linear triblock),

B(AB)_n or a(BA)_n (linear alternating block), or X-(AB)_n or X-(BA)_n (includes diblock, triblock and other radial block copolymers), where A is an elastomeric polyolefϊnic block, B is a thermoplastic block, n is a positive whole number and X is a starting seed molecule.

Such materials may be star-shaped block copolymers (where n=3 or more) or multi-dendrite- shaped block copolymers. These materials collectively belong to the polymeric material referred to herein as SIBS material.

[0040] Alternatively, the skirt 21 and/or the peg 22 of the aqueous drainage device 20 can be realized from another soft elastomeric polymeric material. Preferably, the soft elastomeric polymeric material is biocompatible and biostable within the ocular environment. Moreover, it is preferable that the soft elastomeric polymeric material of the drainage device 20 not naturally attract leukocytes and/or myofibroblasts, which limits encapsulation of the device 20 in the eye, and thus provides unobstructed drainage from the anterior chamber of the eye. An example of an alternate material that may function is this capacity is silicone rubber that has been cleansed of cyclic impurities. Also suitable are the family of methacrylate polymers such as poly(2-phenylethyl methacrylate), poly(2-hydroxyethyl methacrylate, and others of this genera.

[0041] In an illustrative embodiment, the porous structure of the skirt 21 and the peg 22 of the aqueous drainage device 20 is made by compounding a thermoformable water soluble polymer, such as polyethylene oxide (PEO), with the SIBS polymer in the melt phase or in the solvent phase to form a polymer blend. The polymer blend, which is generally a clear-looking plastic, is then well-dried and compression or injection-molded into the structure shown in Figure 2. The device 20 is then rinsed repeatedly in water to remove the water-soluble component, thereby forming a polymer matrix with pores where the water soluble polymer used to reside. The interconnecting pores are generally tortuous in path. Figure 3 is a scanning electron micrograph of the porous polymer matrix thus formed by eluting PEO from SIBS. The porous polymer matrix is usually opaque white in color due to the diffraction of light by the small pore structure. Alternatively, the porous structure can be made by phase inversion where the SIBS polymer is dissolved in a good solvent and then precipitated into a porous embodiment by immersing the polymer in a bad solvent. For example, SIBS can be dissolved in cyclopentane and then immersed in 2-propanol to precipitate the polymer and yield a porous structure. Still alternatively, SIBS can be compounded with an elutable particle, such as sodium chloride crystals, sodium bicarbonate, sugar and the like and then formed into the desired geometry by injection molding and the like. The particle-filled structure is then immersed in a solvent such as water, where the water soluble particle is dissolved out thereby providing a porous matrix with interconnecting pores. Details of the methodology of forming the porous polymeric matrix of SIBS is described in detail in International Patent App. No. PCT/US07/77731 entitled "Porous Polymeric Material For Medical Applications," filed concurrently herewith (Attorney docket number INN-025), which is incorporated by referenced above.

[0042] The pore size of the porous polymeric matrix of the device 20, which defines the smallest microbe that can maneuver through the device 20, is preferably in the range between 0.05 μm to 1.0 μm (and most preferably in the range between 0.2 μm and 0.4 μm). These pores sizes prevent bacteria from penetrating the device 20 and infecting the eye. Further, the porosity is determined to allow a regulated flow through the device 20 that avoids hypotony (deflation of the eye), yet allows the pressure in the eye to drop so as to prevent glaucoma.

[0043] The porosity of the porous polymeric matrix of the device 20 is controlled by controlling the relative weight of water soluble polymer to insoluble polymer. For example, to obtain a porosity of 70%, one would mix 7Og of PEO with 30g of SIBS and rinse out the PEO. Using this porosity measurement, a preferred range of porosity for the porous polymeric matrix is 70% to 30% (and most preferably in the range between 40% to 60%).

[0044] The polymer of the skirt and peg of the device 20 is required to be biocompatible in the eye with little to no tendency to encapsulate. In addition, the polymer must wick water to enable drainage of fluid from the eye. SIBS is well-suited for this application as the water molecule is smaller than the intramolecular strands of the SIBS polymer and thereby water resides in the polymer and helps wick additional water through the porous matrix. Experiments have shown that with porosities in the 50% range, water can flow through these porous matrices at a rate of 1,000 microliters per minute per cm² of surface area (lmm thick) with a pressure head of 8mmHg. As the required pressure drop is 5 to 20mmHg, with a flow rate of 2 to 4 microliters per minute, one need only decrease the diameter or thickness of the device 20 to provide this pressure drop at said flow rate, or adjust the porosity to provide same. [0045] The diameter of the skirt 21 of the aqueous drainage device 20 is preferably in the range between 1 mm and 4 mm (and most preferably between 2 mm and 3 mm). The diameter of the peg 22 of the aqueous drainage device 20 is preferably between 0.25 mm and 1.5 mm (and most preferably between 0.5 mm and 1.2 mm). The overall height of the peg 22 from top to bottom is preferably between 0.4 mm and 0.8 mm (most preferably on the order of 0.6mm), which corresponds to the thickness of the cornea. The thickness of the skirt 21 is preferably on the order of 0.1 mm.

[0046] Figure 4A shows a schematic of the eye where a delamination 40 between layers of tissue in the sclera is formed with a blunt instrument that proceeds into the stroma 13 of the cornea 12. The delamination is formed to essentially provide a tract that is sufficiently deep and wide to accommodate the device 20, with the track being made at a 50% depth through the cornea. Once the tract is formed, a hole 41 (which is preferably equal in diameter to the diameter of the peg 22) is trephined entirely through the cornea such that it transects the tract. This trephined hole 41 is shown in cross-section in Figure 4B. The tract and hole can also be made with a programmable femtosecond laser, as used to create flaps in LASIK, and the track placed precisely in the center thickness of the cornea and the hole at a precise location from the limbus 14.

[0047] Figure 4C shows the device 20 maneuvered into place in the trephined hole 41 and tract 40. The bottom surface 23 of the peg 22 is in fluid contact with fluid in the anterior chamber 7 and the peg 22 extends through the corneal tissue 12. Fluid from within the anterior chamber 7 flows in a regulated manner through the porous polymeric matrix of the peg 22 in the direction of the arrow 43 and exits the top surface 22 of the peg and then wicks along the surface of the cornea 12 and drains into the tear ducts. In this manner, this device 20 can be used to control pressure in the eye as well as to provide lubrication to the cornea to treat dry eye syndrome.

[0048] It was also observed that the top surface 22 of the port 20 must remain congruent with the surface of the cornea as otherwise, if the surface lies below the plane of the cornea; i.e., within the cornea, corneal epithelial cells will grow over the filter and restrict its flow. On the other hand, if the top surface 22 of peg 22 is raised significantly above the cornea, it can irritate the eye lid. It was found that when the top surface 22 of the peg is approximately congruent or slightly raised above the cornea that the eyelid sweeps the surface and prevents epithelial cells from blocking the exit of the device 20.

[0049] Figure 5 shows an actual photograph of a frontal view of a rabbit's eye 54 with the device 20 of Figure 2B implanted therein. For reference purposes, the eye includes pupil 56, iris 57 and limbus 58.

[0050] Although Figures 2 and 5 show a somewhat round design of the device 20, it can be appreciated that the geometry be more crescent-shaped or elliptical to follow the periphery of the limbus and thereby be more aesthetically pleasing.

[0051] Figure 6 shows an alternate embodiment of the present invention where an aqueous humor drainage device 60 is implanted posterior to the limbus in the conjunctival area. The device 60 includes a porous skirt (similar to skit 21 of the embodiment of Figures 2A and 2B) as well as a porous central peg (similar to the peg 22 of the embodiment of Figures 2A and 2B), which can be realized from a porous polymeric matrix as described above. A tube 61 extends from the base of the central peg of device 60, under the limbus and exits in the angle of the anterior chamber. The tube 61 provides a duct for the passage of aqueous humor therethrough. The aqueous humor fluid flows out of the anterior chamber 7 into the upstream end of tube 61 (labeled as 62) and then flow through the porous matrix of the central peg of device 60 in a regulated manner and out the top surface of the central peg and drains to the adjacent conjuctival space. This embodiment of the invention avoids placing the device 60 in the cornea where it may not be as aesthetically pleasing. In a similar embodiment (not shown), the device 60 can be placed just below the conjunctiva such that the conjunctiva acts as a barrier to further prevent bacteria from entering the system. The spaces between the epithelial cells of the conjunctiva are "loose" and therefore fluid can wick through these cells and exit the eye.

[0052] Figures 7A and 7B show still an alternate embodiment of an aqueous drainage device 70 in accordance with the present invention where a porous polymeric matrix 71 as described herein is glued to semi-rigid flange 72. Cadaver tissue 73 (which is typically realized from the cornea, sclera or pericardium) is placed below flange 72 and is secured in place with ring 74. Ring 74 can be threaded onto the lower section of flange 72 or it can be made to snap in place. The cadaver tissue 73 can be sutured to a hole in the cornea or conjunctiva where healing between the cadaver tissue 73 and the patient's natural tissue occurs with time. In this manner, the porous matrix 71 is interfaced with live tissue via cadaver tissue 73. Semi-rigid flange 72 can be made from SIBS with a higher styrene content than the porous matrix 71 or it can be made from polymethylmethacrylate, polycarbonate, polyurethane and the like.

[0053] It is also anticipated that the present invention can be used with an antimicrobial agent loaded into the porous polymeric matrix as described herein. The antimicrobial can be contained within the polymer component of the drainage device and elute out with time. Alternatively, the antimicrobial can be in the pores of the device and elute with time. Still alternatively, the antimicrobial can be attached to the surface of the pores and function to kill bacteria and the like. Exemplary antimicrobials include oligodynamic metals and metal ions such as Ag, Zn, Ba, Cu, Fe, either as ions with counter ions (sulfites, sulfates, nitrates, chlorides, etc.) or as nano-particles or colloids, and the like. These oligodynamic metals can be augmented in their activity by combining them with organic and inorganic acids, such as citric acid, malic acid, maleic acid, boric acid and the like. In addition, antibiotics can be incorporated into the porous polymeric matrix to accomplish same.

[0054] There have been described and illustrated herein several embodiments of glaucoma implant devices that divert aqueous humor from the anterior chamber of the eye and surgical methods associated therewith. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise.

[0055] Thus, while particular methods of manufacture have been disclosed, it will be understood that other manufacture methods can be used. For example, because the copolymer materials described herein have a thermoplastic character, a variety of standard thermoplastic processing techniques can be used to for the devices described herein. Such techniques include compression molding, injection molding, blow molding, spinning, vacuum forming and calendaring, and extrusion into tubes and the like. Such devices can also be made using solvent-based techniques involving solvent casting, spin coating, solvent spraying, dipping, fiber forming, ink jet techniques and the like. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.

Claims

What is claimed is:

1. An apparatus for relieving pressure in an eye, comprising: a structure realized from a porous polymeric matrix that provides for regulated flow of aqueous humor therethrough.

2. The apparatus of claim 1, wherein: said polymeric matrix has a Shore hardness between 5A and 9OA.

3. The apparatus of claim 1, wherein: said polymeric matrix has pore sizes in a range from 0.01 μm to 10 μm.

4. The apparatus of claim 1, wherein: said polymeric matrix is microporous.

5. The apparatus of claim 1, wherein: said polymeric matrix comprises polyisobutylene.

6. The apparatus of claim 1, wherein: said polymeric matrix is loaded with one or more drugs.

7. The apparatus of claim 6, wherein: said one or more drugs include an antimicrobial agent.

8. The apparatus of claim 1, wherein: said structure comprises a generally disc-shaped skirt and a central portion extending downward from said skirt, wherein at least said central portion is realized from said porous polymeric matrix.

9. The apparatus of claim 8, wherein: said skirt and said central portion are integrated as a unitary piece.

10. The apparatus of claim 8, wherein: said skirt includes a top surface opposite a bottom surface, and said central portion extends above said top surface and extends below said bottom surface.

11. The apparatus of claim 8, wherein: said skirt is realized from said porous polymeric matrix.

12. The apparatus of claim 8, wherein: said skirt is realized from tissue.

13. The apparatus of claim 8, further comprising: attachment means for securing said skirt to said central portion.

14. The apparatus of claim 13, wherein: said attachment means comprises a semi-rigid flange surrounding said central portion and a ring that interfaces to a portion of said flange for mechanically supporting said skirt.

15. The apparatus of claim 1, further comprising: an elongate tube extending from said porous polymeric matrix.

16. A method for relieving intraocular pressure in an ocular environment, said method comprising the steps of: a) providing an apparatus having a structure realized from a porous polymeric matrix that provides for regulated flow of aqueous humor therethrough; b) inserting said apparatus into the ocular environment whereby the structure provides regulated outflow of aqueous humor from the anterior chamber of the eye to thereby relieve intraocular pressure of the eye.

17. The method of claim 16, wherein: said structure comprises a generally disc-shaped skirt and a central portion extending downward from said skirt, wherein at least said central portion is realized from said porous polymeric matrix.

18. The method of claim 17, further comprising: securing said skirt to the ocular environment in order to fixate the apparatus therein.

19. The method of claim 17, further comprising: forming a hole through the cornea of the eye, and positioning the apparatus such that the central portion extends into said hole.

20. The method of claim 19, wherein: the central portion of the apparatus is substantially congruent with the top surface of the cornea of the eye.

21. The method of claim 17, wherein: the apparatus comprises an elongate tube extending from a bottom part of said central portion and into the anterior chamber of the eye through a hole formed in the eye.

22. The method of claim 21, wherein: the hole is formed posterior to the limbus of the eye and the central portion and skirt are positioned below the conjunctiva of the eye.

23. The method of claim 16, wherein: said polymeric matrix has a Shore hardness between 5A and 9OA.

24. The method of claim 16, wherein: said polymeric matrix has pore sizes in a range from 0.01 μm to 10 μm.

25. The method of claim 16, wherein: said polymeric matrix comprises polyisobutylene.

26. The method of claim 16, wherein: said polymeric matrix comprises a polymer loaded with one or more drugs.

27. The method of claim 26, wherein: said one or more drugs includes an antimicrobial agent.