Abstract:
A glaucoma drainage device implant foldable and rollable upon itself for the drainage of aqueous humor in the treatment of glaucoma comprising an episcleral plate having both an upper surface and a lower surface and a drainage tube having one end terminating above the upper surface of the episcleral plate whereby the glaucoma drainage device may be delivered to the implant site through the lumen of a needle or cannula. The glaucoma drainage device implant may further comprise retainers for maintaining the implant in the proper operable position; a terminal collar for retention purposes; and a peripheral rim, inflatable in some embodiments, for improved filtration.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. § 119 (e) of currently pending Provisional Application Ser. No.: 60/178,141 filed Jan. 26, 2000 by the same inventor. 
    
    
     BACKGROUND OF THE INVENTION 
     The glaucoma drainage device of the present invention pertains to devices useful in the treatment of recipients having glaucoma. More particularly, the present invention pertains to a glaucoma drainage device that is implanted in the eye of a recipient that minimizes the size of the incision required to implant the device. 
     Glaucoma is a condition in which the optic nerve is damaged. The optic nerve is damaged due to excessively high intraocular pressure in the eye. Excessive pressure occurs when the aqueous humor, the clear liquid in the eye, does not properly drain from the eye. Regardless of the reasons why the intraocular pressure builds in the eye, if left untreated the excessive intraocular pressure will likely damage the optic nerve and cause irreversible loss of eyesight. 
     A method of treating glaucoma when other less invasive methods of treatment such as drugs do not relieve the excessive intraocular pressures in glaucoma patients is incisional filtration implant surgery. In this type of surgery a tube is inserted through an incision, a sclerostomy, in the sclera of the recipient&#39;s eye. The purpose of implanting the drainage tube is to provide a means for the aqueous humor to drain from the eye and thus alleviate the excessive intraocular pressures. The filtration surgery may involve implanting a drainage tube connected to a plate that acts a reservoir that is drained via the drainage tube. A problem associated with implanting conventional glaucoma drainage devices comprising a plate and a tube is the incision required to deliver the device to the implant site. The more extensive the surgery incision required to implant the device the greater the risks of postoperative infection, inflammation and length of healing time of the surgery implant site. 
     SUMMARY OF THE INVENTION 
     The glaucoma drainage device of the present invention comprises a episcleral plate, foldable and rollable upon itself, and a drainage tube connected to the foldable and rollable plate at one end and free at the other end that may be implanted in a recipient&#39;s eye through an injection delivery system for drainage of aqueous humor for the treatment of glaucoma. The present invention may further comprise a peripheral ridge along the upper surface of the episcleral plate to add volume to the plate for improved drainage; retention rings and bands for maintaining the glaucoma drainage device at its intended and implanted location; and a terminal collar located at or near the free end of the drainage tube for preventing migration of the device into the cornea of the recipient. 
     The present invention will provide an effective treatment for glaucoma by improving postoperative filtration and successful reduction of intraocular pressure. Additionally, the common risks associated with glaucoma incisional surgery to reduce the intraocular pressure in glaucoma patients such as postoperative infection, inflammation and the length of surgery site healing time are all believed to be reduced due to the single injection stab incision associated with the present invention as compared to traditional glaucoma incisional surgery using traditional glaucoma drainage devices requiring more extensive incisions. The device of the present invention is capable of being rolled and folded upon itself so that the entirety of the device may be delivered to the implant site via an injection delivery system such as a needle. The episcleral plate itself is sized and shaped to fit on a recipient&#39;s eye to provide adequate filtering and drainage and yet the entire invention is capable of being delivered to the implant site via an injection delivery system. 
     The episcleral plate may be constructed of silicone or other bio-compatible materials that have proven to be well suited for glaucoma drainage devices. Furthermore, in order to effectuate the rolling and folding capabilities of the present invention so that the required incision in the sclera, a sclerostomy, is optimally minimized to an needle injection-sized incision the episcleral plate may be constructed of a material having a memory of its unfolded shape. The memory of the plate material will work to resist permanent deformity of the plate as a result of folding and rolling the plate upon itself for implantation and also work to ensure the plate returns to its intended shape for a proper fit in the recipient&#39;s eye. Special folding techniques may also be used to ensure minimizing deformation of the device. Still other embodiments may have resilient or inflatable veins appropriately disposed in the device so that the device can open to its desired shape once implanted in the recipient&#39;s eye. 
     Other beneficial and useful aspects of the present invention include having an inflatable rim. An embodiment of the present invention having an inflatable rim may be folded and rolled upon itself with the rim in a non-inflated or deflated state for ease of delivery to the implant site. After insertion into a recipient&#39;s eye at the desired location, the inflatable rim of the present invention may be inflated to provide a ridged wall to add volume to the glaucoma drainage device for better filtration. The rim may be inflated with air, B.S.S. or other fluids. 
     The drainage tube of the present device may be a tube with a passageway therethrough for drainage of aqueous humor from the episcleral plate located and implanted on top of the sclera through an sclerostomy to the anterior chamber. The tube may also incorporate pressure regulation capabilities such as valves whereby aqueous humor is allowed to drain through the drainage tube when the intraocular pressure exceeds a predetermined threshold pressure. The drainage tube may further comprise a passageway for drainage of aqueous humor and a passageway for inflating the inflatable rim of embodiments having an inflatable rim. The combined aqueous humor drainage tube and inflation tube may, individually or in combination, be enveloped in a drainage tube sleeve like other embodiments solely having an aqueous drainage tube. 
     In order to avoid the post operative complication of hypotony due to over filtration, the free end of the aqueous shunting tube implanted in the anterior chamber may be covered with a water impermeable, pigmented membrane. This membrane can either be manually opened with a sharp instrument or melted open with an ophthalmic laser to allow the free egress of aqueous humor from the anterior chamber when deemed appropriate by the surgeon. 
     The drainage tube of the device may also have bands, rings or other retention structures affixed thereto for retaining the drainage tube and the implanted device in the desired location. The retention bands, rings or other structures may be sized and configured to prevent and aid in preventing leakage around the drainage tube. The device may also include a terminal collar. The terminal collar is typically located at or near the end of the drainage tube not connected to the episcleral plate. 
     Another benefit of the present invention is that the device may also be implanted by rolling and folding the device and then feeding the rolled and folded device along a guide wire into the sub-tenon&#39;s space of the recipient&#39;s eye. As with the implantation technique involving passing the rolled and folded device through the lumen of a cannula or needle, the device is delivered to the implant site on the recipient&#39;s sclera while the free end of the tube is in place by the terminal collar and/or retention bands to prevent the tube from migrating into the cornea of the recipient. 
     In addition to the above descriptions and benefits, it is important to realize that the present invention may be implanted using conventional and traditional techniques. The advantage gained is that the conjunctival incision made to accommodate the device can be made much smaller. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top plan view of a preferred embodiment of the present invention; 
     FIG. 2 is an elevational view thereof depicting the inflatable rim, 
     FIG. 2A shows the rim deflated and FIG. 2B shows the rim inflated; 
     FIG. 3 is an elevational view of an embodiment of the present invention; 
     FIG. 4 is a depiction of various drainage tube configurations; 
     FIG. 5 is an embodiment of the present invention adapted for pediatric applications; 
     FIG. 6 is an embodiment of the present invention adapted for superior insertion; 
     FIG. 7 is an embodiment of the present invention having a left-sided plate; 
     FIG. 8 is an embodiment of the present invention having a right-sided plate; 
     FIG. 9 is an embodiment of the present invention having a fenestrated plate; 
     FIG. 10 is a perspective of the preferred embodiment of the present invention; and 
     FIG. 11 is a cross-sectional depiction of the present invention in-situ. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention is optimally implanted into the eye of a glaucoma patient by first rolling and folding the episcleral plate upon itself. The rolled and folded glaucoma drainage device of the present invention is then injected into the recipient&#39;s eye at the desired location through an injection delivery system, e.g. a lumen of a cannula or needle. The scleral incision commonly associated with glaucoma incisional implant surgery is thus virtually eliminated. Instead of an incision, the present invention only requires a needle injection-sized penetration for the delivery and implantation of the device. The preferred embodiment can more fully be understood by referring to the included figures and drawings. FIG. 1 shows a plan view of the device  10 . The episcleral plate  2  and the rim  8  located at the peripheral edge of the plate  2  are clearly shown in FIG. 1. A typical drainage tube  12  is also shown. The length of the drainage tube  12  may vary depending on the physical constraints of the recipient. The drainage tube  12  is shown having one end attached to the episcleral plate  2  and a free end. Looking at the free end, there is shown an opening to drainage passageway  4 . This drainage passageway extends all the way through the drainage tube  12 . 
     FIG. 4B depicts one embodiment of the drainage tube  12  having a manually penetratable impermeable membrane  30  occluding the free end of the drainage tube  12 . 
     The rim  8  of the preferred embodiment is inflatable. It may be inflated with a liquid or a gas, including air. The FIG. 2A depicts the rim inflated while  2 B shows it deflated. The drainage tube  12  may have a single drainage passageway  4  or also, in combination or alone, have a passageway  6  leading to the inflatable rim  8  for inflation of the rim  8 . 
     The drainage tube  12  of the preferred embodiment also has a terminal collar  14  located near the free end of the drainage tube  12 . The terminal collar  14  is affixed to the drainage tube  12  for retaining and maintaining the drainage tube in the proper and desired implantation location. It is vitally important to the post-operative success and effectiveness of the glaucoma incisional implant surgery that the glaucoma drainage device is maintained in the intended implanted position in the recipient&#39;s eye. 
     The FIGS. 5 through 9 each depicts other embodiments of the device of the present invention. FIG. 5 is an embodiment of the present invention adapted for pediatric applications. In order to accommodate the reduced anatomy of the pediatric eye, the implant may be downsized. The implant is downsized in all regards with the exception of the drainage tube  12 . The surface area, as well as the shape of the episcleral plate  2  may accordingly be changed in order to safely implant the device between the extraocular muscles in order to minimize the affect on eye mobility and possible strabismus. 
     FIG. 6 is an embodiment of the present invention adapted for superior insertion. This embodiment of the present invention having an episcleral plate  2  area and shape as shown may be advantageous when restrictions caused by preexisting scar tissue or anatomy necessitates the implantation of the device directly in-line with the insertion of anyone of the extraocular recti muscles. This embodiment will allow the episcleral plate  2  to “straddle” the muscles without impinging on the muscles activity while still maintaining adequate surface area for filtration. The indentation shape and depth on the posterior border of the episcleral plate  2  may be of variable design to accommodate the various extraocular recti muscle insertions (i.e. right medial rectus muscle, left superior rectus muscle, etc.). This embodiment may also be scaled down for pediatric applications. 
     FIG. 7 is an embodiment of the present invention having a left-sided plate while FIG. 8 is an embodiment of the present invention having a right-sided plate. The FIG. 7 embodiment of the present invention may be accomplished in circumstances where the implant must be positioned such that the episcleral plate  2  lies substantially to the left of the drainage tube  6  adjoined to the episcleral plate  2 . Alternately, the FIG. 8 embodiment of the present invention may be accomplished in circumstances where the implant must be positioned such that the episcleral plate  2  lies substantially to the right of the drainage tube  12  adjoined to the episcleral plate  2 . In both the left-sided and the right-sided plate configurations, the episcleral plate  2  may be easily folded or rolled upon itself to facilitate implantation into a recipient&#39;s eye by rolling the episcleral plate  2  starting at one end of the plate and rolling the episcleral plate  2  towards the other end. This embodiment too may be downsized to accommodate pediatric use. 
     FIG. 9 is an embodiment of the present invention having a fenestrated plate, i.e. the episcleral plate  2  has apertures located therein. All embodiments of the glaucoma drainage device of the present invention may be modified to further comprise holes located in the episcleral plate  2  as illustratively shown in FIG.  9 . The apertures  16  and  18  facilitate maintaining the present invention in its desired location after implantation. The positioning may be accomplished through an.intact conjunctiva with a manipulating instrument or may be accomplished through small conjunctival incisions. The episcleral apertures may also be used to secure the episcleral plate  2  in position with sutures or other surgical tissue fasteners. Although the episcleral plate  2  in FIG. 9 has two apertures, namely  16  and  18 , other embodiments may have more or less than two apertures. The apertures may vary in number, size and shape—even within a given episcleral plate design to accommodate the potentially variable circumstances encountered during glaucoma drainage device implantation surgery. The apertures in the FIG. 9 extend through the entire thickness of the episcleral plate  2 . The apertures may however only extend partially into a surface of the episcleral plate  2  in other contemplated embodiments of the present invention. 
     The FIG. 11 shows the present invention device in a typical implant application. The device is implanted through an injection-sized scleral incision  26 . The episcleral plate  2  is situated atop the sclera  24  beneath the tenon&#39;s capsule  28 . The drainage tube  12  extends from the episcleral plate through the sclerostomy to provide fluid communication to the anterior chamber of the recipient&#39;s eye for drainage of aqueous humor to relieve intraocular pressure in the recipient&#39;s eye. The terminal collar further retains and maintains the drainage tube of the device in the proper implanted position. 
     While the invention has been described and illustrated with reference to specific embodiments thereof, it is understood that other embodiments may be resorted to without departing from the invention. Therefore the form of the invention set out above should be considered illustrative and not as limiting the scope of the following claims.