FIELD AND BACKGROUND OF THE INVENTION
The present invention relates generally to the field of glaucoma treatment devices and in particular to a new and useful implantable glaucoma shunt for relieving internal pressure in a patient's eye. The new glaucoma shunt has a foldable plate and reservoir which permit the shunt to be injected into a patient's eye using a cannula.
Implantable glaucoma shunts are known which require more extensive surgery or require the shunt to be sutured into place on the patient's eye. Other shunts are simply cylinders which are injected nearly perpendicularly into the patient's eye and held by frictional fit by eye tissue.
U.S. Pat. No. 5,127,901 teaches an ophthalmic implant for draining aqueous humor from the anterior chamber of the eye having a transcleral conduit having an inlet opening at one end thereof for communicating with the anterior chamber of an eye, and an outlet opening at an opposite end of the conduit for draining fluid from the anterior chamber. An elongated arch shaped subconjunctival channel is connected to the conduit and has an inlet opening into the channel for communicating with the outlet opening of the conduit, the channel having an outlet openings for discharging fluid from the conduit, subconjunctivally over the sclera of the eye. A one-way flow resisting valve is provided in the conduit for allowing a flow of fluid to pass under resistance and in only one direction from the inlet to the outlet of the conduit, whereby pressure in the anterior chamber is relieved while avoiding excessive outflow of fluid from the anterior chamber.
The shunt of U.S. Pat. No. 5,127,901 is not foldable, however and must still be implanted into a patient's eye using surgical cutting techniques.
Other glaucoma shunts include U.S. Pat. No. 5,743,868, for example, which discloses a cylindrical drainage tube which can be injected through the surface of a patient's cornea. The tube is formed from a hollow rigid cylinder surrounding a porous core layer. The device is simply pushed into place using a plunger implant mechanism and positioned so that the exterior end is substantially flush with the surface of the cornea. The device lacks any wings or means for securing the device underneath the conjunctiva or sclera.
A plunger device for implanting cylindrical glaucoma drains is taught by U.S. Pat. No. 5,893,837. The device is placed at the end of the plunger for insertion through eye tissue. The glaucoma devices inserted using the plunger do not have wings or reservoir flaps.
U.S. Pat. No. 5,752,928 teaches a glaucoma device having a reservoir plate made of a flexible material, such as silicone rubber. The device is implanted through an incision in the eye followed by suturing the incision.
U.S. Pat. No. 5,178,604 is for a glaucoma implant having a flexible elastomeric plate. The plate is curved to conform to the curvature of a person's eye. The plate is inserted through an incision into a position beneath the portion of the eye known as Tenon's capsule and over the sclera. The plate is sutured to the sclera. The plate can be folded to permit a smaller incision in the eye. A preferred material for the plate is silicone elastomer. The Baerveldt '604 patent does not teach injecting the device into place and no provision is made for securing the device without sutures until after tissue has grown around the device.
A continuation-in-part patent, U.S. Pat. No. 5,397,300, discloses a similar device. The glaucoma device in U.S. Pat. No. 5,397,300 also has a flexible plate. The plate has at least one through hole to permit the growth of scar tissue to assist holding the plate in position following suturing during the implant procedure.
A laser is taught for use in making the incision for implanting a glaucoma device in U.S. Pat. No. 5,626,558. The device has a plate connected to the exterior end of a tube forming the body of the device. The plate may be sutured to the sclera to hold the device in place after insertion.
U.S. Pat. No. 5,370,607 teaches an implant device having a pair of wings extending from a reservoir around the body of a person's eye. The device is inserted through an incision and sutured into place. A tab positioned between the reservoir and the drainage tube in the center of the reservoir between the wings is used to suture the device in place. The wings are used to stabilize the placement of the device underneath the ocular muscles.
U.S. Pat. No. 4,554,918 shows a glaucoma device having a reservoir with a flat attachment plate having holes therethrough for receiving sutures or permitting tissue ingrowth. The plate is preferably made of silicone rubber, polymethyl methacrylate polymer or other similar polymers, among other compositions. A pair of flat rectangular fins extending from the sides of the tube are used to secure the device to the sclera beneath a small flap.
The prior glaucoma shunt devices are either simple tubes or ports injected directly through the eye, rather than implanted below the conjunctiva, or require tissue cutting, extensive tissue manipulation and suturing to successfully implant the device below the conjunctiva.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a glaucoma shunt which can be implanted in a patient's eye using minimally invasive surgery techniques.
It is a further object of the invention to provide an implantable glaucoma device which does not require sutures to hold the device in position once the device has been implanted in a patient's eye.
Accordingly, a new glaucoma device is provided comprising a foldable aqueous tube shunt implant for injecting below the conjunctiva of a patient's eye via a hollow cannula. The device is used to drain aqueous humor from the anterior chamber of a person's eye to help control glaucoma and intraocular pressure.
The device has an internal ostium with a flared lip at one end of a shaft having a flattened wing extending to the sides. A foldable plate and reservoir are provided at the other end of the shaft and connected to an external ostium of the shaft. The flattened wing presents a flat surface to the overlying conjunctiva and helps position the device when used.
The device is preferably made of silicone or acrylic so that the entire implant is foldable and may be rolled up for insertion via the cannula.
Since the entire implant device may be folded and injected into place within a person's eye, the implant can be implanted using a cannula following laser sclerostomy in a minimally invasive procedure and without incisional surgery. Sutures are not needed to hold the implant in place once it has been injected into position. The lip on the inner ostium holds the device in place.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.