Surgery – Instruments – Cutting – puncturing or piercing
Reexamination Certificate
1998-09-16
2001-07-24
Thaler, Michael H. (Department: 3731)
Surgery
Instruments
Cutting, puncturing or piercing
C606S166000, C606S184000, C606S004000, C600S567000
Reexamination Certificate
active
06264668
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an instrument for producing a fistula in a tissue wall of a patient, and more particularly to a fistula in the sclera in the eye of the patient. The instrument is denoted as a trabeculectomy probe.
The instrument is applicable to the formation of such a fistula to relieve intraocular pressure in the anterior chamber of the eye of a patient suffering from glaucoma.
BACKGROUND
Glaucoma is a disease where the intraocular pressure is elevated. It affects significant numbers of our population. The treatment of glaucoma is usually medical, however, medications often fail to control some forms of glaucoma. When further treatment is required a microsurgical operative procedure is performed. This procedure involves constructing a fistula or opening in the tissue wall of the sclera to enhance fluid flow from the internal portion of the eye (ciliary body) which secretes the fluid (aqueous humor) through the newly formed opening. This opening is typically made in a cutting type of procedure. This involves incising the external ocular tissues (conjunctiva) and dissecting the scleral tissues. This dissection results in attendant risks including bleeding, and development of extremely low intraocular pressure or hypotony. Post operative care is prolonged due to the large size of the scleral incisions, the possibility of complications and variability in wound healing. The procedure is generally referred to as a filtering operation, as a trabeculectomy, sclerectomy or lamellar scleral flap procedure. In a so-called full thickness fistulization procedure, a hole of a diameter of 2-4 mm is formed through the sclera. In a so-called partial thickness fistulization, an opening in the form of a slit of 100-300 microns extends through the tissue wall into the anterior chamber and an ostium or aperture of 2-4 mm extends from the slit at the posterior surface of the tissue wall. The trabeculectomy, partial thickness sclerectomy or fistulization, has become the prevalent procedure since a valve effect occurs when a partial thickness aperture is present. Many of the immediate post operative complications of surgery are reduced by the more controlled outflow achieved by this type of surgery.
Recently, lasers have been used to perform fistulizing procedures. These laser procedures are currently used to produce a full thickness fistula by a procedure referred to as laser sclerostomy. This has been performed with holmium, YAG, erbium and other laser penetrating means. In the current mode, (ab externo), a small incision is made after a subconjunctival injection of air or other fluid has been introduced into the subconjunctival space. This fluid allows the laser probe to pass beneath the conjunctival tissue without “button-holing” the tissue. The laser probe is then introduced into the subconjunctival space. The probe is advanced to the sclera proximal to the limbal area of the eye. The laser energy is directed from the laser probe toward the sclera until the energy produces a fistula through the full thickness of the sclera. Once this occurs the laser probe is removed and the initial conjunctival incision is sutured and the procedure is complete.
In the ab interno version of filtering surgery, laser energy is aimed using a contact lens (goniolens) to produce a full thickness opening in the sclera. A mechanical method of producing a fistula using a rotating, cutting blade (trabecuphine) also results in a full thickness opening.
The ab interno fistulizing surgery, by lasers or cutting, suffers, in its present state, from several disadvantages. Ab externo laser surgery has produced only full thickness fistulas. This results in attendant problems with hypotony, choroidal effusion, choroidal hemorrhage and shallowing of the anterior chamber of the eye. The fistula also frequently closes. Modifications of the procedure employ either intra-operative or post-operative injections of anti-scarring agents (antimetabolites) to improve the results. The small size of the fistula (100-300 microns) may be an advantage for controlling fluid flow, but the long term success of such small fistulas may be temporary since they scar down more easily than the larger (2-4 mm) fistulas in guarded filtering surgery (trabeculectomy) by cutting. Larger fistulas in a full thickness procedure (sclerectomy, thermal sclerostomy) produce a greater frequency of complications than guarded procedures.
SUMMARY OF THE INVENTION
The invention addresses the problems of producing a partial thickness fistula, with and without separate conjunctival injections, or post operative injections. The invention provides an instrument to produce a controlled outflow fistula (trabeculectomy). It allows the surgeon to use the same instrument to produce a lamellar scleral flap and a partial thickness fistula without requiring the sequential use of separate cutting implements. The scleral flap is created and made of the proper depth without the use of a forceps. No suturing of a trabeculectomy flap is necessary. The use of adjunctive antimetabolites (Mitomycin C. etc.) is given intra-operatively transconjunctivally prior to the introduction of the instrument in the ab interno and ab externo methods, and through the operative conjunctival incision in the ab externo method.
The instrument may be used in the ab interno or ab externo modes. In one embodiment using an external sub-conjunctival approach, irrigation into and aspiration out of the wound of antimetabolites or other fluids, such as viscoelastics which elevate the subconjunctival space prior to the introduction of the instrument may be employed.
The invention provides an instrument which is a multifunction device that simplifies the procedure which presently requires a larger wound, multiple instruments and an operating room with anesthesia. This simplified procedure may be performed with topical anesthesia alone in an ophthalmologist's office. It may be possible for tissue glues to be used to close the small incision without sutures in the ab externo technique. The ab interno technique is performed using a corneal incision (paracentesis) which is made in a self-sealing fashion, requiring no sutures for wound closure.
The instrument according to the invention is referred to as a trabeculectomy probe, comprises a housing, a blade supported in said housing for extending from the housing to penetrate the tissue wall of a patient and produce an incised slit in said tissue wall forming an opening or tunnel therein. The blade can be utilized to form a scleral flap at the anterior surface of the tissue wall. The housing additionally carries a fistula-forming means for entering said slit, while the blade remains in the slit, to excise tissue from a posterior portion of said wall which bounds the slit to produce an ostium or opening at the posterior surface of the tissue wall to complete the fistula in said tissue wall.
The fistula-forming means can be a laser generating means for producing a tissue-cutting laser beam, or a second blade or a punch.
The probe may further include irrigation and aspiration channels which have respective separate ports connectable to irrigation and aspiration sources.
In the ab interno mode using a second blade as the fistula-forming means, a subconjunctival injection is used to elevate the conjunctiva to avoid penetration of the conjunctiva by the blade penetrating the sclera. The housing is introduced through a corneal incision. The first blade is flat and makes the corneal incision as well as the scleral incision, distal to the corneal incision, to form the opening in the tissue wall as a through slit. The second blade is curved and shaped as a scoop and is displaceable relative to the first blade to be fully advanced to press against an opposed, flat, non-cutting undersurface of the first blade. When fully advanced, the scoop-shaped blade excises a defined section of the sclera or the trabecular meshwork at the posterior surface of the tissue wall to form the ostium. When the probe is removed, the procedure is complete.
In the ab ex
Ladas & Parry
Thaler Michael H.
Woo Julian W.
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