Surgery – Instruments – Corneal cutter or guide for corneal cutter
Reexamination Certificate
1997-12-18
2001-05-15
Buiz, Michael (Department: 3731)
Surgery
Instruments
Corneal cutter or guide for corneal cutter
Reexamination Certificate
active
06231582
ABSTRACT:
FIELD OF THE INVENTION
This invention involves a surgical instrument for intracorneal pocketing. The handheld surgical tool is typically inserted into a corneal incision and maneuvered to create a corneal pocket. This invention also provides a method for creating an intracorneal pocket.
BACKGROUND OF THE INVENTION
Anomalies of the overall shape of the eye often cause appreciable visual disorders, such as hyperopia, myopia, and astigmatism. The surgical treatment of these and other disorders often involve creating a separation or pocket between the stromal layers of the cornea. Various materials, substances, or inserts may be placed within the pocket to effectuate changes in the geometry of the cornea or deliver drugs or other biologic agents.
For example, these disorders may be corrected using surgical methods involving the implantation of polymeric rings (intrastromal corneal rings) in the eye's corneal stroma to change the curvature of the cornea. Previous work involving the implantation of polymethylmethacrylate rings, allograft corneal tissue, and hydrogels is well documented. One of the ring devices involves a split ring design which is inserted into a pocket in the form of an annular channel dissected in the stromal layer of the cornea. See, for instance, the use of intrastromal rings in U.S. Pat. Nos. 4,452,235 to Reynolds; 4,671,276 to Reynolds; 4,766,895 to Reynolds; and 4,961,744 to Kilmer et al. Temirov et al., “Refractive circular tunnel keroplasty in the correction of high myopia”, Vestnik Oftalmologii Mar. 21-31, 1991 suggests the use of collagen thread as intrastromal corneal ring material.
It is also known to use arcuate channels containing a gel-based insert centered on the cornea to correct certain visual disorders. U.S. Pat. Nos. 5,090,955 and 5,372,580, to Simon, suggest introducing a settable polymer or gel into an intrastromal channel and allowing the polymer to set.
These types of procedures typically involve making a partial depth incision into the cornea, either radial or circumferential, and then separating the lamella at a known depth. The separation may be continued or furthered, using a variety of instruments as necessary, until the desired channel or pocket is formed at the desired depth below the surface of the cornea. In U.S. Pat. No. 5,547,468 to Simon et al., for example, once the incision has been formed, a blunt spatula is inserted through the incision to separate the lamella. Following this initial separation of lamella with the blunt spatula, a channel starting instrument is inserted into the incision and then rotated in a manner such that the lamella is separated along an arcuate path.
Creation of the initial separation using an ordinary blunt spatula is often very difficult. There is little visual access to the tip of the instrument at the base of the incision and it may be difficult for the surgeon to feel the bottom of the incision. Improper placement or inadequate manipulation of the instrument by the surgeon may result in an initial separation at the wrong depth relative to the surface of the cornea or no separation at all. Excessive manipulation of the spatula in attempting to initiate the separation at the base of the incision may result in damage or trauma to the incised tissue as well as the tissue below the incision.
There is a need therefor for a pocketing tool constructed to provide a reliable lamella separation at the desired depth below the surface of the cornea which is less sensitive to manipulation difficulties inherent in prior art instruments.
SUMMARY OF THE INVENTION
This invention is a surgical instrument for separating the lamella of a cornea. The instrument has a dissector and a reference region adapted to contact the surface of the cornea. In one aspect of the present invention, the dissector is disposed at an angle relative to said reference region of between about 30° and about 150°, preferably less than about 110°.
The reference region may comprise a planar surface or a curved surface. If the reference region is configured to have a curved surface, it will typically have a radius of curvature in the range of about 6 mm to about 10 mm.
As the dissector is inserted into the incision, the free advancement of the dissector is prevented once the reference surface comes into contact against the surface of the cornea.
The reference region and the dissector, being disposed in an angular relation to one another, converge at an intersection. The instrument handle may then be manipulated to cause the dissector to rotate about a point near the intersection. The intersection of the reference region and the dissector may take the form of a radius or radiused surface. The radius in conjunction with the reference region provide a suitable pivot about which the dissector may be rotated to initiate the desired separation at the dissector tip.
The present invention also involves a method of creating an intrastromal separation or pocket at the base of a partial-depth corneal incision involving inserting an instrument having a reference surface in angular relation to a dissector until the reference surface contacts the surface of the cornea and rotating the instrument about the vertex of the intersection of the reference region and the dissector.
The above is a brief description of some deficiencies in the prior art and advantages of the present invention. Other features, advantages, and embodiments of the invention will be apparent to those skilled in the art from the following description, accompanying drawings and appended claims.
REFERENCES:
patent: 4452235 (1984-06-01), Reynolds
patent: 4573998 (1986-03-01), Mazzocco
patent: 4655774 (1987-04-01), Choyce
patent: 4671276 (1987-06-01), Reynolds
patent: 4766895 (1988-08-01), Reynolds
patent: 4961744 (1990-10-01), Kilmer et al.
patent: 5090955 (1992-02-01), Simon
patent: 5163934 (1992-11-01), Munnerlyn
patent: 5222967 (1993-06-01), Rae et al.
patent: 5372580 (1994-12-01), Simon et al.
patent: 5405355 (1995-04-01), Peyman et al.
patent: 5411510 (1995-05-01), Fugo
patent: 5547468 (1996-08-01), Simon et al.
patent: 5607437 (1997-03-01), Simon et al.
patent: 5653725 (1997-08-01), Simon et al.
patent: WO 95/17144 (1995-06-01), None
patent: WO 97/04726 (1997-02-01), None
patent: WO 98/46192 (1998-10-01), None
Temirov et al. “Refractive circular tunnel keratoplasty in the correction of high myopia”Vestnik Oftamologii(1991) 3:21-31.
Gandianco Isidro
Scholl John A.
Buiz Michael
Ho (Jackie) Tan-Uyenn T.
KeraVision Inc.
KeraVision, Inc.
Macey Harry
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