Surgery – Instruments – Cutting – puncturing or piercing
Reissue Patent
1999-07-29
2001-07-31
Buiz, Michael (Department: 3731)
Surgery
Instruments
Cutting, puncturing or piercing
C606S166000
Reissue Patent
active
RE037304
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a surgical knife blade of the type primarily intended for making incisions in the eye, as for a clear corneal incision. The cutting edges of the blade are defined by the intersection of bevels formed on the blade's anterior surface and posterior surface, with the plane of the bevels with respect to the anterior and posterior surfaces being non-symmetrical.
2. Description of the Prior Art
Numerous prior art devices and blades are known for making incisions in the eye. Since the cornea and sclera are spherical, any blade penetrating their surface at an angle other than 90° will produce an irregular, or curved, incision line resembling a “smile.” Ophthalmic surgeons have struggled with this problem for years, since curvilinear incisions are less likely to reapproximate as quickly, are less efficient, and are much less likely to create a suture-less water-tight seal. In an attempt to create substantially linear, perpendicular incisions, surgeons find themselves applanating the globe of the eye in an attempt to flatten it out, and invariably “dimple down” as soon as the tip of the blade reaches Descemet's membrane. However, problems are created with this “dimpling down” procedure in that this requires the surgeon to lift the back of the blade upwardly in order to point the tip of the blade downward. This maneuver causes the tissue in the corners of the external incision to tip, compromising its water-tight integrity and creating stromal distortion in the path of the tunnel. Lifting the back of the blade also increases the angle of the cut, making it less tangential to the circumferential arc of the cornea. This results in a reduced valve sealing surface area, further comprising water-tight integrity. In an attempt to compensate for this tearing of tissue, surgeons hydrate the corners of the incision. When a conventional flat blade enters a spherical object at an angle, as when making a clear corneal incision, it is the fact that the shoulders of the blade enter the globe closer to the center than the tip that produces the curved, “smile” incision.
While the phenomenon described above is certainly well-known and recognized when one attempts to incise the surface of a spherical member such as the eye, the producing of a curved incision derives most directly from the fact that state-of-the-art blades are typically symmetrical when the anterior surface is compared to the posterior surface. For example, U.S. Pat. No. 5,376,099 to Ellis, et at., discloses an undercut diamond surgical blade. However, when the bevels forming the cutting edges on the anterior surface of the blade are compared with the bevels on the posterior surface of the blade, one immediately recognizes that the bevels are identical. A similar construction is taught in U.S. Pat. No. 5,336,235 to Myers, even though the blade of that invention is slightly curved with respect to its major longitudinal axis.
The ophthalmologic surgical instrument disclosed in U.S. Pat. No. 4,688,570 to Kramer, et al., teaches the use of a cutting blade which is also quite symmetrical when the bevels of one surface of the blade are compared to the bevels on the other surface, those bevels defining the blade's cutting edge.
A variety of blade configurations are disclosed in U.S. Pat. No. 5,098,438 to Siepser, but the blades of that patent have bevels on only one of the blade surfaces.
While the blade disclosed in U.S. Pat. No. 5,201,747 to Mastel is shown as having three cutting edges, the bevels defining those cutting edges on the opposed surfaces of the blade are identical.
The blades disclosed in U.S. Pat. No. 5,203,865 to Siepser are virtually identical to those disclosed in the Siepser '438 patent.
A surgical blade similar to the Siepser blades in that bevels are provided on only one blade surface is taught in U.S. Pat. No. 5,370,652 to Kellan.
Finally, U.S. Pat. No. 5,217,476 to Wishinsky and U.S. Pat. No. 5,224,950 to Prywes each disclose surgical knife blades primarily for use in eye surgery wherein the cutting edges are defined by identical bevels on both surfaces of their respective blades.
It is, therefore, clear that there remains a great need in the art for a surgical knife blade capable of making a straight, linear incision to create a self-sealing clear corneal incision without having to “dimple down” into Descemet's membrane, with the increased risk of tearing tissue at the edges of the incision as is almost always encountered using the blades available today.
SUMMARY OF THE INVENTION
The present invention relates to a surgical knife blade of the type primarily intended for making incisions in the eye. While the blade may be formed from any suitable material such as, for example, precious or semi-precious stones and man-made equivalents thereof, steel, glass, or ceramics, the blade of this invention preferably comprises a diamond. The structure of the blade in a preferred embodiment comprises an elongated body having proximal and distal ends, anterior and posterior opposing surfaces, a shoulder intermediate the proximal and distal ends, first and second longitudinal sides between the proximal end and the shoulder, and first and second cutting edges between the shoulder and the distal end. The first and second cutting edges are formed by the intersection of first and second anterior bevels on the anterior surface with opposed first and second posterior bevels on the posterior surface. In this preferred embodiment the first and second anterior bevels are shorter at the distal end and longer at the shoulder. As used herein, the words “short” and “long” refer to the transverse dimension of the plane defined by the beveled surfaces with regard to the corresponding planar surface of the respective anterior and posterior surfaces. That is to say, the cutting edges formed by the intersection of the first and second anterior bevels with their corresponding first and second posterior bevels are closer to the plane of the anterior surface at the distal end and farther from that same plane at the shoulder.
The opposed first and second posterior bevels formed on the posterior surface are longer at the distal end, and shorter at the shoulder. Thus, as stated above, the cutting edges are farther from the plane of the posterior surface at the distal end and closer to that same plane at the shoulder.
The first and second longitudinal sides are formed by the intersection of third and fourth anterior bevels on the anterior surface with opposed third and fourth posterior bevels on the posterior surface. The third and fourth anterior bevels are substantially equal in length to the length of the first and second anterior bevels at the shoulder, and the third and fourth posterior bevels are substantially equal in length to that of the first and second posterior bevels at the shoulder. Thus, as is clearly illustrated and more fully described below, the third and fourth anterior bevels are relatively longer than the third and fourth posterior bevels.
In a first preferred embodiment, the first and second longitudinal sides of the blade of this invention are substantially parallel. In a second preferred embodiment, the first and second longitudinal edges diverge outwardly from the shoulder to the proximal end.
In this second preferred embodiment, the third and fourth anterior bevels become longer along a longitudinal axis from the shoulder to the proximal end, and the third and fourth posterior bevels become shorter along that same longitudinal axis.
The invention accordingly comprises an article of manufacture possessing the features, properties, and the relation of elements which will be exemplified in the articles hereinafter described, and the scope of the invention will be indicated in the claims.
REFERENCES:
patent: 4688570 (1987-08-01), Kramer et al.
patent: 5098438 (1992-03-01), Siepser
patent: 5201747 (1993-04-01), Mastel
patent: 5203865 (1993-04-01), Siepser
patent: 5217476 (1993-06-01), Wishinsky
patent: 5222967 (1993-06-01), Case
Bee John A.
Van Heugten Anthony
Baker & Botts L.L.P.
Buiz Michael
Rhein Medical, Inc.
Truong Kevin
LandOfFree
Surgical knife blade does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Surgical knife blade, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Surgical knife blade will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2475629