Surgery – Instruments – Corneal cutter or guide for corneal cutter
Reexamination Certificate
1998-09-30
2001-01-09
Buiz, Michael (Department: 3731)
Surgery
Instruments
Corneal cutter or guide for corneal cutter
C606S167000
Reexamination Certificate
active
06171324
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of the invention relates to medical marking devices for marking the eye prior to surgery, and a method of using a medical marking device to make a incision of a predetermined length and width.
2. Brief Description of the Prior Art
Medical marking devices have been developed for various surgical operations which involve making incisions in the eye. The marking devices are used prior to surgery, and provide markings to assist the surgeons in correctly locating the areas of the eye on which a keratome or other surgical knife is to be employed. Such devices function by leaving depressions in the eye or sets of ink marks. In either case, the markings identify the locations where incisions are to be made and/or sutures are to be placed.
Cataract extraction and lens implantation surgery is a commonly employed procedure. The techniques for performing such surgery have evolved over the years to the point where suturing the wound is often unnecessary. One procedure for conducting cataract surgery involves making an incision through both scleral and corneal tissue. Such a procedure for constructing a self-sealing incision during cataract surgery is described in the literature.
1
This procedure involves the use of a marker to create a grid of dots following cautery to allow selection of incision length and location. A perpendicular scleral groove is formed at the appropriate dots, followed by dissection of a scleral tunnel into clear cornea. The incision is complete when the selected keratome enters the anterior chamber. A more recent technique, called the clear corneal approach, is said to offer significant advantages over the above-described scleral approach. Whereas the scleral approach involves an incision through both scleral and corneal tissue, the primary incision is made substantially only through corneal tissue using the clear corneal approach. (The primary incision is used to remove the cataractous lens tissue and insert an intraocular lens.) Also, topical anesthesia may be used when employing the clear coneal approach.
Advantages of the clear corneal approach include faster patient visual recovery, the use of topical anesthesia, no subconjunctival hemorrhage, no cautery, and better refractive results. Selective location of the primary incision has also been said to allow correction for preoperative against-the-rule astigmatism.
The formation of a leak-proof, sutureless incision is desirable whether the scleral or clear corneal approach is employed. The risk of infection is believed to be significantly reduced if leakage can be avoided.
A corneal incision consists essentially of a tunnel created by a scalpel. The tunnel is composed of a “roof” and a “base”. A corneal flap is formed at the distal end of the tunnel base. It is this flap that is pressed against the tunnel roof by intraocular pressure that actually seals the incision. A number of ophthalmologists have conducted research in developing the appropriate corneal incision architecture that would provide a reliable, leak-proof seal. The results of this research indicate that the tunnel length (i.e., the distance from the initial entry site to the tip of the corneal flap) is an important factor in determining the sealability of the incision.
2
A specific recommendation made by surgeons who have employed the clear corneal approach is to create an incision that has a maximum width to length ratio of about three to two.
SUMMARY OF THE INVENTION
The present invention is directed to a corneal marker which allows the length and width of an incision to be controlled within predefined limits. A method of making an incision in eye tissue of selected length and width is also provided.
In accordance with the invention, a corneal marker is provided which includes a handle and a head coupled to the handle. The head includes first, second, third, and fourth marking surfaces positioned for substantial simultaneous engagement of a human cornea. The first marking surface includes an elongate edge portion and is in opposed relation to the fourth marking surface. The second and third marking surfaces include elongate edge portions and are in opposed relation to each other along a second axis running perpendicular to the first axis. The marking surfaces define a generally rectangular outline wherein the width of the outline is about one and one-half times the length of the outline. The width of the outline is defined by the distance between the second and third marking surfaces and the length of the outline is defined by the distance between the first and fourth marking surfaces. The distance between the second and third marking surfaces is preferably but not limited to between about 2.0 and about 3.5 millimeters.
In further accordance with the invention, a corneal marker is provided which includes a handle, a head coupled to the handle, the head including a superior surface, an inferior surface, a front surface, and a rear surface. The rear surface is substantially arcuate to match the contour of the corneoscleral junction. First, second, third, and fourth protuberances extend from the inferior surface of the head. The protuberances include edge portions defining first, second, third, and fourth marking surfaces, respectively. The first protuberance adjoins the rear surface of the head and includes an arcuate edge portion defining the first marking surface. The fourth protuberance is in opposing relation to a central portion of the first protuberance along a first axis. The second and third protuberances are in opposing relation to each other along a second axis running perpendicular to the first axis. The distance between the second and third marking surfaces is between about 2.0 and about 3.5 millimeters. The distance between the first and fourth marking surfaces is less than the distance between the second and third marking surfaces. Preferably, the distance between the second and third marking surfaces is no more than fifty percent (50%) greater than the distance between the first and fourth marking surfaces.
A method is provided by the invention which includes the steps of marking the surface of an eye to provide first, second, third, and fourth markings thereon such that the first and fourth markings are in opposing relation along a first axis and the second and third markings are in opposing relation along a second axis running substantially perpendicular to the first axis. The distance between the second and third markings is not more than about fifty percent (50%) greater than the distance between the first and fourth markings. All four markings are made on corneal tissue. A groove is formed using a surgical knife along the first marking and between the second and third markings substantially perpendicularly into the eye tissue. A surgical knife is caused to form a tunnel running substantially parallel to the surface of the cornea beginning at the grooved end until the tip of the knife coincides with the fourth marking when viewed from the perspective of the surgeon. The knife handle is angled upward to cause the tip of the blade to angle downward, applanating the cornea. The blade is then moved forward into the anterior chamber to complete the incision.
REFERENCES:
patent: 4875767 (1989-11-01), Wright
patent: 5090425 (1992-02-01), Stahl
patent: 5569280 (1996-10-01), Kamerling
patent: 5578049 (1996-11-01), Feaster
patent: 5618292 (1997-04-01), Poler
patent: 5697945 (1997-12-01), Kritzinger et al.
Strength of Clear Corneal Incisions in Cadaver Eyes, Richard J. Mackool, M.D.; R. Scott Russell, M.D. J. Cataract Refract Surg—vol. 22, Jul./Aug. 1996 p. 721-725.
Architecture and Construction of a Self-Sealing Incision for Cataract Surgery, I. Howard Fine, M.D. J. Cataract Refract Surg—vol. 17, Supplement 1991 p. 672-676.*
Cote Dana Michael
Keenan Joseph Francis
Lee Edwin G.
Murphy Michael Joseph
Becton Dickinson and Company
Buiz Michael
Goldberg Jonathan D.
McWha Keith J.
Voellmicke John L.
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