Surgery – Instruments – Corneal cutter or guide for corneal cutter
Reexamination Certificate
1998-04-14
2001-06-26
Buiz, Michael (Department: 3731)
Surgery
Instruments
Corneal cutter or guide for corneal cutter
C606S167000
Reexamination Certificate
active
06251118
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
Field of the Invention
The invention provides surgical instruments that facilitate insertion of radial inserts within the cornea of a patient's eye. The invention also provides a method for implanting radial intracorneal inserts in order to correct such deficiencies in the patient's vision as hyperopia, myopia, and/or astigmatism.
Intracorneal Inserts
Anomalies in the overall shape of the eye can cause visual disorders. Hyperopia (“farsightedness”) occurs when the front-to-back distance in the eyeball is too short. In such a case, parallel rays originating greater than 20 feet from the eye focus behind the retina. Although minor amounts of hyperopia can be resolved in the human eye by a muscular action known as “accommodation”, aging often compromises the ability of the eye adequately to accommodate. In contrast, when the front-to-back distance of eyeball is too long, myopia (“nearsightedness”) occurs and the focus of parallel rays entering the eye occurs in front of the retina. Astigmatism is a condition which occurs when the parallel rays of light do not focus to a single point within the eye, but rather have a variable focus due to the fact that the cornea refracts light in a different meridian at different distances. Some degree of astigmatism is normal, but where it is pronounced, the astigmatism must be corrected.
Hyperopia, myopia, and astigmatism are usually corrected by glasses or contact lenses. Surgical methods for the correction of such disorders are known. Such methods include radial keratotomy (see, e.g., U.S. Pat. Nos. 4,815,463 and 4,688,570) and laser corneal ablation (see, e.g., U.S. Pat. No. 4,941,093).
Another method for correcting those disorders is through the implantation of polymeric rings (intrastromal corneal rings or “ICR's”) in the eye's corneal stroma to change the curvature of the cornea. Previous work involving the implantation of polymethylmethacrylate (PMMA) rings, allograft corneal tissue, and hydrogels is well documented. One of the ring devices involves a split ring design which is inserted into a channel previously dissected in the stromal layer of the cornea. A minimally invasive incision is used both for producing the channel and for inserting the insert. See, for instance, the use of PMMA 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. These documents suggest only the use of circumferential ICR's.
Instead of inserting polymeric rings or arcs into the cornea, radial intracorneal inserts having a significant radial or meridional dimension may be placed within the cornea to adjust corneal curvature and thereby correct or improve vision abnormalities such as hyperopia. This invention provides instruments and a method for implanting such radial intracorneal inserts.
Method and Instruments of this Invention
The invention provides surgical instruments that facilitate insertion of radial inserts within the cornea of a patient's eye. The invention also provides a method for implanting radial intracorneal inserts in order to correct such deficiencies in the patient's vision as hyperopia, myopia, and/or astigmatism.
One method provided by the invention is a method for preparing the cornea of a patient's eye to receive a radial intracorneal insert. In this method, a surgeon makes an incision into the cornea and forms a circumferential channel within the cornea by inserting a channel-forming instrument through the incision. The surgeon also forms a radial pocket within the patient's cornea such that an end of the radial pocket connects to the circumferential channel. The surgeon can place a radial intracorneal insert into the radial pocket, and the surgeon can also place a circumferential insert into the circumferential channel, if desired.
The invention also provides various instruments that the surgeon uses to mark the patient's eye, to form radial pockets, and to position radial intracorneal inserts within radial pockets. A corneal marker is used to place ink-marks on the surface of the patient's cornea to mark various regions where surgery is to be performed. One corneal marker has a number of individual markers incorporated into the marker. This corneal marker has an incision marker, which marks the site on the cornea where the incision mentioned above is to be made; a radial pocket marker, which marks the site on the cornea where a radial pocket is to be formed; and a positioner for positioning the incision marker and the radial pocket marker in the desired locations on the patient's cornea.
A radial-pocket forming instrument is used to form radial pockets into which radial intracorneal inserts are placed. One radial pocket-forming instrument provided by this invention is designed to be inserted into the circumferential channel formed by the method described above to create one or more radial pockets. This radial pocket-forming instrument has a tissue separator positioned on the side of a generally arcuate member that is inserted into the circumferential channel. The radial pocket-forming instrument is inserted into the circumferential channel through the incision made in the patient's cornea and is positioned so that the tissue separator is adjacent to a mark made by the radial pocket marker of the corneal marker described above. The tissue separator is then rotated or translated sideways so that the tissue separator contacts a sidewall of the circumferential channel and pushes between stroma, forming a radial pocket in the patient's cornea.
The surgeon uses a positioning instrument to maneuver a radial intracorneal insert and place the insert within a radial pocket. A radial intracorneal insert is inserted into the circumferential channel through the incision made in the patient's cornea and is positioned so that the radial intracorneal insert is adjacent to a radial pocket. The positioning instrument, which has also been inserted into the circumferential channel through the incision, has a generally arcuate member of a size and shape that fits within the circumferential channel formed within the patient's cornea and also has a tip positioned at or near one end of the generally arcuate member. The tip is used to contact a radial intracorneal insert and move the insert so that an end of the insert enters the radial pocket and seats within the pocket.
The invention is described in greater detail below. Among other factors, the invention is based on the inventors' technical finding that the methods and instruments of this invention which form radial pockets into which radial intracorneal inserts are implanted provide quick and reliable insertion of radial intracorneal inserts within a patient's eye to correct vision deficiencies. Few incisions into the cornea and through the stroma are needed, and thus little suturing is required, and the chance of eye infection is reduced. These technical findings and advantages and others are apparent from the discussion herein.
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Gandionco Sid
Proudfoot Robert A.
Scholl John A.
Silvestrini Thomas A.
Buiz Michael
KeraVision Inc.
KeraVision, Inc.
Macey Harry J.
Ngo Lien
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