Surgery – Instruments – Corneal cutter or guide for corneal cutter
Patent
1996-06-21
1998-08-11
Thaler, Michael H.
Surgery
Instruments
Corneal cutter or guide for corneal cutter
A61B 1732
Patent
active
057921610
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION AND PRIOR ART
The present invention refers to a tunnel forming device and method for permitting the implantation of an intrlamellar ring in the cornea for the correction of ametropias.
The conception of an intracorneal ring has been developed by various authors. Published papers indicate, as one of the main difficulties, an easy and reliable technique for implanting the ring.
"Prior art teachings on the subject of implantation of intralamellar rings include WO-A-9320763 which teaches the use of a single cutting blade to form an incision into which an intralamellar ring may be inserted, and WO-A8810096 which teaches the use of a device for inserting an intralamellar ring in the cornea, in which the ring itself is used to form the incision. Both of the devices described in these patents require the use of complicated positioning equipment."
The techniques known so far are the "pocket discision" and the "lamellar keratectomy" by means of microkeratome. Both techniques, however, have a serious drawback, namely the interface formed at the level of the optical zone, which is detrimental to the transparency and the final visual result. Besides, the microkeratome is an expensive apparatus and requires a high degree of training, thus discouraging most surgeons from using it, especially bearing in mind the cost-benefit relationship.
SUMMARY OF THE INVENTION
The device of the present patent application overcomes these problems, enabling the intracorneal ring to be implanted very easily, besides not causing any corneal alteration. This result is achieved by forming a "tunnel" in the cornea, for implanting the ring, using a symmetrically balanced cutting arrangement.
According to the present invention a device for permitting the implantation of an intralamellar ring in the cornea for the correction of ametropias, comprises: cutting members, each of the cutting members having a free leading end and a supported trailing end to define a circular annular configuration with the leading end of the first cutting member adjacent but spaced from the trailing end of the second cutting member and the leading end of the second cutting member adjacent but spaced from the trailing end of the first cutting member; cutting members at diametrically opposite points with respect to the circular configuration; and peripheral circular finger engaging surface of a diameter greater than that of the circular configuration defined by the cutting members.
The use of a device of this nature in which the tunnel forming cutting members are semicircular results in balanced resistance to rotation which permits the elimination of more complicated positioning equipment as is known in the prior art. In one embodiment of this invention, the device defined above also includes a separate base member having an annular peripheral portion supporting a radially inner guide portion defining an inner diameter substantially equal to the outer diameter of the circular configuration defined by the cutting members. Placement of the base member against the cornea permits it to be used to guide the cutting members during the tunnel forming operation.
In spite of the above, however, the device of the invention has proved to be so simple to use that the base member has been found to be unnecessary. In the preferred embodiment of the invention, therefore, the rigid support means comprise a rigid outer ring and first and second L-shaped support elements, each said element having an axially directed leg having its free end fixed to the trailing edge of a respective cutting member and a radially directed leg having its free end fixed to the rigid ring. Preferably, the manual operating means comprises a tubular part arranged to be coaxial with the rigid outer ring, the ring being mountable over one end of the tubular part.
The device can be manufactured from any rigid, metallic or non-metallic material. Titanium is the preferred material.
In accordance with another aspect of the invention, a method of implanting an interlamellar ring in the cornea
REFERENCES:
patent: 4781187 (1988-11-01), Herrick
patent: 5323788 (1994-06-01), Silvestrini et al.
Database WPI, Week 9345, Derwent Publications, Ltd., London, GB, AN 93-358291 & SU, A, 1 771 730 (Alma-Ata Doctors Training Inst.).
Database WPI; Section P.Q.; Week 9151; Dewent Publications Ltd., London, GB, Class P, AN 91-375417/51 & SU, A, 1 641 326 (Rost. Med. Inst.).
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