Surgery – Instruments – Corneal cutter or guide for corneal cutter
Reexamination Certificate
1999-03-31
2003-07-15
Thaler, Michael H. (Department: 3731)
Surgery
Instruments
Corneal cutter or guide for corneal cutter
Reexamination Certificate
active
06592601
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a corneal surgical apparatus for incising the cornea of an eye of a patient in a layered form at the time of a keratorefractive surgery or the like.
2. Description of the Related Art
In recent years, attention has been focused on LASIK (laser in situ keratomileusis) surgery for effecting keratorefractive treatment wherein after a flap is formed by incising a corneal portion with a thickness of 150 &mgr;m ranging from the corneal epithelium to the corneal stroma with one end of the cornea remaining connected like a hinge, the corneal stroma is cut away or ablated in a refractive correction amount by excimer laser light, and the flap is then returned to its original position. In this LASIK surgery, a corneal surgical apparatus called a microkeratome is used to incise the cornea in a layered form.
Such microkeratome is available that has a suction ring vacuum-fixed to a portion of the cornea ranging from a corneal ring portion to the surface of the conjunctiva, a cornea applanating member for applanating the cornea flatly, and a blade which, while being oscillated in the lateral direction, is linearly moved or rotatively moved in a direction toward the hinge along a guide mechanism provided on the suction ring, so as to incise the cornea into a layered form with a substantially uniform thickness.
The guide mechanism is arranged such that a rack is provided on the suction ring, while a rotating gear meshing with the rack is provided on the blade side so that the blade is moved while being guided by the rack as the rotating gear is rotated. Another known guide mechanism is arranged such that the blade is moved along a guide groove provided on the suction ring.
In addition, the following mechanisms are also known: one in which the lateral oscillation of the blade and the movement of the blade toward the hinge are effected by a single motor provided in an apparatus body; one in which rotatively driving forces of two motors in a controller provided separately from the apparatus body are respectively transmitted to a blade oscillating mechanism and a blade moving mechanism in the apparatus body through two wires, so as to separately control the oscillation and movement of the blade; and one in which the oscillation speed and the translation speed of the blade can be variably set, respectively.
However, as for the microkeratome which has a guide mechanism or a gear mechanism on the suction ring, there are cases where the patient's eyelashes bite into the guide mechanism during a surgical operation to stop the movement of the blade. In this case, it is necessary to resume the operation after removing the eyelashes, but this imposes an adverse effect on the patient's eye. Further, a layered incision with an equal thickness cannot be realized by the re-operation. Since the guide mechanism causes abrasion dust, there is apossibility that the abrasion dust enters into the patient's eye if the guide mechanism is provided on the suction ring.
The characteristics of the cornea and the intraocular pressure differ depending on the patient's eye, but in the case of the microkeratome in which the lateral oscillation and movement of the blade are effected by one motor, it is difficult to optimize the relationship between the feeding movement and the lateral oscillation for obtaining a satisfactorily smooth surface as the incised surface.
In the case of the microkeratome in which the rotatively driving forces of two motors in a controller are transmitted to the blade oscillating mechanism and the blade moving mechanism through the two wires, the wires hinder the surgical operation.
In addition, unless the relationship between the set oscillation speed and the set translation speed of the blade is appropriate, the following problems can possibly occur. If the translation speed is excessively faster than the oscillation speed (the oscillation speed is excessively slower than the translation speed), the cut surface of the cornea may become nonuniform. On the other hand, if the translation speed is excessively,slower than the oscillation speed (the oscillation speed is excessively faster than the translation speed), frictional heat may occur on the cut surface, or extra time is needed until the incision is completed, so that the efficiency is poor.
SUMMARY OF THE INVENTION
In view of the above-described problems, it is an object of the present invention to provide a corneal surgical apparatus which eliminates the possibility of an interruption of surgery caused in connection with a guide mechanism and which permits a satisfactory surgical operation appropriate to the condition of the patient's eye without imposing an adverse effect on the patient's eye.
Another object of the present invention is to provide a corneal surgical apparatus which makes it possible to perform the incision of the cornea efficiently and satisfactorily by appropriately setting the oscillation speed and the translation speed of the blade.
To overcome the above-desciribed objects, the present invention is characterized by the following features.
(1) A corneal surgical apparatus for incising a cornea of a patient's eye in a layered form using a blade, includes:
a blade moving shaft supported rotatably and axially movably, wherein axial movement of the blade moving shaft causes the blade to advance or retract and rotation of the shaft causes the blade to make lateral oscillation;
first driving means, having a first motor, for axially moving the blade moving shaft by rotation of the first motor; and
second driving means, having a second motor, for rotating the blade moving shaft by rotation of the second motor.
(2) The corneal surgical apparatus according to (1), wherein the first driving means includes:
a feed screw portion which is rotated by the rotation of the first motor; and
a connecting member meshing with the feed screw portion and rotatably holding the blade moving shaft.
(3) The corneal surgical apparatus according to (1), wherein the second driving means includes:
a rotation transmitting member for holding the blade moving shaft axially slidably, and rotating the blade moving shaft by the rotation of the second motor.
(4) The corneal surgical apparatus according to (3), wherein the blade moving shaft includes a spline shaft having a first portion circular in section and a second portion noncircular in section, and the second portion is slidable with respect to the rotation transmitting member.
(5) The corneal surgical apparatus according to (1), further includes:
controlling means for controlling the first driving means so as to cause the blade to advance or retract at a predetermined moving speed, and controlling the second driving means so as to oscillate the blade at a predetermined oscillation speed.
(6) The corneal surgical apparatus according to (5), further includes:
setting means for variably setting at least one of the moving speed and the oscillation speed.
(7) The corneal surgical apparatus according to (6), further includes:
determining means for determining whether or not a relationship between the moving speed and the oscillation speed is appropriate.
(8) The corneal surgical apparatus according to (7), further includes:
storing means for storing a relative allowable setting range of the moving speed and the oscillation speed,
wherein the determining means determines whether or not the relationship between the moving speed and the oscillation speed is appropriate on the basis of the allowable setting range stored in the storing means.
(9) The corneal surgical apparatus according to (1), further includes;
setting means for variably setting two parameters which respectively correspond to a moving speed of the blade defined by the first driving means and an oscillation speed of the blade defined by the second driving means;
storing means for storing a relative allowable setting range of the moving speed and the oscillation speed;
limiting means for limiting the allowable setting range of one o
Kozawa Katsuhiko
Sugimura Masahiro
Toh Minoru
Finnegan Henderson Farabow Garrett & Dunner LLP
Nidek Co. Ltd.
Thaler Michael H.
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