Surgery – Instruments – Corneal cutter or guide for corneal cutter
Reexamination Certificate
2000-03-02
2001-03-20
Truong, Kevin (Department: 3731)
Surgery
Instruments
Corneal cutter or guide for corneal cutter
Reexamination Certificate
active
06203555
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 keratorefrative surgery or the like.
2. Description of the Related Art
In recent years, attention has been focused on a LASIK surgery (laser in situ keratomileusis) for the keratorefrative surgery wherein a flap is formed by incising a portion with a thickness of about 0.15 mm from the corneal epithelium to the corneal stroma with a part of the cornea remaining connected like a hinge, ablating the corneal stroma in a refractive correction amount by an excimer laser light, and returning the flap to its original position. In the LASIK surgery, a corneal surgical apparatus called microkeratome is used for incising the cornea in a layered form.
As a corneal surgical apparatus, one comprising a suction ring to be vacuum-fixed to a part of the cornea from a corneal ring portion to the surface of the conjunctiva, a cornea applanating member for applanating the cornea flatly, and a blade movable toward the hinge while being oscillated laterally so as to incise the flattened cornea into a layer form with a substantially uniform thickness, is known.
As a mechanism for the blade lateral oscillation, as shown in
FIG. 13A
, one comprising a rotation shaft
301
to be rotated by a driving device such as a motor, an eccentric pin
302
provided at the tip end of the shaft
301
, a transmitting member
304
having a vertical groove
303
to be engaged with the pin
302
is proposed. The transmitting member
304
having a blade
300
fixed thereto is held movably in the lateral direction (right and left direction, that is, the direction perpendicular to the paper surface in
FIG. 13
) in a receiving groove formed in a blade holder
305
and a holder block
306
. When the shaft
301
is rotated by drive of the motor, force is applied on the transmitting member
304
in the lateral direction according to the circumferential movement (circular motion) of the pin
302
engaged with the vertical groove
303
. Accordingly, the transmitting member
304
oscillated laterally (moved in the right and left direction), and further, the blade
300
fixed to the transmitting member
304
is oscillated laterally as well.
However, according to the conventional mechanism, as shown in
FIG. 13B
, by the circumferential movement of the pin
302
, not only the force in the lateral direction but also force in the vertical direction (up and down direction) is applied to the transmitting member
304
. That is, since the pin
302
with the circumferential movement comes in contact with the wall of the vertical groove
303
so that force is applied on the transmitting member
304
in the vertical direction due to the friction force generated by the contact, the transmitting member
304
is oscillated laterally while being moved also in the vertical direction. Therefore, if the shaft
301
is rotated at a high speed, the transmitting member
304
and the blade
300
generate vertical oscillation (up and down movement) called “rampage” in addition to the lateral oscillation.
The “rampage” hinders stable incision as well as generates a loss in terms of the efficiency of converting the rotational motion to the lateral oscillation. Moreover, since the corner part of the transmitting member
304
is contacted with a blade holder
305
and the holder block
306
frequently so as to be applied with a large force, the parts are worn out rapidly so that the life cycle thereof is shortened.
The displacement amount of the transmitting member
304
to be displaced vertically and laterally (in the up and down, and right and left directions) according to the circumferential movement of the pin
302
corresponds to the eccentric amount of the pin
302
, but as to the vertical direction, since the transmitting member
304
is held by the blade holder
305
and the holder block
306
in the vertical direction, the transmitting member
304
(and the blade
300
) is displaced (vertical oscillation) for the gap with respect to each member. Therefore, accurate production without a gap among the transmitting member
304
, the blade holder
305
and the holder block
306
would prevent the vertical oscillation (that is, “rampage”), however, much labor is required for meeting the demand particularly in mass production so as to increase the cost.
SUMMARY OF THE INVENTION
In view of the above-mentioned problems, an object of the present invention is to provide a corneal surgical apparatus capable of forming a good flap by preventing “rampage” of a blade. Effects of the apparatus include efficient generation of lateral oscillation, restraint of the cost rise according to high accuracy of the mechanism, and high durability.
In order to solve the above-mentioned problems, the 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, comprising:
a suction ring unit, having a circular opening, that is to be vacuum-fixed onto a peripheral part of the cornea;
a rotatable shaft;
an eccentric pin projecting from a distal end of the shaft, the eccentric pin being located at a position offset from a rotational central axis of the shaft; and
a cutting unit movable in an incising direction above the suction ring unit, the cutting unit including:
cornea applanating means that applanates the cornea within the opening into a substantially flat form;
a blade that incises the cornea;
a first oscillation transmitting member having a part with which the eccentric pin is engaged;
a second oscillation transmitting member having a part with which a part of the first oscillation transmitting member is engaged; and
a holder that holds the first and second oscillation transmitting members to be movable in a lateral direction which is perpendicular to the rotational central axis of the shaft,
wherein movement of the second oscillation transmitting member in the lateral direction causes the blade to be moved in the same direction.
(2) A corneal surgical apparatus according to (1), wherein the blade is fixed to the second oscillation transmitting member.
(3) A corneal surgical apparatus according to (1), wherein the first oscillation transmitting member includes:
a vertical groove elongating in a direction perpendicular to both of the lateral direction and the rotational central axis of the shaft, the eccentric pin being engaged with the vertical groove; and
a pin part extending toward the second oscillation transmitting member;
wherein the second oscillation transmitting member includes a pin receiving part with which the pin part of the first oscillation transmitting member is engaged.
(4) A corneal surgical apparatus according to (1), wherein the holder holds the first and second oscillation transmitting member to be movable linearly in the lateral direction.
(5) A corneal surgical apparatus according to (1), wherein the first oscillation transmitting member includes a shaft part rotatable about an axis different in location from the rotational central axis of the shaft, the shaft part having at least one of a recess and a protrusion, and
wherein the holder includes a bearing part that rotatably supports the shaft part and that has a part with which the shaft part is engaged, the holder holding the first oscillation transmitting member to be rockable in the lateral direction.
(6) A corneal surgical apparatus according to (5), wherein the holder holds the second oscillation transmitting member to be movable linearly in the lateral direction.
(7) A corneal surgical apparatus according to (5) , wherein the shaft part of the first oscillation transmitting member includes two shaft parts respectively located on an upper part and a lower part of the first oscillation transmitting member, and
wherein the bearing part includes two bearing parts respectively supporting the two shaft parts.
(8) A corneal surgical apparatus according to (5), wherein the shaft part of the first oscillation tra
Amano Masanori
Shibata Ryoji
Sugimura Masahiro
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Nidek Co., Ltd
Truong Kevin
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