Surgery – Instruments – Corneal cutter or guide for corneal cutter
Reexamination Certificate
1998-07-31
2001-08-21
Dawson, Glenn K. (Department: 3761)
Surgery
Instruments
Corneal cutter or guide for corneal cutter
C606S167000
Reexamination Certificate
active
06277134
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a corneal surgical apparatus for incising the cornea of patient's eye in a layered form in keratorefractive surgery or photorefractive keratectomy (PRK).
In recent years, attention has been focused on LASIK (laser in situ keratomileusis) for effecting keratomileusis (keratorefractive) treatment wherein after a flap is formed by incising a corneal portion of 150 &mgr;m thickness ranging from the corneal epithelium to the corneal stroma with one end of the corneal portion 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 returned to its original position. In this surgery, a corneal surgical apparatus called microkeratome is used to incise the cornea in a layered form. So called “upper hinge flap method” in which the hinge is formed on the upper side (upper eyelid side) of the patient's eye is effective to prevent the deviation and the like of the flap during adhesion of the cornea after the surgery is complete, and thus generally adopted to the PRK recently.
A typical microkeratome includes a suction unit for vacuum-adhering a corneal surface, a cornea applanating member for applanating a corneal portion projecting from an opening portion of the suction unit, and a blade linearly moved in the direction toward the hinge while being oscillated in the lateral direction so as to incise the applanated corneal portion into a layered form with a substantially uniform thickness.
In addition, in recent years, there has been proposed a microkeratome having a blade which is pivoted by using a single pivotal axis as its reference while oscillating the blade so as to form a hinged flap.
Each of these microkeratomes are designed to make oscillation of the blade for incision of the relatively hard Bowman's membrane underlying the corneal epithelium (particularly for the start of the cutting), but is disadvantageous in that a complicated mechanism is required to make the linear motion of the blade (or pivoting motion of the blade with one axis as the reference) while oscillating the blade.
With the type in which the blade is advanced linearly, a feeding mechanism for linearly feeding the blade and a holding mechanism thereof occupy an area in the feeding direction, so that the patient's cheek hinders the formation of the upper hinge flap.
On the other hand, with the type in which the blade is pivoted by using one axis as the reference, since the feeding pitches of the blade differ between the side close to the pivoting axis and the side remote from it, the incision differs depending on the position on the edge of the blade, so that the incised surface tends to be nonuniform.
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 is capable of effecting smooth incision with a simple mechanism.
It is another object of the present invention to provide a corneal surgical apparatus which makes it possible to easily form an upper hinge flap.
It is still another object of the present invention to provide a corneal surgical apparatus which is capable of smoothly effecting the incision by the blade and of obtaining a satisfactory incised surface.
To attain the above-noted and other objects, the present invention is characterized by being provided with the following features:
(1) A corneal surgical apparatus for incising a cornea of patient's eye in a layered form, comprising:
fixing means, having an opening, for fixing a periphery of said cornea relative to said apparatus so that said cornea projects from said opening;
applanating means for applanating said cornea projecting from said opening;
a blade for incising said cornea applanated by said applanating means; and
moving means for moving said blade so that points on said blade depict arcuate loci of the same shape.
(2) A corneal surgical apparatus according to (1), wherein said blade is moved by said moving means without making an oscillating motion.
(3) A corneal surgical apparatus according to (1), wherein said moving means includes:
first and second links, each rotatably coupled to said blade, said first and second links being parallel to each other and equal in length to each other, and
rotating means for rotating rotational shafts of said first link and said second link in synchronism with each other.
(4) A corneal surgical apparatus according to (1), wherein said moving means includes:
first and second links, each rotatably coupled to said blade, said first and second links being parallel to each other and equal in length to each other, and
rotating means for rotating rotational shafts of said first link and said second link in synchronism with each other, and
wherein positions of the rotational shafts of said first and said second links, and a position of an edge of said blade coupled to said first and said second links are determined in relation to a position of a center of said opening and a size of said opening, so that said opening provided in said fixing means partially remains outside of a movable range of said blade moved by said moving means.
(5) A corneal surgical apparatus according to (1), further comprising:
restricting means for restricting movement of said blade to secure a hinge in the cornea incised by said blade.
(6) A corneal surgical apparatus according to (1), further comprising:
suspending means for suspending and supporting said moving means, said applanating means, and said blade with respect to said fixing means.
(7) A corneal surgical apparatus according to (1), wherein a direction of an edge of said blade is in parallel to a longitudinal direction of said fixing means.
(8) A corneal surgical apparatus according to (1), wherein said moving means and said blade are bilaterally symmetrical, and said apparatus further comprising:
attaching means for attaching said moving means and said blade in an inverted form with respect to said fixing means.
(9) A corneal surgical apparatus according to (1), further comprising:
driving means for driving said moving means; and
controlling means for controlling said driving means to vary a moving speed of said blade during incision.
(10) A microkeratome for use in photorefractive keratectomy, comprising:
a suction unit having a vacuum ring;
a coupling unit mounted on said suction unit;
a transfer unit mounted on said coupling unit and having a parallel link mechanism; and
a cutting unit including:
a base;
a cornea applanating portion fixedly provided on said base; and
a blade fixedly provided on said base,
wherein said base of said cutting unit is supported to said transfer unit by said parallel link mechanism.
(11) A microkeratome according to (10), wherein a relative positional relationship between said cornea applanating portion and said blade is kept constant by said base.
(12) A microkeratome according to (10), wherein said blade is in non-contact with said cornea applanating portion.
(13) A microkeratome according to (10), wherein said parallel link mechanism moves said base so that any portions on said blade orbits along arcuate loci of the same shape.
(14) A microkeratome according to (10), wherein said base of said cutting unit is rotationally mounted about a stationary point via said parallel link mechanism.
(15) A microkeratome according to (14), wherein said stationary point corresponds to a center of an opening of said suction unit.
(16) A microkeratome for use in photorefractive keratectomy, comprising:
a suction unit having a vacuum ring;
a coupling unit mounted on said suction unit;
a cutting unit having a blade;
a transfer unit mounted on said coupling unit and having a parallel link mechanism,
wherein said cutting unit is rotationally mounted about a stationary point via said parallel link mechanism.
(17) A microkeratome according to (16), wherein said stationary point corresponds to a center of an opening of said suction unit.
(18) A parallel link mechanism, adapted to a microkeratome, fo
Amano Masanori
Hagiwara Takashi
Dawson Glenn K.
Nidek Co. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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