Surgery – Instruments – Light application
Reexamination Certificate
1997-11-25
2001-02-20
Dvorak, Linda C. M. (Department: 3739)
Surgery
Instruments
Light application
C606S004000, C606S011000, C606S012000
Reexamination Certificate
active
06190374
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for operating upon a cornea for correcting ametropia of the cornea by using a laser beam, and more particularly to the apparatus suitable for not only the correction of hypermetropia or myopia but also the correction of presbyopia.
2. Description of Related Art
An apparatus for operating upon a cornea is well-known that a corneal surface is ablated by using a laser beam, and ametropia of an eye-ball is corrected by changing a corneal curvature.
There are some types of ametropia of an eye; myopia, astigmatism, hypermetropia, also presbyopia in which someone cannot recognize a near point as they become older. An apparatus for the correction of presbyopia has been well-known as shown in the specification of U.S. Pat. No. 5,314,422. In this apparatus, as shown in
FIG. 16
, two flat plates
101
and
102
are slidable in opposite directions respectively so as to open an aperture in a shape of a crescent, thereby a part of a cornea is irradiated with a laser beam through the aperture. As a result of this, the cornea is corrected so as to have double focal points like presbyopia glasses having additional lenses. Upon the operation, a frame
100
for supporting to allow the two plates to slide is mounted and fixed on the eye.
However, the above-mentioned apparatus has some demerits as follows. Apart from the body of the apparatus for operating upon the cornea which the laser beam is emitted, this apparatus also has a special mask for use in the correction of presbyopia. Since frame
100
should be mounted on the eye for positioning, it may be difficult to achieve such an accurate positioning so as to adjust within an expected ablation area.
Also, apart from the positioning of the laser beam, since the close-open operation for the two plates
101
and
102
is controlled, it is difficult to make the size of the aperture and the position of the beam be involved. Therefore, it is important to give attention to the beam irradiation for completely covering the aperture.
Further, because the correction degree is controlled by the close-open control of the aperture, it is difficult to adjust the amount of laser-beam irradiation in combination with the close-open operation of the aperture.
In addition, since the mask is arranged for covering the surface of the eye-ball, it results in another problem that an observation of the eye may be difficult during the laser irradiation.
SUMMARY OF THE INVENTION
An object of the invention is to overcome problems described above and to provide an apparatus for operating upon a cornea, which is capable of achieving the correction of presbyopia easily without any additional apparatus for presbyopia.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, an apparatus for operating upon a cornea for delivering a laser beam having wavelength in an ultraviolet range emitted from a laser light source to the cornea, and for correcting ametropia by ablating the cornea with the laser beam, the apparatus comprises a correcting-hypermetropia optical system having a first aperture to restrict an ablation area, for correcting hypermetropia by changing a passing area for the laser beam, input means for inputting information necessary for defining a corneal shape after ablation, controlling means for defining an ablation shape based on the information inputted by the input means, and for driving the laser light source and the correcting-hypermetropia optical system, and a second aperture located by decentering for the center of the cornea, for transmitting the laser beam within an area of a near-point portion, whereby correction of presbyopia may be performed so that the cornea has double focal points by driving the laser light source and the correcting-hypermetropia optical system under condition that the second aperture is located at a predetermined position.
In another aspect of the present invention, an apparatus for operating upon a cornea for delivering a laser beam having wavelength in an ultraviolet range emitted from a laser light source to the cornea, and for correcting ametropia by ablating the cornea with the laser beam, the apparatus comprises a correcting-myopia optical system having an variable aperture at a aperture diameter, for correcting myopia by changing a passing area for the laser beam, input means for inputting information necessary for defining a corneal shape after ablation, controlling means for defining an ablation shape based on the information inputted by the input means, and for driving the laser light source and the correcting-myopia optical system, and intercepting means for intercepting the laser beam within an area of a near-point portion, whereby correction of presbyopia may be performed so that the cornea has double focal points by driving the laser light source and the correcting-myopia optical system under condition that the intercepting means is located at a predetermined position.
Also, in another aspect of the present invention, an apparatus for operating upon a cornea comprises a laser light source for emitting a laser beam having a beam intensity of Gaussian distribution, an ablation optical system for correcting ametropia of cornea by a method that an eye to be operated is irradiated with the laser beam emitted from the laser light source, a circular aperture located in the ablation optical system, for restricting an area which is ablated by the laser beam, beam moving means for moving the laser beam passed through the circular aperture in a direction of Gaussian distribution, beam rotating means for rotating a moving direction of the laser beam which is moved by the beam moving means, information input means for inputting information about the ablation area, controlling means for controlling one ablation for correcting hypermetropia with making the circular aperture shift based on the information inputted by the information input means, or for controlling other ablation for correcting myopia with partially intercepting the ablation area of the laser beam, whereby the cornea is ablated so as to have double focal points, and the correction of presbyopia may be performed.
As described above, and in accordance with the present invention, the apparatus enables the correction of presbyopia within the expected ablation area without using any additional apparatus for presbyopia apart from the body of the apparatus for operation on for a cornea.
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Amano Masanori
Makino Hirokatsu
Dvorak Linda C. M.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Nidek Co. Ltd.
Ruddy David M.
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