JP3655020B2 - Cornea surgery device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a corneal surgical apparatus that corrects an eye refractive error using a laser beam, and more particularly to a corneal surgical apparatus suitable for correcting an asymmetric cornea.
[0002]
[Prior art]
In recent years, a technique called PRK (Photo-refractive Keratectomy), in which a corneal surface is excised using a laser beam and the curvature of the cornea is changed, has attracted attention.
[0003]
In this correction surgery, a method using a variable circular aperture or a variable slit aperture is known when reshaping the surface of the cornea for refractive correction such as myopia and astigmatism. In myopia correction, a variable circular aperture can be used to change the ablation area of the laser beam. Myopic astigmatism can be achieved by changing the ablation area of the laser beam using a variable slit aperture.
[0004]
[Problems to be solved by the invention]
However, in all conventional corrective operations, the laser beam is irradiated symmetrically with respect to the optical axis of the light guide optical system that guides the laser beam to the cornea. On the other hand, it was not possible to reshape the corneal surface which can be reshaped only symmetrically and the curvature of the corneal surface is asymmetric with respect to the eye axis.
[0005]
In view of the above-described problems, it is an object of the present invention to provide a corneal surgery device that enables refractive correction of a cornea having an asymmetric shape.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is characterized by having the following configuration.
[0007]
(1) In a corneal surgical apparatus that includes a light guide optical system that guides a laser beam having a wavelength in the ultraviolet region to the cornea, and ablate the cornea with the laser beam to correct a refractive error, a circular shape that limits an irradiation region of the laser beam An irradiation area limiting means having at least one of an aperture of an ellipse or a slit and capable of changing the size of the aperture , and the center of the projection image on the cornea of the aperture as the optical axis of the light guide optical system Control the operation of the irradiation area deviation means to be deflected, the irradiation area restriction means and the irradiation area deviation means, and change the deviation amount of the center of the projection image according to the size of the aperture, Control means for correcting myopia or myopic astigmatism of an asymmetric shape by superimposing irradiation areas of different sizes shifted from the center of the projected image It is characterized by.
[0008]
(2) In a corneal surgery apparatus that includes a light guide optical system that guides a laser beam having a wavelength in the ultraviolet region to the cornea, and corrects the refractive error by ablating the cornea with the laser beam, the irradiation region of the laser beam is Fan-shaped irradiation area limiting means for limiting to a fan shape, irradiation area variable means for changing the irradiation area limited to a fan shape by the fan-shaped irradiation area limiting means, and rotating the fan-shaped irradiation area limiting means about the optical axis And rotating means, and control means for controlling the driving of the rotating means and the irradiation region restriction varying means so as to ablate the refractive power (curvature) of the cornea in the astigmatic axis direction .
[0018]
[Example 1]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic layout diagram of an optical system and a control system of the apparatus according to the first embodiment.
[0019]
Reference numeral 1 denotes a laser light source. In this embodiment, an excimer laser having a wavelength of 193 nm is used. The excimer laser beam emitted from the laser light source 1 is a pulse wave, and a typical shape thereof is a top hat whose beam intensity distribution is substantially uniform in the horizontal direction (X-axis direction) as shown in FIG. The distribution is F (W), and the vertical direction (Y-axis direction) is a Gaussian distribution F (H).
[0020]
Reference numerals 2 and 3 denote plane mirrors. The laser beam emitted from the laser light source 1 in the horizontal direction is deflected upward by 90 ° by the plane mirror 2 and again deflected in the horizontal direction by the plane mirror 3. The plane mirror 3 can be moved in the vertical direction (arrow direction) by the mirror driving device 4, translates the laser beam emitted from the laser light source 1 in the Gaussian distribution direction, and transmits the laser beam to the optical axis L of the light guide optical system. The target object is uniformly excised. This point is described in detail in Japanese Patent Application Laid-Open No. Hei 4-242644 (name of invention “Ablation Device by Laser Beam”), and this is incorporated herein by reference.
[0021]
Reference numeral 5 denotes an image rotator which is rotationally driven around the optical axis L by the image rotator driving device 6 to rotate the laser beam around the optical axis.
[0022]
A variable circular aperture 7 restricts the ablation region to a circular shape. The opening diameter of the circular aperture 7 is changed by the rotation of the motor 8a of the opening driving device 8. Further, the circular aperture 7 is moved in a direction (X direction, Y direction) in a plane perpendicular to the optical axis L by motors 9a and 9b of the moving device 9 (see FIG. 3).
[0023]
Reference numeral 10 denotes a variable slit aperture that limits the ablation region to a slit shape. The opening width of the slit aperture 10 is changed by an opening mechanism such as a motor 11a provided in the opening driving device 11. The slit aperture 10 is rotated by a motor 12a of the rotating device 12, and the direction of the slit opening can be freely changed. Further, the slit aperture 10 is moved in a direction (X direction, Y direction) in a plane orthogonal to the optical axis L by motors 13a and 13b of the moving device 13 (see FIG. 4).
[0024]
Reference numeral 14 denotes a projection lens for projecting the circular aperture 7 and the slit aperture 10 onto the cornea Ec of the patient's eye. Reference numeral 16 denotes a dichroic mirror that reflects the 193 nm excimer laser beam and transmits visible light. The laser beam that has passed through the projection lens 14 is reflected by the dichroic mirror 16 and bent 90 ° to the cornea Ec of the patient's eye. Is guided. The patient's eye Ec is preliminarily positioned so as to be in a predetermined position during the surgery (the positioning means is not related to the present invention, so the description is omitted).
[0025]
Reference numeral 17 denotes an observation optical system having a binocular surgical microscope, and the left and right observation optical systems are positioned so as to sandwich the dichroic mirror 16. A commercially available binocular observation optical system can be used, and since the configuration itself is not related to the present invention, the description thereof is omitted. Reference numeral 20 denotes a control device that controls the entire apparatus, and reference numeral 21 denotes a data input device for inputting refractive power data and the like of the patient's eye. The control device 20 controls driving of each device based on input information such as a preoperative corneal shape and a postoperative corneal shape (correction power, axial angle) input from the data input device 21.
[0026]
The operation of the apparatus having the above configuration will be described. First, taking a flat plate of PMMA or the like instead of the cornea as an example, a method of correcting asymmetric myopia and correcting asymmetric astigmatism will be described.
[0027]
A method of correcting asymmetric myopia will be described with reference to FIG. In this refraction correction, a circular aperture 7 is used, and the slit aperture 10 is left open. First, an initial setting is made at a position where the center of the aperture of the circular aperture 7 coincides with the optical axis L (or a position displaced with respect to the optical axis L), and within the central circular region S1 in FIG. Ablate. In the irradiation of the laser beam for ablation, the plane mirror 3 is sequentially translated to move the laser beam in the Gaussian distribution direction and ablate one surface from end to end of the irradiation region. Next, the image rotator 5 is rotated to change the moving direction of the laser beam, and ablation is performed again from end to end of the irradiation region. This is repeated from three directions and the irradiated area is excised to a uniform depth.
[0028]
When the first circular region S1 is ablated, the circular aperture 7 is moved so as to decenter the opening center of the circular aperture 7 by a minute distance from the initial position (moving in the direction of the arrow in FIG. 5) and circular. Ablation is performed in a circular region S2 in which the aperture diameter of the aperture 7 is widened by a minute amount. As in the first case, the laser beam is ablated by irradiating the laser beam by the parallel movement of the plane mirror 3 and the rotation of the image rotator 5. At this time, since the ablation is further overlapped in the previously ablated circular region S1, the ablation is deeper than the region ablated for the first time.
[0029]
Subsequently, the third ablation is performed. The circular aperture 7 is moved so as to decenter the opening center of the circular aperture 7 by a further minute distance from the previous position, and the inside of the circular region S3 in which the opening diameter of the circular aperture 7 is further increased by a minute amount is ablated.
[0030]
As shown in FIG. 5 (b), the cross-sectional shape in the eccentric direction is as shown in FIG. 5B by repeatedly performing the overlapping movement with the eccentric movement and the opening diameter of the circular aperture 7 gradually widened and the ablation region displaced. It is possible to obtain a shape having a large curvature in the direction of eccentric movement and a small curvature in the opposite direction. Thereby, asymmetrical myopia correction becomes possible.
[0031]
Next, a method for correcting astigmatism will be described with reference to FIG. In this refraction correction, a slit aperture 10 is used (the opening diameter of the circular aperture 7 is set in accordance with the ablation region). First, the slit opening center is initially set to a position deviated from the optical axis L, and the slit is opened to ablate the first region R1 (laser beam irradiation is performed in the same manner as in myopia correction). ). When the ablation in the first region R1 is completed, the aperture center is decentered by a small amount with respect to the optical axis, and the ablation is performed in the region R2 in which the slit width is slightly expanded. By repeating this, as shown in FIG. 6B, the cross-sectional shape in the eccentric direction can have a large curvature in the direction of eccentric movement and a small curvature in the opposite direction. Thereby, asymmetrical astigmatism correction becomes possible.
[0032]
In the above-described method, the sizes of the openings of the circular aperture 7 and the slit aperture 10 are gradually increased, but conversely, they may be narrowed from a wide area.
[0033]
Next, asymmetric cornea correction surgery by the above method will be described. The operator inputs data relating to the corneal shape before and after the operation of the patient's eye and data relating to the refractive power using the input device 21. The ablation area and its shape are determined according to the program stored in the control device 20 based on the input data, and the control device 20 controls the operation of each component. When the data can be input, alignment is completed while observing the patient's eyes with the observation optical system 17, and laser beam irradiation is performed.
[0034]
In the case of asymmetrical myopia correction, the control device 20 moves the circular aperture 7 in the eccentric direction to control the driving of the moving device 9 in accordance with the program control based on the input data, and drive the aperture. The drive of the apparatus 8 is controlled to change the opening diameter, and ablation is sequentially performed.
[0035]
When performing astigmatism correction with an asymmetrical shape, the control device 20 controls the driving of the rotating device 12 so that the longitudinal direction of the slit opening is orthogonal to the direction of eccentricity, and then controls the driving of the moving device 13 to make the asymmetry. The slit aperture 10 is moved in the eccentric direction to be controlled, and the driving of the opening driving device 11 is controlled to change the opening diameter, thereby sequentially performing ablation. As a result, the asymmetric shape of the cornea of the patient's eye is shaped.
[0036]
The embodiments described above can be variously modified. For example, in the mechanism of the circular aperture 7 of the embodiment, when the circular aperture 7 can be tilted with respect to the optical axis direction and a rotatable mechanism is added, the projected shape can be an ellipse. Thereby, as shown in FIG. 7, it is possible to correct myopic astigmatism having an elliptical asymmetric shape.
[0037]
In addition, regarding the opening drive of the slit aperture 10 of the embodiment, a mechanism may be provided in which the slit shielding portions are not opened evenly but separately. When asymmetrical astigmatism correction is performed, the apertures of the slit shielding portions are individually controlled to deviate the center of the aperture from the optical axis. In this case, since the slit aperture itself does not have to be moved with respect to the optical axis as in the embodiment, the moving device 13 need not be provided.
[0038]
As for astigmatism correction, when a fan-shaped aperture (see FIG. 8) that can control the opening of the opening in a fan shape is used, as shown in FIG. 9, the astigmatism axis has a different refractive power (curvature). Ablation having an asymmetric shape with respect to the orthogonal direction can be performed.
[0039]
[Example 2]
The second embodiment is an example of performing asymmetrical ablation by optically deviating the ablation region limited by the aperture (circular aperture 7 or slit aperture 10) limiting the ablation region.
[0040]
FIG. 10 is a diagram illustrating a schematic arrangement of an optical system and a control system of the apparatus according to the second embodiment. The same components as those in the embodiment are denoted by the same reference numerals, and the description thereof is omitted. A projection lens 40 projects the circular aperture 7 or the slit aperture 10 onto the cornea. The projection lens 40 is moved in a plane perpendicular to the optical axis L by the moving device 41. The projection lens 40 has a size that can sufficiently project the aperture even when it moves. The moving mechanism of the moving device 41 is configured by the same mechanism as the moving devices 9 and 13 shown in the first embodiment.
[0041]
With such a configuration having the projection lens 40 and the moving device 41, the control device 20 controls the driving of the moving device 41 to be asymmetrical according to the program control based on the input data relating to the corneal shape. While moving the projection lens 40, the size of the opening of the circular aperture 7 or the slit aperture 10 is changed, and ablation is sequentially performed. Accordingly, the aperture region (opening center) projected onto the cornea can be sequentially decentered, and asymmetrical refractive correction can be performed as shown in FIGS.
[0042]
Further, as a method for optically deviating the ablation region of the second embodiment, a modification example shown in FIG. 11 may be used. Two prisms 50 and 51 are arranged on the projection optical axis of the projection lens 14 (same as in the first embodiment). The prisms 50 and 51 are rotatable around the optical axis L by rotating devices 52 and 53, respectively. Aperture regions (opening centers) projected onto the cornea are sequentially decentered by the deviation of the projected light beam created by the rotation angles of the prisms 50 and 51, and reshaped into an asymmetric shape with different curvatures. it can.
[0043]
In each of the above embodiments, the beam is moved in the Gaussian direction. However, the movement of the beam can be omitted by expanding the beam so as to cover the aperture area. it can.
[0044]
Various modifications of the present invention are possible, and these are also included in the present invention as long as the technical ideas are the same.
[0045]
【The invention's effect】
As described above, according to the present invention, refraction correction of a cornea having an asymmetric shape can be performed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an optical system and a control system of a corneal surgery apparatus according to a first embodiment.
FIG. 2 is a diagram showing a typical shape of an excimer laser beam.
FIG. 3 is a diagram showing an aperture driving device and a moving device of a circular aperture.
FIG. 4 is a view showing an aperture driving device, a rotating device, and a moving device of a slit aperture.
FIG. 5 is a diagram for explaining asymmetric myopia correction;
FIG. 6 is a diagram for explaining astigmatism correction having an asymmetric shape.
FIG. 7 is a diagram illustrating correction of asymmetric myopic astigmatism with an elliptical shape.
FIG. 8 is a diagram illustrating an example of a fan-shaped aperture that opens in a fan shape.
FIG. 9 is a diagram showing ablation of an asymmetric shape by an aperture opening in a fan shape.
FIG. 10 is a diagram illustrating a schematic arrangement of an optical system and a control system of the apparatus according to the second embodiment.
FIG. 11 is a diagram illustrating a modification example of the apparatus according to the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser light source 7 Circular aperture 8 Aperture drive device 9 Moving device 10 Slit aperture 11 Aperture drive device 12 Rotating device 13 Moving device 14 Projection lens 20 Control device 21 Data input device

Claims (2)

In a corneal surgery apparatus that includes a light guide optical system that guides a laser beam having a wavelength in the ultraviolet region to the cornea, and ablate the cornea with the laser beam to correct a refractive error, a circular, elliptical, or An irradiation area limiting means having at least one aperture of the slit and capable of changing the size of the aperture , and the center of the projected image of the aperture on the cornea with respect to the optical axis of the light guide optical system. And controlling the operation of the irradiation area deviation means, the irradiation area restriction means, and the irradiation area deviation means to change the deviation amount of the center of the projection image according to the size of the aperture. characterized in that it comprises a control means for correcting myopia or myopic astigmatism asymmetrically shaped by overlapping size irradiation area of different shifted center, the Corneal surgery apparatus. In a corneal surgical device that has a light guide optical system that guides a laser beam having a wavelength in the ultraviolet region to the cornea, and ablate the cornea with the laser beam to correct a refractive error, the irradiation region of the laser beam is limited to a fan shape Fan-shaped irradiation area limiting means, irradiation area variable means for changing the irradiation area limited in a fan shape by the fan-shaped irradiation area limiting means, and rotating means for rotating the fan-shaped irradiation area limiting means about the optical axis; A corneal surgery apparatus comprising: a control means for performing ablation so as to control the driving of the rotating means and the irradiation region restriction varying means so that the refractive power (curvature) in the astigmatic axis direction of the cornea is different .

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