JPH0351183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. OBJECTIVES OF THE INVENTION A-1. Field of Industrial Application This invention relates to a corneal surgical device for correcting ocular refractive power such as myopia and astigmatism.

A-2 Prior Art In the past, glasses and contact lenses were mainly used to correct eye refractive powers such as myopia and astigmatism, but in recent years, sharp blades such as diamond scalpels have been used to correct eye refractive powers such as myopia and astigmatism. Radial keratotomy has become known as a method of correcting refractive power by changing the shape of the corneal surface by creating a scar on the cornea. However, this technique requires extremely skilled operation of the cutting instrument, which is an obstacle to its widespread use. Therefore, the use of lasers for radial keratotomy was eagerly awaited, and development was hurried.

As is well known, there are many types of lasers, but
Materials that have a large thermal effect due to irradiation are not suitable.

This is because tissue destruction around the incision is significant and has a negative effect on the cornea. By appropriately controlling the intensity and irradiation time of excimer lasers, especially AγF excimer lasers with a wavelength of 193 nm, it becomes possible to make incisions with less thermal effects and with a cut edge that is not much different from that of a diamond scalpel.

A-3 Problems to be Solved by the Present Invention An object of the present invention is to provide a corneal surgical device for correcting ocular refractive power using excimer laser light, and more specifically, a corneal surgical device for correcting the refractive power of the eye using excimer laser light. An object of the present invention is to provide a device for correcting refractive power abnormality by irradiating the surface with excimer laser light and damaging it.

B. Structure of the Invention B-1 Means for Solving the Problems In order to achieve the above object, the corneal surgery device of the present invention has an energy distribution that is substantially uniform in one direction in the cross section of the light beam and non-uniform in a different direction. In a corneal surgery device that has a laser emitting means that emits a laser beam in the ultraviolet region having a cylindrical lens or a cylindrical mirror having a generatrix direction in a direction having a substantially uniform energy distribution and arranged to focus laser light on a substantially tangential plane of the cornea in a direction perpendicular to the generatrix, and the cylindrical lens or It is characterized by having a rotation means for rotating the cylindrical mirror around the optical axis of the eye to be examined, and an image rotator that rotates in synchronization with the rotation means.

RO-2 Embodiment An embodiment of the present invention will be described below with reference to the drawings. Figure 1 is a layout diagram of the optical system of one embodiment, Figure 2
The figure shows the layout of the slit lamp observation system. 1st
In Figures 1 and 2, 1 is an excimer laser oscillator used for corneal surface incision, and 2 is an optical laser oscillator that is on the same optical axis as the excimer laser and used for aiming to determine the irradiation area. A He-Ne laser) is used. 3
4 is a mirror for reflecting the laser beam from the He-Ne laser oscillator 2; 4 is a dichroic mirror for transmitting the laser beam from the He-Ne laser oscillator 2 and reflecting the excimer laser; 5 and 6;
is a mirror for transmitting each laser beam of the excimer laser 1 and the He-Ne laser 2 to the surgical eye 15;
7 is an aperture for controlling the position and length of the laser beam on the eye to be examined, and is moved in the direction of the arrow. 8 is an image rotator for constantly controlling the direction of the cross-sectional shape of the laser beam for irradiating the surgical eye 15 with excimer laser light;
9, 13, 13a are mirrors. Reference numeral 10 indicates an eyepiece lens, and 11 indicates a microscope objective lens, forming a slit lamp microscope section. 12 is the operator's eye; a cylindrical lens 14 is for focusing the laser beams of the excimer laser oscillator 1 and the He-Ne laser oscillator 2 transmitted from the mirrors 13 and 13a onto the cornea in a slit shape; ，
13a, it rotates around the optical axis X of the surgical eye. Cylindrical lenses are made of materials such as synthetic quartz that have high UV transmittance. Reference numeral 16 indicates the top surface of a table that houses excimer laser, He--Ne laser oscillators, their power supplies, and the like.

The laser beam emitted from the helium-neon laser oscillator is reflected by the mirror 3, and becomes coaxial with the excimer laser beam by the mirror 4. Both laser beams pass through the table top surface 16 as shown in the figure. It is reflected by mirrors 5 and 6 located inside the slit lamp, and the aperture 7,
Image rotator 8 and mirrors 9, 13, 1
A slit beam is formed on the corneal surface by the cylindrical lens 14 via the lens 3a.

In radial keratotomy, it is necessary to uniformly incise the corneal surface of the surgical eye 15. However, the excimer laser beam emitted from a commercially available excimer laser oscillator has a rectangular beam cross section as shown in FIG. In the horizontal direction (referring to the longitudinal direction), the energy distribution is a uniform distribution F(w) over the width w of the beam, but in the vertical direction, it is a Gaussian (Gaussian distribution) FH across the beam height H. ing. Considering this energy distribution, if the light is focused by a horizontally extending cylindrical lens having a uniform energy distribution, a slit-shaped laser beam having a uniform energy distribution in the longitudinal direction can be obtained.
Additionally, in order to make the width of the beam uniform on the corneal surface, the laser beam focused by the cylindrical lens must travel toward the center of curvature of the cornea, and moreover, the approximate center of the beam should be on the cornea. The focal plane is made to substantially coincide with the tangential plane 15a of the cornea at a position in contact with the cornea. This point will be explained with reference to FIG.

Although there are some differences depending on the person, the maximum size of the cornea is 13 mm in diameter, and the optical zone (the area used optically for viewing) has a minimum diameter of 3 mm.
mm, the tangential plane 15a of the cornea at the central part from the edge P ₁ of the optical zone to the edge P ₂ of the cornea, that is, at the position P ₃ separated by about 4 mm from the optical axis
Alternatively, the focal plane is made to coincide with a plane slightly parallel to the center of the cornea. In this case, the deeper the depth of focus, the better.

Radial keratotomy corrects the refractive power by changing the surface shape of the cornea by making radial scratches in eight directions on the corneal surface, as shown in FIG. It is necessary to rotate around the optical axis X passing through the center of the cornea. At this time, in order to always focus the laser beam into a slit shape as described above, it is necessary to rotate the image rotator 8 at the same time, and the rotation angle is determined by the rotation angle of the mirror 13,
13a and the rotation angle of the cylindrical lens 14. In addition, the aperture 7 is adjusted to match the incision position and length determined before the surgery, depending on the refractive error of the surgical eye.

The aperture 7 can be moved left and right in the directions of the arrows.

Furthermore, since the excimer laser light is ultraviolet rays, and therefore ozone is generated, there will be no problem if an inert element gas such as titanium gas is filled or flowed. Although not shown in the drawings, in order to more accurately focus the corneal surface, a double beam of aiming light may be introduced and focusing may be performed in a coincident manner. Furthermore, cylindrical lens 14 and mirror 1
Cylindrical mirror 1 as a substitute for 3 and 13a
4' and mirrors 13, 13b, and 13c can be used as shown in FIG.

For a cylindrical mirror, its generating line is the tangent plane 1
5b, and so that the optical path of the laser beam reflected by the cylindrical mirror is parallel to the optical axis X passing through the center of the cornea. The reason why the laser beam is removed from the optical axis X by the mirror 13b is that since the cylindrical mirror is placed near the optical axis X, the cylindrical mirror obstructs the optical path of the laser beam.

In this embodiment, the cylindrical mirror is arranged so that the optical axis X and the optical path of the laser beam are parallel to each other, but the optical path can be tilted by adding a mirror at an appropriate position.

In this invention, the cross section of the laser beam emitted from the excimer laser oscillator 1 is a rectangle having a width W in the horizontal direction and a height H in the vertical direction, as shown in FIG.
Alternatively, a cylindrical mirror 14' is used to condense the laser beam so that the vertical direction thereof substantially coincides with the tangential plane to form a slit shape. and a device for controlling the position and length of the laser beam on the surgical eye,
For example, the aperture 7 is used to control the position and length of the slit.

In this way, a slit-like incision, indicated by the symbol 17 in FIG. 5, is made in the cornea. If eight equally spaced radial incisions of the same length are to be made, after making slit-shaped incisions as shown in symbol 17, rotate the image rotator 8 and the optical system including the cylindrical lens 14 or cylindrical mirror 14'. Then, the direction of the cross-sectional shape of the laser beam irradiated onto the cornea is rotated by 45 degrees, and the excimer laser is oscillated at a predetermined intensity for a predetermined time to make an incision shown by symbol 17a in FIG. In this way, the direction of the beam is rotated by 45 degrees to make eight radial incisions.

Note that the shape of the vertical incision indicated by symbol 17b in FIG. If the focal plane does not match, the incision shape will be different from a slit shape due to defocus, as shown in FIG. , In the corneal part far from the focal plane, the incision width becomes as shown in C in the same figure, and the incision width becomes unnecessarily wide in the part shown in C.
In addition, since the beam is blurred, incisions of uniform width and depth cannot be achieved.

C. Effects of the Invention As is clear from the above description, according to the present invention, the energy distribution in the longitudinal direction of the slit-shaped cross section of the laser beam guided to a predetermined position on the cornea can be made almost uniform, and the laser irradiation position can be moved. However, the energy distribution does not change. Therefore, the resection depth can be precisely controlled, precision surgery can be performed, and surgery using an excimer laser scalpel, which does not depend on skill, can be performed instead of the surgery that requires skill, which was conventionally performed using a diamond scalpel. .

[Brief explanation of drawings]

FIG. 1 is a side view of an optical system showing an embodiment of the present invention, FIG. 2 is a layout of a slit lamp observation system used in the embodiment of FIG. 1, viewed from above, and FIG. 3 is an excimer A diagram showing the cross-sectional shape and energy distribution of the laser beam, FIG. 4 is a diagram showing the focal position, and FIG. 5 is a front view showing an example of corneal incision.
FIG. 6 is a diagram showing different shapes of incisions, and FIG. 7 is a layout diagram of another embodiment as seen from the side of the optical system. 1... Excimer laser oscillator, 2... Aiming laser oscillator, 8... Image rotator, 13, 13
b, 13c...Mirror, 14...Cylindrical lens, 14'...Cylindrical mirror, 15...Surgical eye, 15a...Tangential plane of cornea.

Claims (1)

[Scope of Claims] 1. A laser beam emitting means for emitting a laser beam in the ultraviolet region having an energy distribution that is substantially uniform in one direction in the cross section of the light beam and non-uniform in a different direction; In a corneal surgery device that linearly ablates the cornea to a predetermined depth using a laser beam guided to a predetermined position, the generatrix direction is in the direction having the substantially uniform energy distribution, and the cornea is roughly cut in a direction perpendicular to the generatrix. A cylindrical lens or a cylindrical mirror arranged to focus laser light on a tangential plane, a rotation means for rotating the cylindrical lens or cylindrical mirror around an optical axis of the eye to be examined, and a rotation means synchronized with the rotation means. A corneal surgical device comprising: a rotating image rotator; 2. The corneal surgical device according to claim 1, wherein the light guiding optical system is arranged so that the center of the direction of uniform energy distribution is substantially a contact point of the tangential plane.