JPH0344532B2 - - 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 surgery device for correcting ocular refractive power such as myopia and astigmatism.

A-2 Prior Art In the past, glasses and contact lenses have been used to correct eye refractive powers such as myopia and astigmatism, but in recent years glasses and contact lenses have been used to correct eye refractive powers such as myopia and astigmatism. A method of correcting refractive power by changing the shape of the corneal surface, ie, radial keratotomy, is known.

However, this surgery requires a high level of skill, which is an obstacle to its widespread use. Therefore,
The use of lasers for radial keratotomies was eagerly awaited, and development was hurried.

As is well known, there are many types of lasers, but
Irradiation that has a large thermal effect is not suitable because it has an adverse effect on the cornea, such as significant tissue destruction around the incision. However, if the intensity and irradiation time of an excimer laser, especially an AγF excimer laser with a wavelength of 193 nm, are appropriately controlled, it is possible to make an incision with little thermal effect and a cut that is not much different from that of a diamond scalpel. One method of using an excimer laser for correcting eye refractive power is to place a mask with slits on the cornea and then irradiate the excimer laser along the slits.

A-3 Problems to be Solved by the Invention In this method of corneal surgery using excimer laser light, since the beam shape in the cross section perpendicular to the laser beam is large, most of the beam from the laser light source is reflected by the mask, resulting in substantial However, only a small portion of the beam is used for incision, resulting in low efficiency and long incision times.

B. Structure of the Invention B-1. Means for Solving the Problems In order to solve the above-mentioned problems, 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. a standard optical system that includes a light source that emits a light beam in the visible range and indicates the irradiation position of the surgical laser; In a corneal surgery device that partially excises the cornea with a surgical laser that irradiates a parallel light beam toward a mask placed on the mask and passes through a slit formed in the mask, the direction having the substantially uniform energy distribution and A Galileo optical system consisting of a cylindrical lens formed so that the orthogonal direction is approximately the width of the slit formed in the mask, and a length in the direction having the approximately uniform energy distribution to maintain the uniformity of the energy distribution. It is characterized by having a reduction optical system that is formed to a predetermined size, and an image rotator that rotates around the optical axis of the surgical eye.

R-2 Example In Figures 1 and 2, 1 has a wavelength of 193 nm.
This is an AγF excimer laser light source. The cross-sectional shape of a laser beam emitted from a commercially available laser light source in a direction perpendicular to the beam is rectangular as shown in FIG. Specifically speaking, in the commercial product 1,
It is a rectangle with a horizontal (longitudinal) width of about 18 mm and a vertical height of about 6 mm. The energy distribution of this beam having a rectangular cross section is a uniform distribution F(W) in the horizontal direction and a Gaussian (Gaussian distribution) F(H) in the vertical direction.

Again, in FIGS. 1 and 2, 2 is a prism that changes the horizontal beam width W of the AγF excimer laser beam to a size W appropriate for surgery. The diameter of the cornea varies from person to person, but it ranges from 10 mm to 12 mm, so the horizontal beam width W required for surgery is 13 mm.
A certain degree is sufficient. Therefore, with Prism 2,
The width W is narrowed down to w while maintaining the uniformity of the horizontal energy distribution.

3 is a cylindrical convex lens, and 4 is a cylindrical concave lens. Both lenses constitute a Galileo optical system, and the generatrix of the cylindrical surface of both lenses is oriented in a horizontal direction corresponding to the longitudinal direction of the rectangle of the laser beam cross section. It is arranged as follows. Therefore, as shown in FIG. 2, the height H of the laser beam emitted from the laser light source 1 is narrowed down to the height h by both lenses. The cross-sectional shape of the laser beam exiting the cylindrical concave lens 4 is focused into a rectangular beam with a horizontal width w of approximately 13 mm and a vertical height h of 300 to 900 μm. Since the size is reduced from /7 to 1/20, the energy density increases accordingly.

5 is a dichroic mirror, and 6 is an image rotator for changing the direction of the rectangular cross section of the laser beam when irradiating the excimer laser beam onto the eye 9 to be treated so as to match it with the slit of the mask, which will be described later. This image rotator can be rotated manually or electrically by a drive device (not shown) about the optical axis of the eye to be treated.

Reference numeral 7 denotes a He--Ne laser light source constituting the aiming optical system, and the laser light from this light source acts as a guide light for the AγF excimer laser light, which is invisible to the naked eye due to ultraviolet rays. The laser beam from the He-Ne laser light source 7 has a beam cross-sectional shape adjusted by a beam expander or the like (not shown), and the laser beam from the AγF excimer laser light source has a rectangular cross-section w x
Form into the same shape as h. formed like this
The He-Ne laser beam (guide beam) is reflected by the dichroic mirror 5 and becomes coaxial with the AγF excimer laser beam. In order to avoid the influence of the difference in refractive index due to the difference in wavelength between the He-Ne laser beam and the excimer laser beam, the He-Ne laser beam is The laser beam and excimer laser beam are coaxial. A standard optical system using this guide light makes it possible to irradiate invisible excimer laser light in line with the slits of the mask.

Note that the size of the cross-sectional shape of the beam of the excimer laser, the width W in the horizontal direction and the height H in the vertical direction.
and h are not necessarily defined by determining the horizontal or vertical direction with the earth as the coordinate, but as mentioned above, the direction of the larger dimension in the rectangle of the beam cross section where the energy distribution of the beam is uniform. Here, we will call the horizontal direction, and the direction of small dimensions where the energy distribution is Gaussian, the vertical direction. This is because commercially available lasers have excimer laser light sources arranged in this direction.

FIG. 4 is a front view of the mask 8 placed on the cornea of the eye to be treated. The number and length of the slits are determined before surgery depending on the refractive error of the treated eye, and a mask with slits is prepared accordingly. In the case of the mask in this figure, there are 8
Slit 8a of the book is open. The rectangle shown by the broken line with horizontal width w and vertical height h is
The range of the laser beam (beam cross section) that is irradiated in line with the two horizontal slits of the mask 8 is shown. In this state, the cornea is incised along the two horizontal slits of the mask by irradiating the excimer laser at a predetermined intensity for a predetermined time. Next, the image rotator 6 is rotated to rotate the direction of the irradiation beam onto the mask by 45 degrees, and then the excimer laser beam is irradiated again. In this way, the image rotator is rotated so that 4
By changing the direction of the beam in two directions and irradiating the laser beam, the incision of the cornea is completed in line with the eight slits of the mask 8.

FIG. 5 is a diagram showing how the cornea is incised, and the parallel laser beam irradiated as shown by the arrow incise the cornea 10 to the same width as the 30 μm width of the slit of the mask 8. The intensity and time of the excimer laser are controlled so that the depth of the incision is determined according to the refractive error of the treated eye.

Since excimer laser light is ultraviolet light, it generates ozone in the air. Therefore, in the device of this invention, inert gas such as nitrogen gas is filled inside the device to protect the optical system, and inert gas is flowed in front of the patient to prevent ozone generation. Take measures such as avoiding bad odors. In addition, synthetic quartz or the like with good ultraviolet transmittance is used as the material for the prisms and lenses.

C. Effects of the Invention According to the present invention, the density of the energy distribution can be increased in order to narrow down the vertical height H of the beam cross section of the excimer laser light to a dimension h that is close to the width of the slit of the mask. Since the beam width W in the direction can be changed to a size W suitable for the surgery while maintaining uniformity of energy distribution, the resection depth can be accurately controlled and energy efficiency can be increased. .
Furthermore, with the standard optical system and image rotator,
Since the excimer laser beam can be effectively irradiated in the direction of the slit of the mask, the efficiency of using the excimer laser can be increased and the incision time can be shortened. Furthermore, since incisions can be made at symmetrical positions across the center of the cornea at the same time, unnecessary effects on the cornea, such as astigmatism caused by surgery, can be avoided.

[Brief explanation of drawings]

1 and 2 are a plan view and a side view showing an optical system according to an embodiment of the present invention, FIG. 3 is a diagram showing the cross-sectional shape and energy distribution of a laser beam emitted from an excimer laser light source, and FIG. The figure is a front view showing how the mask is irradiated with a laser beam, and FIG. 5 is an enlarged longitudinal sectional view showing how the cornea is incised. 1... AγF excimer laser light source, 2... Prism, 3... Cylindrical convex lens, 4... Cylindrical concave lens, 5... Dichroic mirror, 6... Image rotator, 7... He constituting the aiming optical system
-Ne laser light source, 8... mask, 8a... slit, 9... eye to be treated.

Claims (1)

[Scope of Claims] 1. A laser emitting unit that emits a surgical laser in the ultraviolet range whose energy distribution is substantially uniform in one direction in the cross section of the light beam and non-uniform in a different direction, and a light source that emits a light beam in the visible range. and a standard optical system that indicates the irradiation position of the surgical laser, and the surgical laser is irradiated with a parallel beam of light toward a mask placed on the cornea, and transmitted through a slit formed in the mask. A corneal surgical device for partially ablating the cornea with a surgical laser, comprising a cylindrical lens formed such that a direction perpendicular to the direction having the substantially uniform energy distribution is approximately the width of the slit formed in the mask. A Galileo optical system, a reduction optical system that forms the length in the direction with the almost uniform energy distribution to a predetermined size while maintaining the uniformity of the energy distribution, and an image that rotates around the optical axis of the surgical eye. A corneal surgical device comprising: a rotator;