JP3207170B2 - Laser surgery equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser surgical apparatus for correcting a refractive error by correcting a cornea, and in particular, a hyperopic correction can be performed by reducing a corneal curvature of a hyperopic eye and increasing a refractive power. The present invention relates to a laser surgical device.

[0002]

2. Description of the Related Art In recent years, a technique (Photo-refractive Keratectomy) of correcting a refractive error of an eyeball by removing a surface of a cornea with a laser beam and changing a curvature of the cornea has been attracting attention. However, currently, only myopia correction is performed, and hyperopia correction is hardly performed. The reason is as follows. As shown in FIG. 1, myopia correction can be performed relatively easily by changing the laser ablation area using a normal circular variable aperture, since it is sufficient to cut the central part of the cornea deep and the peripheral part to a shallow convex lens shape. . In contrast, hyperopia correction requires that the central part be shallow and the peripheral part be deep and cut into a concave lens shape as shown in FIG. 2, so that the center of the laser beam is interrupted by a circular aperture and its size is changed. This is because a normal aperture has to do difficult things.

Several methods have been proposed to date for performing this difficult aperture control. Tokuhei 4-
No. 33220 (GB 8608821) "Shaping a Surface Using a Laser"(Applicant's Summit) shows a method of using a special mask to ablate the peripheral part deeper than the central part and cut it into a concave lens shape. (See FIG. 3). The mask used in this method has a resistance of a predetermined shape (profile) to the laser beam, and the shape is made by changing the thickness or the structure of the mask material. When the cornea is irradiated with the laser beam through the mask, a part of the laser beam is selectively absorbed, and the other part is transmitted to the corneal surface according to the shape of the mask, and the surface is selectively ablated. The mask for correcting hyperopia can be cut into a concave lens shape by forming the mask such that absorption is large at the center and transmission is small, and absorption is small at the periphery and transmission is high.

Further, Japanese Patent Application Laid-Open No. 64-86968 (FR)
8708963) "Apparatus for performing corneal surgery on the eye" (Applicant IBM) shows an ablation method that irradiates a laser while rotating or translating a lobe-shaped aperture (see FIG. 4). The lobe-shaped aperture used in this method has a predetermined shape, and corneal ablation is performed by intermittently superimposing a large number of lobe images of the laser beam by this aperture, and as a result, the ablation required for refraction correction is performed. Ablation changes the curvature of the cornea. Therefore, the aperture for correcting hyperopia is wider at a portion corresponding to the peripheral portion of the cornea than at the central portion of the cornea, so that the peripheral portion is more ablated.

Japanese Patent Application Laid-Open No. 2-84855 (SU 445777) is similar to Japanese Patent Application Laid-Open No. 64-86968.
2) "Apparatus for correcting refractive error of the eye" (Applicant)
It is also located at Mezotraslevoy Nauchinotev-Czechski Complex “Microhilrgia Glza”.

[0006]

However, these methods for correcting hyperopia have the following disadvantages.

In the former method using a special mask,
Since the shape of the mask varies depending on the corneal curvature and the correction power of the eye to be corrected, different masks are required for the preoperative corneal curvature and correction power, and a large number of mask shapes are required. There must be. In addition, since the amount of corneal ablation for correction depends on the shape of the mask, the accuracy of the mask shape is an important factor, and accordingly, there is a drawback that manufacturing becomes difficult.

Further, in the latter method of displacing the lobe image, the shape of the lobe-shaped aperture changes depending on the corneal curvature and the correction power before correction as in the above case, so that the number of types of apertures becomes very large. There is a disadvantage that it will.

SUMMARY OF THE INVENTION In view of the above drawbacks, an object of the present invention is to provide a laser surgery apparatus for refraction correction that can reduce corneal curvature and correct hyperopia with a simple configuration without preparing many masks and apertures. It is in.

[0010]

In order to achieve the above object, the device of the present invention has the following features.

(1) In a laser surgical apparatus for correcting a refractive error by ablating the cornea, an ultraviolet laser is used.
Excimer Les emits - having a laser light source, a circular opening
It has an aperture and a linear light-shielding edge.
Beam-shaped shaping means having light-shielding means whose position is variable
And the laser light having passed through the shaping means is subjected to corneal abrasion.
Beam rotating means for rotating the laser beam while being displaced with respect to the center of the illumination area, and laser beam passing through the shaping means.
Irradiation is performed by the system rotating means, and the ring width and the corneal ablation
Ring-shaped at different distances from the center of the lamination area
Abrasion is performed sequentially, and the concave lens is removed from the optical part of the cornea.
Correction of hyperopia for removing cornea-like corneal tissue.
And features.

(2) In a laser surgical apparatus for correcting a refractive error by ablating the cornea, an ultraviolet laser is used.
Excimer laser light source for emitting light, an aperture having a circular opening, and light shielding means having a linear light shielding edge.
Beam-shaped shaping means, and a laser beam passing through the shaping means.
The light is displaced relative to the center of the corneal ablation area.
The cornea is rotated by the beam rotating means
A ring-shaped abrasion concentric with the center of the abrasion area
Ring forming means for performing
The width and width of the ring formed by the brass forming means
Ring-shaped abrasion with different inner diameter of ring
By adjusting the corneal optic from the concave lens-shaped corner
And hyperopia correcting means for removing the membrane tissue . (3) Abrasion of cornea to correct refractive error
In a laser surgical apparatus, an laser emitting an ultraviolet laser.
Kisima laser light source and correcting intensity distribution of the laser light
An optical system, an aperture with a circular opening and a linear shield
Beam shape having light shielding means capable of changing the position of the light edge
Shaping means, and rotating the laser light passing through the shaping means.
Ring-shaped concentric with the center of the corneal abrasion area
Perform the abrasion to change the ring width and ring inner diameter.
The ring-shaped abrasion
Resecting concave corneal tissue from more corneal optics
And hyperopia correcting means .

[0013]

Embodiments of the present invention will be described below with reference to the drawings. (Overall Optical System) FIG. 5 is an arrangement diagram of an optical system according to one embodiment.

Reference numeral 1 denotes a laser light source. In the embodiment, an excimer laser is used. The laser beam emitted from the laser light source is reflected by mirrors 2 and 3. The mirror 3 is movable in the direction of the arrow, and when the myopia is corrected, the laser beam is uniformly cut by scanning in a direction having an uneven intensity distribution described later. This point
The details are described in Japanese Patent Application No. 2-416767 (title of the invention: ablation apparatus using a laser beam), so please refer to it.

Reference numeral 4 denotes a rotatable elongated flat plate aperture, and FIG. 6 is a view of the aperture seen from above. The aperture 4 escapes from the optical path when correcting myopia, and is inserted into the optical path when correcting hyperopia. The aperture 5 is a circular aperture having a variable opening diameter. The aperture 4 is arranged in close proximity to the aperture 5 and the aperture 5 is
In a position conjugate to Therefore, an image of the beam shape on the aperture is formed on the cornea 9.

The laser beam having passed through the apertures 4 and 5 passes through a projection lens 7 through an image rotator 6, is bent 90 ° by a plane mirror 8, and reaches a cornea 9.

Reference numeral 10 denotes a binocular observation optical system. The left and right observation optical axes are positioned so as to sandwich the plane mirror 8.
Since the details of the binocular observation optical system are not relevant to the present invention, they are omitted. (Explanation of Correction of Hyperopia) The correction of hyperopia using the above-described optical system will be described.

FIG. 7 shows a typical sectional shape of an exit beam of an excimer laser. When the apertures 4 and 5 are viewed from the laser light source side, they are as shown in FIG. 8. The laser beam is cut at the center by the aperture 4 and at the periphery by the aperture 5, and the beam in the hatched portion passes through the apertures 4 and 5. I do. The beam having the hatched shape is projected onto the cornea 9 by the projection lens 7 to ablate the cornea. The image of the laser beam is rotated by an image rotator 6 (which may be arranged between the projection lens 7 and the cornea 9) between the apertures 4, 5 and the projection lens 7 to move the ablation area. When several shots are repeatedly irradiated in this way, ablation is performed in a ring shape as shown in FIG. At this time, the outer diameter D ₁ of the ring is determined by the opening diameter d of the aperture 5 and the projection magnification of the projection lens 7, and the inner diameter D ₂ is determined by the beam cutting width e of the aperture 4 and the projection magnification of the projection lens 7. .

As described above, the aperture 4 is a rotatable flat plate as shown in FIGS. 6 and 8, and the width e of the aperture with respect to the beam changes as shown in FIG. As a result, assuming that the thickness of the aperture 4 is 0, the transmission amount T of the laser beam passing through the apertures 4 and 5 is θ
When = 0 °, the beam is not cut by the aperture 4 and passes through the entire circular opening having the diameter d of the aperture 5. Therefore, if the transmission amount is “1”, the transmission amount with respect to the rotation angle of the aperture 4 is It looks like 11. Therefore,
As for the ablation region of the laser beam on the cornea 9, when θ is increased from 0 ° and the width at which the beam is cut by the aperture 4 is increased, all the circular regions having the diameter D ₁ when D ₂ = 0 are ablated. From the state, the inner unablated circular region having a diameter D ₂ increases, and when θ = θ _d , the width e of the aperture 4 becomes equal to the opening diameter d of the aperture 5, and D ₂ = D _1. Is not ablated.

The angle θ that the aperture 4 makes with the beam optical axis
Changing the, by changing the diameter D ₂ of a circular area that is not inside the ablation ring-like ablation region, ablating the shallow central cornea, the peripheral portion is deeper concave shape as shown in FIG. 2, the correction of hyperopia eye It can be performed.

The excimer laser beam has an intensity distribution as shown in FIG. 7, and when this is rotated and ablated as it is, the center of the beam (the center of rotation of the laser beam by the image rotator) is closer to the periphery as shown in FIG. Are also removed. Therefore, the angle θ of the aperture 4
The control and rotation control of the image rotator of D ₂ by, it is necessary to perform this is taken into account to. In order to avoid such an annoyance, a filter having a transmittance distribution as shown in FIG. 13 is inserted between the laser light source 1 and the aperture 4 in FIG. 5 to make the intensity distribution of the laser beam substantially uniform. You don't have to consider

In the embodiment described above, the width of cutting the laser beam is changed by rotating the aperture 4, but the width e can be changed by another method. Also, instead of cutting the center with an aperture,
A similar method can be performed by a method of controlling the interval between beams divided into two by a plurality of mirrors as shown in FIG.

The apparatus operates a drive unit such as a motor under the control of a computer. However, since this operation method itself has no feature, the description thereof is omitted.

[0024]

According to the present invention, it is possible to reduce the corneal curvature by excision of the cornea into a concave lens shape by a simple mechanism without preparing a large number of masks and apertures different for each of the preoperative corneal curvature and the correction power. It is possible to correct hyperopia.

[Brief description of the drawings]

FIG. 1 is a view showing a resected portion of a cornea of a subject eye for correcting myopia.

FIG. 2 is a diagram showing a resected portion of the cornea of the eye to be corrected for hyperopia.

FIG. 3 is a diagram showing an example of a resection method in which aperture control for correcting hyperopia is performed.

FIG. 4 is a diagram showing another example of a resection method in which aperture control for correcting hyperopia is performed.

FIG. 5 is a layout diagram of the optical system of the present embodiment.

FIG. 6 is a view of an aperture of an elongated flat plate as viewed from above.

FIG. 7 is a diagram showing a typical cross-sectional shape of an output beam of an excimer laser.

FIG. 8 is a diagram of an elongated flat plate aperture and a circular aperture as viewed from the laser light source side.

FIG. 9 is an explanatory view showing ablation in a ring shape.

FIG. 10 is a diagram showing a change in aperture width with respect to a beam.

FIG. 11 is a diagram showing a change in a transmission amount of a laser beam with respect to a rotation angle of an aperture of an elongated flat plate.

12 is a diagram showing a shape to be cut off when ablation is performed by rotating the beam of the excimer laser having the intensity distribution shown in FIG. 7 as it is.

FIG. 13 is a diagram showing the relationship between the transmittance of the laser light source and the aperture of the elongated flat plate.

FIG. 14 is a diagram illustrating a method of controlling beams by a plurality of mirrors.

[Explanation of symbols]

 1 laser light source 3 mirror 4,5 aperture 6 image rotator

Claims (3)

(57) [Claims] 1. A laser surgical apparatus for correcting a refractive error by ablating a cornea, and emitting an ultraviolet laser.
To excimer Le - The light source, APA with a circular opening -
The light-shielding edge has a linear light-shielding edge and the light-shielding edge can be positioned.
Beam-shaped shaping means having variable shading means;
The laser beam that has passed through the shaping means is applied to the ablation area of the cornea.
Beam rotating means for rotating in a state of being displaced with respect to the center of the beam, and a beam rotating hand for passing the laser light passing through the shaping means.
Irradiation by a step, ring width and abrasion of the cornea
Ring-shaped abrasion at different distances from the center of the
Corneal optics from the optics of the cornea
A laser surgery device , comprising: hyperopia correcting means for removing membrane tissue . 2. A laser surgical apparatus for correcting a refractive error by ablating a cornea, and emitting an ultraviolet laser.
Excimer laser light source and aperture with circular opening
Beam having light-shielding means having a light- shielding edge having a linear shape
Beam shaping means, and laser light passing through the shaping means.
Displaced relative to the center of the corneal ablation area
Abrasion of the cornea by rotating the beam in a state
Perform ring-shaped ablation concentric with the center of the
Ring-shaped abrasion forming means, and ring-shaped abrasion
The width of the ring formed by the
Overlap ring-shaped abrasion with changed inner diameter
The corneal tissue from the optical part of the cornea
And a hyperopia correcting means for resecting the laser . 3. A method of correcting a refractive error by ablating a cornea.
Emit UV laser in laser surgery device to correct
Excimer laser light source, and an intensity distribution of the laser light.
Correcting optics, aperture and straight line with circular aperture
With light-shielding means in which the position of the light-shielding edge is variable
Beam shaping means, and laser light passing through the shaping means.
Rotate and rotate phosphor concentric with the center of the corneal ablation area.
Abrasion in the shape of a ring
Overlap ring-shaped abrasion with changed diameter
The corneal tissue in the form of a concave lens can be removed from the optical part of the cornea
A laser surgery device comprising: hyperopia correcting means for resecting .