JP2764104B2 - Corneal treatment device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corneal treatment device used for corneal shaping operations such as refractive correction and corneal transplantation.

[Related Art] In order to perform a corneal shaping operation such as refraction correction or corneal transplantation, it is necessary to always adjust a treatment laser beam to be applied to a predetermined position of the cornea. On the other hand, there are two kinds of movements of the eyeball, rotation and lateral displacement, and these movements cannot be avoided even if the head is fixed to an operating table or the like. Therefore, when performing corneal shaping surgery or the like, a laser beam for treatment is always irradiated to a predetermined position of the cornea,
It is necessary to move the irradiation position according to the movement of the eyeball.

[Problems to be Solved by the Invention] However, since the conventional corneal treatment apparatus does not have an accurate moving means of the irradiation position corresponding to the movement of the eyeball, the suction device does not move the eyeball during the operation. Or if the eyeball is not fixed using an eyeball fixation device with a needle,
There is a disadvantage that corneal shaping treatment cannot be performed. In addition, there is a problem that the use of such an eyeball fixing device gives a significant discomfort to the patient.

[Object of the Invention] An object of the present invention is to perform a corneal shaping operation or the like without causing a significant discomfort to a patient by irradiating a therapeutic laser beam to a predetermined position of the cornea by following the movement of an eyeball. An object of the present invention is to provide a corneal treatment device that can be used.

[Summary of the Invention] The gist of the present invention for achieving the above object is to provide a corneal treatment apparatus for irradiating a therapeutic laser beam to a cornea, a detecting means for detecting a movement of an eye to be inspected, And an irradiation position control means for controlling an irradiation position of the treatment laser light.

[Embodiment of the Invention] The present invention will be described in detail based on the illustrated embodiment.

FIG. 1 shows a configuration diagram of a corneal treatment device according to the present invention,
Reference numeral 1 denotes a laser device, and a laser beam from the laser device 1 is applied to the eye E along an optical axis 01 via deflectors 2 and 3 and a dichroic mirror 4. In the reflection direction of the light beam from the eye E of the dichroic mirror 4,
A half mirror 5, a lens 6, and a television camera 7 are arranged. Further, a lens 8 and an illumination light source 9 are provided in the direction of incidence on the half mirror 5. The output of the television camera 7 is connected to a television monitor 10 and a signal processor 11,
The output of the signal processor 11 is connected to the drive units of the deflectors 2 and 3, respectively.

The therapeutic laser light L1 emitted from the laser device 1 passes through the deflectors 2 and 3 that two-dimensionally correct the traveling direction,
The light passes through the dichroic mirror 4 and is irradiated onto the cornea Ec of the eye E to be examined. An excimer laser beam or the like is generally used as the treatment laser beam L1, and when used for refraction correction, it can be cut radially or the surface can be evaporated to change the shape of the cornea Ec. On the other hand, the illumination light beam L2 from the illumination light source 9 illuminates the eye E through the lens 8, the half mirror 5, and the dichroic mirror 4. At this time, a reflected image Er of the cornea Ec of the eye E is generated by the illumination light beam L2, and the reflected image Er is photographed by the television camera 7 via the dichroic mirror 4, the half mirror 5, and the lens 6, and
The image is displayed on the television monitor 10. In the drawing, a pupil Ep and a corneal reflection image Er are projected on a television monitor 10. At this time, data captured by the television camera 7 is simultaneously sent to the signal processor 11, and the position of the cornea Ec is calculated. Done. The signal processor 11 determines the deflector 2 based on the calculated data,
3 and the control laser beam L1 is always emitted to the cornea Ec
Is controlled to irradiate a predetermined position.

Next, means for obtaining the corneal vertex position in the signal processor 11 will be described. The corneal vertex position referred to here is a line segment Oc connecting the entrance pupil center P and the corneal curvature center C as shown in FIG.
Refers to a point O crossing the cornea Ec. The distance r between the corneal vertex O and the corneal curvature center C or the like is determined in advance by a keratometer, and the distance l between the corneal vertex O and the entrance pupil center P is determined in advance by an ultrasonic tonometer.

FIG. 3 shows an image on the television monitor 10 and a corneal reflection image Er.
Is actually captured by the television camera 7. The pupil center P can be obtained from the signal of the television camera 7, and the center of the pupil Ep can be calculated and displayed from several scanning lines. As is clear from FIG. 2, the corneal curvature center C overlaps the corneal reflection image Er on the surface of the television monitor 10, so that the corneal vertex O is on an extension line connecting the corneal reflection image Er and the pupil center P. In FIG. 2, the distance between the corneal reflection image Er and the pupil center P in the direction of the line segment orthogonal to the optical axis O1 is y1, and the corneal reflection image is
Assuming that the distance between Er and the corneal vertex O is y2, y2 = y1 · (l +
r) / r. Therefore, if the distance y between the corneal reflection image Er and the pupil P on the television monitor 10 is obtained, the corneal reflection image Er
A corneal vertex O exists at a position of a distance y · (l + r) / r from the distance. The distance y is a corneal reflection image based on the scanning line.
Er, the position of the pupil center P can be calculated and then calculated. Since the head is fixed so that the eyeball does not move in the front-back direction, the corneal vertex O
Should be obtained.

The therapeutic laser beam L1 emitted from the laser device 1
Can accurately change the optical path by the deflectors 2 and 3 whose operation is controlled based on the corneal vertex O calculated by the signal processor 11 as described above, so that a predetermined position of the cornea Ec can always be irradiated. Becomes

4 and 5 show a second embodiment, FIG. 4 is a front view of an index image on a pupil, and FIG. 5 is a configuration diagram of a corneal treatment apparatus to which the calculation method is applied. In FIG. 4, the Purkinje first image P1 and the fourth Purkinje image are used as index points for calculating the corneal position.
The image P4, that is, the reflection image of the front surface of the cornea Ec and the reflection image of the back surface of the crystalline lens are used. These two reflected images P1 and P4 are in a relationship of a real image and a virtual image to each other, and when the eyeball is tilted, the interval between the images P1 and P4 changes. Therefore, the direction of the eyeball can be measured in advance at the interval between the two images P1 and P4. On the other hand, the corneal curvature center C is a corneal curvature radius r measured in advance from the surface image P1.
And the direction of the illumination light beam. If the position of the corneal curvature center C and the inclination of the eyeball are known, the position of the corneal vertex O can be obtained by drawing a straight line from the corneal curvature center C according to the inclination of the eyeball, as in FIG.

In FIG. 5, the treatment laser beam L3 emitted from the laser device 20 is arranged so as to be projected onto the eye E through the scanner 21. An illumination light source 22 is disposed diagonally forward of the eye E, and a lens 23 is disposed between the illumination light source 22 and the eye E. In the direction of reflection from the illumination light source 22 to the eye E of the illumination device, the lens 24 and the split prism 25
Are disposed in the reflection directions on both sides of the split prism 25, and position sensors 28 and 29 are provided at the focal positions of the lenses 26 and 27, respectively.

The treatment laser light L3 emitted from the laser device 20 enters the scanner 21, and is scanned two-dimensionally in a plane perpendicular to the treatment laser light L3. This scanner 21 is formed of, for example, two stepping motors and the like, and the therapeutic laser beam L3
Is circularly scanned on the cornea Ec, and is used for operations such as cutting out a portion necessary for transplantation. The therapeutic laser beam L3 scanned by the scanner 21 is applied to the cornea Ec of the eye E along the irradiation axis O2.
Irradiated on top. On the other hand, the driving light beam L4 from the illumination light source 22 illuminates the eye E through the lens 23, and the Purkinje images P1,
Form P4. These images P1 and P4 are shifted from the reflection axis O3 to the lens
An image is formed once in the vicinity of the splitting prism 25 via 24, deflected by the splitting prism 25, and re-imaged on the position sensors 28 and 29 via lenses 26 and 27, respectively. The position sensors 28 and 29 generate position signals of the Purkinje images P1 and P4, and feed back the signals to the scanner 21 to correct the scanning position so that the therapeutic laser beam L3 is always irradiated to a predetermined position of the cornea Ec.

The method of obtaining the corneal vertex O according to the second embodiment will be described with reference to FIG. 6. Purkinje images P1 and P4 are the optical axis Oc of the eye E to be examined.
They are formed on almost the same plane when viewed from the direction. The distance between the Purkinje images P1 and P4 viewed from this direction is such that f1 and f2 are the focal lengths of the systems forming the first and fourth images P1 and P4, respectively, and the optical axis
The angle formed between Oc and the irradiation axis O2, and between the optical axis Oc and the reflection axis O3 is θ
Then, (f1 + f2) tan θ is obtained. When this is viewed from the direction of the reflection axis O3, it becomes (f1 + f2) tan θ · cos θ. This value is measured in advance before the irradiation with the laser beam L3. The interval when the eye E moves, that is, when the optical axis Oc moves by Δθ, is (f1 + f2) tan · (θ + Δθ) · cos (θ−Δθ). This value as a function of Δθ is calculated in advance from the previously measured value and θ, and is calculated in advance. By referring to these values from the distance between the Purkinje images P1 and P4 measured during irradiation, Δθ can be determined. If the direction of the optical axis Oc of the eye E is known,
The corneal vertex O can be obtained as follows. That is, from FIG. 1 P1, a half of the corneal curvature radius r in the illumination light beam direction.
If it advances only by this distance, it will reach the position of the center of curvature C, and if it returns by the inclination θ + Δθ from this center of curvature C, it will reach the corneal vertex O.

With such a configuration, the light beam L4 emitted from the illumination light source 22 irradiates the cornea Ec of the eye E to be examined, and the Purkinje first image
P1 and a fourth image P4 are formed, and the position information of these images P1 and P4 is captured by the position sensors 28 and 29. Therefore, based on the output signals from the position sensors 28 and 29, the signal processor 11 performs the above-described arithmetic processing, calculates the position of the corneal vertex O, and controls the scanner 21. The emitted therapeutic laser beam L3 is scanned by the scanner 21.
As a result, an accurate two-dimensional scanning of the optical path is performed, and a predetermined position of the cornea Ec is irradiated. Therefore, similarly to the embodiment shown in FIG. 1, it is possible to always irradiate the therapeutic laser beam L3 to a predetermined position of the cornea Ec even with the movement of the eyeball.

[Effects of the Invention] As described above, the corneal treatment device according to the present invention can perform an operation without giving a patient any remarkable discomfort.

[Brief description of the drawings]

The drawing shows an embodiment of the corneal treatment apparatus according to the present invention,
FIG. 2 is a configuration diagram thereof, FIG. 2 is an explanatory diagram of a corneal vertex position calculation,
FIG. 3 is an explanatory diagram by a television monitor, FIG. 4 is a front view of an index image on a pupil, FIG. 5 is a configuration diagram of another embodiment, and FIG. 6 is an explanatory diagram of corneal vertex position calculation. Reference numerals 1 and 20 denote a laser device, 2 and 3 deflectors, 4 a dichroic mirror, 5 an illumination light source, 7 a half mirror, 9 a television camera, 10 a television monitor, 11 a signal processor, 21 a scanner, 22 is an illumination light source, 25 is a split prism,
28 and 29 are position sensors.

Claims (3)

(57) [Claims] 1. A corneal treatment apparatus for irradiating a therapeutic laser beam to a cornea, a detecting means for detecting a movement of an eye to be inspected;
A cornea treatment device, comprising: irradiation position control means for controlling an irradiation position of the treatment laser light in accordance with the movement of the eye to be examined. 2. The cornea according to claim 1, wherein said irradiation position control means changes an irradiation position of said therapeutic laser light by changing a reflection angle of a mirror arranged in an optical path of said therapeutic laser light. Treatment device. 3. The corneal treatment apparatus according to claim 1, wherein said detecting means detects the movement of the subject's eye based on a corneal reflection image.