JPH01232959A - Cornea treatment apparatus - Google Patents

Abstract

PURPOSE:To irradiate the predetermined position of the cornea with treatment laser beam so as to follow the movement of an eyeball without especially performing the fixing of the eyeball, by controlling the irradiation direction of the treatment laser beam so as to irradiate the predetermined position of the cornea with the treatment laser beam on the basis of the obtained surface position of the cornea. CONSTITUTION:The illumination luminous flux L2 from an illumination beam source 9 illuminate an eye E to be examined through a lens 8, a half mirror 5 and a dichroic mirror 4. At this time, the reflected image Er of the cornea Ec of the eye E to be examined is generated by the illumination luminous flux L2 but taken by a television camera 7 through the dichroic mirror 4, the half mirror 5 and a lens 6 to be projected on a television monitor 10. The pupil Ep and the cornea reflected image Er are projected on the television monitor 10 but the data taken at this time by the television camera 7 is simultaneously sent to a signal processor 11 to calculate the position of the cornea Ec. The signal processor 11 sends a control signal to deflectors 2, 3 on the basis of the calculated data to perform control so that treatment laser beam L1 always irradiates the predetermined position of the cornea Ec.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a corneal treatment device used in corneal shaping operations such as refractive correction and corneal transplantation.

[Conventional technology] To perform corneal plastic surgery such as refractive correction and corneal transplantation,
It is necessary to adjust the treatment laser beam so that it always irradiates the cornea at a predetermined position. - On the other hand, there are two types of eyeball movements: rotation and lateral displacement, and these movements are unavoidable even if the head is fixed to an operating table or the like.

When performing corneal plastic surgery or the like, it is necessary to move the irradiation position according to the movement of the eyeball so that the therapeutic laser beam is always irradiated to a predetermined position on the cornea.

[Problems to be solved by the invention] However, since conventional corneal treatment devices do not have a means for accurately moving the irradiation position in response to the movement of the eyeball, suction is required to prevent the eyeball from moving during the surgery. A disadvantage is that corneal shaping treatment cannot be performed without fixating the eye using a device or an eye fixation device with a needle. Furthermore, the use of such an eyeball fixation device has the problem of causing significant discomfort to the patient.

[Objective of the Invention] The object of the present invention is to make it possible to irradiate a predetermined position of the cornea with therapeutic laser light by following the movement of the eyeball without fixing the eyeball in particular! ! It is an object of the present invention to provide a corneal treatment device that allows corneal plastic surgery and the like to be performed without causing significant discomfort to a person.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to provide a corneal treatment device that irradiates a therapeutic laser beam to a predetermined position of the cornea, which uses a plurality of anterior segment reflection images produced by an illumination light source and a center of the pupil. Measure the coordinates of at least two points of the
means for determining a corneal surface position existing on an extension line of a line segment connecting two points; The present invention is a corneal treatment device characterized by comprising means for controlling an irradiation direction.

[Embodiments of the invention] The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows a configuration diagram of a corneal treatment device according to the present invention, and
is a laser device, and the laser beam from laser device 1 is transmitted through deflectors 2, 3 . The light is irradiated onto the eye E through the guichroic mirror 4 along the optical axis O1. In the reflection direction of the luminous flux from the eye E side of the guichroic mirror 4,
A half mirror 5, a lens 6, and a television camera 7 are arranged. In addition, a lens 8 is placed in the direction of incidence on the half mirror 5.
, an illumination light source 9 is provided. Also, TV camera 7
The output of the signal processor 11 is connected to the television monitor lO1 signal processor 11, and the output of the signal processor 11 is respectively connected to the drive section of the deflector 2.3.

The therapeutic laser beam Ll emitted from the laser device 1 passes through a deflector 2.3 that two-dimensionally corrects the traveling direction.
The cornea Ec of the eye E to be examined is transmitted through the guichroic mirror 4.
irradiated on top. Excimer laser light is generally used as the therapeutic laser beam Ll, and when used for refractive correction, it is cut radially or the surface is evaporated areawise to improve corneal E.
The shape of c can be changed. On the other hand, the illumination light source 9
The illumination light flux L2 from the lens 8, the half mirror 5, and the glaucroic mirror 4 illuminates the eye E to be examined.

At this time, a reflected image Er of the cornea Ec of the eye E to be examined is generated by the illumination light flux L2, and this reflected image Er is photographed by the television camera 7 via the gicroic mirror 4, half mirror 5, and lens 6, and is displayed on the television monitor. In the 0 drawing displayed on IO, the pupil Ep and the corneal reflection image Er are displayed on the television monitor IO, but at this time, the data captured by the television camera 7 is simultaneously sent to the signal processor 11, The position of the cornea Ec is calculated. The signal processor 11 sends control signals to the deflectors 2 and 3 based on this calculated data, and controls the Fukagawa laser beam Ll to always irradiate a predetermined position on the cornea Ec.

Next, the means for determining the corneal apex position in the signal processor 11 will be explained.
The distance @r between the corneal apex 0 and the center of corneal curvature C, which is the point O where c intersects the cornea Ec, is determined by, for example, a keratometer, and the distance 9 between the corneal apex 0 and the entrance pupil center P is determined by, for example, the ultrasound eye axis. It shall be determined in advance using a meter.

FIG. 3 shows an image on the television monitor 10, and shows a corneal reflection image E.
r is actually imaged by the television camera 7. The pupil center P can be determined from the signal from 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 center of corneal curvature C is
Since it overlaps with the corneal reflection image Er on the surface of the television monitor 10, the corneal apex 0 is located between the corneal reflection image Er and the pupil center P.
It is on the extension line that connects. In FIG. 2, if the distance between the corneal reflection image Er and the pupil center P in the direction of a line perpendicular to the optical axis 01 is yt, and the distance between the corneal reflection image Er and the corneal apex O is y2, then y2=yle (10 r )/r. Therefore,
If the distance #y between the corneal reflection image Er and the pupil 2 on the television monitor 10 is calculated, the distance y・(
Corneal vertex 0 exists at the position of ρ+r)/r. Note that the degree distance My is based on the corneal reflection image Er, I based on the scanning line.
It can be calculated by calculating after finding the position of the II hole center P. Note that since the head is fixed so that the eyeballs do not move in the front-back direction, the corneal vertex 0 can be found two-dimensionally.

The optical path of the therapeutic laser beam L1 emitted from the laser device I can be accurately changed by the deflector 2.3 whose operation is controlled based on the corneal apex O calculated by the signal processor 11 as described above. It becomes possible to always irradiate a predetermined position of the cornea Ec.

4 and 5 show a second embodiment, in which 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 first Purkinje image P1 and the fourth Purkinje image P1 are used as index points for calculating the corneal position.
Image P4. That is, a reflected image of the surface of the cornea Ec and a reflected image of the back surface of the crystalline lens are used.

These two reflected images Pi and P4 are in the relationship of a real image and a virtual image, and when the eyeball is tilted, the distance between the images P1 and 24 changes. Therefore, the direction of the eyeball can be measured in advance at the interval between the two images Pi and P4. On the other hand, the center of corneal curvature C can be easily determined from the surface image P1 using the radius r of corneal curvature measured in advance and the direction of the illumination light beam. If the position of the center of corneal curvature C and the inclination of the eyeball are known, the position of corneal vertex 0 can be determined by drawing a straight line from the center of corneal curvature C according to the inclination of the eyeball, as in FIG.

In FIG. 5, the therapeutic 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 arranged diagonally in front of the eye E to be examined, and a lens 23 is arranged between the illumination light source 22 and the eye E to be examined. A lens 24,
A split prism 25 is arranged, and lenses 26 and 27 are arranged in the reflection direction on both sides of the split prism 25, respectively.
A position sensor 28 is located at the focal position of the lens 26 and 27.
．． 29 are provided respectively.

Treatment laser light L3 emitted from the laser device 20
enters the scanner 21 and is scanned two-dimensionally within a plane perpendicular to the therapeutic laser beam L3. This scanner 21 is formed of, for example, two stepping motors, etc., and is used for tasks such as circularly scanning the cornea Ec with the therapeutic laser beam L3 and resecting the part necessary for transplantation. The therapeutic laser beam L3 scanned by the scanner 21 is irradiated onto the cornea Ec of the eye E to be examined along the irradiation axis 02. On the other hand, the driving light beam L4 from the illumination light source 22 passes through the lens 23 to the subject's eye E.
to form Purkinje images P1 and P4. These images Pi and P4 are once formed near the dividing prism 25 from the reflection axis 03 via the lens 24, and are then focused on the 1-dividing prism 2.
5 and are again reflected onto position sensors 28, 29 via lenses 26, 27, respectively. Body sensor 28.29 is Burkine image PI, P4
A position signal is generated and fed back to the scanner 21, and the scanning position is corrected so that the therapeutic laser beam L3 is always irradiated to a predetermined position on the cornea Ec.

The method of determining the corneal apex O in this second embodiment will be explained with reference to FIG. 6. Purkinje images Pi and P4 are formed on almost the same plane when viewed from the optical axis Oc force direction of the eye E to be examined. The distance between Purkinje images P1 and 24 seen from this direction is fl,
Let f2 be the focal length of the system that forms the first and fourth images PI and P4, respectively, and the optical axis Oc, the irradiation axis 02, and the optical axis O
If the angle between c and reflection axis 03 is 0, then (10F2
)tanθ. When this is viewed from the direction of the reflection axis 03, it becomes (N+f2) tan θ and cos θ. This value is measured in advance before irradiation with the laser beam L3.The interval when the eyeball of the eye E to be examined moves, that is, the optical axis Oc moves by Δθ, is (fl+f2)tan・(θ+Δθ)Φcog(θ
−−〇) This value as a function of Δθ can be calculated from the previous measurement value and θ, so it should be calculated in advance.
10 can be determined by referring to these values from the distance between the Burkinier images Pi and P4 measured during irradiation. Optical axis O of eye E to be examined
If the direction of c is known, the corneal vertex O can be determined as follows. That is, if it advances from the first image P1 in the direction of the illumination light beam by 1/2 of the corneal curvature radius r, it will reach the position of the center of curvature C, and if it moves back from the center of curvature by an amount equal to the slope θ+Δθ, it will reach the corneal apex 0.

With this configuration, the light beam L4 emitted from the illumination light source 22 illuminates the corner 11Ec of the eye E to form the first Purkinje image P1 and the fourth image P4, and these images Pi,
Position information of P4 is captured by position sensors 28 and 29. Therefore, the position sensor 28.29
Based on the output signal from the laser device 20, the signal processor 11 performs the above-mentioned arithmetic processing, calculates the position of the corneal apex 0, and controls the scanner 21. L3 is subjected to precise two-dimensional scanning of the optical path by the scanner 21, and is irradiated to a predetermined position on the cornea Ec. Therefore, similarly to the embodiment shown in FIG. 1, it is possible to always irradiate the therapeutic laser beam L3 to a predetermined position on the cornea Ec even when the eyeball moves.

[Effects of the Invention] As explained above, the corneal treatment device according to the present invention can correct the position of the therapeutic laser beam by monitoring the position of the cornea on the television during irradiation with the therapeutic laser beam.
Corneal shaping surgery can be performed without using an eye fixation device or the like, and the surgery can be performed without causing significant discomfort to the patient.

[Brief explanation of the drawing]

The drawings show an embodiment of the corneal treatment device according to the present invention.
The figure is its configuration diagram, and Figure 2 is an explanatory diagram of corneal apex position calculation.
FIG. 3 is an explanatory diagram using a television monitor, FIG. 4 is a front view of a target image on a pupil, FIG. 5 is a configuration diagram of another embodiment, and FIG. 6 is an explanatory diagram of corneal apex position calculation. Code 1.20 is a laser device, 2.3 is a deflector, 4
is a graphical mirror, 5 is an illumination light source, 7 is a half mirror, 19 is a television camera, 1° is a television monitor, 11 is a signal processor, 21 is a scanner, 22 is an illumination light source, 25 is a splitting prism, 28.29 is a position sensor. Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] 1. In a corneal treatment device that irradiates therapeutic laser light to a predetermined position on the cornea, the coordinates of at least two points among multiple anterior segment reflection images and the center of the pupil from the illumination light source are measured, and these two points are connected. means for determining a corneal surface position existing on an extension of the line segment; and controlling the irradiation direction of the therapeutic laser beam so as to irradiate the therapeutic laser beam to a predetermined position of the cornea based on the obtained corneal surface position. A corneal treatment device characterized by comprising means for: