JPH02261449A - Apparatus for surgerical care of abnormal view eye - Google Patents

Abstract

PURPOSE: To realize the correct shape of a cornea after treatment by providing an optical system whose maximum diameter is equal to the diameter of a human cornea, and whose distributor is capable of converting parallel cylindrical laser radiation beams to circular beams with variable diameter. CONSTITUTION: A distributor 3 of a laser radiation energy density incorporates two taper lenses 5, 6 arranged in series on a common optical axis with their tops facing each other and with an equal angle of refraction. An objective lens 7 of a microscope is positioned along the radiation path of a laser 1 past a second lens 6. At the time of a surgical operation, a slice 17 is removed by an interaction of effective laser radiation beams 20 and a cornea 4. The irradiation starts at the maximum diameter of the effective radiation beam from the central region of the cornea 4, reducing the period of irradiation with an increase in the diameter of effective beams. Thus, the slice 17 of the cornea 4 can be removed under an properly selected irradiation condition. As a result, a coreneal surface after the surgical treatment is realized in a predetermined shape as planned.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an apparatus for the surgical treatment of anomalous vision (ie, myopia and hyperopia).

(Prior Art and Problems to be Solved by the Invention) As one of the conventional devices for the surgical treatment of abnormal vision, an ultraviolet pulsed laser-1 and a laser radiation energy density exceeding the cross-sectional area of the laser beam are used. It is known to have a distributor for distributing the laser beam, and the distributor is installed so as to cross the path of the laser beam (Report
f the 'CentreScientiffique
IBM'+ Paris, France, Doc
umentNo., F2O3, 1986, Han
na et al-+'ExcimerLaser
Refractive Keratoplasty').

In the device described above, the distributor of laser radiation energy density actually comprises a rotating disk with a slit of a pre-estimated shape.

This is due to the effect of a number of laser pulses, with a predetermined ratio of the repetition frequency of the radiation pulses and the rotational frequency of the slitted disc, changing the shape of the corneal surface in a manner that corrects the dysopia.

However, only a part of the cornea is exposed to the radiation at each instant, which prevents obtaining a smooth surface with a preset contour. This part depends on the shape of the slit and its angular position at that time.

Since each radiation pulse removes one layer from the cornea with vertical walls, the shape of this layer follows the shape of the slit.

The required shape of the corneal surface is approximated by a stepped surface such that many shallow depth layers are removed to obtain a smooth surface.

This lengthens the surgical time. That is, for a long time,
It requires precise fixation of the patient's eyeball to the laser beam, which impedes free performance of the surgical procedure. Additionally, this also lengthens the surgical time since the laser radiation energy is utilized inefficiently. In addition, during manufacturing, precise accuracy is required in manufacturing the slit and its rotation mechanism, and the angular position of the slit and the time correlation between the slit position and the moment of emission of the laser pulse. Accurate measurements are required.

Another device for the surgical treatment of abnormal vision, particularly myopia, is described by 'Am, Journ, of Ophtha.
1mology'.

v, 103+ i, 13+ part 11, M,
B, McDonald et al, +'Refra
CTTV Surgery with the Ex
cimer La5er +p, 469.1987.

In the device described above, the density distribution of the laser radiation energy is created as a diaphragm placed across the path of the laser beam. The diameter of this diaphragm changes in steps from pulse to pulse according to a computer program designed to change the shape of the corneal surface to provide the required myopia correction.

Similar to the previous device, the use of the device described above exposes only a portion of the cornea to the radiation at each instant, and this portion depends on the diameter of the diaphragm at a given time, and this portion is dependent on the diameter of the diaphragm at a given time, and the use of the above device results in a smooth corneal surface. prevent you from getting it. In addition, many shallow depth layers are removed from the surface of the cornea, which means that
It requires the patient's eye to be precisely fixed to the laser beam for a long period of time, thus lengthening the surgical time. In addition, this also lengthens the surgical time since the laser radiation energy is utilized inefficiently.

Furthermore, another device for the surgical treatment of dysopia includes an ultraviolet pulsed laser 1 and a distributor for distributing the laser radiation energy density over the cross-sectional area of the laser beam. It is known that the laser beam is installed across the path of the laser beam (PC
T/S U 8 B100280).

In the above device, the laser radiation energy density distributor is formed as an optical cell whose first and second optical windows are placed across the path of the laser beam. The optical windows mentioned above are made of a material transparent to the laser radiation, and the inner surfaces of these windows are surfaces of rotation of the second order, i.e. paraboloids,
Formed as a hyperboloid or spherical surface. The optical cell described above is also filled with a liquid medium that can partially absorb the laser radiation. The known device described above makes it possible to obtain a smooth corneal surface of the required shape.

However, the aforementioned devices suffer from the problem that the laser radiation is partially absorbed by the liquid medium contained within the optical cell, which increases the surgical time and does not properly utilize the laser radiation energy. was there.

Furthermore, manufacturing the above-mentioned optical cell windows formed as secondary rotating surfaces is a technically complex task. This is because the optical cell window must be manufactured with great precision, as any deviation from the preset shape of the optical cell window will adversely affect the accuracy of the patient's corneal shape. be. Preoperative adjustment of the device is also a very complex task.

[Means to solve the problem]

The present invention is characterized in that it has an ultraviolet pulse laser 1 and a distributor that distributes the laser radiation energy density over the cross-sectional area of the laser beam, and the distributor is installed to cross the path of the laser beam. In an apparatus for surgical treatment of the optic eye, at least two distributors distributing the laser radiation energy density over the cross-sectional area of the laser beam are arranged on one common optical axis.
An optical system that incorporates two tapered lenses and a microscope objective and is capable of converting a parallel cylindrical laser radiation beam into an annular beam of variable diameter, the maximum diameter of which is comparable to the diameter of the human cornea. It is a certain thing.

The laser radiation energy density distributor of the above proposed device for the surgical treatment of ametropia may have two tapered lenses having equal refraction angles and opposing each other at their apexes.

Here, the objective lens of the microscope may be positioned past the second tapered lens along the path of the laser radiation.

The above laser radiation energy density distributor may also be
There are two tapered lenses, of which the second and third
The tapered lenses of the lenses may face the laser at their bottom surfaces and have equal refraction angles when viewed along the path of the radiation, where the objective lens of the microscope is the first along the path of the laser radiation. and a second tapered lens.

Furthermore, the above laser radiation energy density distributor is
It may have three tapered lenses facing the laser at their bottom surfaces. Here, the objective lens of the microscope may be placed between the first and second lenses, and the third
The lens may be placed along the path of the laser radiation, have a conical recess, and have an angle of refraction equal to 90°-α.

Here, α indicates the refraction angle of the second lens along the path of the laser radiation.

In all embodiments of the invention, the second tapered lens is movable along the optical axis along the path of the laser radiation.

[Effect]

The device for the surgical treatment of ametropia according to the invention allows a predetermined corneal shape to be achieved with a high degree of accuracy due to the substantially reduced operating time. This reduction in surgical time means that at every moment,
This is due to the fact that the entire radiation flux emitted by the laser acts on the surface of the cornea being treated, minimizing the loss of energy in the distributor of the laser radiation energy density of the proposed device. Moreover, in the proposed device adjustments for correction of a preset amount of myopia can be easily made. Such an adjustment would cause one of the distributor's tapered lenses to become stepped.
) is carried out by moving with the help of an electric motor. Manufacturing a tapered lens is a technically simpler task compared to manufacturing an optical cell window that is a rotational quadratic. The device according to the invention is therefore simpler to manufacture and can be built up to a reasonable degree of accuracy.

Other things derived from the invention will become clear from the following description of some specific embodiments with reference to the accompanying drawings.

〔Example〕

As shown in FIG. 1, the apparatus for the surgical treatment of anomalous eyes, that is, myopia and hyperopia, according to the present invention includes an ultraviolet pulsed laser-1 and a laser beam having a radiation energy density of 2 degrees. , which is placed across the path of the laser beam 2 to determine the diameter of the area of surgery on the patient's cornea 4 .

The laser radiation energy density distributor 3 incorporates two tapered lenses 5 and 6 arranged in series on a common optical axis, with their vertices facing each other and having equal refraction angles α. have. A microscope objective 7 is then placed along the path of the radiation of the laser 1 past the second lens 6. All optical components mentioned above are made of materials transparent to laser radiation, for example quartz. A second tapered lens 6 placed along the path of the laser radiation is connected to a stepped electric motor 8 in this embodiment.
With the help of the Huf
It constitutes a flexible system.

The optical objective 7 consists of a series of converging lenses 9 and a series of diverging lenses 10 and is calculated to minimize aberrations, as in variable magnification microscope systems.

FIG. 2 shows another embodiment of the device for surgical treatment of anomalous vision of the present invention. Here, the radiant energy density distributor 3' consists of three lenses 5 receiving the laser 1 at their respective bottom faces and having equal refraction angles.
, 11.12 and the first along the path of the radiation of laser 1.
The microscope objective lens 13 is inserted between the second lens 5 and the second lens 11. All optical components of the device embodiments described above are also made of materials transparent to laser radiation, such as quartz. A second tapered lens 11 placed along the path of the laser radiation can also be moved along the optical axis by means of a stepped electric motor 8 . The microscope objective lens 13 consists of a diverging lens 14 and a converging lens 15, and is calculated to minimize aberrations.

FIG. 3 shows another embodiment of the device for surgical treatment of dysopia of the present invention.

Here, the radiant energy density distributor 3# is also
The three lenses 5, 11, 16 receiving the laser 1 at the bottom of each and the microscope objective 13' consist of a diverging lens 14' and a converging lens 15', the parameters of these lenses being as shown in FIG. Microscope objective lens 1
This is different from the parameters of the third component. A microscope objective 13' is inserted between the first tapered lens 5 (FIG. 3) and the second tapered lens 11 along the path of the radiation of the laser 1. Unlike the previously described embodiments, the third tapered lens 16 has the shape of an inverted cone (with a conical recess), and the refraction angle is 90° - α
be equivalent to. Here, α is the refraction angle of the first tapered lens 5 and the second tapered lens 6 placed along the path of the laser radiation. All optical components of the distributor 3' described above are also made of a material transparent to laser radiation, for example quartz. A second tapered lens placed along the path of the laser radiation is also driven by a stepped electric motor 8.
It is possible to move it along the optical axis mentioned above.

The choice of which embodiment of a device for the surgical treatment of ametropia depends on how the device can be manufactured and the requirements regarding minimum aberrations of the device's optical system.

The device shown in FIG. 1 is a smaller (space-saving) embodiment of the device shown in FIGS. 2 and 3, which requires a high degree of manufacturing precision and is more difficult to adjust. Because it uses a focused radiation beam and an optical system with minimal aberrations, it allows surgery to be performed with a higher degree of precision.

The device shown in FIG. 3 is more compact than the device shown in FIG. 2, although the provision of the inverted conical lens 16 complicates manufacturing techniques.

The device for the surgical treatment of dysopia according to the invention operates as described below.

The operation of the device shown in FIG. 1 will be discussed below for the treatment of myopia.

The corneal surface of a normal eye is described by the equation of a paraboloid of revolution with radius of curvature R.

The corneal surface 4 of a myopic eye (FIGS. 4 and 6) has at its apex a radius of curvature R, which is smaller than that of a normal eye, i.e., according to the equation of a paraboloid of rotation, R, < R. Described.

For myopia surgery, a layer surrounded by two paraboloids with different curvatures, such as the shaded section 17, should be removed from the cornea.

During the treatment of myopia, the energy density of the output from the laser l (Fig. 1) is determined by the beam cross-sectional area (i.e.
A parallel, cylindrical radiation beam 2 uniformly distributed over a circle with a diameter of
cone wall thickness
It is transformed into a conically shaped beam 18 with D/2·cosβ and an interior angle 2β. Here, β depends on the refraction angle α and refractive index n of the tapered lens 5, and sin β= (nl (1-s fn”α)−I (1
-n's i n"α) )Xs fnα
(1) Furthermore, the laser beam 18 passes through a second tapered lens 6 with the same refraction angle α and is converted into an annular beam 19 with an annular wall thickness equal to D/2. Here, the taper lens 6 is stepped.
pped) Continuous movement along the above-mentioned optical axis is possible by means of an electric motor 8. The annular beam thus created smoothly changes its outer diameter. here,
In the embodiment of the present invention, a configuration is provided in which the value of DI can be adjusted within a range having a minimum value and a maximum value D11lax described below. The above minimum value is D (i.e., if the above ring is a circle and the inner diameter of the ring is O
). The above value of the outer diameter of the ring is related to the position of the tapered lens 6 according to the following (2).

pl-I)+21 ・tanβ (2) Here, l is the displacement of the tapered lens 6 (indicated by reference numeral 6 in FIG. 1) from the position of the 0 point,
At this 0 point position, the beam is -D. Equation (2) is established when the distance a between the vertices of the tapered lenses 5 and 6 is selected as shown in Equation (3) below.

a=(D/2tanβ)−[L−((DOD)·tanα)/2] Here, D is the diameter of the tapered lens 5, and L is the thickness of the tapered lens 5.

Having passed through the tapered lens 6 , the parallel radiation beam 19 , whose cross section is annular, passes through the microscope objective 7 . Here, the beam 19 described above has a variable outer diameter and wall thickness d
is converted into a parallel annular beam 20 with . The beam 20 is then immediately directed onto the cornea 4.

The wall thickness d of the beam 20 is continuously varied by varying the distance between lenses 9 and 10 in the microscope objective 7.

Thus, D,=D,-K. where K is a scaling factor smaller than 1, i.e. the cross-sectional area of the beam 20 is larger than the maximum diameter of the ring D t = D + ′″a!,
D- varies in the range between the circles. In this case, the diameter Dt
-D1'''1 K has a size comparable to the outer diameter of the patient's cornea 4.

The wall thickness d of the annular beam 20 is selected to match the surgical conditions and the parameters of the laser l.

In this case, it is desirable to choose the smallest possible value d, taking into account correctly the diffraction properties of the radiant energy density distributor 3.

When using the apparatus according to the embodiment of FIG. 2, for the treatment of myopia, a parallel beam 2 outputted by the laser 1 and whose energy density is uniformly distributed over the diametrical cross-sectional area is
As in the previous embodiment, the first tapered lens 5
through the cone wall thi
ckness) D/ 2 .cos β and an internal angle 2β. Furthermore, the beam 18 passes through the spherical lenses 14 and 15 forming the microscope objective 13 and has a constant average diameter;
It is transformed into an annular beam 22 with a progressively decreasing wall thickness. The focal plane 21 of the beam 22 intersects the surface of the angle M4;
perpendicular to the optical axis of the device.

The annular beam 22 that has passed through the microscope objective 13 then passes through a conical variable magnification microscope system consisting of tapered lenses 11 and 12. Here, the above-mentioned beam is first converted into a conically shaped beam 23 and then into an annular beam 24 with a variable diameter D2 and a progressively decreasing wall thickness d. The minimum cross-sectional area of the beam 24 is essentially a circle with a diameter of 2d, the value of d being chosen to match the laser parameters of the distributor 3' and the surgical conditions. The value of d above is chosen to be the smallest possible value and is primarily determined by the diffraction properties of the distributor 3'.

The diameter is varied to the required value by continuously moving a tapered lens 11 placed along the path of the laser radiation along the optical axis by means of a stepped electric motor 8. can be done.

In the embodiment of the device shown in FIG. 3, the operation of the radiant energy density distributor 3'' differs from the distributor 3' of FIG. 2 in the following respects: the annular beam passing through the microscope objective 13'; 22 is the tapered lens 11 and 16
passes through a cone-shaped microscope system. The lens 16 has an inverted conical shape, where:
The above beam is first converted into a cone-shaped beam 25 and then into an annular beam 26 with a variable diameter and a wall thickness d decreasing along the path of the radiation. The minimum cross-sectional area of the associated beam is also a circle with a diameter of 2d, and the parameters of the beam 26 are also stepped (s).
(stepped) can be varied by continuously moving the tapered lens 11 along the optical axis by means of an electric motor 8.

The distributor 3'' of FIG. 3 is more compact than the distributor of FIG. 2 for the following reason: the maximum value of the diameter D! cornea 4
The distance C between the bottom surfaces of the tapered lenses 11 and 16 constituting the conical microscope system in the distributor 3# is always equal to the distance between the bottom surfaces of the lenses 11 and 12 in the distributor 3'. In other words, the inequality c<b always holds true.

It is known that when biological tissue is exposed to far ultraviolet light, such tissue detaches (disappears). For a range of values of radiant energy density, the thickness of the layer of tissue that is ablated is directly proportional to the energy density.

During surgery, the active laser radiation beam 20 (FIG. 1) interacts with the cornea 4 to remove the segment 17 (FIG. 4). Similarly, section 17 in FIG.
) and 26 (FIG. 3) and the cornea 4. Irradiation starts from the central region of the cornea 4 with the maximum diameter of the effective radiation beam. The irradiation time is then decreased as the effective beam diameter increases.

By suitably selected irradiation conditions, the section 17 (FIGS. 4 and 6) of the cornea 4 can be removed. Here, the section 17 is surrounded by two paraboloids of revolution, one at the myopic corneal surface and the other after irradiation with the laser 1 (in Figs. 1-3). Corresponds to the surface of the cornea 4. The irradiation is carried out before the removal of the myopia (shaded section 17 in FIGS. 4 and 6).

The hyperopic corneal surface has a radius of curvature R, which is larger than the radius of curvature R in the normal eye at the apex, i.e.
It is described by the equation of a paraboloid of revolution, with R,>R. For hyperopic surgery, a layer surrounded by two paraboloids with different curvatures, equal to the shaded section 27 in FIGS. 5 and 7, should be removed. Surgical treatment of hyperopia is performed in the same way as described for myopia. The only difference is that the irradiation of the cornea 4 starts from the periphery of the cornea with the maximum diameter of the effective radiation beam and is carried out with the irradiation time gradually decreasing with the diameter of the effective radiation beam.

In order to further understand the essence of the present invention, the following examples will be further described.

One embodiment of a device for the surgical treatment of dysopia according to the present invention was constructed and tested as shown in FIG. To change the refraction of the test rabbit's eye, wavelength 1
Excimer laser-1 radiation of 93 nm A+F molecules is used and shaped into a parallel cylindrical beam of diameter D=6 mm. All stationary components of the radiant energy density distributor 3# are made from optical crystals (n-1,559). The first tapered lens 5 has a convex surface (ie, a cone) and has a refractive angle α-10°.

Further, the third taper lens 16 has an inverted conical shape, and the refraction angle of 90°-α*-76° is constantly fixed. The second tapered lens 11 has a conical shape and has a refraction angle α*-14°, extending the distance 1=1 along the optical axis.
50 mm, so that the value of D can be adjusted in the range from 8 to 0.5 mm. Moreover, the thickness of the wall of the ring is constant d=0.25 mm on the effective irradiation surface.

The repetition frequency of the radiation pulses emitted by the laser 1 is equal to 15 Hz and the pulse energy varies from 100 to 3
It can vary in the range of 00 mJ. Surgical procedures in 16 eyes of 8 rabbits resulted in changes in corneal refraction of 0.5 to 5 dioptries, depending on the parameters of effective radiation.

〔Effect of the invention〕

When the device according to the invention is used in practice, the accuracy with which the treated cornea exactly achieves the predetermined shape is
This is an 8- to 0-fold improvement compared to similar devices with variable diaphragms. There is also a 7-8 times improvement in reducing surgical time compared to similar devices with variable diaphragms and a 3-4 times improvement compared to devices in which the radiant energy density distributor is an optical cell. Ru.

The above-mentioned increased accuracy in accurately achieving a predetermined shape of the post-treatment corneal surface is primarily due to the substantially reduced surgical time. This is also due to the fact that the entire radiation flux emitted by the laser 1 acts on the surface of the cornea 4 at any time.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the apparatus for the surgical treatment of anomalous eyes according to the present invention, having two tapered lenses; FIG. Fig. 3 is a block diagram of an embodiment of the apparatus according to the present invention in which three tapered lenses are provided; FIG. FIG. 4 is a schematic diagram of a patient's eye at the stage of treating myopia using the device shown in FIG. 1; FIG. 5 is a schematic diagram of the patient's eye at the stage of treating hyperopia using the device shown in FIG. FIG. 6 is a schematic illustration of a patient's eye in the stage of treating myopia with the device of FIG. 2 or FIG. 3, and FIG. FIG. 2 is a schematic diagram of a patient's eye in stages. [Explanation of symbols] 1... Laser, 2... Radiation beam, 3...
...Distributor, 4...-Cornea, 5.6--Taper lens, 7--Microscope objective lens, 8--Snapto electric motor, 9.10-Divergent lens, 11.12--Taper lens , 13.13'...-Microscope objective lens,
14, 15--convergent lens, 16...-inverted conical lens, 17...--section indicated by diagonal lines, 18...-laser conical beam, 19...-annular beam, 20...--
Parallel annular beam, 21 - focal plane, 22... - annular beam, 23 - conical beam, 24 - annular beam, 25
・−・−Conical beam, 26・−・Annular beam, 27・
−・Intercept indicated by diagonal lines. E4 0 shots 0 shots Vladimir Pakhlovych Yegorofaleksey Alefsandrovich Kharizov Soviet Union, Moscow, Keramicheski Proyezd. Nishiki, Corbus 1. Kvarchila 34 Soviet Union,
Moscow, Uritsa Shirokaya, 13. Corbus 2.
Kvarchira 13

Claims (5)

[Claims] 1. An anomaly comprising an ultraviolet pulsed laser (1) and a distributor (3) for distributing the laser radiation energy density over the cross-sectional area of the laser beam, the distributor being placed transversely to the path of the laser beam. In an apparatus for surgical treatment of the optic eye, a distributor (3) distributing the density of the energy emitted by said laser (1) across the cross-sectional area of the laser beam on one common optical axis. at least two tapered lenses (5, 6) and a microscope objective (7) arranged
It is possible to convert the parallel cylindrical radiation beam (2) of the laser (1) into an annular beam (20) with a variable diameter, the maximum diameter of which is the same as that of the human cornea (4
) A device for the surgical treatment of dysopia, characterized in that it is an optical system comparable in diameter to that of the eye. 2. Said radiant energy density distributor (3) has two tapered lenses (5, 6) with opposite vertices and equal refraction angles (α), and said microscope objective (7)
2. Device according to claim 1, characterized in that the lens (6) is located past the second tapered lens (6) along the path of the radiation. 3. Said radiant energy density distributor (3) has three tapered lenses (5, 11, 12) with their respective bottom faces directed towards said laser (1), said second and third
the lenses have equal refraction angles when viewed along the radiation path, and the microscope objective (13) has the first tapered lens (5) along the path of the radiation of the laser (1). Device according to claim 1, characterized in that it is inserted between the lens and the second tapered lens (11). 4. Said radiant energy density distributor (3'') has three tapered lenses (5, 11, 16) facing the laser (1) at their bottom surface, and the objective lens (13') of said microscope Along the path of radiation of the laser (1) a first lens (5) and a second lens (11
) and placed along the path of the radiation of the laser (1), the third lens (16) has a conical recess, and the second lens (16) along the path of the laser radiation ( 11
2. Device according to claim 1, characterized in that the angle of refraction is made equal to 90° - α, where α represents the angle of refraction. 5. 5. Device according to any of claims 1 to 4, characterized in that the second tapered lens (6 or 11) along the path of the radiation of the laser (1) is movable along the optical axis.