JPH0753167B2 - Non-orthotopic surgical treatment device - Google Patents

Description

FIELD OF THE INVENTION The present invention relates generally to medicine, and more specifically to ophthalmology, and more particularly to devices for surgical treatment of ametropia (dystrophy).

At present, laser treatment methods are adopted worldwide in the practice of ophthalmic surgery, especially laser assisted methods for the correction of refractive errors of the eye by the radiation emitted by UV-excited lasers. The most urgent problem for an engineering laser ophthalmic surgery unit for the above purposes is to obtain the required cross-sectional shape of the irradiation applied to the cornea, so that the output laser radiation has a non-uniform energy density across the cross-sectional area of the beam. It should be characterized by a non-symmetric distribution, especially a rectangular (uniform) distribution. However, the distribution energy density in pump lasers has not made the most urgent problem of how to change the non-uniform and asymmetric distribution of laser radiation into a uniform distribution.

[Conventional technology]

The devices developed to date for the surgical treatment of non-emmetropia comprise the following components arranged on one common optical axis: an ultraviolet pulsing laser and a total ray cross-sectional area. For uniform distribution of the laser radiation density, a device for forming the required distribution of the laser radiation energy density over the entire ray cross-sectional area, and a projection lens (SPIE, Vol. 908, Tissue) Interactions with, 1988, P, R, Ioder et al., "Ray Distribution System for UV Laser Ablation of the Corneal", 77-
(See page 82).

In the device described above, the unit of uniform distribution of the laser radiation energy density is made as a mirror rotation system, whose effect is similar to the optically known Dove prism. A uniform distribution of the laser radiation energy density over the cross-sectional area of the ray is obtained by rotating this ray as a whole around its optical axis. In this case, a non-uniform distribution remains for each individual radiation pulse and the homogeneity eventually results in averaging the matrix of successive radiation pulses. This homogeneity of the distribution with the aid of this known system is only effective for lasers which are characterized by a uniform and unchanged energy density distribution over the ray cross-section. Therefore, in the presence of radical excursions in the distribution, to get a uniform density distribution for practically all practical lasers is to ablate a portion of the laser beam where the energy distribution is diffuse and monotonous. Only possible by. However, this is associated with inconvenient energy loss, harmed accuracy and extended surgery duration.

[Problems to be Solved by the Invention]

The main essential object of the invention is to provide a laser radiation over the ray cross-section that ensures a uniform distribution over the ray cross-section in each laser radiation pulse and has an arbitrary energy distribution of the rays exiting the laser. An object is to provide a device for the surgical treatment of ametropia, characterized by the structure of the unit for the uniform distribution of energy density.

[Means for Solving the Problems]

The essence of the invention is a device for the surgical treatment of ametropia, which comprises the following components arranged on one common optical axis: an ultraviolet pulsed laser.
According to the present invention, there is provided a device comprising a unit for uniformly distributing a laser radiation energy density over the entire ray cross-sectional area, a device for forming a required distribution of the laser radiation energy density over the entire ray cross-sectional area, and a projection lens. It lies in the fact that the units with a uniform distribution of energy density are formed as waveguides of rectangular cross section.

The waveguide can also be formed as a parallelepiped of square cross section and an additional lens can be placed in front of it along the path of the laser radiation.

In this case, it is desirable that this additional lens can vibrate on a plane perpendicular to the optical axis.

The waveguide can also be formed as a pyramid frustum whose large bottom surface faces the laser.

In this case it is expedient for the pyramid to be able to oscillate about the geometric center of the laser bottom in two mutually perpendicular directions perpendicular to the optical axis.

〔Example〕

Ametropia (refractive error) as shown in FIGS. 1 and 2.
The device for surgical treatment of comprises the following components arranged in series on a common optical axis:
An ultraviolet pulse generating laser 1, a rectangular cross-section diaphragm 2, and a unit 3 for evenly distributing the energy density of the radiation emitted by the laser 1 over the cross-sectional area of the light beam, along the path of the radiation emitted by the laser 1. A unit 3 integrally connecting an additional lens 4 placed over the diaphragm 2 and a rectangular cross-section waveguide 5 arranged over the additional lens.
And a projection lens 7 for directing the laser radiation onto the cornea 8 of the patient.

This additional lens can vibrate independently in two mutually perpendicular directions on a plane perpendicular to the optical axis, so that the mounting part of this lens is connected to the output member of the mechanical vibration device 9. There is.

The lens 4 has different focal lengths f ₁ and f ₂ in the plane of the sagittal suture of the skull on the meridian plane (shown as focal points F ₁ and F _{2 in the} drawing) and its curved surface is virtually It is a crossed cylinder.

The waveguide 5 in the given embodiment is in fact a hollow parallelepiped of square cross section, the inner surface of the wall of which is a parallelepiped.
10 has a specular coating.

Used as the forming device 6 is a circular diaphragm with a variable cross section, or a rotating disk with slits of a certain shape, or else an optical cell featuring variable radiation absorption over its entire cross-sectional area.

The projection lens 7 forms an image of the plane P of the exit end of the waveguide 5 on the cornea 8.

Unlike the embodiment described above, what is shown in FIGS. 3 and 4 is that the unit 3 ′ for the uniform distribution of the laser radiation energy density essentially has its larger bottom surface facing the laser 1. It is shaped like a truncated pyramid. This pyramid can oscillate around the geometric center of its smaller base, '0', in two mutually perpendicular directions perpendicular to the optical axis. The bottom surface is connected to the output member of the mechanical vibration device 9. This pyramid (ie waveguide 11)
Are made of a material transparent to laser radiation, eg magnesium fluoride, whereas the outer pyramid surface is provided with a high degree of optical quality finish by precision polishing.

The embodiment of the device for surgical treatment of ametropia shown in FIGS. 1 and 2 according to the invention operates as follows.

A radiation beam 12 emitted from the laser 1 passes through a rectangular cross-section diaphragm 2 having adjustable elements as follows: height (a) and width (b). The diaphragm 2 cuts off a desired portion from the laser beam 12. The ray 13 then passes through the lens 4 to change its cross-sectional area and angular aperture. After passing through the lens 4, the light ray 13 has a focal length f ₁
Focus on two focal planes of and f ₂ . Lens 14
The ray 13 that has passed through is characterized by having a variable rectangular cross section whose dimensions are determined by the distance S from the plane of the lens 4 to the plane of observation H. Distance 'and the distance S> width b of the cross section at f _2' height a of the cross-section of the radiation beam 13 in S> f ₁ and is as follows.

In the given embodiment of the device, a '= b' = C.

In this case the distance The ray at the end of the radiation ray 13 entering the waveguide 5 in the plane H of observation at is projected onto the wall of the mirror waveguide 5 having a C × C cross section, the exit end of this waveguide being It is located on a plane P separated by a distance l from a plane H equal to the length of the active part of the waveguide 5.

where l = n (S−f ₁ ) = m (S−f ₂ ), where
For any even number of n, m = 2,4,6 ..., the radiation ray 13 entering the waveguide 5 is a system of elementary rays that have undergone different numbers of reflections from the walls of the waveguide 5. It is divided into (n + 1) and (m + 1). Each of these elementary rays fills the entire exit end of the waveguide 5.

A typical example of splitting the incident ray 13 into 35 elementary rays is shown in FIG. 5, where n = 6, m = 4 and the curve 14 is of equal intensity of the ray 12 at the output of the laser 1. Represents the area, line 15 represents the boundary of ray 13 through diaphragm 2, dotted line 16 represents the 35 elementary rays of emitted ray 13,
Each of these rays is projected onto the exit end of the waveguide 5 (plane P), so that this exit end is completely filled.

The energy density distribution in the plane P at the exit end of the waveguide 5 is actually the interference pattern resulting from the interference of the radiation rays (n + 1), (m + 1).

Effective radiation intensity at the point with coordinates (X, Y) at the exit end of the waveguide 5. Equal to, where E ₁ , E ₂ ... is the intensity of the radiation at the (X, Y) point of the corresponding wave, Are interference terms, each directly proportional to cos δ _ij , where Δij indicates the optical difference between the tracks of waves i and j, and λ is the wavelength of the radiation.

From the intensity distribution averaged over the period t of the interference pattern, cos δij = 0 To get

Therefore, the energy density distribution at the exit of the waveguide 5 after being averaged with respect to the period t of the interference pattern practically results in a ray (n
It is the sum of the distribution values of +1) · (m + 1). For example, the root mean square deviation of the energy density is given by a random division of the incident ray 13 into (n + 1) · (m + 1) equal elemental rays. It is reduced by a factor of 2.

So let's roughly estimate the period of the interference pattern.

For simplicity, consider the interference of two rays in a hollow waveguide, two rays that have passed through the device without being reflected from the wall and another ray that has undergone one reflection. The distance between adjacent intensity maxima, ie l ≦ 300mm, (S-f ₁ ) 50mm, C7mm, λ0.2μm,
Period t <10 μm.

The actual distance between the maximum (minimum) adjacent strengths is substantially
It is lower than the above values due to the interference of a large number of radiation rays, which are characterized by wide range differences in the track. The exact calculation of the interference pattern is very difficult, so we assume a value of t10 μm as an upper estimate of the interference heterogeneity measure of the radiation intensity distribution at the waveguide exit. The required averaging of the low cycles in the process automatically causes the ophthalmic surgery procedure to consist of about 500 to 1000 pulses of radiation emitted by Laser 1, during which the doctor Interference patterns due to accidental eye movements due to intrinsic eye vibrations (vibrations of the eye) at frequencies up to 300Hz, which are neither controlled by the patient nor by the patient, and also due to the patient's heartbeat, respiratory action, vibration of the unit itself, etc. This is because the complete erasure of

Notwithstanding the factors mentioned above, a complete averaging of the interference pattern occurs at the exit end of the waveguide 5 due to the vibrations made by the lens 4 in the two mutually perpendicular directions.

Due to the above factors of the unit 3, the vibration of the lens 4 with an amplitude of more than 10 μm to 20 μm leads to a perfect averaging of the interference pattern corresponding to successive radiation pulses, and also the sudden radiation intensity (hot) of the laser 1. Spot) will be erased.

6 and 7 show the action of the unit 3 for a uniform distribution of the radiation energy density, FIG. 6 shows the distribution of the laser radiation energy over the entire cross sectional area of the ray 12 in the meridional plane, and FIG. The distribution at the exit (plane P) of the waveguide 5 is shown.

The radiant ray emerging from the exit end of the waveguide 5 passes through a shaping device 6 of the required distribution of the laser radiant energy density over the cross-sectional area of this ray, where the energy density of the radiant ray which is uniform in the plane P is given. Can be changed according to the rules necessary to proceed with the surgery. As the forming device 6, a circular diaphragm having a variable cross section, a rotating disk having a slit of a predetermined shape, or the laser 1 over the entire cross-sectional ray area.
Photovoltaic cells characterized by variable absorption of radiation can be used. Furthermore, a radiation beam 17 passes through the lens 7 and is projected onto the cornea 8 of the operated eye. The lens 7 is a plane P
Image is arranged on the cornea 8.

One embodiment of the apparatus shown in FIGS. 3 and 4 operates similarly to the embodiment shown in FIGS.
The only difference is that after passing through the diaphragm 2, it directly reaches the inlet of the waveguide 11.

Furthermore, the radiation ray 13 passes through a waveguide 11 in the shape of a square pyramidal frustum, which pyramidal frustum Where b ′> b, the inlet and a ″ · b ″, where a ″ <
a'and b "<b ', in particular outlets of the dimensions a" = b "and a' = b '.

The central part of the emitted ray 12 entering the waveguide 11 passes through this waveguide without being reflected, whereas the peripheral part of the ray 13 gives 1,2,3 ... p reflections on one plane. It reflects 1,2,3 ... q on the other plane perpendicular to this plane. This results in (2p + 1) · (2q + 1) radiant rays passing through the exit end of the waveguide, each of these rays filling the entire exit end, resulting in a uniform distribution of radiant energy density. The angular aperture of the radiation emitted from the pyramid-shaped waveguide 11 (α
₁ , α ₂ ) is equal to α ₁ = 2pβ ₁ and α ₂ = 2qβ ₂ in the meridional plane and the plane of the cranial sagittal suture, respectively, where β
₁ and β ₂ respectively indicate the apex angle of the pyramid on the meridional plane and the plane of the cranial sagittal suture.

The length l of the waveguide 11 should comply with both conditions:

As a result of the angular rotation of the base of the larger pyramid around the center '0' in two mutually orthogonal directions, the incoming ray is (2p + 1) · (2q + 1) elemental rays per specific laser pulse. Will be subject to a constant new division into, which will result in additional homogenization of the radiation energy density in a timely manner.

The distribution of the radiation intensity at the exit end of the pyramidal waveguide results in (2p + 1) · (2q + 1) ray interference.

Now, let's evaluate the period of the interference pattern.From this point of view, the interference of the radiation rays that have passed through this waveguide without being reflected from the wall of the waveguide and the side surface of the cone with the apex angle β Consider the interference of rays reflected by.

The distance between the adjacent maximum (minimum) portions of the radiation intensity, that is, its period is Is.

For typical values of λ = 193 mm with β 0.02 to 0.04,
The cycle t is as follows.

As in the embodiment shown in FIGS. 1 and 2,
In the embodiment under consideration, such a degree of interfering heterogeneity is totally ignored for introducing ocular surgical procedures.

Angular rotation of a small angle γ on the order of 0.01 radians about the point '0' made by the base of the larger pyramid results in a linear displacement of the outlet edge by a length of Δ (a ″).

Here, "a" represents the size of the outlet end. Becomes

The above values are completely ignored for eye surgery.

This oscillation at the waveguide entrance end results in the complete elimination of the effect of the interference pattern from the continuous radiation pulse, which is even more pronounced that it completely eliminates the effect of the macroscopic heterogeneity of the incoming laser beam. Easy to prove.

〔The invention's effect〕

According to the invention, this device for the surgical treatment of ametropia is characterized by virtually complete utilization of the laser energy and an arbitrary distribution of the radiation energy density at its output,
It also makes it possible to substantially increase the accuracy of the operation and reduce the operation time by at least twice.

[Brief description of drawings]

1 is a schematic side view of an embodiment of an apparatus for surgical treatment of ametropia with a parallelepiped-shaped waveguide according to the invention; FIG. 2 of FIG. FIG. 3 is a plan view, FIG. 3 is a side view of the device of FIG. 1 provided with a waveguide in the shape of a truncated pyramid, FIG. 4 is a side view of FIG. 3, and FIG. FIG. 6 shows a pattern of laser beams divided into different patterns in a tube, FIG. 6 showing a direction X perpendicular to the axis of the beam emitted from the laser.
FIG. 7 is a distribution curve of laser radiation energy density E (shown as ordinate) along (appearing as abscissa), FIG. 7 being a view of FIG. 5 at the waveguide exit. 1 ... Plasma emitting laser, 2 ... Diaphragm, 3,3 '... Unit for uniform distribution of laser radiation energy density over the entire laser beam cross-sectional area, 4 ... Additional lens, 5 ... Waveguide, 6 ... Required distribution forming device for laser radiation energy density across the entire laser beam cross-sectional area, 7 ... Projection lens, 8 ... Corneal, 9 ... Mechanical vibration device, 10 ... Waveguide inner surface, 11 ... Waveguide, 12 ...... Laser radiation ray, 13 …… Diaphragm passing radiation, 14 …… Equivalent ray density curve, 15 …… Diaphragm outline (aperture) line, 16 …… Line of laser beam that is divided into elemental rays.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Albina Ivanovna Ivasina Soviet Union, Moskoh, Ulitsa 800-Lethia Moskvi, 8, Kubalchilla 73 (72) Inventor Leonido Feodosievichrynik Soviet Union, Mosko, Tegninskaya Urica, 17, Kvartilla 36 (72) Inventor Alexander Dmitrievich Semenov Soviet Union, Moskoh, Yaroslavsko Echosse, 8, Corpus 2, Kvarchira 648 (72) Inventor Hradimil Stepanovich Turin Soviet Union, Moskoh, Ulyza Ivanas Punyna, 2 , Kvarchira 292 (72) Inventor Mikhail Yuryevich Orlov Soviet Union, Moskoh, Ulitsa Malaya Bronnaya, 17, Kubaruchila 1 (72) Inventor Efim Natanovic Beirin Soviet Union, Mosko, Ulitzhabel Fnaya Maslovka, 21, Kubaruchila 83 (72) Inventor Evgenina Umovich Levzier Soviet Union, Moskoa Rezkos, Petrovsk , Kvartilla 63 (72) Inventor Igor Anatolyevich Skvortsov Soviet Union, Leningrad, Prospect Nauki, 10, Corpus 2, Kvartilla 56 (56) Reference JP-A-1-15046 (JP, A) JP-A-62- 299263 (JP, A) JP 59-14848 (JP, A) JP 62-109565 (JP, A) JP 60-253430 (JP, A) JP 63-289523 (JP, A) Special table Sho 62-503150 (JP, A)

Claims (4)

[Claims] 1. A component arranged on a common optical axis, that is, an ultraviolet pulse generating laser (1), a unit (3) for uniformly distributing a laser radiation energy density over the entire ray cross-sectional area, and a ray. In a device for surgical treatment of non-emmetropia, which comprises a device (6) for forming the required distribution of the radiation energy density of the laser (1) over the entire cross-sectional area and a projection lens (7). The uniform distribution unit (3) is a waveguide, which is formed as a parallelepiped of square cross section, and an additional lens (4) is provided in front of the waveguide along the path of the laser radiation, Laser lens (1)
An apparatus for surgical treatment of non-orthotopia, which is characterized in that a radiation beam emitted from the device is dimensionally matched with an entrance of a waveguide. 2. Device according to claim 1, characterized in that the additional lens (4) is able to oscillate with respect to the optical axis in a plane perpendicular to the optical axis. 3. A component arranged on a common optical axis, that is, an ultraviolet pulse generating laser (1), a unit (3) for uniformly distributing a laser radiation energy density over the entire ray cross-sectional area, and a ray. In a device for surgical treatment of non-emmetropia, which comprises a device (6) for forming the required distribution of the radiation energy density of the laser (1) over the entire cross-sectional area and a projection lens (7). Surgical treatment of astigmatism, characterized in that the uniformly distributed unit (3) is a waveguide, the waveguide of which is formed as a pyramidal frustum whose large bottom surface faces the laser. apparatus. 4. The pyramid frustum according to claim 3, wherein the pyramid frustum is capable of vibrating in two directions perpendicular to the optical axis around the geometric center of the laser bottom surface. Equipment.