JPH0333015B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to ophthalmic surgery involving surgery on the outer surface of the cornea.

[Conventional technology]

The above surgeries include corneal transplants and corneal incisions. Such surgeries have traditionally required skilled manipulation of cutting instruments. However, even if a sharp blade is used, simply penetrating the surface of the cornea will apply horizontal pressure to the somatic cells that are moved to both sides of the wound. means.

This horizontal pressure damages multiple cell layers on both sides of the wound, greatly impairing its ability to heal and resulting in the formation of scar tissue.

[Problem that the invention seeks to solve]

Therefore, Japanese Patent Application No. 59-239583 filed by the inventor provides a background explanation on the effects of various useful laser wavelengths in ophthalmological treatment, particularly in treatment of the corneal surface.

Radiation at ultraviolet wavelengths has been described as desirable due to its high photon energy. This photon energy has a very efficient impact on cellular tissue, and the molecules of the tissue are decomposed by the optical impact, resulting in tissue removal by photolysis.

Molecules at the irradiated surface are broken into smaller volatile fragments without heating their remaining underlying layers. This removal mechanism is photochemical, ie, direct destruction of intermolecular bonds.

The effects of photoheating and/or photocoagulation are neither distinctive nor noteworthy in ablation at ultraviolet wavelengths. And cell damage adjacent to photolytic removal is of little concern.

The intensity steps of this removal process are based on ultraviolet wavelengths (approximately
For radiation exposure at wavelengths in the range of 400 nm or less, an energy density of 1 joule/cm ² is required to cut a depth of 1 micron (1 μ).

In an earlier patent application, in order to inscribe the surface of the cornea,
Techniques are disclosed for scanning a laser beam over the surface in a controlled pattern to impart new curvature to the surface to achieve optical correction of an eye with an optical defect.

However, the scanning and scanning controls for implementing such techniques suffer from being relatively complex and expensive.

Japanese Patent Application No. 61-132,613, filed by the inventor on June 6, 1988, describes a non-scanning technique for changing the optical properties of the eye by means of ultraviolet laser radiation. In this technique, a controlled change in laser spot size allows corneal engraving to achieve a properly corrected shape. This technique includes the programmed use of zoom lenses and/or various characterized mask techniques.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide improved apparatus and techniques for surgically operating the outer surface of the cornea.

Another object of the present invention is to simplify and reduce the cost of devices and techniques for surgically correcting the optical properties of the eye by surgical treatment of the outer surface of the cornea.

A special object of the invention is to treat myopia, hyperopia and/or hyperopia in the eye.
or to achieve the above objectives by surgical techniques and devices that reduce astigmatic conditions.

Another specific object of the present invention is to provide an improved surgical technique for corneal transplant surgery.

A further specific object of the invention is to provide an automated device for safely performing ultraviolet irradiation in corneal surgery.

Another object of the invention is to achieve the above objectives without using scanning techniques or devices.

[Means for solving problems]

According to the invention, for a non-scanning laser characterized by ultraviolet radiation irradiated with such energy that it is possible to photolytically ablate the cornea, i.e. the epithelium, Bowman's membrane and stromal level,
The above objectives are achieved using a device that effectively fixes the position of the eyeball.

The irradiation flux density and exposure time are controlled to reach the desired ablation depth.

Unlike the scanning and variable spot processing disclosed in the earlier application, the scoring operation involves the interposition of an optical screen, wedge-shaped object, or mirror that provides a pre-characterized transmission or reflection in the projection path of the laser beam to the eye. achieved by. More particularly, the cross-section of the laser beam projection onto the eye corresponds to all the frontal areas that carry out the desired curvature correction, for example has a diameter of 6 to 7 mm and is centered on the optical axis of the eye. are doing. Intermediately located devices are then characterized by transmission or reflection that varies as a function of the radius around the optical axis. Under such circumstances, the laser irradiation at the corneal entry region has a correspondingly characterized luminous flux density with a correspondingly characterized ablation penetration capacity per unit exposure time. Therefore, for myopia or hyperopia correction, the number of diopters of surface correction achieved is: is a function of exposure time. Also for astigmatism correction, the number of dioptres of cylindrical correction achieved in a given angular direction across the optical axis is also a function of time, but it is For illumination cross-sectionally characterized by a symmetrically decreasing flux density at .

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, the clamping means 10 is arranged so that the eye 11 to be treated (lying face up) aligns the downwardly curved portion of the central axis 12' of the beam output from the fixed laser device 13. (i) Immobilize the patient's head. The fixed laser device 13 is supported by a table or other base 13'. The optical system for irradiating the laser beam to the eye 11 is (a)
(b) a reflector 14 having precharacterized reflection properties; The laser radiation incident on the cornea thus includes a function of a circumferentially uniform radius around the central axis of the projection beam 12. Cabinet 16 contains programmable means such as a power supply for the laser system and a microprocessor for exposure control.

Preferably, the clamping means 10 has the reference numeral 17
It has a head fixation means for stabilizing the patient's head in the area of the patient's temple indicated by , and an eyeball holding means (18 in FIG. 2) stabilizes the patient's head in the area of the cornea sclerosis.
It covers the surrounding area. Further, desirably, the optical fixing means 20 includes the table or the base 1.
3'. The optical fixation means 20 has a viewing crosshair and a lens, so that the untreated eye 11' can see the crosshair as if at infinity. The line of sight 21 of the means 20 is parallel to the shaft aperture, and adjustment means (not shown) provide the necessary adjustable offset for the patient's pupil distance and the special adjustment of the means 20 from the shaft 12. Can be adapted to mounting offsets. For treatment of the other eye 11', eye 11 can be fixed with similar fixation means together with other fixation means (not shown) and corresponding adjustable offset means. Alternatively, the fixing means 20 can be adjustably mounted with a modified offset on the opposite side of the zoom lens arrangement 14. For treatment of the eyeball 11', the clamping means 10 is indexed transversely to the laser 13 to the extent that it aligns the axis 12 with the eyeball 11' to be subsequently treated, thereby making it possible to use the fixation means. Eyeball 11 is positioned.

The eye retention means 18 of FIG. 2 includes a hollow ring having a converging axial end wall 23 of air-permeable material contoured to retain the eye through the membrane-corneal region. Side connection to vacuum pump 2
4 allows the wall 23 to hold the eyeball. External protrusion or flange means 25 have been omitted from FIG. 1 for the sake of simplicity, but the means suggested in FIG. This allows for connection at intervals.

Laser 13 preferably emits ultraviolet light, ie, wavelengths substantially less than 400 nanometers. Gas laser is 351n fluoride neon laser
m, 337nm with nitrogen laser, 337nm with chloride neon laser
308nm, 248nm with krypton fluoride laser, 193nm with argon fluoride laser, and fluorine laser
Frequency doubling techniques, which generate a wavelength of 157 nm and have been applied to other lasers in this range, including crystal lasers, provide yet another source.

Lamda, Götzteingen, Germany
One of the currently commercially available lasers from Physik GmbH, such as the argon fluoride laser model EMG-103, is satisfactory for laser 13. For this product, the maximum energy per pulse is 200 millijoules, the pulse repetition rate is 200 pulses/second, and the maximum energy per pulse is 200 millijoules.
×10 ⁵ shots (pulses) are possible at this pulse repetition rate in one charge of included gas before the rated power is reduced by half. However, full power rating is not required in use of the present invention. The pulse width is approximately 15+1 seconds and the typical beam shape is square. However, as shown, the aperture in mask 26 reduces the laser beam to a circular cross section.

For the situation shown in FIG. 1, the reflective surface of element 14 is inclined at 45° with respect to the incident laser beam, thereby providing a position 90° from axis 12' according to the precharacterized properties of element 14. and is reflected onto axis 12, which is aligned with the optical axis of eyeball 11. The maximum area of the element 14 available for reflection of the beam 12' is therefore an ellipse with the minor axis equal to the diameter of the laser beam and the major axis √2 times the minor axis. FIG. 3 shows a circumferentially uniform radial distribution of laser beam density directed to the eye 11 due to reflection by element 14 under the characterized reflection conditions described in connection with FIG. It is a simplified drawing used for explanation. Since shading is inadequate to represent pre-characterized reflections, such pre-characterization is first performed as an optically graduated wedge shape to produce the gradual removal shape (FIG. 7). And second, it is shown as a smoothly progressing wedge shape as schematically defined in either FIG. 5 or FIG.

6 and 7 illustrate the application of the present invention to the optical modification removal of the outer surface 30 of the eye to eliminate myopia. Myopia means that the radius of curvature of the outer surface 30 is too short for distant objects to be imaged on the retina. On the other hand, the dashed line 31 indicates the final curve to which the outer surface of the cornea is to be modified in order to obtain a diopter reduction effect.
To obtain curve 31, the minimum desired photolysis occurs at the outer boundary 29 and the maximum photolysis at the center 28. To produce such a result, a maximum flux density of the laser beam at the center of the exposed area of the cornea characterizes the ablation action, and a minimum (zero or virtually zero) of the laser beam at the periphery of the exposed area is required. There is a luminous flux density. Between these extremes, the luminous flux density is graded as a series of concentric annular bands, as suggested in FIG. For the reduction of myopia, these annular bands are the product of a series of similar bands representing uniform reflection in the circumferential direction, and the reflection is a function of increasing with decreasing radius. That is understood.

However, since the reflector 14 must be elliptical, each band of progressively increasing reflection must be an ellipse, as shown by the plurality of ellipses in FIG.
Each ellipse in the figure has a similar major/minor axis ratio, and the reflection along the minor axis changes stepwise from a maximum at the center to a minimum at the periphery (-X, +
X), it is also understood that the reflection along the principal axis changes stepwise from a maximum value at the center to a minimum value at the periphery.

FIG. 7 shows the gradual removal effect of exposing the eyeball 11 for a predetermined time to ultraviolet laser radiation characterized by the above-mentioned distribution of luminous flux density that can be attributed to the corresponding reflection distribution in the reflector 14. FIG. In the outer annular zone where the reflection is minimum, the luminous flux density is the minimum, so for these outer annular zones (between diameters D ₁ and D ₂ in Figure 7), the removal penetration into the cornea is Occurs very little or not at all. In the next inner annular zone (between diameters D ₂ and D ₃ ) the cumulative increase in reflection also results in a cumulative increase in ablative penetration. Subsequent cumulative increases in such ablative penetration then occur cumulatively as a function of the decreasing radius of successive annular bands. The last annular zone is a small central circle of diameter D _o where the maximum shadow thickness suggests maximum ablative penetration due to the maximum reflection at the elliptical center of the reflector 14.

The progressively thicker stepwise opacity of FIG. 7 (implying a corresponding stepwise increasing ablative penetration of the cornea) defines a new, larger-diameter curved surface for the removed area of the cornea. is buried. Theoretically, there exists a stepwise characteristic leading to a new shape, but for a sufficiently large number of annular bands with progressively varying flux densities, the individual steps will no longer be visible individually; The cornea is characterized by a smooth new spherical anterior surface. This is especially true during the period of approximately 2 days after surgery, by which time the thin epithelial layer has expanded to cover the newly characterized surface smoothly and protectively.

As generally indicated above, the pre-characterized graded nature of the reflection in the reflector 14 can be replaced by a mirror surface with a continuously varying reflection. Such a mirror surface is illustrated in Figure 5, where it has a maximum at the center and a minimum (zero) at the periphery, regardless of whether it is observed along the major or minor axis. Become. The direction of the auxiliary axis is represented by the increasing radius range (R _x ),
The direction of the principal axis is represented by an increasing radius range (R _Y ). Naturally, the newly formed removal surface due to the smoothly changing reflection as shown in FIG. 5 is necessarily smooth and completely free from step effects.

It can be seen that the degree of myopia reduction achieved by the pre-characterized reflection in reflector 14 is a function of exposure time. Therefore, a sufficient database of diopter reductions for determining exposure times at a given maximum luminous flux density makes it possible to accurately set the required time for a given diopter reduction for a given patient. . For very large corneal-curvature aberrations, the same reflector 14 may, for example, reduce the 1 or 2 diopter reduction required in some patients for relatively short exposure times, or in other patients with longer exposure times. can be utilized to produce different degrees of surface reduction representing the two or more diopter reduction required. Also, since it is desirable to operate on some patients with one level of care at a time, for example, a desired reduction of 3 diopters may be achieved by 2 diopters on the first visit, and with the same equipment and reflector 14. Allow the patient to make judgments and accommodate for the purpose of modification for a few days before deciding whether and exactly how much further ablation exposure should be done with the next modest but shorter ablation exposure. You can set a period.

What has been said for the reduction of myopia is equally applicable to the correction of hyperopia. Here, the reflection at the reflector 14 is necessary such that the maximum luminous flux density of the laser beam is applied to the outer diameter D ₁ of the exposed area of the cornea, and the luminous flux density decreases progressively and in the central region It becomes zero. This may be a stepwise progression, as shown by the multiple concentric circles of FIG. 3 (and the ellipses of FIG. 4), or a continuous progression, as shown by the curves of FIG. In either case, the resulting removed shape is an increase in corneal curvature (i.e., curved surface with a shorter radius).

The above-described parts of FIG. 1 are identified by reference numbers in FIG. 10, but here reflector 14
The characterized reflective surface is shown as a beam splitter as applied to a suitable transparent flat plate such as quartz. In this case, the transmitted beam 1 as well as the reflected beam 12 emanating from the beam splitter are
2 exists. As shown, the transmitted beam 12 is collected and dissipated by suitable means 19, commonly referred to as an absorber. However, the transmitted light is
In the fact that it always has a constant proportional relationship to the radiation dose delivered to the eye along axis 12,
It will be understood that the absorption means 19 as described above may also be used as a radiation dose measurement means.

Similarly, as shown in FIG. 11, via reflection in the transmitted beam 15 on the axis 12'', the beam can be used for corneal ablation of the eye 11;
The reflected component on the other axis 12 can be directed to absorption means 19 . In this case, the reduction in myopia is such that the beam splitter 14 exhibits maximum reflection at the largest elliptical circumference and minimum (virtually zero) reflection at the center, with the intermediate circumference decreasing as the distance from the center decreases. This is achieved when the reflection is characterized by a progressive decrease. And hyperopia reduction is achieved when the reflection is maximum at the center and minimum (substantially zero) at the maximum ellipse circumference.

The foregoing discussion with respect to FIGS. 1-5 assumes a pulsed laser, exemplified by an excimer laser. However, other lasers are known which emit at energy levels suitable for current use and at ultraviolet wavelengths. These other lasers will emit continuously for a controlled period of time. for example,
Organic dye lasers using suitable organic dyes are 266
Continuous wave, quadrupled frequency neodymium operating in mm
It is designed to produce laser radiation in the 380 nm region when pumped by an ultraviolet laser source such as a YAG laser. In this case, the 380 nm organic laser radiation
A suitable non-linear crystal, such as a deuterium phosphate (KDP) crystal or a potassium titanium phosphate (KTP) crystal, doubles the frequency and brings the emission wavelength to 190 nm.

It will be understood that FIGS. 1 to 9 therefore also represent other cases, in which the ultraviolet laser radiation on shaft 12 is transmitted to cabinet 1.
The treatment period is continuous wave in nature, predetermined by the program within 6, and the timing is set by the surgeon based on his experience, but as a decision from a database of accumulated experience; Address diopter changes as a function of exposure time.

The configuration of FIGS. 12, 13, and 14 is as follows:
Additionally, the above-described principles of the present invention can be used for corrective sculpting of the cornea to achieve the desired final curved Fournel-type distribution and to achieve hyperopic correction or myopic correction as shown. Show what you get. Such surgery (i.e. Fresnel type) is used when, in the surgeon's judgment, a single smoothly developed eugonal surface necessarily requires excessive removal of tissue in the peripheral area of the deep cut. . In order to avoid cuts that are too deep, FIGS. 12 and 13 show that the final reduced curved surface as shown at 31 in FIG. shows an increase in In the outer ones 72 of these annuli, the curvature and depth of the cuts are adapted to produce a continuous curve 71 (ie without Fresnel steps). However, intermediate annular region 73 effectively achieves continuity of curve 71 with a smaller amount of corneal ablation. Finally, inner circular region 74 effectively obtains curve 71 with minimal removal of corneal tissue.

Tissue removal in the center is shown at Δ74 with respect to Fresnel cut 74 in FIGS. Curved surface 7
This is only a small fraction of the maximum removal depth Δ71 required to achieve similar optical correction at 1. FIG. 14 shows a preparatory design for the auxiliary axis of the elliptical reflector in order to achieve Fresnel-type cuts of the above-mentioned size for the different annular bands 72, 73, 74 using the apparatus of FIG. 1 or 10. Figure 3 illustrates a characterized reflection distribution. Within each of these annular bands, maximum reflection is in the inner range (Rx) and reflection tapers off to the outer range (Rx).
is the minimum at . For a given exposure, a new curved surface 71 can thus be achieved in the outer annular zone 72. In the annular band 73, this new curved surface has continuity displaced in the axial direction at 71'. Then, at a point further axially shifted, there is a continuation to a new curved surface that is more effective within the central circular region 74 at 71''.

FIG. 15 illustrates reflection considerations at reflector/beam splitter 14 when using the apparatus of FIG. 1 or FIG. 16 to achieve hyperopia reduction. In each concentric annulus for making a Fresnel-type removal cut for this purpose as shown, the reflection is maximum (virtually zero) in the inner range (Rx) and gradually increases. It is maximum in the outer range (Rx).

If the invention is implemented in the sense of FIG. 1 or FIG. 10, what has been said for the curves of FIGS. are completely reversed, i.e. high reflection in the inner range and gradually decreasing and lowest reflection in the outer range (as shown in Figure 14) in each Fresnel ring. The transmission of maximum luminous flux density in the outer range (Rx) of the body and a gradual decrease to the lowest (nearly zero) luminous flux density in the inner range (Rx).This distribution pattern allows for the reduction of hyperopia. A given exposure via axis 12'' can be achieved.
Similarly, corneal exposure aimed at reducing myopia through axis 12'' can be achieved with the reflection characteristics shown in FIG. 15.

FIG. 16 shows an embodiment of the invention which utilizes a fully circular cross-section beam of laser output onto axis 12' (shaft 12' is bent downward by a fully reflective surface, not shown). ). This beam enters an inclined beam splitter 50. The beam splitter 50 is removably fixed to an adapter 51 which is supported by the eyeball support and fixation means 18 described in connection with FIG. However, in FIG. 16, the inclination angle α of the normal 52 (to the surface of the splitter 50) from the axis 12' results in a reflection characterized such that the reflected component 53 is practically circular rather than elliptical. As such, it has been intentionally kept small. Therefore, in the beam splitter 50, FIG. 3 is used together with FIG. 8 to explain the uniform reflection distribution in the circumferential direction over the beam diameter _D1 . For exposure to reduce myopia, a splitter 50 is selected that has the characteristics that the luminous flux density of the transmitted laser irradiation is maximum at the center of the beam, and the luminous flux density decreases to a minimum (almost zero) at the maximum diameter _D1 . It will be done. and beam diameter D ₁
FIG. 3 is likewise taken along with FIG. 5 to explain the reflections at the splitter 50 over the entire range. Therefore, for exposure to reduce hyperopia, a splitter 50 is selected that has the characteristics that the luminous flux density of transmitted laser irradiation is maximum at the maximum diameter D ₁ and that the luminous flux density decreases to the minimum (almost zero) at the center of the beam. . In the use of the invention in FIG.
The angle α is such that the reflected component on axis 53 is free from interference with other structures, except for shearing by suitably arranged absorbing means (not shown) of the nature shown at 19 in FIGS. 10 and 11. chosen so that it will not be scattered by

FIG. 16 also shows that when heat dissipation is required when installing the adapter 51 near the eyeball 11,
It is shown that an annular manifold 54 is provided having an inlet and an outlet to ensure the flow of coolant.

With respect to the installed position in the opposing receiving bore 55 of the adapter 51, each such disc is provided with pre-characterized features to assist in manually turning on and off selected circular beam splitter discs 50 of different characteristics. Opposed protruding tabs may be provided for placing fingers on the outside of the attached reflective area (diameter D ₁ ). Here, the transmission function is inversely related to the reflection function.

17 and 18 show that the characterized circular beam splitting area (diameter D ₁ ) of the selectively available disc 50' provides a reduction modulus to reduce astigmatism due to the transmitted component of the beam splitting. 16 shows that the embodiment of FIG. 16 can be further utilized if it is characterized to do so. This feature allows the maximum flux density to pass on a diametrical line across the characterized region, with a gradual decrease in the luminous flux with distance of lateral deviation from said diametrical line,
This reduction is symmetrical on both sides of the diameter line.

In FIG. 17, a characteristic region 57 of the disk 50'
The shading representing the reflection at is therefore darkest at the most laterally offset position from the single diameter line specified by the 0° index mark on the periphery of the disc. Other angles are shown in the range of plus 90° and minus 90° on opposite sides from the zero index mark. These angles are read against fixed reference marks 58 imprinted on the adapter 51. In addition, suitable key means (not shown) or other angular reference means for reference to the vertical or horizontal meridian of the eye are provided on the fixing means 18 within the apparatus of the adapter 51 or at the zero index position of the disc 50'. is independently set by the surgeon so that it has a true relationship with the direction of the meridian concerned. In this case, manual angular indexing in the direction of the prescribed astigmatism axis relative to the fiducial 58 of the disc 50' is all that is necessary for correct orientation for the ablative surgery. All that remains then is to set the exposure timing program for the desired or prescribed degree of ablative diopter reduction.

Although the invention has been described in detail with respect to various embodiments, various modifications can be made without departing from the scope of the invention. For example, the discussion of transmission or reflection having a distribution as a linear function of radius (or effective radius) has been illustrated as a gradual smooth continuum, but for some reasonable purposes it may be non-linear.

In particular, as shown by the curves in Figures 19 and 20, such nonlinear functions are quasi-parabolic, whether the exposure is for myopia correction (Figure 19) or for hyperopia correction (Figure 20). become. In the case of FIG. 19, the maximum transmittance is on the central axis of the projected laser beam 12, so the transmittance function (i.e. the shape of the flux density distribution) is quasi-parabolic with respect to the diameter in the orthogonal cross section of that beam. The apex of the maximum laser beam density is on the central axis and decreases from there to zero at the maximum diameter R _cc of the circular area in which myopia correction is to be performed.

In the hyperopic correction case of FIG. 20, the minimum (i.e., zero or near zero) transmission is at the center of the projected laser beam 12, so that at any diameter of the orthogonal cross-section of that beam, the transmission function is also quasi-parabolic, but its apex lies at the outermost radius R _cc of the circular region that performs hyperopic correction.

Regarding hyperopia correction, it is clear from what has been said with respect to Figure 9 that the stroma is dug deepest at the periphery of the surgical field and is therefore proportional to the amount of light exposure for laser surgery, i.e. the amount of light refraction to be corrected. A relatively sharp circular edge remains. The formation of such sharp edges causes problems in epithelial regeneration in the surgical area. This is because epithelial regeneration occurs best on essentially continuous surfaces, ie, uninterrupted by sharp edges or sharp discontinuities. To avoid the formation of such sharp edges, FIG. 20 shows that the projection laser beam 20 should have a larger cross-section than the hyperopia correction region. This results in an external annular region of smooth surface surrounding and continuous with the hyperopia correction circular region. In FIG. 20, the radius increase ΔR indicates this annular portion. In this annular portion ΔR, the transmittance decreases linearly outward in the radial direction from a maximum value at R _cc to a minimum at the radius R _b of the laser beam. This radius increase ΔR is 5 to 5 of the radius R _cc of the circular area to be corrected.
15%, preferably about 10%.

This linear decrease in transmittance results in the smallest slope at any point of the annulus, allowing for the deepest corneal drilling (e.g. for a 10 diopter correction over a 5 mm diameter correction area). depth
100 microns), this linear characteristic is best. However, when the depth is shallow, such as when the correction is less than 5 diopters, it is better to have a nonlinear relationship (as shown by the dashed line over the range of ΔR in Figure 20) for the radius (in the ΔR region). It is possible to create a continuous and smooth continuity between the corrected part of R _cc and the original, unsurgical corneal surface part.

We have described a method for minimizing or preventing the occurrence of sharp edges during corneal removal to correct hyperopia; this method is useful for correcting hyperopic astigmatism,
It is equally applicable to correction of astigmatism which requires an increase in cylinder radius to remove astigmatism. In that case, the maximum depth of corneal removal is at the lateral outer border of the astigmatism correction, leaving a relatively sharp edge there. The formation of these edges is substantially prevented by preadjusting the laser beam laterally outward of these regions of maximum depth so that its flux density is substantially zero. Now, if we consider that the curve in Fig. 20 shows the transmissivity change in the outward lateral direction (i.e., the luminous flux density change) during astigmatism correction,
It can be viewed as representing half of the transmittance distribution in an orientation perpendicular to the astigmatism correction in a predetermined direction. Similarly, FIG. 19 shows a similar distribution for myopic astigmatism. The description "(width)" in FIGS. 19 and 20 applies to each astigmatism correction.

In the above description, the mirrors 14 and 50 are described as beam splitters having transmittance and reflectivity characterized by the distribution of transmittance and reflectance. Here, the term "beam splitter" is to be understood as merely an example of a filter for characterizing the cross-sectional density distribution of the beam 12 projected onto the patient's eye.

Thus, by means of a suitably characterized circular filter 15 in the beam projection path through the plane mirror 14, a corneal ablation of the above-mentioned characteristics can be achieved. In this way, the filter may be a thin filter-like gradient filter, or a filter that provides characteristic transmission or reflection characteristics in the radial direction by changing photographic half-tones. Alternatively, it may also be a perforated plate with micropores provided in the plate at a density that provides the desired transmission properties. The substrate for such a filter can be chosen from fused silica, lithium fluoride, calcium fluoride and barium fluoride.

[Brief explanation of the drawing]

1 is a schematic perspective view showing the general structure of the operating parts of the present invention; FIG. 2 is a simplified cross-sectional view showing the eye retention fixing means used in the apparatus of FIG. 1; , 5, 6 and 7 are simplified illustrations to illustrate the nature of the ablative sculpting of the cornea carried out using the apparatus of FIG. 1 when correcting a myopic condition, and FIGS. 8 and 9, respectively. Corresponding to FIGS. 5 and 6, FIG.
Figures 0 and 11 are schematic diagrams illustrating two different configurations used in the present invention, Figures 12, 13, 14, and 15 are schematic diagrams illustrating two different configurations used in the present invention, respectively, and Figures 12, 13, 14, and 15 are schematic diagrams illustrating two different configurations used in the present invention, and Figures 12, 13, 14, and 15 are diagrams for achieving a Fresnel-type optical correction shape at the anterior surface of the cornea. A simplified diagram showing the case where the present invention is used in
FIG. 4 is a graph explaining myopia correction, FIG. 15 is a graph explaining hyperopia correction, FIG. 16 is a diagram similar to FIG. 2 showing still another embodiment of the present invention, and FIG.
The figure is a plan view of one of a plurality of selectable beam splitting elements available in the embodiment of FIG. 16, with the selected element being used for laser ablation correction of astigmatic conditions. Figure 18 is the 17th
FIG. 4 shows reflection as a function of diametric distance at cross section 18-18 of the figure. FIGS. 19 and 20 are graphs showing changes in the transmittance of the projection laser beam in the beam cross section in different surgeries. 10: Clamping means, 11: Eye to be treated, 1
2: Laser beam, 13: Fixed laser device, 1
4: reflector, 16: cabinet, 17: head fixing means, 18: eyeball holding means, 19: absorption means,
20: Optical fixation means, 23: End wall, 24: Side connection port, 30: Outer surface of the eye.

Claims (1)

Claims: 1. An engraving device for operating on the outer surface of the cornea of a patient's eye, comprising: laser means for producing a circular output beam in the ultraviolet region of the electromagnetic spectrum; beam splitter means having a precharacterized beam splitting function for splitting the reflected and transmitted component beams into a reflected component beam and a transmitted component beam; (b) the luminous flux density distribution in one of the component beams is a uniform decreasing function in the circumferential direction of the radius around the central axis of the one component beam, and (b) in the other component beam of the reflected and transmitted component beams; The luminous flux density distribution is a uniform increasing function in the circumferential direction of the radius around the central axis of the other component beam, whereby:
When the axis of the one component beam is aligned with the axis of the myopic eye, it produces a myopia-correcting surface modification to the anterior corneal surface of the myopic eye, and the axis of the other component beam is aligned with the axis of the hyperopic eye. The above-mentioned engraving device is characterized in that it produces a hyperopia-correcting curved surface change on the anterior corneal surface of the hyperopic eye. 2. In an engraving device for surgically operating on the outer surface of the cornea of a patient's eye, laser means for generating a circular output beam in the ultraviolet region of the electromagnetic spectrum, and laser means disposed within said beam to transmit the laser emitted light with a reflected component beam. and beam splitter means having a pre-characterized beam splitting function to split the reflected component beam into a circumferentially uniform decreasing function of radius about an axis, which results in a myopia-correcting curved modification to the anterior corneal surface when the axis of the reflected component beam is aligned with the axis of the eye; The above-mentioned engraving device is characterized in that: 3. The engraving device as set forth in claim 2, wherein the energy absorbing means is disposed within the path of the transmitted component beam. 4. In claim 2, the laser means generates a beam with a circular cross-section of a size equal to the projection area of the cornea to be operated, and the circular cross-section is (a) a part of the diameter of the circular cross-section; (b) at least one circular ring radially continuous with said inner circle, said pre-characterization of said beam splitter means having a diameter corresponding to said inner circle; Limited to a priori characterization, the circular cross-section is further characterized in that in its circular annulus, the luminous flux density distribution is a uniform function in the circumferential direction of the radius;
and characterized in the same sense and within substantially the same density limits as apply to said inner circle, thereby providing that in the course of irradiating the cornea of the eye with a single laser beam, . The engraving device as described above, wherein Fresnel type corneal curvature correction can be obtained in both the inner circle and the circular ring. 5. In an engraving device for surgically operating on the outer surface of the cornea of a patient's eye, laser means for producing a circular output beam in the ultraviolet region of the electromagnetic spectrum, and laser means disposed within said beam to transmit the laser emitted light with a reflected component beam. and beam splitter means having a pre-characterized beam splitting function to split the reflected component beam into a circumferentially uniform increasing function of radius about an axis, which results in a myopia-correcting curved modification to the anterior corneal surface when the axis of the reflected component beam is aligned with the axis of the eye; The above-mentioned engraving device is characterized in that: 6. The engraving device according to claim 5, characterized in that the energy absorbing means is disposed within the path of the transmitted component beam. 7. In claim 5, the laser means generates a beam with a circular cross-section of a size equal to the projection area of the cornea to be operated on, the circular cross-section being (a) a fraction of the diameter of the circular cross-section; (b) at least one circular ring radially continuous with said inner circle, said pre-characterization of said beam splitter means having a diameter corresponding to said inner circle; Limited to a priori characterization, the circular cross-section is further characterized in that in its circular annulus, the luminous flux density distribution is a uniform function in the circumferential direction of the radius;
and characterized in the same sense and within substantially the same density limits as apply to said inner circle, thereby providing that in the course of irradiating the cornea of the eye with a single laser beam, . The engraving device as described above, wherein Fresnel type corneal curvature correction can be obtained in both the inner circle and the circular ring. 8 In claim 5, the luminous flux density distribution (i) is a uniform increasing function in the circumferential direction of the radius with the maximum density at the first radial limit of the hyperopia correction region, and (ii) The engraving device as described above is characterized in that it is a uniform decreasing function in the circumferential direction of the radius from the maximum density to the minimum density at the second radial limit of the laser beam cross section. 9 In an engraving device for surgically operating on the outer surface of the cornea of a patient's eye, laser means for producing a circular output beam in the ultraviolet region of the electromagnetic spectrum, the laser means being disposed within said beam and transmitting the laser emitted light with a reflected component beam; and beam splitter means having a pre-characterized beam splitting function to split the component beam into a circumferentially uniform decreasing function of radius about an axis, which results in a myopia-correcting surface modification to the anterior corneal surface when the axis of the transmitted component beam is aligned with the axis of the eye; The above-mentioned engraving device is characterized in that: 10. The engraving device according to claim 9, characterized in that the energy absorbing means is arranged in the path of the reflected component beam. 11. According to claim 9, the laser means generates a beam with a circular cross-section of a size equal to the projection area of the cornea to be operated on, the circular cross-section being: (a) a fraction of the diameter of the circular cross-section; (b) at least one circular ring radially continuous with said inner circle, said pre-characterization of said beam splitter means having a diameter corresponding to said inner circle; Limited to a priori characterization, said circular cross-section is further characterized in that in its circular ring, the luminous flux density distribution is a uniform function in the circumferential direction of the radius, and the same meaning applies to said inner circle. and within substantially the same density limits, such that in the course of irradiating the cornea of the eye with a single laser beam, both the inner circle and the circular annulus The engraving device described above is characterized in that Fresnel type corneal curvature correction can be obtained. 12. In claim 9, the beam splitter means is placed in the center of the disc, and the eye-contacting pedestal supports the disc in a slightly tilted position, where the beam splitter means The engraving device as described above, characterized in that the geometrical normal is offset by a small angle from the center line of the eye. 13. In an engraving device for surgically operating on the outer surface of the cornea of a patient's eye, laser means for producing a circular output beam in the ultraviolet region of the electromagnetic spectrum, and laser means disposed within said beam to transmit the laser emitted light with a reflected component beam. and beam splitter means having a pre-characterized beam splitting function to split the component beam into is a circumferentially uniform increasing function of the radius around the axis, thereby
An engraving device as described above, characterized in that when the axis of the transmitted component beam is aligned with the axis of the eye, it produces a hyperopia-correcting curvature modification to the anterior corneal surface. 14. The engraving device according to claim 13, wherein the energy absorbing means is arranged in the path of the reflected component beam. 15. In claim 13, the laser means generates a beam with a circular cross-section of a size equal to the projection area of the cornea to be operated on, the circular cross-section being (a) a fraction of the diameter of the circular cross-section; (b) at least one circular ring radially continuous with the inner circle;
said pre-characterization of said beam splitter means is limited to a pre-characterization of said inner circle;
The circular cross section further includes, in the circular ring,
characterized in that the luminous flux density distribution is a uniform function in the circumferential direction of the radius and within substantially the same density limits as applied to said inner circle; The above engraving device is characterized in that, in the process of irradiating the cornea of the eye with a single laser beam, Fresnel type corneal curvature correction can be obtained in both the inner circle and the circular ring. 16. In claim 13, the beam splitter means is placed in the center of the disc, and the eye-contacting pedestal supports the disc in a slightly inclined position, in which the beam splitter means is placed in the center of the disc. The engraving device as described above, characterized in that the geometrical normal is offset by a small angle from the center line of the eye. 17 In claim 13, the luminous flux density distribution (i) is a uniform increasing function in the circumferential direction of the radius with the maximum density at the first radial limit of the hyperopia correction region, and (ii) The engraving device as described above is characterized in that it is a uniform decreasing function in the circumferential direction of the radius from the maximum density to the minimum density at the second radial limit of the laser beam cross section. 18. In an engraving device for surgically operating on the outer surface of the cornea of a patient's eye, laser means for producing a circular output beam in the ultraviolet region of the electromagnetic spectrum, and laser means disposed within said beam to transmit the laser emitted light with a reflected component beam. and a beam splitter means having a pre-characterized beam splitting function for splitting into a component beam, the pre-characterization of the beam splitter means being such that the luminous flux density distribution in the transmitted component beam passes through the center of said beam. symmetrical about a single diameter line, said distribution being configured such that the luminous flux density decreases symmetrically and continuously on both sides of said diameter line, and said beam splitter means means arranged for selective rotation about a central axis of the beam, thereby rotationally adjusting said beam splitter means to a predetermined axis for astigmatism correction to align said transmitted component beam; The above engraving device is characterized in that astigmatism is removed or reduced by irradiating the cornea. 19. In claim 18, the beam splitter means is placed in the center of the disc, and the eye-contacting pedestal supports the disc in a slightly tilted position, where the beam splitter means The engraving device as described above, characterized in that the geometrical normal is offset by a small angle from the center line of the eye. 20 In claim 18, the beam splitter means is placed at the center of the disc, and a mounting base that contacts the eye supports the disc so that its center coincides with the central axis of the eye. The above-mentioned engraving device is characterized by: 21. An engraving device for operating on the outer surface of the cornea of a patient's eye, comprising laser means for producing an output beam in the ultraviolet region of the electromagnetic spectrum, said output beam having a central axis and a predetermined luminous flux density distribution. and the laser beam irradiation intensity is limited to remove a fraction of the predetermined maximum penetration of the stromal region of the cornea in a unit time, whereby the predetermined irradiation time is: be ascertainable to achieve a predetermined maximum penetration into the stroma and positioned within said beam for delivery to the cornea without substantially altering the spatial and temporal coherence of said beam; pre-characterizing means for generating a pre-characterized illumination beam, said pre-characterizing means that the luminous flux density distribution in said pre-characterized beam transmitted to the cornea is such that the luminous flux density distribution in said pre-characterized beam a circumferentially uniform decreasing function of the radius around the axis, thereby providing myopia correction relative to the anterior corneal surface when the axis of the pre-characterized beam is aligned with the optical center of the eye. means for effecting a curvature modification and controlling the irradiation time of the pre-characterized beam on the cornea according to said pre-determined irradiation time, thereby obtaining a pre-characterized beam associated with a pre-determined maximum penetration An engraving device as described above, characterized in that, depending on the defined irradiation time, the same pre-characterizing means are used to produce a pre-selected one of a plurality of different diopter changes. 22 In claim 21, the pre-characterizing means are placed in the center of the disc, and the eye-contacting mounting base supports the disc in a slightly inclined position, in which the geometry of the center of the disc is The above-mentioned engraving device is characterized in that the optical normal is deviated from the center line of the eye by a small angle. 23. The engraving device according to claim 21, wherein the pre-characterizing means is a thin film-like gradient film. 24 In claim 21, the pre-characterizing means is a thin film-like gradient filter, the gradient filter has a substrate transparent to the laser radiation wavelength, and is realized by optical processing. An engraving device as described above, characterized in that it has a halftone coating, the halftone coating being provided with a predetermined characterization. 25. Claim 21, wherein the pre-characterizing means is a thin film-like gradient filter, and the gradient filter has a substrate that is opaque to the laser emission wavelength;
The engraving device as described above, wherein the substrate has a large number of distributed micro-apertures, and the distribution of the micro-apertures follows the luminous flux density distribution. 26. The engraving apparatus according to claim 21, wherein the precharacterizing means is a thin film gradient filter reflector having precharacterized reflection characteristics. 27. An engraving device for operating on the outer surface of the cornea of a patient's eye, comprising laser means for producing an output beam in the ultraviolet region of the electromagnetic spectrum, said output beam having a central axis and a predetermined luminous flux density distribution. and the laser beam irradiation intensity is limited to remove a fraction of the predetermined maximum penetration of the stromal region of the cornea in a unit time, whereby the predetermined irradiation time is: be ascertainable to achieve a predetermined maximum penetration into the stroma and positioned within said beam for delivery to the cornea without substantially altering the spatial and temporal coherence of said beam; pre-characterizing means for generating a pre-characterized illumination beam, said pre-characterizing means that the luminous flux density distribution in said pre-characterized beam transmitted to the cornea is such that the luminous flux density distribution in said pre-characterized beam a circumferentially uniform decreasing function of the radius around the axis, thereby providing hyperopic correction relative to the anterior corneal surface when the axis of the pre-characterized beam is aligned with the optical center of the eye. means for effecting a curvature modification and controlling the irradiation time of the pre-characterized beam on the cornea according to said pre-determined irradiation time, thereby obtaining a pre-characterized beam associated with a pre-determined maximum penetration An engraving device as described above, characterized in that, depending on the defined irradiation time, the same pre-characterizing means are used to produce a pre-selected one of a plurality of different diopter changes. 28 In claim 27, the pre-characterizing means are placed in the center of the disc, and the eye-contacting mounting base supports the disc in a slightly inclined position, in which the geometry of the center of the disc is The above-mentioned engraving device is characterized in that the optical normal is deviated from the center line of the eye by a small angle. 29. The engraving apparatus according to claim 27, wherein the pre-characterizing means is a thin film-like gradient filter. 30 In claim 27, the pre-characterizing means is a thin film-like gradient filter, the gradient filter has a substrate transparent to the laser emission wavelength, and is realized by optical processing. An engraving device as described above, characterized in that it has a halftone coating, the halftone coating being provided with a predetermined characterization. 31. Claim 27, wherein the pre-characterizing means is a thin film-like gradient filter, and the gradient filter has a substrate that is opaque to the laser emission wavelength;
The engraving device as described above, wherein the substrate has a large number of distributed micro-apertures, and the distribution of the micro-apertures follows the luminous flux density distribution. 32. The engraving apparatus according to claim 27, wherein the precharacterizing means is a thin film gradient filter reflector having precharacterized reflection characteristics. 33 In claim 27, the luminous flux density distribution (i) is a uniform increasing function in the circumferential direction of the radius with the maximum density at the first radial limit of the hyperopia correction region, and (ii) The engraving device as described above is characterized in that it is a uniform decreasing function in the circumferential direction of the radius from the maximum density to the minimum density at the second radial limit of the laser beam cross section. 34. An engraving device for operating on the outer surface of the cornea of a patient's eye, comprising laser means for producing an output beam in the ultraviolet region of the electromagnetic spectrum, the output beam having a central axis and disposed within said beam. , having pre-characterizing means for transmitting only a pre-characterized beam to the cornea, the pre-characterizing being such that in the pre-characterized beam transmitted to the cornea, the luminous flux density distribution passes through the center of said beam. symmetrical about a single diametrical line, said distribution being configured such that the luminous flux density decreases symmetrically and continuously on both sides of said diametrical line, transmitting said pre-characterizing means to the cornea; means for selectively rotating the beam about the central axis of the pre-characterized beam;
Thereby, by rotationally adjusting said pre-characterizing means to a predetermined axis for astigmatism correction, reduction of astigmatism removal is achieved by irradiation of the cornea aligned with said pre-characterized beam. The above-mentioned engraving device. 35. In claim 34, the pre-characterizing means are placed in the center of the disc, and the eye-contacting mounting base supports the disc in a slightly inclined position, in which the geometry of the center of the disc is The above-mentioned engraving device is characterized in that the optical normal is deviated from the center line of the eye by a small angle. 36 In claim 34, the pre-characterizing means is placed in the center of the disc, and a mounting base that contacts the eye supports the disc so that its center coincides with the central axis of the eye. The above-mentioned engraving device is characterized in that: 37. The engraving apparatus according to claim 34, wherein the pre-characterizing means is a thin film-like gradient film. 38 In claim 34, the pre-characterizing means is a thin film-like gradient filter, the gradient filter has a substrate transparent to the laser radiation wavelength, and is realized by optical processing. An engraving device as described above, characterized in that it has a halftone coating, the halftone coating being provided with a predetermined characterization. 39. Claim 34, wherein the pre-characterizing means is a thin film gradient filter, the gradient filter having a substrate that is opaque to the laser emission wavelength;
The engraving device as described above, wherein the substrate has a large number of distributed micro-apertures, and the distribution of the micro-apertures follows the luminous flux density distribution. 40. The engraving apparatus according to claim 34, wherein the pre-characterizing means is a thin film-like gradient filter reflector having pre-characterized reflection characteristics. 41. An engraving device for operating on the outer surface of the cornea of a patient's eye, comprising laser means for producing an output beam in the ultraviolet region of the electromagnetic spectrum, the output beam having a central axis and disposed within said beam. , having pre-characterizing means for transmitting only a pre-characterized beam to the cornea, the pre-characterizing being such that in the pre-characterized beam transmitted to the cornea, the luminous flux density distribution passes through the center of said beam. symmetrical about a single diametrical line, said distribution being configured such that the luminous flux density increases symmetrically and continuously on both sides of said diametrical line, and said pre-characterizing means being transmitted to the cornea. means for selectively rotating the beam about the central axis of the pre-characterized beam;
Thereby, by rotationally adjusting said pre-characterizing means to a predetermined axis for astigmatism correction, reduction of astigmatism removal is achieved by irradiation of the cornea aligned with said pre-characterized beam. The above-mentioned engraving device. 42. The engraving apparatus according to claim 41, wherein the pre-characterizing means is a thin film-like gradient filter. 43 In claim 41, the pre-characterizing means is a thin film-like gradient filter, the gradient filter has a substrate transparent to the laser radiation wavelength, and is realized by optical processing. An engraving device as described above, characterized in that it has a halftone coating, the halftone coating being provided with a predetermined characterization. 44. Claim 41, wherein the pre-characterizing means is a thin film gradient filter, the gradient filter having a substrate that is opaque to the laser emission wavelength;
The engraving device as described above, wherein the substrate has a large number of distributed micro-apertures, and the distribution of the micro-apertures follows the luminous flux density distribution. 45. The engraving apparatus according to claim 41, wherein the precharacterizing means is a thin film gradient filter reflector having precharacterized reflection characteristics. 46 In claim 41, in the biaxially outward directions of the single diameter line, the luminous flux density distribution is such that: (ii) uniformly increasing as one moves laterally outward from said maximum luminous flux density of said first biaxial limit; The above-mentioned engraving device is characterized in that the function decreases to .