ES2618323T3 - Device for the treatment and diagnosis of eye tissues - Google Patents

Abstract

Device for minimally optical treatment - even non-invasive and detection of eye tissues, with a pulsed laser (1) and a device for focusing laser radiation on a linear, surface or three-dimensional sample, developing the trajectory of the rays of the treatment from the laser (1) to the eye (12) of the patient through a quick switch (3), a deviation system x and (4), an optical lens (5), a first divider beam (6) and focusing optics (9) with a precision adjustment of z direction (8), the first beam splitter (6) being transparent for a portion of the radiation directed to the eye (12) in the direction of a detector (7) for the measurement and control of the power, as well as for the radiation coming from the eye (12) in the direction of a titration ray path, the switch (3) being designed to switch the pulse power of laser radiation between a treatment level to, in which a therapeutic effect is obtained, and a level of diagnosis, which is lower than the level of treatment, and in which fluorescence generated intraocularly in the cornea tissue is produced by the excitation of multifotons, possessing the laser radiation pulses - repetition frequencies in the megahertz range, and - pulse energies in the picojoule range or in the nanojoule range, and - focusing on a diameter less than 5 μm, and the device also comprising: - devices (6, 13, 15, 16, 17) for the measurement of said fluorescence generated by the excitation of multifotons.

Description

image 1

DESCRIPTION

Device for the treatment and diagnosis of eye tissues

The invention relates to a device for minimally-even non-invasive eye surgery by means of the

5 optical treatment of the tissue by means of laser radiation. Preferably, the refractive corneal surgery device is used for the treatment of defective vision, and diagnosis and control of the online therapy can also be carried out. The device can also be used for other interventions in the eye, for example, for glaucoma therapy, in order to again allow, by laser-induced tissue separation (canal perforation), the regulated evacuation of chamber water or reduce chamber water production through the

10 partial removal of the ciliary body. In addition, cysts and tumors and other pathological tissue modifications in and inside the eye can be diagnosed and treated with laser (puncture).

Until now, refractive cornea surgery is usually performed with invasive mechanical methods, by means of laser radiation or a combination of mechanical methods with a laser treatment.

In laser treatment without mechanical methods, an excimer laser with a normal

15 laser wavelength that is well absorbed in the ultraviolet (UV) field with pulse lengths in the nanosecond range. The ablation process is based on the so-called photoablation. In the treatment with the excimer laser, it is removed from the surface of the cornea, starting with the so-called epithelial layer, tissue with an approximate depth of 100 gm, in order to achieve a correction of the refractory capacity. Relatively poor healing as a result of the optical separation of the epithelial layer represents an inconvenience.

20 On the contrary, in the so-called LASIK procedure, an upper part of the cornea is partially "lifted" first with a mechanical device (microkeratome). The partially separated cornea sheet, the so-called flap, is lifted on one side, releasing the tissue layer below for tissue removal. The optical tissue ablation follows by means of a UV excimer laser. After laser treatment, the flap retracts and adheres to the cornea through adhesion forces. The flattening of the cornea as well

25 generated serves to correct myopia. The drawback of this treatment consists in the relatively high percentage (usually 5%) of complications as a result of the initial mechanical intervention. In addition, because of the mechanical effect, for example, strong friction, the flap can slide again too long after therapy.

Therefore, the attempt of a minimally-even non-invasive optical therapy is of particular importance

30 inside the cornea, especially in the so-called stroma layer, without damaging the surface of the eye. This can be carried out in principle by high intensity focused laser radiation with wavelengths in the field of visible wavelengths (NIR) near infrared of up to approximately 1200 nm.

The shedding of material is normally carried out in case of extremely high intensities in the field of orders of magnitude of GW / cm and TW / cm by ionization of biomolecules as a consequence of the absorption of non-resonant multifotons. The first free electrons thus generated activate a process that results in laser-induced optical rupture and plasma formation through cumulative amplification effects due to the reciprocal effect with the electromagnetic field of laser radiation and the absorption of energy associated with it by inverse radiation due to deviation. Through the rapid expansion of the plasma a dynamic high pressure field is created that causes the generation of a shock wave that is

40 expands radially. The percentage of material ablation caused by shock waves and bubble formation (cavitation bubbles, gas bubbles) is called photodisruption [Juhasz and other IEEE Journal of Selected Topics in Quantum Electronics 5 (1999) 902-909]. Ablation fragments can also be transported optomechanically outside the field of interaction [Loesel and other Appl. Phys. B 66 (1998) 121128].

45 So far the tests were carried out with nanosecond pulses, picosecond pulses and femtosecond pulses [for example, Krasnov. Arch. Ophthalmol. 92 (1974) 37-41; Stern and others Arch. Ophthalmol. 107 (1989) 587-592; Niemz and other Lasers Light Ophthalmol. 5 (1993) 149155; Vogel and others Invest. Light Ophthalmol. 5 (1993) 149-155; Juhasz and other Lasers Surg. Med. 19 (1996) 23-29].

The nanosecond pulses require high pulse energies and show, as a consequence of a high

50 percentage of high mechanical energy, only limited therapeutic possibilities in the field of corneal surgery (Steinert and Puliafito). The Nd: YAG laser in opthalmology. Philadelphia, PA: W.B. Saunders, 1985: 11-21). The threshold for therapeutic rupture drops in the use of shorter pulses. Thanks to the use of reduced energy pulses it is possible to reduce the percentage of destructive mechanical energy as demonstrated by the use of PS pulses. However, no optimal treatment was achieved here, which

55 should be attributed especially to the formation of bubbles [Niemz et al. Lasers Light Ophthalmol 5 (1993) 149-155; Gimpel and others Int. Ophthalmol. Clin. 37 (1997) 95-102; Ito et al. J. Refract. Surg. 12 (1996) 721-728]. Thus, the diameter of the cavitation bubbles in the use of nanosecond pulses is normally 1 mm to 2 mm, in the case of picosecond pulses of 0.2 mm to 0.5 mm, [Vogel et al. Proc. SPIE 1877 (1993) 312-322]. More favorable therapeutic effects are expected through the use of femtosecond pulses.

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The research carried out so far related to refractive cornea surgery with femtosecond pulses is based on the use of pulses with pulse energies in the range of microjoules and millijoules with pulse repetition frequencies in the range of Hz to kHz and points of laser lighting with a diameter of several micrometers [eg, Kurtz et al. J. Refract. Surg. 13 (1997) 653-658]. Thus, Kurtz and others describe a

5 device characterized by a repetition frequency of 10 Hz, an illumination point of 26 μm in diameter, pulse energies of up to 10 mJ and a variable pulse duration [Kurtz et al., J. Refract. Surg. 13 (1997) 653-658].

Lubatschowski and others use a laser system with a repetition frequency of 1000 Hz, a maximum pulse energy of 1 mJ and an illumination point diameter of 7 μm [Graefe's Arch. Clin. Exp. Ophthalmol. 238 (2000) 10 33-39]. Devices of this type that are normally composed of a laser oscillator and an amplifier and that also include "pulse elasticity" and "pulse compression" modules, require a lot of space, assistance and are costly. This state of the art is directed exclusively to the therapeutic aspect. No measurements are expected in the eye tissue. Here a laser pulse diameter in the field of 5-10 μm is proposed. The repetition frequency (repetition rate) is 1 kHz. Pulse energies are clearly 15 above the range of nanojoules. With these devices and laser parameters, incisions can be made inside the cornea normally with a width of more than 10 μm and thus eliminate the material. In addition, a flap can be optically generated. In the market it is possible to acquire a corresponding equipment. In this case, femtosecond pulses of the wavelength of 1053 nm are used. The radiation is focused in the eye on a point with the diameter of 3 μm and is positioned intraocularly by means of a scanning device. The

20 irradiation points fit closely next to each other at a distance of more than 5 μm in the form of a spiral, although displaced in time. The material is separated from the inside to the surface of the cornea, so that the flap generated by means of laser radiation can be folded to the side with the help of a negative pressure. In this way the mechanical generation of the flap is suppressed.

A procedure for photorefractive keratectomy is described in US patents 5,993,438 and EP 0 903 133

25 intrastromal describing the photodisruption of material in the stroma, the material affected by the photodisruption corresponding approximately to the focus volume normally with a diameter of 10 μm to 25 μm and the illumination point being placed so that its spatial distance corresponds to one to two generated bubble diameters, generating, with respect to the optical axis, layers treated with central symmetry laser that can practice the desired cavity in the stroma. In the present invention a method is described in which a

30 pulse repetition frequency in the 10 Hz and 100 kHz range. Preferred frequencies are from 1 kHz to 10 kHz and an illumination point with a diameter of approximately 10 μm. The known technical solutions are based on the application of photodisruption, that is, on the mechanical effect of shock waves and bubbles. In principle, the tissue subjected to photodisruption is absorbed by the cornea or removed from the cornea.

In US patent 6,146,375, tissue photodisruption for the treatment of pulse glaucoma is reported.

35 of femtoseconds and picoseconds partly with the help of chemical substances that modify the dispersion behavior of the eye.

In the procedures employed so far by means of pulses of femtoseconds there is the disadvantage of the relatively high pulse energies used so far in the order of magnitude of microjoules that give rise to unwanted mechanical effects, especially as a consequence of the effects of the bubbles , the so-called 40 Bubbles, and the shock waves associated therewith by the photodisruption process. Thus, the formation of bubbles with a size of 25 μm is reported using pulses of 2 μJ with a pulse duration of 300 fs in the water and on coagulations of collagens inside the interaction zone [Lubatschowski et al., Graefe´ s Arch. Clin. Exp. Ophthalmol. 238 (2000) 33-39]. In addition, in the case of these relatively high pulse energies, autofocus effects can be induced that can lead to unwanted damage to the

45 surrounding tissue. The use of these relatively high pulse energies also requires laser systems with amplifiers that are very expensive and involve a lot of assistance.

The disadvantage is also that the femtosecond laser systems applied so far for corneal surgery do not allow a high resolution analysis of the laser treatment. Normally, separate optical systems are used for diagnosis (for example, Arashima et al., EP 0 850 614 A1). In this document you

50 describes a system comprising a laser for corneal ablation, an additional lighting system and a photographic device.

US 5,984,916 describes a procedure and a device for laser eye surgery based on the use of irradiation points of approximately 10 μm, pulse frequencies of up to 100 KHz and energy densities of 0.2 - 5 μJ / 10 μm2. However, energy densities and frequencies of

55 such pulses require the use of complicated laser systems with amplifiers, pulse elasticity and pulse compression units, as well as pulse energies in the range of more than 0.2 μJ. An integrated diagnostic system is not provided.

Against the state of the art according to the above-mentioned article by Lubatschowski et al., The present invention is based on the task of expanding the versatility of the system in a device for minimally-up to optical treatment.

60 non-invasive eye tissue.

The device according to the invention is described in patent claim 1.

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The dependent claims describe advantageous improvements of the device.

The device allows a high precision hitherto not reached with possible incision widths of the order of less than 2 μm without significant mechanical loss of the surrounding tissue generated by photodisruption and autofocusing. The use of economical and easy-to-handle systems should be possible. By

On the other hand, the same device must allow three-dimensional imaging (Imaging) of the tissue for diagnosis, for objective analysis, for optical control of online treatment and for high-resolution three-dimensional optical analysis of treatment with To be.

Next, the effectiveness of the invention is shown by exemplary embodiments, its function being explained in more detail. It looks on the:

10 Figure 1A: HE-stained freeze cuts of a region with laser incisions documenting the precise cut in the stroma of a pig's eye with laser pulses of sub-nanojoule femtoseconds. One measurement provided normal incision widths in the range of 0.3 μm to 1 μm.

Figure 1B: reflectance images directly after making 5 incisions in the stroma of a pig's eye with respectively 20 ms of total ray residence time per pixel and a 512 line scan

15 pixels

Figure 2: images of activated autofluorescence with an average wavelength of 800 nm and Second Harmonie Generation (SHG) with high three-dimensional resolution at different tissue depths, that is, in the z-direction, of a pig's eye. The different layers of corneal tissue and different cells can be clearly recognized.

Figure 3: fluorescence image 2 s after the laser therapy was performed with 2 ms of time

20 total ray permanence per pixel. The luminescent region along the incision has a width of approximately 0.8 μm. The luminescence of a bubble represents the only major luminous area.

Figure 4: reflectance images that were made 4 s, 15 s, 30 s and 45 s after the ablation of material with a "Linescan 6" and that provide information on Bubble kinetics. Therefore, the life of these "Bubbles" is in the field of less than half a minute.

Figure 5: A basic representation of a device according to the invention with a simple laser beam.

Figure 6: representation as Figure 5, however with a laser beam divided into several individual rays.

For minimally-to-non-invasive optical treatment, for the generation of three-dimensional images, for the control of on-line optical treatment and for the high-resolution three-dimensional optical analysis of laser treatment of eye tissues, especially of the cornea, radiation focused on the spectral range of 500 nm 30 to 1200 nm is used, composed of pulses of femtoseconds with a pulse energy in the range of picojoules and in the range of nanojoules with a high repetition frequency in the range of MHz and an irradiation point with a diameter of less than 5 μm, preferably less than 1 μm, that travel along the target to be treated at a normal distance of less than 5 μm, allowing precise treatment by direct selective destruction of different cells or components of cell or different intraocular tissue structures without destruction

Irreversible of surrounding tissue areas, which allows three-dimensional photographing of the treated or treated tissue or different cells or different cell components before and after laser therapy by detecting fluorescence, preferably non-linear excited autofluorescence , or reflectance, as well as allowing on-line therapy control by on-line detection of resolved plasma illumination in space and / or time.

40 With only a single device it is possible to perform laser therapy and the generation of three-dimensional images (Imaging) of the tissue for the analysis of the objective, for the control of the on-line optical treatment and for the high-resolution three-dimensional optical analysis of the treatment with laser According to the invention a device is used for the treatment and for the diagnosis which is composed of a compact femtosecond laser without an amplifier in the field of 500 nm to 1200 nm, a lightning guidance system including a scanning device, a stretcher

45, a fast power regulator for switching between diagnostics (objective search and effect control) with lower power radiation and therapy with higher power radiation, one or more photon detectors, monitors, lightning switches , as well as proper control and hardware and software. In order to allow a detection of the signals resolved in time, caused by the reflectance, the fluorescence and the illumination of the plasma with a resolution in the range of PS, a fast detector, usually a fast PMT, is

50, according to the invention, couples a module for counting the different photons in correlation with time. For an on-line observation of the effects a video camera can be used additionally.

Targets with a numerical aperture greater than 0.8, normally greater than 1.0, and irradiation points are positioned at a distance of less than 5 μm, normally less than 1 μm.

To perform laser therapy, T-ray intensities of more than 100 GW / cm2 are used and for the

55 diagnosis lower intensities. The different intensities required are generated by varying the laser power in the sample. The power regulator must allow the choice between diagnosis and therapy, as well as the regulation of the light intensity respectively necessary depending on the depth of the tissue area to be recognized or treated.

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It has been found that by means of laser pulses of suitable femtoseconds in the range of subnanojoules and nanojoules, the ablation of intraocular material can be obtained. This was possible thanks to the use of compact and easy to handle laser systems. The use of complicated amplifier laser systems is not necessary. A precision hitherto not reached of <1 μm of incision width in the stroma and epithelial tissue could be obtained.

5 In this case it was possible to detach different cells, separate different collagen fibers or separate entire tissue areas without damaging the surrounding tissue areas as a result of photodisruption.

In particular, it has been shown that the pulses of 170 femtoseconds of the central wavelength of 800 nm and repetition frequency of 80 MHz with the use of a focus lens of the numerical aperture 1.3, which allows irradiation points of less than 1 μm, make it possible to release material in the cornea with an average power of 10 60 mW, which corresponds to a pulse energy in the Sub-nJ range. The irradiation point was shifted to the target with a galvanometer scanner. The displacement was performed in phases of less than 1 μm, usually less than 0.5 μm. The temporal distance of a displacement was less than 100 μs. The residence time of the ray per irradiation point is also in the range of microseconds, usually in a range less than 10 ps. Each point was irradiated up to 5000 times, usually 200 to 500 times

15 approximately. Incision widths less than 1 pm could be obtained without damaging the surrounding tissue cells. These incision widths could be achieved both in the epidermis, in the Bowman membrane, as well as in the stroma.

Figure 1A shows histological freezing tissue sections stained with "Uli" dyes of a pig eye demonstrating laser-induced removal of material. An average power of 80 mW was used. The lightning was guided

20 5 times along a line (scan line), the time of permanence of the ray per pixel being 20 ms in total. The incision width obtained varies, therefore, from 0.3 μm to approximately 1 μm. There is no evidence of thermal or mechanical injury of adjacent tissue areas.

Figure 1B shows reflectance images that were carried out with the same device directly after making the material separations. Through these images it has been proven that as a consequence of the laser-induced separations of material, highly reflective areas were created along the incision edges. These can be reproduced three-dimensionally by means of laser radiation of equal wavelength, however with a significantly lower average power of less than 1 mW, using suitable photon detectors. The width of these reflective zones along the incision also has values less than 1 pm and, therefore, correlates approximately with the incision width

30 real recognizable in histological image. Interestingly, the bubbles generated during the shedding of material also showed a measurable reflection that clearly differs from the periphery. With a lower reflective intensity, although clearly visible, 3D reflectance images show clearly reflective structures of different cells in the epithelial layer, especially the reflective nucleus and cell membranes, as well as probably collagen structures inside the stroma.

35 With the same device it was also possible to make fluorescence images. With an average power of 2 mW to 5 mW it was possible to perform, by means of excitation of endogenous fluorophores multifotons in the focus volume of subfemto-liters and by fluorescence detection with a photomultiplier through the exploration of planes at different tissue depths, a three-dimensional image of the cornea before and after laser surgery. In particular, the different layers of cornea tissue could be clearly located, specifically the layer

40 epithelial, Bowman's membrane and opaque cornea by means of autofluorescence. Figure 2 shows corresponding 800 nm corresponding autofluorescence images of high three-dimensional resolution at different tissue depths of a pig's eye.

Especially by the excitation of two photons the fluorescence of the reduced coenzyme NAD (P) H, as well as flavins, can be represented. The different cells can be clearly located by means of fluorescence.

45 The stromal collagen fibers also show an evident autofluorescence and SHG radiation.

Here it was also found that the bubbles created by means of laser treatment can be excited by the action of the lower power laser light until a luminescence clearly exceeds the intensity of the autofluorescence. In addition, the treated areas along the cutting area show an autofluorescence that differs from the surrounding areas. In this way it is possible to highlight the effect of the treatment with a high contrast

50 (figure 3).

Plasma luminosity generated during laser irradiation could be detected with the same photomultiplier directly during laser treatment along the treatment area. Thus, it is possible to provide representative information on the action of locally resolved intensive laser radiation and, consequently, carry out an online therapy control.

55 If high-spectrum illumination of the lens is used with white light or preferably with the near-infrared light of a halogen lamp or LEDs during laser treatment, it is possible to detect the effects of laser treatment online, especially the formation and disappearance of bubbles, by measuring the reflectance, for example, with a 50 Hz CCD camera and, for example, storing and reproducing them on a video recorder or on a PC.

Through the measurement of the reflected and dispersed photons, as well as the fluorescence photons, representative information relative to the effect obtained and the incision width can be established directly after the laser therapy is performed. On the other hand it is possible to analyze the formation of bubbles and their dynamic behavior as illustrated in Figure 4. Normally, the created bubbles have measures of less than 5 μm and disappear in a few seconds as represented in the reflection images of 4 s , 15 s, 30 s and 45 s after the detachment of cellular material (6).

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5 Since in the case of adequate pulse energies in the sub-nanojoule range, material ablations close to the threshold values for optical breakage can be carried out and it was not possible to find any indication of mechanical damage to the periphery, the detachment of material should probably not be attributed to a photodisruption, but simply to an evaporation of the material as a result of purely thermal effects or a detachment of photochemical material (bond breakage due to the entry of energy induced by the

10 absorption of multifotons). This assumption is supported by investigations that originated bubbles close to the threshold value that do not represent the typical short-lived cavity bubbles created by photodisruption [Lubatschowski et al., Graefe's Arch. Clin. Exp. Ophthalmol. 238 (2000) 33-39].

Figure 5 shows the device. As a source of irradiation for the shedding of material, the excitation of the fluorescence and the luminescence of the bubbles, as well as the obtaining of reflectance radiation, a compact femtosecond laser 1 with a high repetition frequency with a high repetition frequency is used. normal value around 80 MHz. The central laser wavelength is in the range of 700 nm to 1200 nm, a normal value is 800 nm. The operation of the laser 1 is coupled to a pedal switch 2. The laser beam affects a quick switch 3 with integrated power regulator. This switch is normally an electro-optical switch with response times in the microsecond range. It is also able to vary the laser power and reduce the initial power of the laser 1 in orders of magnitude. The lightning strikes an explorer 4 that normally consists of two galvanometer mirrors for the x-y deflection. The beam transmits a scanning and magnifying optics 5 before deviating to the focusing optics 9 through a deflection mirror 6 that acts as a beam splitter. Normally the deflection mirror 6 reflects approximately 99% of the radiation. The transmitted percentages of the 1% radiation affect a detector 7 that carries out the power measurement and, where appropriate, makes an activation signal available. The focusing optics 9 can be adjusted with nanometer precision by means of a piezo-driven regulator 8 and thus vary the plane of focus. A mechanical clamping device 11 serves to fix the position of the eye and can accommodate a glass window 10 with a thickness of 170 jim. The beam is focused on the eye 12. The radiation reflected or created in the eye 12 is transmitted, by means of a first beam splitter 6, in a reduced percentage, usually 1%, and is directed through a splitter mirror 13 as a 30 second beam splitter, on the one hand, to a radiation detector 15, usually a CCD camera, by means of a playback optic 14. The image that is created can be recorded online three-dimensionally resolved by a video recorder 16 and a personal computer 17. Luminescence radiation is conducted to a radiation detector 20 through beam splitters 6 and 13, one of the optics 18 and a filter 19. This radiation detector 20 detects fluorescence, luminescence of plasma and luminescence of bubbles. According to the invention, this radiation detector 20 can be a photomultiplier (PMT) with normal response time, a fast PMT in combination with a "Single Photon Counting" module (SPC) with time resolution in the PS range. or a spectrometer with photon detector, usually a polychromator and a CCD camera.

The signal is processed superficially and representatively in space depending on the position of the scanner 4 and, where appropriate, taking into account the signal of the detector 7 with an appropriate image treatment in the computer

40 staff 17.

If the optic 18 represents a suitable reproduction optic, 5 CCD cameras can also act as detectors.

In addition, a module 21 can be integrated, as shown in Figure 6, which, instead of the scanning procedure with only one ray, also allows simultaneous or virtually simultaneous scanning with several rays. A module 21 like this can normally be integrated into the laser beam path between switch 3 and scanner 4. This module may include known multilenticular devices or beam splitters. A temporary displacement of the partial rays in the range of femtoseconds or picoseconds is also possible. In this case, the distribution of the partial rays in the objective may favorably be a matrix in the form of a rectangular surface or of a circular surface or in the form of a line. In module 21, or connected to it

50 before or after in the ray path, a power regulator that preferably acts as a reducer can be arranged, in order to reduce the continuous laser radiation according to the invention from the "treatment level" to the "diagnostic level".

Reference List

55 1 Laser

2 footswitch

3 switch

4 X-Y deviation system

5 Magnification optics

image6

6

First beam splitter

7

Detector for measurement and power control

8

Z direction precision adjustment

9

Focus optics

5

10 Glass window

eleven

Mechanical clamping device

12

Eye

13

Second beam splitter

14

Playback optics

10

fifteen Radiation detector for reflectance radiation

16

Video recorder

17

Personal computer

18

Optics

19

Filter

fifteen

twenty Radiation detector for secondary radiation

twenty-one

Module for division and, where appropriate, the time shift of the laser beam

Claims (12)

image 1 1. Device for minimally-to-non-invasive optical treatment and detection of eye tissues, with a pulsed laser (1) and a device for focusing laser radiation on a linear, surface or 5-dimensional sample, developing the path of the rays of the treatment from the laser (1) to the eye (12) of the patient through a rapid switch (3), a deviation system x and (4), an optical lens (5), of a first beam splitter (6) and focusing optics (9) with a precision adjustment of z direction (8), the first beam splitter (6) being transparent to a portion of the radiation directed to the eye (12 ) in the direction of a detector (7) for power measurement and control, as well as for radiation from the eye (12) in the direction of a 10 evaluation ray path, the switch (3) being designed to switch the power of the laser radiation pulses between a treatment level, in which a therapeutic effect is obtained, and a diagnostic level, which is less than the level of treatment, and in which fluorescence generated intraocularly in the corneal tissue is produced by the excitation of multifotons, having the pulses of laser radiation 15 -repeat frequencies in the megahertz range, and-pulse energies in the picojoule range or in the nanojoule range, and -focusing on a diameter less than 5 μm, and the device also comprising: -devices (6, 13, 15, 16, 17) for the measurement of said fluorescence generated by the excitation of 20 multifotons 2. Device according to claim 1, providing devices (8, 9), in order to modify a focus plane of the laser radiation pulses in the cornea tissue with nanometer precision, to perform the optical diagnosis at different depths of tissue, especially in the epithelial layer, the Bowman membrane and the 25 sclera. 3. Device according to one of claims 1 or 2, an excitation of two photons of the fluorescence being carried out with the laser radiation pulses at the diagnostic level. Device according to claim 1, characterized in that the switch (3) is at the same time a power regulator. Device according to one of the preceding claims, characterized by two titration radiation paths that are initiated through a beam splitter (13), specifically 35 -a first evaluation radiation path to a chamber (15) and -a second evaluation radiation path to a radiation detector (20). 6. Device according to one of the preceding claims, characterized in that the diagnostic level is It is below the threshold for a photodisruption in the cornea tissue. 40 Device according to claim 1, the devices (6, 13, 15, 16, 17) comprising the measurement of said fluorescence generated by the excitation of multifotons: a beam splitter (13) in the path of the rays of assessment for the division of reflectance radiation and secondary radiation into radiation detectors (15 or 20) specifically provided for it. Four. Five Device according to claim 7, the devices (6, 13, 15, 16, 17) being designed for the measurement of said fluorescence, generated by the excitation of multifotons, to connect the outputs of the radiation detectors (15 or 20 ) to assessment devices (17) and indicating devices (16) sets. Device according to claim 8, the devices (6, 13, 15, 16, 17) being designed for the measurement of said fluorescence, generated by the excitation of multifotons, to also connect the output of the detector (7) for measurement and control of power, to evaluation devices (17) and indicating devices (16) sets. 10. Device according to one of claims 7 to 9, the radiation detector (20) being for radiation 55 secondary in the devices (6, 13, 15, 16, 17) for the measurement of said fluorescence, generated by the excitation of multifotons, a photomultiplier. Device according to one of claims 7 to 9, the radiation detector (20) being for secondary radiation in the devices (6, 13, 15, 16, 17) for measuring said fluorescence, generated by the 60 multifoton excitation, a fast photomultiplier in combination with an individual photon counter with a resolution in time in the order of magnitude of PS. 12. Device according to one of claims 7 to 9, the radiation detector (20) being for radiation secondary in the devices (6, 13, 15, 16, 17) for the measurement of said fluorescence, generated by the excitation of multifotons, a spectrometer with photon detector. 8 image2 13. Device according to claim 12, the radiation detector (20) for secondary radiation being a polychromator in combination with a CCD camera. Device according to one of claims 7 to 13, further comprising a module (21) disposed between the switch (3) and the deviation system xy (4) for dividing the laser beam into several individual rays displaced in space . 15. Device according to claim 14, characterized in that the module (21) is suitable for displacing the individual rays in time also in the order of magnitude of femtoseconds to picoseconds. 9