Apparatus, interface unit, suction ring and method to monitor corneal tissue

Abstract

An apparatus and a method for cutting or ablating corneal tissue of an eye provide for detection of electromagnetic radiation exiting the eye. A detector is provided and coupled to a computer controlling the cutting or ablating laser radiation so that a two- or three-dimensional image of radiation exiting the eye can be generated.

Claims

1. An apparatus for treating corneal tissue of an eye, the apparatus comprising: a source configured to emit pulsed laser radiation; an optical unit configured to guide and focus the laser radiation relative to the corneal tissue; a detector configured to detect electromagnetic radiation exiting the eye; a suction ring unit adapted to be connected to the eye; and an interface unit adapted to be coupled to the suction ring, the interface unit having a conical wall defining a cavity within a structural component of the conical wall, wherein the focused laser radiation from the optical unit is guided through the cavity toward the corneal tissue, and wherein the structural component of the conical wall contains an internal beam path to guide the electromagnetic radiation exiting the eye towards the detector.

2. The apparatus according to claim 1, wherein the electromagnetic radiation exiting the eye has a wavelength shorter than the wavelength of the pulsed laser radiation.

3. The apparatus according to claim 1, wherein the source of laser radiation emits laser pulses in the nanosecond, picosecond, femtosecond, or attosecond range.

4. The apparatus according to claim 1, the detector performing time dependent detection of the electromagnetic radiation.

5. A method for monitoring corneal tissue of an eye, the method comprising: attaching an interface unit to a suction ring that is attached to the eye, the interface unit having a conical wall defining a cavity within a structural component of the conical wall; directing pulsed laser radiation through the cavity onto or into the eye to generate electromagnetic radiation that exits the eye; collecting the electromagnetic radiation that exits the eye in a beam path internal to the structural component of the interface unit; guiding the electromagnetic radiation along the beam path internal to the structural component of the interface unit towards a detector; and detecting the radiation with the detector.

6. The method according to claim 5 wherein the collected radiation is collected before, during, or after a surgical treatment of the eye.

7. The apparatus of claim 1, wherein the detector is offset from the optical unit by a distance substantially equal to a radius of a top of the interface unit such that the detector is axially aligned with an upper portion of the structural component of the conical wall.

8. The apparatus of claim 7, further comprising a window on the upper portion of the structural component of the conical wall that allows the electromagnetic radiation exiting the eye and traveling through the internal beam path to exit the structural component of the conical wall.

9. The apparatus of claim 1, wherein, the electromagnetic radiation exiting the eye comprises at least one of Second Harmonic Radiation (SHR), Third Harmonic Radiation (THR), plasma radiation, and fluorescence radiation caused by the laser radiation.

10. The apparatus of claim 9, wherein the interface unit is substantially transparent to the Second Harmonic Radiation (SHR), Third Harmonic Radiation (THR), plasma radiation, or fluorescence radiation caused by the laser radiation.

11. The apparatus of claim 1, wherein an outer surface of the structural component of the conical wall is coated with a material that prevents radiation from another source from entering the internal beam path.

12. The apparatus of claim 1, wherein an internal surface of the structural component of the conical wall is coated with a reflecting material that reduces a loss of intensity of the radiation exiting the eye.

13. The apparatus of claim 1, wherein an internal surface of the structural component of the conical wall further includes one or more filter to prevent one or more wavelength of the radiation exiting the eye to reach the detector.

14. The method for monitoring corneal tissue of an eye of claim 5, further comprising positioning the detector offset from the optical unit by a distance substantially equal to a radius of a top of the interface unit such that the detector is axially aligned with an upper portion of the structural component of the conical wall.

15. The method for monitoring corneal tissue of an eye of claim 14, wherein an upper portion of the structural component of the conical wall includes a window that allows the electromagnetic radiation exiting the eye and traveling through the internal beam path to exit the structural component of the conical wall.

16. The method for monitoring corneal tissue of an eye of claim 5, wherein, the electromagnetic radiation exiting the eye comprises at least one of Second Harmonic Radiation (SHR), Third Harmonic Radiation (THR), plasma radiation, and fluorescence radiation caused by the laser radiation, and wherein the interface unit is substantially transparent to the Second Harmonic Radiation (SHR), Third Harmonic Radiation (THR), plasma radiation, or fluorescence radiation caused by the laser radiation.

17. The method for monitoring corneal tissue of an eye of claim 5, wherein an outer surface of the structural component of the conical wall is coated with a material that prevents radiation from another source from entering the internal beam path.

18. The method for monitoring corneal tissue of an eye of claim 5, wherein an internal surface of the structural component of the conical wall is coated with a reflecting material that reduces a loss of intensity of the radiation exiting the eye.

19. The method for monitoring corneal tissue of an eye of claim 5, wherein an internal surface of the structural component of the conical wall further includes one or more filter to prevent one or more wavelength of the radiation exiting the eye to reach the detector.

Description

(1) Exemplary embodiments of the invention will be described in more detail in the following on the basis of the drawings:

(2) FIG. 1 shows schematically an apparatus for treating corneal tissue of an eye; this apparatus can also be used to generate short laser radiation pulses for generating one of the group comprising SHR, THR, plasma radiation, and fluorescence radiation;

(3) FIG. 2 shows a suction ring and the interface unit of an apparatus according to FIG. 1 in exploded representation;

(4) FIG. 3 shows schematically an arrangement of a detector in an apparatus according to FIG. 1 or 2, and

(5) FIG. 4 shows another schematic example of an arrangement of a detector in an apparatus according to FIG. 1 or 2.

(6) As is shown in FIG. 1, an apparatus for monitoring, cutting and/or ablating corneal tissue of an eye comprises a laser source 10 emitting laser radiation 12 suitable for e.g. LASIK procedures. The laser radiation emitted by laser source 10 may comprise, after focussing, power densities suitable for monitoring, cutting or ablating corneal tissue.

(7) An optical unit 14 forms and focuses the emitted laser radiation, as is known to a person skilled in the art of LASIK. The focused laser radiation 16 is scanned across the area of an eye 18 to be treated e.g., for monitoring, cutting a flap or for performing ablation of corneal tissue or other refractive procedures mentioned above. The radiation is focussed onto/into the eye's cornea 20.

(8) A suction ring 22 is attached to the anterior surface of the cornea. To generate a vacuum between the suction ring and the cornea, a vacuum pipe 22B in a socket 22A of the suction ring 22 is connected to a vacuum pump (not shown).

(9) An interface unit 30 is attached to the suction ring 22 also by vacuum, which is generated through vacuum pipe 22C connected to a vacuum pump (not shown).

(10) The interface unit 30 is sometimes called in the art an eye cone. In the context of this specification, the term interface unit covers mechanical elements connected, directly or indirectly, to the suction ring 22. More specifically, the term interface unit also covers the so-called mechanical interface unit. According to embodiments of the invention, in addition to the suction ring and the interface unit, there may be a coupling unit 40 as shown in FIGS. 3 and 4. Such a coupling unit may be in between the suction ring 22 and the interface unit 30 (as shown in FIGS. 3 and 4) or, the coupling unit may be arranged in between the coupling unit 30 and the optical unit 14.

(11) The focussed pulsed laser radiation 16 comprises, at its focus spot, sufficient power density in order to generate photodisruption or photoablation. Such photo disruptions or photoablation comprise a plasma that is suitable to generate, in a non-linear optical effect, the SHG and the THG of the impinging laser radiation, i.e. the radiation exiting the eye in response to the laser radiation having a wavelength of one half of the wavelength of the laser radiation and one third of the wavelength of the laser radiation, respectively.

(12) Radiation with the afore-mentioned wavelengths is represented by arrows in FIG. 1. This radiation exits the eye 18 and enters a part 32, particularly the wall of the interface unit 30. This part 32 of the interface unit 30 is transparent and/or translucent with regard to the electromagnetic radiation 26 exiting the eye 18. The path of said radiation through part 32 of interface unit 30 is indicated by arrows 28 in FIG. 1. As is shown, the electromagnetic radiation exiting the eye 18 passes through a window 34 and enters a detector 36, e.g., a photon counter. Additional Filters (not shown) can be positioned in the path of said radiation in order to prevent radiation having unwanted wavelengths from entering the detector 36.

(13) In the embodiment shown in FIG. 1, inside the conical wall of the interface unit 30, a beam path is provided for the radiation, indicated by arrows. The outer surface of said wall may be coated to prevent any radiation other than the radiation 26 exiting the eye from entering the beam path. Also, the internal surfaces of the walls of the interface unit 30 may be coated with a reflecting surface, such that the photons exiting the eye are guided with minimum loss of intensity to the detector 36.

(14) A computer 38 controls both the laser source 10 and the optical unit 14, in particular with regard to the timing of the laser pulses and the scanning of the focussed laser spot relative to the cornea 20. Therefore, computer 38 knows the position where the electromagnetic radiation 26 is generated so that the computer can generate a map on which the photons counted by detector 36 are co-ordinated to the position in the cornea where the SHG, the THG, the plasma or the fluorescence radiation, depending on how the detector is adjusted for monitoring, are generated.

(15) By mapping different layers in the cornea, a three-dimensional image can be generated representing the three-dimensional emission of the SHG, THG, plasma and/or fluorescence radiation, respectively. Said image can be displayed to the surgeon, who may use the image to derive conclusions regarding the substructures within the treated cornea.

(16) FIG. 2 shows a suction ring 22 and interface unit in exploded representation. In the drawings, subject-matter of the same or similar nature is denoted by identical reference numerals so that a repeated description is not necessary.

(17) FIG. 3 shows an embodiment of an apparatus for diagnosis and/or cutting and/or ablating of corneal tissue of an eye wherein, in addition to what is shown in FIGS. 1 and 2, a coupling unit 40 is provided in between the suction ring 22 and the interface unit 30. Whether or not the apparatus comprises, in addition to the suction ring 22, a coupling unit or whether the interface unit 30 is coupled directly to the suction ring 22, depends on the particular design of the apparatus. According to embodiments of the present invention, said part that is transparent or translucent for electromagnetic radiation 26 exiting the eye 18 can be part of the suction ring 22 and/or the coupling unit 40 (if any), and/or of the interface unit 30.

(18) In the embodiment shown in FIG. 3, a detector 36a (corresponding to the detector 36 described above) is arranged directly above the coupling unit 40 at the distal end of the interface unit 30.

(19) In the embodiment shown in FIG. 3, a coupling unit 40 is arranged in between the suction ring 22 and the interface unit 30. Alternatively, according to the particular design of the apparatus, a coupling unit may also be arranged on the other side of the interface unit 30, i.e. in between the interface unit 30 and the optical unit 14.

(20) In the embodiment shown in FIG. 4, a detector 36B is arranged at the proximal end of the interface unit 30. Optical fibres 42 guide the photons which are to be detected from the distal end of interface unit 30 to the detector 36B.