Abstract:
An irradiation system for opthalmological applications includes: a radiation source ( 1 ) for changing the biomechanical properties of the cornea; an optical system for directing the radiation towards the tissue; a beam-splitter ( 3 ) which couples out a part of the radiation directed towards the tissue for measuring or monitoring purposes; the beam-splitter also being set up in order to combine a further radiation of a different wavelength with the first-mentioned radiation; a controller for controlling the system, including a sensor; a mechanical stand ( 16 ) for supporting an irradiation unit ( 17 ); and interfaces for exchange of data.

Description:
SUMMARY OF THE INVENTION 
     The invention relates to an irradiation system for opthalmological applications for the purpose of achieving changes in the biomechanical properties of components of the eye, particularly of the cornea. For this purpose, the present invention employs an electromagnetic radiation designated here as ‘primary radiation’, preferably within the spectral range from 300 nm to 800 nm: This radiation is preferably generated with LEDs or laser diodes. The electromagnetic radiation designated here as ‘primary radiation’ is not intended to bring about any so-called photoablative effect—that is to say, an effect with which tissue is removed from the eye, as occurs in the case of a reshaping of the cornea, for example in accordance with the LASIK procedure. Rather, the primary radiation according to the invention serves to change the tissue, in particular the cornea, as regards its biomechanical properties without removing tissue. A change in the biomechanical properties, of the cornea for example, obtains when the tissue is changed in its elasticity (‘hardens’). For this purpose the state of the art is familiar with so-called photosensitisers—that is to say, active substances—which are injected into the tissue and which promote there the stated effect of the change in biomechanical properties of the tissue. As a result, the primary radiation according to the invention accordingly brings about a biomechanical stabilisation of the cornea. 
     For this purpose the invention provides an irradiation system of the initially stated type, exhibiting the following components:
         a. at least one radiation source for a primary radiation, which emits electromagnetic radiation within the range from 300 nm to 800 nm which in the irradiated tissue brings about, photochemically and/or photophysically, a change in the biomechanical properties, particularly of the cornea,   b. an optical system with at least two lenses and devices, in order to direct the radiation at a predetermined distance towards the tissue to be irradiated, wherein means are provided in order to adjust a temporally and/or spatially variable intensity distribution of the radiation,   c. at least one diaphragm which is designed and arranged in such a way that together with the optical system it generates a predetermined irradiation region,   d. at least one beam-splitter which couples out a part of the radiation directed towards the tissue for measuring or monitoring purposes and/or is set up for observation purposes and/or for real-time diagnosis and/or for bringing the stated radiation together with a further radiation of a different wavelength from a further radiation source,   e. a controller for controlling or regulating at least one of the radiation sources, including at least one sensor for, for example, the current consumption of the radiation source, the temperature of one or more components of the system, the temperature of the environment, or the atmospheric humidity of the environment,   f. an electrical power pack for supplying power to the irradiation system,   g. a mechanical stand for supporting an irradiation unit which includes at least the components named in features a., b., c., d., in relation to the tissue to be irradiated,   h. a display device for displaying data that are relevant for the irradiation system, such as the emission of radiation, treatment parameters or possible misadjustments,   i. an electronic interface between the controller and an external computer for the purpose of transmitting data such as, for example, duration of irradiation, dose, light distribution, measured data, data from databases, and   j. an interface or an input device for the input of data by a user, such as, for example, irradiation times or irradiation dose.       

     LEDs, thermal light-sources with associated filters, or lasers are preferably employed as radiation sources in the irradiation system described above. 
     Further configurations of the invention are described in the further claims and in the following description of embodiments with reference to the Figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically, an irradiation system for medical applications; 
         FIG. 2  a detail of the irradiation system; 
         FIG. 3  a further embodiment of an irradiation system for medical purposes, with two subsystems; 
         FIG. 4  schematically, embodiments of irradiation fields; 
         FIG. 5  a further detail of an irradiation system for medical purposes, with a calibrating device; 
         FIG. 6  a further detail of an irradiation system for medical purposes; 
         FIG. 7  schematically, an adapter for an irradiation system of the aforementioned type for the purpose of positioning in relation to an eye; 
         FIG. 8  a further embodiment of an adapter, similar to  FIG. 7 ; 
         FIG. 9  the interaction of a medical radiation system with an adapter; 
         FIG. 10  a centering of irradiation means; 
         FIG. 11  a treatment system with adjusting devices for optical components; 
         FIG. 12  a variant of the embodiment shown in  FIG. 11 ; 
         FIG. 13  a variant of  FIG. 12  and 
         FIG. 14  a device for exchanging optical elements. 
     
    
    
     DETAILED DESCRIPTION 
     The irradiation system for medical purposes according to  FIG. 1  exhibits a radiation source  1  for electromagnetic radiation, for example an LED, a laser, or a thermal light-source. The radiation is focused onto tissue  5  to be treated via a lens  2  and a semitransmitting mirror  3  as well as a further lens  4 . 
     The embodiments of the invention described here are suitable, in particular, for opthalmological use of the irradiation system. 
     An active substance that enables or promotes the photochemical and/or photophysical effects of the radiation introduced into the tissue has been introduced into the tissue  5  to be treated. 
     The irradiation region is denoted by reference symbol  13 . 
     An irradiation unit  17  is supported on a stand  16  in such a way that a predetermined distance  11  is adjustable between the optical element  4  of the irradiation unit  17  arranged last in the radiation path and the tissue  5  to be irradiated. 
     With the beam-splitter  3  varying functions can alternatively be obtained: 
     On the one hand, with the beam-splitter  3  a part of the radiation emitted from the radiation source  1  can be coupled out and supplied to a measuring device  10  which, for example, measures the energy and/or the intensity distribution and/or the time distribution of the radiation. 
     On the other hand, with the beam-splitter  3  a part of the radiation reflected back from the tissue  5  can also be supplied to an observation device  9 . 
     According to a third variant, with the beam-splitter  3  the radiation emitted from the radiation source  1  can be combined with a further radiation, the further radiation then being emitted from a further radiation source which is arranged in the structural element provided with reference symbol  9 . The further radiation then preferentially has a different wavelength from that of the radiation emitted from the radiation source  1 . 
     A controller  7  serves for controlling, inter alia, the stated components  1 ,  10  and  9 . 
     The controller  7  receives data from a sensor  15  which registers important parameters of the irradiation system, such as, for example, the current consumption of the radiation source, temperatures of the system and/or of the environment, the atmospheric humidity of the environment and further quantities. 
     A power pack  14  serves for supplying power to the irradiation unit  17 . 
     A display element  18  serves for displaying parameters of interest, such as the emission of light, treatment parameters of interest with respect to the patient, or even possible errors arising. 
     An interface  8  is connected to the controller  7  and serves for connecting the same to an external computer (not shown) for the purpose of transmitting data that are relevant for the treatment, such as, for example, the durations of irradiation, the irradiation dose, the light distribution, measured data of interest, or even for transmitting data from a database. 
     An interface  19  may be provided for the purpose of communicating data to the controller  7  and, in particular, for connecting a PC to input devices for the user with respect to the details of the treatment. 
     Structural elements that correspond to one another or that are functionally similar are provided with the same reference symbols in the Figures. Note that in a further embodiment of an irradiation system depicted in  FIG. 3 , two subsystems may collectively include two ( 2 ) lenses  2 , two ( 2 ) beam splitters  3 , two ( 2 ) further lenses  4 , two ( 2 ) diaphragms  12 , and two ( 2 ) observation means  9 , to irradiate two regions of tissue  5 , each provided with active substance  6 , at two areas  13 . 
       FIG. 2  shows a detail of the irradiation system represented in  FIG. 1 , wherein in the treatment unit  17  in the beam path upstream of the lens  4  an optical element  20  is arranged which has a diffractive or holographic effect, in order to generate a predetermined and selectable light distribution in the irradiation region  13 . 
     In modification of the embodiment described above, the optical element  20  may also be a temporally variable light modulator, for example a liquid-crystal modulator, in order to generate a selectable light distribution in the irradiation region  13 . 
     In modification of the embodiments described above, the optical element  20  may also generate an adjustable and variable light distribution in the tissue  5  by movement in space. 
     According to a further variant, there may be provision to arrange at the position of the optical element  20  a change gear (revolver)  21 —shown in FIG.  14 —with which varying optical elements—such as, for example, absorbers  22 —are capable of being moved into the radiation path, in order to generate a predetermined light distribution in the radiation region  13 . In this case a chemical active substance  6  ( FIG. 2 ) has been introduced into the region of the tissue  5  to be irradiated, in order to enable or at least promote the physical or chemical effect of the radiation. Such chemical active substances are known as such. 
       FIGS. 12 and 13  show modifications of the embodiments described above, wherein optical elements, as indicated by the arrow  23 , are displaceable in space, in order to adjust the light distribution in the irradiation field  13 . 
     These embodiments also enable the distance  11  between the irradiation unit  17  and the tissue  5  to be irradiated to be adjustable. 
     The diaphragm  12  shown in  FIG. 1  is preferentially controllable (adjustable) as regards its diaphragm aperture and/or with regard to its distance in relation to the other optical elements. 
     According to a variant, the diaphragm  12  may be configured as a rotating mask in such a manner that differing regions of the beam are masked out by the rotating diaphragm (mask) in each instance in the course of rotation, so that a temporally and spatially varying radiation dose on the tissue  5  occurs. For instance, a helical mask generates a parabolic light distribution in the radiation region  13 . 
     The irradiation system will be described in more detail in the following with regard to the diagnostic means optionally provided in the block  9 : 
     The measuring means  9  may, for example, be an instrument for optical coherence tomography. The measuring instrument  9  may optionally also be an instrument for measuring the optical length of the eye, or a measuring means for ascertaining the topography of the cornea in real time. 
     Another configuration provides that the measuring means  9  is a wavefront-diagnosis system for measurement in real time of the wavefront that is reradiated from the tissue  5 . 
     The measuring means  9  may optionally also be a Scheinpflug camera. 
     Another configuration provides that the measuring means  9  is a video system for imaging. The measuring means  9  may also be a camera system for electronic imaging. 
     A further configuration provides that the measuring means  9  is a microscope for visual observation of the treatment. 
     On the other hand, the measuring means  9  may be a spectrometer for fluorescence analysis. 
     On the other hand, in another configuration the measuring means  9  may be a system for registering the movements of the eye (so-called eye tracker). 
     Another configuration provides that the measuring means  9  is an instrument for measuring the thickness of the cornea and/or of the epithelium. 
     The measuring means  9  may also be an instrument for distance measurement from the eye (relative to the optical components). 
     In the following, varying functions of the beam-splitter  3  according to varying embodiments of the invention will be elucidated: 
     As already indicated above, in a first variant of the invention the beam-splitter  3  serves to combine a radiation of a different wavelength with the radiation coming from the radiation source  1  (so-called primary radiation), the radiation source for the second radiation (secondary radiation) being seated in the block denoted by  9 . In the case of the secondary radiation, it may be a question, for example, of radiation with a wavelength that is suitable for UV photoablation of corneal tissue. 
     According to another variant of the invention, the secondary radiation may be selected in such a way that it achieves a fluorescence effect in the irradiated tissue, devices then being provided in order to evaluate the fluorescence radiation. 
     A further variant of the use of the beam-splitter  3  provides that the secondary radiation has a wavelength that is suitable to thermally excite the tissue  5  to be irradiated and in this way to promote the desired effects. 
     A further variant of the function of the beam-splitter  3  is a secondary radiation which has been selected in such a way that it lies within the visible optical region (visible for the patient) and serves as so-called fixation beam or target beam. 
     According to another variant, the beam-splitter  3  serves to split up the primary radiation into two beam paths, so that a (smaller) beam part can be input into a measuring device  10  for measuring purposes. In this case, the signal of the measuring device  10  is passed to the controller  7  for processing. 
     According to another variant, the beam-splitter  3  is capable of being moved by electrically drivable means  24 —see FIG.  11 —in such a way that the irradiation region  13  can be guided (scanned) over the tissue  5 . 
     In the following, details of the controller  7  will be elucidated: 
     The controller  7  may be designed in such a way that it emits the stated primary radiation in temporally pulsating manner or continuously. 
     The controller  7  may also be programmed in such a way that the power of the primary radiation is adjustable in temporally varying manner. In this case a special configuration provides that the power of the primary radiation emitted by the source  1  before an actual start of treatment is held below a predetermined threshold value over a predetermined time interval, in order to carry out adjustments or measurements with the radiation within this predetermined time interval. After the time interval, the radiation can then be raised above the stated threshold value, in order to achieve a desired chemical and/or physical effect. 
     The controller  7  may be capable of being controlled via a foot pedal for the purpose of emitting the radiation. It is also possible to operate the controller  7  via a remote control for the purpose of emitting the radiation. 
     If several radiation sources—for example, several LEDs—are provided for generating the primary radiation, the controller  7  can drive individual radiation sources in each instance, in order to control a desired spatial and/or temporal intensity progression of the radiation. 
     The block  10 —indicating, in particular, a measuring device—according to  FIG. 1  is, in particular, a photodetector with which the radiation dose per unit time and over the temporal progression of the treatment is measured. In this case there may be provision that a signal is passed by the measuring device  10  to the controller  7 , in order to control the temporal progression of the radiation in the treatment plane in accordance with a predetermined program. If deviations arise with regard to a measured parameter in comparison with the set progression of the program, the controller  7  can change the radiation in such a way—in the manner of a closed control loop—that the stated parameter again lies within the set range. 
     If the block  9  in  FIG. 1  denotes a so-called eye tracker; an appropriate signal concerning the movement of the eye can then be passed to the controller  7  (in the Figures the connecting lines between the functional blocks indicate the reciprocal exchange of data), and the controller  7  can then actuate a motor  24  ( FIG. 11 ), in order to guide the movable beam-splitter  3  in a manner corresponding to the movement of the eye. 
     According to a further embodiment, the controller  7  is designed in such a way that it drives the movable stand  16  and in this way adjusts the position of the irradiation unit  17  in relation to the tissue  5 . 
     The controller  7  is programmed in such a way that it takes account of data received from, for example, a computer via an interface, in particular with respect to the thickness of the cornea, the thickness of the epithelium, the riboflavin concentration (the latter is an example of an active substance  6  in the tissue  5 ), in order to ascertain optimal values for the treatment with regard to the dose and the temporal progression of the intensity, and then to control the system correspondingly. 
     In similar manner, the controller  7  can also evaluate measured data received via an interface with regard to optical parameters—that is to say, in particular with regard to the wavefronts and the topography—in order to ascertain optimal treatment data and to control the system correspondingly. 
     Analogously use may also be made of pre-operative and post-operative measured data, in order to compute optimal radiation parameters for the treatment. 
     The computation of data in the controller  7  is preferably effected in real time (online). 
     In the following, some configurations of the stand will be elucidated: 
     The stand  16  ( FIG. 1 ) serves generally for positioning the irradiation unit  17  in relation to the tissue to be irradiated. For example, it may be a question of a table stand. For this purpose the stand may exhibit a spring-articulation arm—that is to say, an arm that is biased via springs in an initial position by way of rest position and that is capable of being swiveled out of this initial position by a user and then capable of being locked in the swiveled position. It is also possible to configure the mechanical stand  16  in such a way that it is capable of being positioned by means of electric motors, one-dimensionally, two-dimensionally or three-dimensionally. 
     It is also possible to connect the stand  16  directly to a patient&#39;s bed or a patient&#39;s chair. 
     In the following, some properties of the user interface  19  will be elucidated: 
     The user interface  19  enables, in particular, the input of the temporal and spatial progression of the radiation intensities. In this connection, in particular a progression of the intensity distribution is provided that is variable over time. 
     Moreover, the user interface  19  enables the input of patient data such as cornea thickness, epithelium thickness, concentration and type of the active substance  6  in the tissue, said active substance also being designated as ‘photosensitiser’. Optical measured data can also be input via the user interface  19 . 
     In the following, embodiments according to  FIG. 10  will be elucidated: 
       FIG. 10  shows two light-sources  25  which, in particular, may take the form of laser diodes. These beams are likewise directed towards the irradiation region  13  ( FIG. 10 ). They serve for spatial adjustment and, in particular, centering of the system. The radiation of the light-sources  25 , which is reflected from the tissue  5 , can, for example, be separated on the basis of the wavelengths via the lens and the partially transmitting mirror  3  and can be evaluated with a camera system (at the location of the block  9 ), in order to enable a spatial adjustment of the radiation. For this purpose, in particular the beam directed towards the tissue  5  via the lens  4  and the aligning beam of at least one of the light-sources  25  in the set condition are concentric. The angle at which the beam of the at least one light-source  25  (in  FIG. 10  two are shown) impinges on the tissue  5  is predetermined and known precisely. 
     Some details of a device for positioning the irradiation system in relation to an eye to be treated will be elucidated in the following with reference to  FIGS. 7 through 9 . 
     The irradiation unit  17  is positioned in relation to the eye via an adapter  26  ( FIG. 7 ).  FIGS. 7 and 8  show the component parts of the eye  27  schematically. The adapter  26  has a face-shaped shell overall, so that movements of the eye during the irradiation are prevented. 
     The adapter  26  has, moreover, an applanation mould  29 ,  28  (cf.  FIG. 7 ,  FIG. 8 ) which is transparent in respect of the radiation that is used and, where appropriate, reflected. The applanation mould  28  is pressed onto the cornea and deforms the cornea in desired manner. For example, the shape of the applanation mould  28  may be—corresponding to the diagnosis—spherical, aspherical bitoric, or described by a Zernike polynomial. The Zernike polynomial may extend to the 10 th  order. 
     The applicator  26 , which encloses and supports the cornea all around, may, according to one embodiment, be provided with means in order to deliver the medicament to be injected into the tissue, specifically in defined doses. In the applicator a small pump may be provided which is capable of being driven electrically by the controller  7 , in order to transfer the medicament into the cornea. 
     The applanation mould of the adapter  26 —that is to say, the mould with which the adapter shapes the tissue to be treated, that is to say, in particular, the cornea, by gentle pressing—may be configured in such a way that the tissue is shaped only in parts—that is to say, in certain selected regions. These shaped regions may lie inside and/or outside the irradiated zone.  FIG. 9  illustrates an example interaction of a medical irradiation system  17  and the adapter  26 . 
     The mechanical adapter  26  may exhibit sensors, the arrangement of which is indicated by reference symbol  30 . For example, the sensors can ascertain biomechanical properties of the tissue. The sensors  30  may also be provided in order to ascertain the concentration of the chemical active substance in the tissue. 
     The sensors  30  may also be designed in order to ascertain an active-substance concentration in the anterior chamber of the eye. 
     Overall, the adapter  26  may be provided with a mechanical suction apparatus with respect to the eye  27 . In this case a sensor may be provided, in order to measure the pressing force on the eye and to pass a corresponding signal to the controller  7 . 
     The adapter  26  may also be provided with a mechanical system in order to remove the epithelium of the tissue. 
     An external calibration system will be described in the following, in particular with regard to  FIG. 5 : 
     In the arrangement according to  FIG. 5 , an irradiation unit  17  is represented as regards its components of interest here (otherwise it corresponds to  FIG. 1 ), without interacting with an eye to be treated. The eye has been replaced by a calibration means  31 . With the calibration system  31  the functioning of the irradiation system is tested before it comes into operation on the eye. 
     The calibration means  31  may be, for example, an energy sensor, a spectrometer, a beam-profile camera, a time-measuring device, a photometer, or a fluorescent medium in respect of the active radiation. The calibration means  31  supplies signals to the controller  7 , so that a closed control loop with respect to the radiation emitted via the radiation source  1  is capable of being generated via the controller. 
     The calibration means  31  may also be integrated into the applicator and may then be employed during the treatment. 
     An applicator  32  for medicaments will be described in the following with regard to  FIG. 6 : 
     According to  FIG. 6 , an applicator  32  for medicaments is arranged close to the irradiation area  13  on or in the tissue to be treated. The applicator  32  may be an injector, a drip system or a spray system. The applicator  32  may also be controlled as regards its delivery of medicaments via the controller. 
     Control of the applicator  32  via the controller  7  can preferably be effected in combination with a diagnosis during the treatment by means of the diagnostic means arranged in the block  9 —that is to say, in the form of a closed control loop. 
       FIG. 4  shows special configurations of the irradiation of the tissue. The irradiation region  13  may accordingly exhibit, for example, the special configurations  33  shown in FIG.  4 —that is to say, for example, a closed circular shape according to  FIG. 4 , top, or an annular shape according to  FIG. 4 , bottom. An elliptical shape with defined eccentricity may also be chosen for the irradiation field. The stated light shapes may also be combined—for example, in temporal succession—depending on the diagnosis.