Method for determining irradiation parameters and irradiation device

Abstract

The invention relates to a method for determining illumination parameters for the operation of a laser (2) for illuminating one or more target regions of a retina (16) of an eye (4) by means of an illumination beam (11), the retina being illuminated by an illumination device (5, 6) under defined illumination parameters. The illumination parameter (5, 5 ') is completely or partially illuminated, and at least one record, in particular at least one camera image, of at least one target region of the retina is captured during and / or shortly after the illumination, and wherein at least an initial value of the illumination parameter is determined using the record or the camera image, to illuminate one or more target regions of the retina. The invention also relates to a corresponding device in the form of an expanded ophthalmoscope, so that the initial value of the irradiation parameter during the retinal laser treatment can be determined objectively with the lowest possible complexity.

Description

Technical Field

[0001] The present invention belongs to the field of medical measurement technology, and in particular relates to a method for determining irradiation parameters of a target area of ​​a retina of an eye. Background Art

[0002] Among the methods known for the treatment of various eye diseases, laser treatment of the retina can induce tissue changes by so-called laser photocoagulation. For all types of tissue treatment using lasers, it is important to know as much as possible in advance about the interaction of the laser beam used with the tissue of the individual patient.

[0003] For this purpose, it is known from the prior art to use lasers to perform so-called titration injections, i.e. to expose certain tissue areas of the retina to a laser beam under specific conditions in order to experimentally determine the effects of a laser treatment of a specific intensity on the tissue. The disadvantages of this method are, on the one hand, that certain areas of the retina are exposed without sufficient prior knowledge of the stress caused by the laser treatment and, on the other hand, that a certain amount of time is required to evaluate such experiments, since one has to wait for the tissue to react to the experimental laser treatment. Although each titration injection takes only a few seconds, multiple titration injections, especially titrations of variable intensity, are often used to determine the tissue reaction to different laser intensities. If the titration effect is still below the visibility threshold in the color image, the titration effect can also be determined by other examination methods.

[0004] For example, a method is known from WO 2011 / 038935 A1, in which, in conjunction with a titration injection on a retinal area, an image of the retina is captured by a camera, from which a discoloration of the laser-irradiated tissue area can be detected. In addition, a difference image is generated between the camera images taken before and after the titration, so that the effect of the titration can be derived from the difference value. Summary of the invention

[0005] Against the background of the prior art, the object of the present invention is to produce a method and a device for determining irradiation parameters for the operation of a laser for irradiating one or more target areas of the retina of an eye, by means of which the irradiation parameters can be determined as reliably as possible, with as little loss of time as possible and with as little complexity as possible.

[0006] According to the invention, this object is achieved by a method having the features of claim 1 .

[0007] Accordingly, the present invention relates to a method for determining illumination parameters for the operation of a laser for irradiating one or more target areas of the retina of an eye by means of an illumination beam, wherein the retina is fully or partially illuminated by an illumination device under defined illumination parameters, and during and / or shortly after the illumination, at least one optical recording, in particular at least one camera image, of at least one target area of ​​the retina is captured, and wherein at least initial values ​​of the illumination parameters are determined using the recording or the camera image in order to irradiate the one or more target areas of the retina.

[0008] The aim of the method is to enable the determination of the irradiation parameters of the laser operation as quickly, automatically and reproducibly as possible before treatment. According to the prior art, it is common practice to experimentally apply laser injections (titration injections) to areas of the retina to determine the reaction of the tissue of an individual patient. The surgeon then usually assesses the degree of tissue discoloration caused by the laser effect based on personal impressions and adjusts the irradiation parameters of the laser during the actual treatment.

[0009] The method according to the invention makes it possible to completely dispense with or significantly reduce the test runs of the laser before treatment. By using retinal recordings or camera images acquired in real time, the assessment of individual retinal tissues is objective, transparent, understandable, reproducible and verifiable.

[0010] By utilizing the method according to the invention, it is possible to determine conclusively the irradiation parameters for subsequent operation of the laser for irradiating in the described manner, so that the retina has to be exposed to laser radiation only for treatment and for experimentally determining the necessary laser intensity in the context of a titration process.

[0011] The illumination means can be a visible light source, such as a light emitting diode or a laser, such as the therapeutic laser itself, a surface illumination, such as by an illuminated reflective surface, a frosted glass plate illuminated from behind or a matrix of light emitting diodes or another broadband light source. Illumination outside the visible spectral region in the infrared or ultraviolet range can also be considered. In this case, the defined illumination parameters can be understood to mean, for example, the luminous intensity and the wavelength or wavelength distribution of the emitted illumination. For example, these can be set to specific values ​​or characteristics. Alternatively or additionally, it is also possible to measure illumination parameters, such as illuminance, illumination intensity distribution and spectral / wavelength distribution, which can then be used when evaluating the recording. It should also be noted that radiation in the non-visible range can also be used, such as radiation in the infrared range, wherein the captured recording or camera image in this case is also an infrared image recorded with the corresponding detector. For example, hyperspectral sensors can also be used for recording. It is also possible to automatically or manually select certain areas of the retina, such as target areas, for illumination. During the automatic selection, certain geometric illumination patterns can be specified and selected. The method may also use raster / scanning illumination and scanning methods, in which, for example, a target area or the entire retina is illuminated with a focused light source covering only a narrow defined area, and the reflection is detected by a light-sensitive, non-position-resolved sensor such as a photodiode. In this way, the entire area of ​​the retina can be optically scanned continuously, and an optical image with reflectivity and / or absorption intensity can be generated. Conversely, the entire retina can also be illuminated simultaneously, and light reflected from a limited area of ​​the retina can be detected in all areas of the retina or in a target area by a spatially resolved optical sensor, thereby generating an optical image of the retina with reflectivity and / or absorption intensity.

[0012] In the context of the present invention, optical recording may also be understood as optical imaging recording of, for example, the retina.

[0013] For example, fundus photography, fundus reflexometry, autofluorescence imaging, photoacoustic imaging and functional optical coherence tomography methods, which are implemented by corresponding lighting devices and lighting methods, can also be used as imaging methods for capturing a recording or camera image of the retina. These methods can be used, for example, to determine the pigmentation intensity of the retina, which has a decisive effect on the absorption intensity of the irradiation light beam used later. However, the pigmentation intensity can generally also be determined from the brightness of the retina recorded in the image or camera image.

[0014] Often, only certain single or multiple target areas of the retina are treated with a laser beam. In this case, it may be sufficient to illuminate the target area and capture a record or camera image of the target area. However, it may also be useful to capture a record / camera image of the entire retina, since taking into account the pigmentation intensity, it is also possible to estimate the required irradiation intensity of the laser during treatment in other areas of the retina that are not intended to be treated. Other additional non-local characteristics of the person being treated may also be taken into account when determining the necessary irradiation intensity. More information on this topic is provided below.

[0015] A particular embodiment of the method described above may also provide that the intensity of the pigmentation of one or more target areas of the retina and / or the intensity distribution of the pigmentation on the retina is determined by means of the recording or the camera image in order to determine the initial value of the illumination parameter.

[0016] It can also be provided that, in order to determine initial values ​​for the illumination parameters of one or more target areas of the retina, additional correction values ​​are determined as a function of expected absorption and / or scattering of the illumination light beam in the vitreous body of the eye on the way to the target area to be irradiated, wherein the correction values ​​are in particular determined as a function of the optical quality of the optical recording, in particular as a function of image sharpness or image contrast.

[0017] The sharpness or contrast of the image can be evaluated based on imaging inhomogeneities of the retina, such as blood vessels or ganglia. The sharpness / contrast information obtained from different areas of the retina can be compared with each other and / or with stored reference images to evaluate the influence of scattering / absorption in the vitreous of the eye on the sharpness of the image on the way to the relevant retinal area and to determine general parameters of the eye or also depending on the location on the retina.

[0018] For example, it may be advantageous to detect the melanin pigmentation of the retina, for which purpose the retina is illuminated with light of a wavelength in the visible range, or even only with light of a wavelength that is particularly well absorbed by the melanin pigmentation.

[0019] Illumination and / or detection wavelengths in the range of 450 nm to 1064 nm may be advantageous for the measurements. In particular, measurements at 514 nm, 532 nm or 577 nm may be advantageous. The scattering and absorption of the irradiation by melanin is strong in this region. Furthermore, wavelengths where the absorption intensities of melanin and blood differ significantly may also be advantageous. It may be useful to compare recordings at a wavelength of 480 nm (local minimum absorption in the blood) with recordings at 550 nm (local maximum absorption in the blood). For example, a reference value for the reflectivity measurement may be a mastoid, which is a nerve node and shows a strong reflection in a healthy state, or an area with blood vessels, where the presence of oxygen-rich or oxygen-depleted blood can be selectively detected, and a useful comparison value may be generated using a suitable wavelength capable of detecting these blood variants.

[0020] During subsequent retinal laser treatment, the irradiation beam will be partially absorbed or scattered, since the vitreous body of the eye is not 100% transparent. This influence should be taken into account when determining the irradiation parameters of the laser, so that a laser intensity slightly higher than that required for direct treatment of the retina is selected to compensate. The absorption of the irradiation beam depends on the individual characteristics of the vitreous body of the patient to be treated. In the method according to the invention, this absorption can be estimated, since the illumination intensity with which the retina is illuminated is known and the intensity of the backscattered signal (e.g. reflected light) depends on the intensity of the pigmentation of the retina and the absorption of light in the vitreous body. In order to be able to separate the two effects that influence the backscattering, multiple measurements can be performed under different optical conditions. Further details are provided below.

[0021] In many cases, it may be useful to illuminate the retina with radiation of a known wavelength distribution, which radiation in particular includes infrared radiation and / or light in a wavelength range absorbed by melanin, to generate a camera image, wherein the luminous intensity of the lighting device and / or the total power of the light incident on the retinal unit area and / or the power of the light incident on the retinal unit area in a specified wavelength range is additionally determined, and wherein initial values ​​of illumination parameters of the retina are determined using brightness values ​​and / or colors of the camera image.

[0022] Based on empirical values ​​for the required intensity of the irradiation beam in relation to previously measured brightness values ​​of the retina, initial values ​​for the irradiation parameters in the individual case can be determined, wherein, for example, the absorption of the irradiation beam by the vitreous body can be represented by an assumed constant value, which may depend on the age of the patient, for example.

[0023] Furthermore, it can advantageously be provided that the thickness of the retina is determined for one or more target areas and taken into account when determining the initial values ​​of the irradiation parameters, wherein the thickness of the retina is determined in particular by creating an OCT thickness map of the retina and / or the type and intensity of pigmentation in different areas of the human body other than the retina to be treated, in particular the type and intensity of pigmentation of the iris of the eye or the skin or the hair are used to determine the initial values ​​of the irradiation parameters.

[0024] By using OCT measurements (Optical Coherence Tomography), the thickness of the retina can be determined depending on location, for example by detecting edema in the retina, which usually absorbs part of the laser radiation itself, so that certain parts of the irradiation beam do not reach the pigmented layer during the actual treatment. OCT thickness maps can therefore be used to determine location-dependent correction variables for irradiation parameters in the entire area or in parts of the retina.

[0025] In a further embodiment of the method, provision can also be made for one or more predetermined or specifiable reference images or reference recordings to be used, in addition to the captured recordings or camera images, for determining the initial values ​​of the illumination parameters.

[0026] For example, a reference recording or a reference image may represent a target state of the retina, which may be compared with the captured image / camera image in order to perform a difference value analysis and determine the necessary irradiation intensity or the necessary irradiation parameters or their initial values ​​based on the difference between the captured image and the reference image. The irradiation parameters determining the treatment intensity or the irradiation intensity may typically include the intensity of the laser beam, i.e. its energy, as well as its cross-sectional area in the impact area / target area or the size of the laser beam spot as well as the duration and number of emitted laser pulses and the pauses between the laser pulses. Finally, the reference recording may also be obtained, for example, from a database or from a previously recorded recording / camera image of the same patient.

[0027] In a further embodiment of the above method, it can also be provided that, in order to determine the illumination parameters or at least the initial values ​​of the illumination parameters of one or more target areas of the retina to be irradiated, at least two measurements are performed under different lighting conditions to determine independently of each other, on the one hand, the pigmentation intensity of the target area and, on the other hand, the expected absorption rate of the illumination light beam in the eye lens on the way to the target area, in particular at least one of the following parameters is changed in two or more measurements: the size of the focused light spot on the retina, wherein the deviation of the expected light intensity distribution over the area of ​​the focused light spot is measured in each case, the direction of incidence of the illumination light beam of the illumination device through the pupil and vitreous body for irradiating the respective target area, the direction of incidence and / or exit direction of the detected reflected illumination light beam of the illumination device to the target area, and the wavelength range or wavelength distribution of the illumination light beam of the illumination device.

[0028] This method makes it possible to determine the distribution of pigmentation intensity on the retina on the one hand and the absorption of the laser beam by the vitreous body on the other hand as a function of the laser target point on the retina and the light path, independently of one another. For such a measurement, for example, the light path when illuminating the target area of ​​the retina can be changed for various consecutive individual measurements, but the same target area can be illuminated and recorded in each case. On the other hand, while the light path remains unchanged, the illumination device can also illuminate the target area of ​​the retina in different ways in several measurements, so that the influence of the reflectivity of the retina can be changed by the illumination with light of different spectra or different wavelength ranges.

[0029] Alternatively or additionally, it can also be provided that, in order to determine the illumination parameters of one or more target areas of the retina to be irradiated, the pigmentation intensity of the target area and / or the expected absorption rate of the illumination light beam in the eye lens on the way to the target area is determined by performing at least two measurements, one measurement of the absorption and / or reflection properties of the area of ​​the papilla and / or at least one blood vessel or part of a blood vessel of the retina, another measurement of the absorption and / or reflection properties of the area of ​​the papilla and / or at least one blood vessel or part of a blood vessel of the retina, and the third measurement of the absorption and / or reflection properties of one of the other areas of the retina to be irradiated.

[0030] The method may further provide that, in order to determine the illumination parameters of one or more target areas of the retina to be illuminated, at least two locations of the retina are illuminated successively or simultaneously with different illumination characteristics, in particular different illumination intensities, and the intensity of the reflected signal is recorded in each case, wherein, for the locations measured in this way, in each case a functional relationship between the illumination characteristics, in particular the illuminance, and the intensity of the reflected signal is determined, and by comparing the functional relationship at the measurement locations, in particular the slope of the function curve, the slope of the function curve is determined; the intensity of the reflected signal is determined, in particular the slope of the function curve in the case of a linear relationship, and by comparing the functional relationship at the measurement locations, in particular the slope of the function curve, the reflectivity ratio at the measurement locations is determined, wherein in particular one of the locations is located on the surface of a papilla or a blood vessel or at least partially includes the latter.

[0031] The optic nerve head (papillary) is usually devoid of pigment and reflects light much more strongly than the pigmented parts of the retina. Furthermore, the reflectivity of the papillary region depends only slightly on the properties of the individual patient's retina. Therefore, the papilla can serve as a "reflectance standard" or reference against which the intensity of pigmentation is measured in comparison.

[0032] The veins of the retina can also be detected and used to make comparative measurements in the retinal areas defined by them. The blood flowing through has different absorption properties than melanin.

[0033] The absorption also depends on whether the blood is saturated with oxygen or not, i.e. which type of blood vessel is used. In order to be able to measure and evaluate these absorption and reflection properties in blood vessels in a differentiated manner, it is useful to carry out reflectance or absorbance measurements at illumination light wavelengths that are particularly strongly affected by oxygen-saturated light or deoxygenated blood. As an alternative to the corresponding selection of illumination light, it is also possible to select correspondingly meaningful wavelengths at the detection end.

[0034] It has been found that a functional relationship between the lighting characteristics, in particular the illuminance on the one hand, and the intensity of the reflected radiation at a location on the retina on the other hand, allows a good determination of a value representing the reflectivity of the retina at said location. If a linear relationship exists between the illuminance and the intensity of the reflected radiation, a linear regression method can be used, for example, to determine the gradient of a straight line forming a graph of a plurality of measurement functions in order to compensate for measurement errors. The slope of the straight line can then be assigned to the various measurement locations on the retina, thereby forming a relative measurement of the reflectivity. The reflectivity value assigned to the measurement location can then be calibrated by comparison with a corresponding correlation (in particular the gradient of the straight line) at locations where the reflectivity is known or can be well estimated. The reflectivity at a location on the retina can then be used to determine the absorption intensity of the irradiation beam.

[0035] The wavelength of the radiation illuminating the various measurement locations can also be used as a variable illumination property, so that two locations are then illuminated in succession with radiation of different wavelengths, the intensity of the reflected radiation is measured in each case, and the functional relationship of the two locations is determined and compared.

[0036] The differentiation of reflectance at different wavelengths can be achieved by continuous illumination at different wavelengths with simultaneous broadband detection (or detection by wavelength window adaptation) or by broadband illumination covering a continuous spectrum or by illumination with a laser array containing multiple individual wavelengths. In the latter case of broadband excitation / illumination, wavelength-selective detection of the reflected radiation is then provided, for example by defining color channels, using wavelength-selective filters or using a spectrometer or multispectral camera.

[0037] Since the reflectivity of the papillary region varies only slightly, the properties determined in the first step and the deviations of the reflectivity values ​​determined therefrom from the reference values ​​can be attributed to the effects of absorption and / or scattering of radiation on the measurement path through the individual patient's eye.

[0038] Thus, the deviation of the measured reflectivity at a reference location, such as a papilla or a blood vessel, from a reference value can be used to determine attenuation due to absorption and / or scattering within the eye.

[0039] By taking multiple measurements at different locations of the retina, the influence of pigmentation on the captured recording or captured camera image on the one hand and the influence of vitreous absorption on the other hand can be determined independently of one another in the evaluation and taken into account when determining the illumination parameters. It should also be noted that the direction of incidence and the direction of exit of the illumination beam also refer to the optical path of the laser beam through the vitreous.

[0040] The type of link between the illumination parameters and the detection variables / signals of the corresponding captured recording or corresponding captured camera image on the one hand, and the illumination parameters of the laser operation on the other hand, can take many forms. In the simplest case, this can be a mapping table, which can exist as a multidimensional matrix and can be stored, for example, in a computer or a non-local or distributed data processing system. The link can also be in the form of an algorithm or a neural network, which can be trained, for example, using self-learning or guided learning methods.

[0041] In this context, the present invention may also relate to a method for training an algorithm or a neural network to determine initial values ​​for irradiation parameters according to the method described above, wherein, for a plurality of individualized treatments, a data set of target areas to be irradiated determined from images and the associated illumination parameters and in particular secondary information additionally acquired in each case as input information and, on the other hand, said irradiation parameters set as outcome variables during the respective subsequent laser treatments are linked together as training data.

[0042] For example, the training data may initially be obtained by a parallel operation of conventional methods and the method described herein, wherein, as described above, under defined lighting conditions, recordings or camera images are captured and the necessary treatment intensity, i.e. the intensity of the treatment laser beam, e.g. represented by laser power, pulse duration, number of pulses and repetition rate, is determined in a conventional manner using a titration method. This can then be linked to previously recorded recordings / camera images of the target area of ​​the retina to be treated, so that the learning system is trained using these data.

[0043] Individualized treatment for training the algorithm can also be performed according to the method of the invention described above, wherein initial values ​​for the irradiation parameters are first determined, then the treatment is started, and the success of the treatment is evaluated by checking the discoloration of the target area, and the irradiation parameters are corrected if necessary. The algorithm can be further trained for improvement by entering correction values ​​or linking correction values ​​to the illumination parameters and the initially determined initial values ​​for the irradiation parameters.

[0044] Additional secondary information can be input as variables which prove to be influential in determining the irradiation parameters. Such secondary information can be, for example, certain parameters of the patient's age and health status as well as specific parameters of the patient's retina to be treated. For example, the measured overall pigmentation intensity of the skin or the iris of the eye or the measured pigmentation intensity of the patient's hair, eyebrows or skin as well as the color of the skin pigmentation, the color of the iris and the color of the hair can be taken into account.

[0045] When determining the initial values ​​of the irradiation parameters for all target areas, for example, one or more of the following calibration parameters of the person to be treated can also be used for calibration: measured overall skin pigmentation intensity, measured overall eye iris pigmentation intensity, measured hair (hair, eyebrows) pigmentation intensity, skin pigmentation color, iris color, hair color. Such calibration can also provide, for example, that the listed variables are not included in the algorithm for determining the irradiation parameters, but after determining the irradiation intensity, the result is calibrated using the specified variables, for example by multiplying the irradiation intensity given by the laser energy and the laser pulse length by a specific calibration factor t. Or the result is calibrated using the variables, for example by multiplying the irradiation intensity given by the laser energy and the laser pulse length by a specific calibration factor.

[0046] The present invention may also relate to a method for determining irradiation parameters for the operation of a laser for irradiating one or more target areas of the retina of an eye with an irradiation beam, wherein first, according to the above method, initial values ​​of the irradiation parameters are determined, wherein then at least one target area is irradiated with a titration beam or an irradiation beam having the initial parameters, then at least one continuous record or continuous camera image of the one or more target areas of the retina irradiated with the irradiation beam is acquired, and, using the continuous record and / or continuous camera images and the initial values ​​of the irradiation parameters, at least continuous values ​​of the irradiation parameters for irradiating the one or more target areas of the retina are determined.

[0047] In this way, the initial values ​​of the irradiation parameters initially determined can be checked as soon as possible after application for their success and adjusted if necessary, or continuous irradiation parameters can be determined based on these values. The corresponding correction can also be used, for example, to provide the algorithm with further training data and thus improve it.

[0048] Finally, in addition to the method described above, the present invention also relates to a device for irradiating one or more target areas of the retina of an eye with an illumination beam, having a laser for generating said illumination beam, illumination means for illuminating at least one or more target areas of said retina with defined illumination parameters, optical recording means, in particular a camera, for capturing at least one record or image of at least one target area of ​​said retina, and processing means configured to determine at least initial values ​​of illumination parameters using said illumination parameters and said optical record or camera image in order to irradiate one or more target areas of said retina with the illumination beam.

[0049] The device can be used to carry out various embodiments of the method described above. The processing device can be designed as a data processing device, which comprises an algorithm that assigns initial values ​​of the illumination parameters to the lighting parameters and to the variables recorded with the recording or camera image. The algorithm can be fixed or can be trained with training data as part of a learning system with artificial intelligence as described above. For example, the processing device can also include a neural network that can learn by forming its links in the manner described by the training process.

[0050] For example, the above-mentioned device can be completely independent of the treatment device with the treatment laser or can also be connected to the treatment device or integrated into the treatment device. For example, the device according to the invention can also be partially centralized, wherein the processing device can be arranged non-locally in a server or another type of remote data processing system and receive the determined data via a suitable communication method. In this way, the processing device can receive measurement data from many different locations and be trained, and the local treatment device can be remotely controlled. In this way, it can be ensured that the processing device is optimally trained using actual data from one or more patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The invention will be shown below in the form of an embodiment with the aid of the drawings and will be explained below.

[0052] In the figure:

[0053] Figure 1 shows an ophthalmoscope with a device for illuminating the retina of an eye,

[0054] Figure 2 A flow chart showing a method for determining initial values ​​of irradiation parameters,

[0055] Figure 3 An image showing the target area of ​​the retina,

[0056] Figure 4 A magnified view showing the path of light through the vitreous body of the eye to the retina,

[0057] Figure 5 shows an example of illumination parameters, recorded measured values ​​representing a target area of ​​the retina and assigned initial values ​​for the illumination parameters,

[0058] Figure 6 A second flow chart of the method is shown, in which initial values ​​of the irradiation parameters are first determined and then checked,

[0059] Figure 7 A third flow chart is shown which illustrates a method of training an algorithm which is perfected in a self-learning process and assigns initial values ​​of the illumination parameters to the lighting parameters and other correction variables,

[0060] Figure 8 schematically showing the links between input and output variables for training the algorithm, and

[0061] Fig. 9 , 10 , 11 show the functional relationship between the illumination of the papilla / optic nerve and other retinal areas and the intensity of reflected radiation under three different conditions. DETAILED DESCRIPTION

[0062] Figure 1 A device according to the invention or a device for carrying out the method according to the invention is shown in the form of an ophthalmoscope or a device which combines the functionality of an ophthalmoscope with the functionality of a retinal laser therapy.

[0063] The device has an illumination device 5 with a radiation source 5', which is configured to direct an illumination beam 14 onto the patient's eye 4 and the retina 16. This allows the retina 16 to be properly illuminated to capture a recording or camera image. For example, the illumination can be equipped with a light emitting diode or an infrared diode as a light source, or with another type of light source providing a defined wavelength spectrum. For example, the light source can also be an ultraviolet UV light source.

[0064] The ophthalmoscope also has a camera 6 with a sensor referenced 7. For example, the sensor may be a CCD or CMOS sensor. Instead of the camera 6, any other type of device may be provided, such as a scanning device, for detecting radiation reflected or scattered by the retina.

[0065] The purpose of operating the illumination device 5 and camera 6 or equivalent is to obtain the most accurate, spatially resolved measurement data from the retina 16 under defined illumination conditions by recording images of the reflected radiation, thereby recording or determining the properties of the target area to be treated.

[0066] The illumination beam 14 and the reflected radiation 15 are appropriately collimated or focused in a manner known per se by a suitable optical system 13 with mirrors and lenses. The optical system 13 also has a beam splitter 12, which enables the laser beam from the treatment laser 2 to be directed onto the retina 16. Alternatively, the laser beam can also be coupled without a beam splitter, for example by directing it to the side slightly offset with respect to the illumination light. A control unit 8 can be provided to control the laser 2, which on the one hand controls the illumination device 5, for example by triggering it, and on the other hand captures a camera image from a camera 6 and controls the laser 2 directly. The control unit 8 can also control a deflection mirror 3, which directs the beam path of the illumination beam 11, so that individual target areas on the retina 16 can be treated.

[0067] For better control of the laser 2 , according to the invention, processing means 19 are provided which allow accurate processing of the recordings / camera images coming from the camera 6 and associating them with known and defined parameters of the illumination of the retina 16 .

[0068] For example, the ophthalmoscope also has a sensor 100, for example in the form of a camera, which is able to measure the pigmentation color and pigmentation intensity of the patient's skin, hair and / or iris.

[0069] Input means may also be provided, by which such parameters may be entered. In any case, these parameters are transmitted to the processing means 19 and taken into account when determining initial values ​​for the irradiation parameters.

[0070] In the past, the intensity of laser treatment, i.e. the intensity and / or duration of the laser pulses operating the laser 2, was set by the operator based on his own assessment after evaluating the retinal recordings. First, a titration pulse was directed onto the retina and its effect was assessed to adjust the laser intensity.

[0071] By illuminating the retina with known illumination parameters and linking them to the recording of the retina, the intensity of the laser treatment can be assigned to these partially specified, partially measured values ​​for each target area on the retina in an objective manner by the processing device 19 for the laser treatment of each target area on the retina, wherein the intensity is given by the energy of the laser, the size of the laser spot on the retina, the number, repetition rate and duration of single or multiple pulses and the length of the pauses between the pulses. With the method according to the invention, at least initial values ​​for such an irradiation by the irradiation beam 11 can be determined, with which initial values ​​the treatment of the retina can be carried out.

[0072] Figure 2 A flow chart of a method according to the invention is shown, wherein in a first step 20 the lighting parameters of the lighting device 5 are specified. However, the lighting parameters may also already exist and be specified in the lighting device. Alternatively, for example, the individual lighting parameters may be specified by the processing device 19 and sent to the lighting device 5. It is also possible to measure lighting parameters, such as illuminance, lighting intensity distribution and spectral / wavelength distribution, which measurements may then be used in the evaluation.

[0073] In a second step 21, the illumination device 5 or the light source 5' is switched on and the retina is illuminated continuously or in pulses. At the same time, the reflected radiation can be recorded by the camera 6 in a subsequent step 22. Step 22 can be performed simultaneously with the illumination 21 or also with a delay relative to the illumination, for example if fluorescence radiation is recorded which is known to be emitted after the excitation radiation.

[0074] In step 23, the illumination parameters and the measured values ​​recorded by the camera are then linked together in the processing device 19 by means of an assignment function (e.g. an assignment algorithm) and, by means of the linking, the initial values ​​of the illumination parameters to be converted into illumination by the operation of the laser 2 are determined from these variables. Only after the initial values ​​have been determined can the treatment 24 be started, which represents a further step. In the figure, the step 24 of the actual treatment is separated from the determination of the initial values ​​of the illumination parameters by a dashed line 25.

[0075] Figure 3A schematic diagram of the retina 16 of an eye with different target areas is shown. A target area 28 at the edge of the retina is shown, which is not as important for the actual visual performance of the eye as the target areas 25, 26, 27 in the center of the retina 16. The different shading of the various target areas is intended to represent different pigmentation intensities or other varying parameters of the various target areas. This should clearly indicate that different target areas for treatment with the laser 2 require different irradiation parameters. The size of the target areas 25, 26, 27, 28 can vary and can also be as small as the laser 2 allows for spatially resolved treatment. Figure 3 and Figure 4 The papilla is also shown and labeled 40. The papillary region remains untreated and can serve as a reflectance reference compared to the melanin bearing areas of the retina.

[0076] Figure 4 A cross section of the vitreous body of an eye 4 with an eye lens 29 and a retina 16 is shown. A point or target area 32 is marked on the retina, which can also be specifically illuminated with two different illumination beams 30, 31. Depending on the position at which the illumination beams 30, 31 enter the eye lens, the beams take different paths through the lens and vitreous body when reaching the point 32. If the measured values ​​of the reflected light recorded by the camera 6 are compared in terms of intensity, the scattering or attenuation of the light on the various paths through the vitreous body can be recorded in different ways. By varying the illumination beams, the entire vitreous body of the eye 4 can be measured gradually, so that the influence of the vitreous body on the illumination and irradiation beams on the retina by attenuation and scattering can be determined for all areas of the eye.

[0077] Alternatively, it is also possible to allow two different illumination beams 30 to reach a point 32 on the retina 16 via the same optical path, but to vary the wavelength of the illumination light, for example, so that the same optical path through the vitreous body can be used for both beams, but, for example, in one case the wavelength selected corresponds to the optimal absorption wavelength of melanin on the retina, while in the other case the wavelength selected is different from this. If the wavelength-dependent attenuation of the vitreous body is neglected in the first step, this allows the pigmentation of melanin on the retina to be measured in a first approximation independently of the inhomogeneities of the vitreous body of the eye. Alternatively, the illumination beam can also have a broad spectrum or contain multiple wavelength ranges simultaneously. In this case, the sensor can distinguish between broad wavelength ranges, even beyond the optically visible range, by wavelength-selective evaluation. For example, a hyperspectral sensor can be used for this purpose. Bayer filters can also be used to image the retina.

[0078] The combined measurement of both the optical path and the wavelength changes can then also be used to determine the wavelength-dependent attenuation value of the vitreous body as a function of position. In this way, once the parameters of the light source 5' are known, the attenuation of the incident light or incident radiation on the retina and the influence of the optical path in the backscattered radiation can be taken into account, so that the pigmentation intensity of melanin on the retina can be objectively determined, for example.

[0079] Figure 5 The linked structure of the lighting parameters, the measured values ​​of the recorded / camera image and the initial values ​​of the illumination parameters is schematically shown. The lighting parameters 33 are designated as x1 to x n , for example, where the individual parameters represent in each case the illumination level for a specific target area, i.e. the radiant energy or power emitted by the illumination source, or the power distribution of the emitted radiation in individual wavelength ranges, i.e. the shape of the wavelength spectrum with corresponding intensities. 35 refers to mapping functions or link functions, which can be designed, for example, as a self-learning algorithm.

[0080] 34 refers to the parameters y1 to y2 of the measurement values ​​captured by the camera 6 for a specific target area. m If the parameters of these measurements are associated with the illumination parameters, this results in an n-tuple of initial values ​​of the illumination parameters 36, which are designated z1 to z o , and for example specifying the focal size of the laser on the retina, the radiation intensity of the laser, the pulse duration and / or the number of pulses emitted to one or more target areas.

[0081] One object of the present invention is to determine the optimal initial values ​​of the irradiation parameters for each target area. This result is initially achieved by determining initial values, such as Figure 5 25 in FIG. 1 . The actual laser operation of the laser 2 can then take place, thereby treating the retina, and the effect of the laser treatment on the retina can then be performed by repeating the process, i.e. illuminating the retina with defined parameters and determining a camera image or recording. The results of the re-recorded camera image can be compared with the initially recorded camera image and differences can be determined, which show the effect of the treatment by the laser 2. If the effect of the laser during the treatment does not correspond to the treatment goal to be achieved, the algorithm 35 can be corrected or trained and a new set of illumination parameters can be determined based on the illumination parameters during the second illumination and the measurement data recorded with the second camera image.

[0082] Figure 6 First, it is shown that Figure 2The sequence of process steps 20 to 24 shown is followed by a further step 21' of illuminating the retina with defined illumination parameters and simultaneously or offset recording of a camera image in a step 22', followed by a further step 23' of combining the illumination parameters and the measurement data recorded with the camera image to form new illumination parameters.

[0083] Figure 7 Shows repeated Figure 6 Flowchart of a flowchart structure in which, after a first laser effect 24, a further laser treatment 24' is carried out after a relinking 23' taking into account the illumination parameters and the camera measurement data. Furthermore, the illumination parameter information determined during the correction process in step 23' is used in a loop to improve the linking algorithm performed in process steps 23 and 23'. Feedback from the correction variables can be used to continuously improve the linking algorithm, wherein the linking between the illumination parameters, the camera measurement data and the initial values ​​of the illumination parameters is based on said linking algorithm. For this purpose, treatments for the same person or a group of people, for example people with similar clinical presentations, can be taken into account to improve the algorithm. For this purpose, the algorithm can also be stored centrally, for example in a server or in the cloud, and retrieved for individual treatments, and then the correction variables are fed back to the server or the cloud, so that the algorithm can be trained using as much training data as possible from different treatment processes at different locations.

[0084] Figure 7 It is also shown that in a further processing step 37, additional parameters are measured for the individual patient or his eye or retina, which are input into the linking step 23 for calibration. To this end, in step 37, for example, integrated quantities of the retina, such as the average pigmentation or the intensity of the coloration of the iris of the eye or the color of the iris or the intensity of the skin pigmentation of an individual or the color of the skin pigmentation and / or the color and intensity of the pigmentation of the hair of an individual, can be measured with a sensor, in particular a camera, and input into the linking step 23. The influence of these variables can also be taken into account when training the allocation algorithm or can be input as calibration parameters for the individual treatment.

[0085] Figure 8 The schematic diagram shows the correction of the illumination parameters 36' by comparing them with the original illumination parameters x1 to x n and the measurement data y1 to y determined from the camera image m Prior to a separate training step, initial values ​​36 of the illumination parameters are assigned to the above input parameters, and the algorithm receives a data set with illumination parameters z1 'to z1 '. o 'Corresponding correction data 36', which are interpreted as optimized result data and improve the algorithm.

[0086] The method optimizes the linking algorithm after the desired number of training runs and thus also the initial values ​​of the illumination parameters in a first step.

[0087] Fig. 9 , 10 Figures 1 and 11 show the functional relationship between illumination and reflected radiation intensity for three different cases, each targeting the papilla / optic nerve and other locations on the retina. The figure representing the papilla is marked 50 in each case, and the figure representing the location in the target area for treatment is marked 51 in each case.

[0088] In principle, the method for determining the absorption intensity involves illuminating a specific location in the papillary region or on a blood vessel or on the retina, which is different from the target area, with several different illumination intensities and simultaneously measuring the intensity of the reflected radiation, which allows direct conclusions to be drawn about the intensity of the retinal pigmentation. The functional relationship between illumination intensity and reflected radiation intensity is linear and therefore approximates a straight line. At least, if Fig. 9 , 10 As shown in Figures 1 and 11, a straight line can be drawn through the measured points using linear regression. The same procedure is performed for one or more locations in the target area of ​​the retina to be treated later by radiation. The gradient of the determined straight line represents the reflectivity at the respective location. Since the reflectivity at the vascular area and the papilla can be well estimated and is largely unaffected by other conditions of the individual retina, the determined values ​​can be used to calibrate the measured values ​​of the reflectivity values ​​at other locations. Therefore, the measured values ​​of the intensity of the radiation reflected from the papilla or vascular area can also be used to estimate the scattering and absorption losses of the radiation on the way to the corresponding location (the papilla or blood vessel or other location where the reflectivity is known) and on the way back to the sensor after reflection, where using the sensor, the intensity of the reflected radiation can be determined. Then, since the scattering and absorption values ​​characterize the light path through the vitreous body of the eye, these scattering and absorption values ​​can also be assumed to be used to irradiate other areas of the retina.

[0089] Specifically, Fig. 9 An example of the reflectance and absorption intensity of the macular area corresponding to the standard case is shown.

[0090] Fig.10 Shown is a case where the gradient of the line representing the macula is lower, and therefore the reflectance measured relative to the gradient of the second line representing the papilla is lower, and therefore the absorption and pigmentation intensity are higher compared to the normal case.

[0091] Fig.11 Shown in Fig. 9 and Fig.10In the case shown in FIG. 5 , the slope of the line representing the macula is greater than the slope of the line representing the papilla. Therefore, the measurement results represent a situation where the macula has a higher reflectivity and a correspondingly lower absorption intensity and pigmentation. Since the slope of the line 50 representing the papilla measurement is significantly lower than that of the macula, the measurement results are shown in FIG. Fig. 9 and Fig.10 The slope of the curve in Fig. 9 and Fig.10 If the situation is the same, then Fig.11 In the case shown, the absorption and / or scattering of the eye is significantly stronger. The attenuation coefficient can be calculated from Fig. 9 , Fig.10 and Fig.11 The attenuation coefficient is calculated from the difference in the slope of the straight line marked 50 in Fig.11 The scattering and absorption of the eye are measured and can be taken into account in the irradiation during treatment.

Claims

1. A method for determining illumination parameters for operation of a laser (2) for illuminating one or more target areas of a retina (16) of an eye (4) with an illumination beam (11), wherein: The retina is fully or partially illuminated by an illumination device (5, 5') under defined illumination parameters and during and / or shortly after the illumination at least one optical recording, in particular at least one camera image, of at least one target area of ​​the retina is captured, and wherein at least initial values ​​of the illumination parameters are determined using the recording or the camera image in order to illuminate one or more target areas of the retina.

2. The method according to claim 1, characterized in that: The intensity of the pigmentation of one or more target areas of the retina and / or the intensity distribution of the pigmentation on the retina is determined from the recording or the camera image in order to determine initial values ​​for the illumination parameters.

3. The method according to claim 1 or 2, characterized in that: In order to determine initial values ​​for the irradiation parameters of one or more target areas of the retina, correction values ​​are determined depending on the expected absorption and / or scattering of the treatment light beam in the vitreous body of the eye on the way to the target area to be irradiated, said correction values ​​being determined in particular depending on the optical quality of the optical recording, further in particular depending on the image sharpness or image contrast.

4. The method according to claim 1, 2 or 3, characterized in that: In order to generate a camera image, the retina is illuminated by radiation with a known wavelength distribution, the radiation in particular comprising infrared radiation and / or light in a wavelength range absorbed by melanin, wherein, within a defined wavelength range, the luminous intensity of the lighting device and / or the total power of the light incident on a unit area of ​​the retina and / or the power of the light incident on a unit area of ​​the retina are additionally determined, and wherein brightness values ​​and / or colors of the camera image are used to determine initial values ​​for illumination parameters of the retina.

5. The method according to claim 1, 2, 3 or 4, characterized in that: The thickness of the retina is determined for one or more target areas and taken into account when determining the initial values ​​of the irradiation parameters, wherein the thickness of the retina is in particular determined by creating an OCT thickness map of the retina, and / or is characterized in that the type and intensity of pigmentation in different areas of the human body other than the retina to be treated are used to determine the initial values ​​of the irradiation parameters, in particular, the type and intensity of pigmentation of the iris of the eye or the skin or the hair are used to determine the initial values ​​of the irradiation parameters.

6. The method according to any one of claims 1 to 5, characterized in that In addition to the captured image or camera image, one or more predetermined or specifiable reference records or reference images are used to determine initial values ​​for the illumination parameters.

7. The method according to any one of claims 1 to 6, characterized in that In order to determine the illumination parameters of one or more target areas of the retina to be irradiated, the pigmentation intensity of the target area on the one hand and the expected absorption rate of the treatment light beam in the eye lens on the way to the target area on the other hand are determined independently of each other by performing at least two measurements under different lighting conditions, in which in two or more measurements, at least one of the following parameters is especially varied: the size of the focused light spot on the retina, the deviation of the expected light intensity distribution over the area where the focused light spot is measured in each case, the direction of incidence of the illumination light beam of the illumination device through the pupil and vitreous body for irradiating the respective target area, the direction of incidence and / or exit direction of the detected reflected illumination light beam of the illumination device to the target area, and the wavelength range or wavelength distribution of the illumination light beam of the illumination device.

8. The method according to any one of claims 1 to 7, characterized in that In order to determine the irradiation parameters of one or more target areas of the retina to be irradiated, the pigmentation intensity of the target area and / or the expected absorption rate of the treatment light beam in the eye lens on the way to the target area are determined by performing at least two measurements, characterized in that one measurement is for the absorption and / or reflection characteristics of the area of ​​the papilla and / or at least one blood vessel or part of a blood vessel of the retina, and the second measurement is for the absorption and / or reflection characteristics of one of the other areas of the retina to be irradiated.

9. The method according to any one of claims 1 to 8, characterized in that In order to determine the illumination parameters of one or more target areas of the retina to be illuminated, at least two locations of the retina are illuminated successively or simultaneously in each case with different illumination characteristics, in particular different illumination intensities, and in each case the intensity of the reflected signal is recorded, characterized in that for the locations measured in this way, in each case a functional relationship between the illumination characteristics, in particular the illumination, and the intensity of the reflected signal is determined, in particular the slope of the functional curve in the case of a linear relationship, and the reflectivity ratio at the measurement locations is determined by comparing the functional relationship, in particular the slope of the functional curve, at the measurement locations, wherein in particular one of the locations is located on the surface of a papilla or a blood vessel or at least partially comprises the latter.

10. A method for training an algorithm or a neural network to determine initial values ​​of irradiation parameters according to any one of claims 1 to 9, characterized in that For a plurality of individualized treatments, data sets of target areas to be irradiated determined from the images and the associated illumination parameters and in particular secondary information additionally acquired in each case as input information and, on the other hand, said illumination parameters set as outcome variables during the respective subsequent laser treatment, are linked together as training data.

11. The method according to any one of claims 1 to 10, characterized in that When determining the starting parameters for all target areas, calibration is performed in each case using one or more of the following calibration parameters of the person to be treated: measured overall skin pigmentation intensity, measured overall eye iris pigmentation intensity, measured hair pigmentation intensity, skin pigmentation color, iris color, hair color.

12. A method for determining irradiation parameters for the operation of a laser for irradiating one or more target areas of the retina of an eye with a treatment beam, wherein initial values ​​of the irradiation parameters are initially determined according to the method of any one of claims 1 to 11, wherein at least one target area is then irradiated with a titration beam or a treatment beam having the initial parameters, wherein at least one continuous recording or continuous camera images of the target area of ​​the retina irradiated with the treatment beam are then acquired, and wherein using the continuous recording or the continuous camera images and the initial values ​​of the irradiation parameters, at least continuous values ​​of the irradiation parameters for irradiating one or more target areas of the retina are determined.

13. A device for irradiating one or more target areas of the retina of an eye with a therapeutic light beam, comprising a laser for generating the therapeutic light beam, an illumination device for illuminating at least one or more target areas of the retina with defined illumination parameters, an optical recording device, in particular a camera, for capturing at least one optical record or image of at least one target area of ​​the retina, and a processing device configured to determine at least initial values ​​of illumination parameters using the illumination parameters and the record or camera image in order to irradiate the one or more target areas of the retina with the therapeutic light beam.

Images