METHOD AND DEVICE FOR DETERMINING THE OPERATING STATE OF A LIGHT IMPLANT

Description

Technical field of the invention

[0001] The present invention relates to a method for determining the operating state of a light implant. The invention also relates to a device for diagnosing the operation of the light implant. State of the art

[0002] Recently, it has been proposed to slow the progression of a pathology by using light (any electromagnetic radiation ranging from ultraviolet to far infrared through visible light). This principle is notably used in the form of an intracranial cerebral implant, comprising a light source responsible for illuminating an area of ​​the brain in order to treat the pathology. The implant can notably be in the form of an optical fiber at the end of which the light is diffused.

[0003] Patent applications US 2014 / 288386 A1, US 2021 / 178175 A1, EP3302687A1, EP3723851A1 and EP3834884A1 describe such intracranial probes.

[0004] However, once these probes are implanted, it is difficult to know whether the light is properly diffused at the tip of the probe. Indeed, the light source may be defective, the optical fiber may be broken or poorly implanted. As a result, the operating status of the implant is sometimes difficult to determine without having to remove it for disassembly and inspection.

[0005] There is therefore a need for a simple solution for determining the operating status of an intracranial light implant as described in prior art documents.

[0006] The aim of the invention is to propose a technical solution enabling this objective to be achieved. Statement of the invention

[0007] This aim is achieved by a method for determining the operating state of a light implant implanted in the brain of a living being, said light implant comprising a light source responsible for emitting light into the brain of the living being, said method using a diagnostic device which comprises a receiver of a light signal transmitted through a first eye of the living being and means for determining the operating state of the light implant from the received transmitted light signal,

[0008] Said method comprising: A step of positioning the receiver of the diagnostic device opposite the first eye of the living being, A step of measuring a light signal received by the receiver when the light implant is activated, A step of comparison between the data representative of the light signal received by the receiver and at least one reference data, A step of determining the operating state of the light implant between a functional state and a non-functional state taking into account the result of the comparison step.

[0009] According to a particular feature, said reference data is pre-stored or acquired during a calibration step of the diagnostic device.

[0010] According to another feature, the calibration step consists of a step of measuring a reference light signal, carried out when the light implant is deactivated.

[0011] According to another particularity, the step of determining the operating state of the light implant consists of determining at least one difference between said reference data and one of said data representative of the light signal received and comparing said difference with a predetermined threshold value.

[0012] According to another feature, the method comprises a step of positioning a point light source opposite a second eye of the living being and a step of activating said point light source.

[0013] The invention also relates to a diagnostic device used to implement the method as defined above, the device comprising a mechanical support on which said receiver is fixed and means for determining the operating state of said light implant, connected to said receiver and configured to process data from said receiver.

[0014] According to a particular embodiment, the receiver is a camera.

[0015] According to another particular embodiment, the receiver comprises one or more photodiodes.

[0016] According to a particular feature, the device comprises a point light source fixed to said support and intended to be arranged opposite a second eye of the living being, in parallel with the receiver.

[0017] According to a particular embodiment, the mechanical support comprises an optical plate provided with a chin rest and on which said receiver is fixed.

[0018] According to another particular embodiment, the mechanical support includes a mask to be placed around the head of the living being.

[0019] According to a particular feature, the mask comprises two glasses, a first glass receiving said receiver and a second glass receiving a point light source. Brief description of the figures

[0020] Other features and advantages will appear in the detailed description which follows, given with reference to the attached drawings in which: There Figure 1 illustrates the operating principle of a light implant used in the context of the invention and that of the diagnostic device of the invention; The Figure 2 represents a first example of embodiment of the diagnostic device according to the invention; The Figure 3 represents a second example of embodiment of the diagnostic device according to the invention; Detailed description of at least one embodiment

[0021] In reference to the Figure 1, the invention relates to a device 3 for diagnosing the functioning of a light implant 1 intended to be implanted in the brain 2 of a living being. When it functions correctly, this light implant 1 is intended to emit light to at least one area of ​​the brain 2 of the living being. By light or light signal, we mean any electromagnetic radiation which goes from ultraviolet to far infrared via the visible.

[0022] The implant 1 uses at least one light source 10 and comprises a probe 11 through which the light is diffused. The probe 11 may be in the form of an optical fiber responsible for conveying the light from the light source 10 to its distal end, located close to the tissues to be treated. The principle of production of the implant may be varied. Patent applications EP3302687A1, EP3723851A1 and EP3834884A1 describe such intracranial probes. The term implant means that the device comprises at least one part implanted in the brain of the living being, even if it may possibly comprise parts located outside the body of the living being.

[0023] According to a particular aspect of the invention, the diagnostic device 3 comprises: Possibly a mechanical support; A receiver 31 of a light signal transmitted through the eye of the living being, fixed to said mechanical support; Means 32 for determining the operating state of the light implant;

[0024] The objective of the diagnostic device 3 is to determine the operating state of the light implant 1 placed inside the skull of the living being by detecting the presence or absence of a light signal S transmitted through the eye 20 of the living being. The diagnostic device 3 has the particularity of being non-invasive, that is to say that it is placed outside the body of the living being.

[0025] The receiver 31 is configured to collect the photons emitted by the light implant 1 and which are scattered by the tissues and exit via the eyeball.

[0026] Different receiver implementation variants can be considered: A detector using one or more photodiodes, A very sensitive camera.

[0027] In all cases, the receiver 31 must be able to measure very low optical powers (between femtoWatt and nanoWatt) and with sufficiently short integration times (of the order of a minute or less) so that the examination is compatible with a measurement on a living being.

[0028] In a non-limiting manner, the receiver 31 may in particular be a commercial multi-pixel photon counting detector, based on avalanche photodiodes in Geiger mode, or a large diameter silicon photodiode allowing a strong solid angle of detection. This type of detector does not provide an image, but a point value; however, their sensitivity can be much higher than that of a camera, and they are more compact and faster. It is possible to add a lens with a large numerical aperture in front of the detector, to collect the most photons. This lens then plays the role of a condenser.

[0029] According to a particular aspect of the invention, the observation must be carried out with a minimum of stray light. In other words, the observation is advantageously carried out in conditions of total darkness to avoid any light pollution due to the environment. By way of example and in a non-limiting manner, the ambient light level must be at least one order of magnitude lower than that of the light signal transmitted through the eye.

[0030] According to a particular aspect of the invention, the means 32 for determining the operating state of the light implant may comprise a microprocessor to which the receiver 31 is connected. They are responsible for interpreting the data representative of the signals received by the receiver. Different processing modes may be envisaged for determining the operating state of the light implant: First processing mode: This may involve recovering a first reference light signal, with the light implant deactivated, and storing one or more reference data representative of this first light signal; This measurement is advantageously carried out in total darkness; Then, after activation of the implant, a second light signal is measured at the receiver 31; One or more of the data representative of the second light signal is compared with one or more of the corresponding reference data; Second processing mode: One or more reference data are pre-stored in the factory and correspond to a reference state in which the system is placed in total darkness; The rest of the processing is identical to that described above;

[0031] By data representative of a light signal, we mean a maximum light intensity, for example taken at the level of one or more pixels of the captured image (by the camera), an average of several measured light intensities... Any other data could be considered.

[0032] If the compared data are identical, the means 32 for determining the operating state of a light implant 1 can conclude that the light implant 1 is defective. If one or more of the data from the second signal received differ from those representative of the first signal, the determination means 32 can conclude that the light implant 1 is functional. It is possible to set a threshold above which the means 32 for determining the operating state of the implant determine that one or more of the data from the second signal differ sufficiently from those representative of the first signal.

[0033] Without limitation, a simple processing mode is as follows: A first image, with the intracerebral light implant 1 switched off, allows the dark conditions to be checked: the signal or the measured image only corresponds to the noise of the detector or the camera; Then, a second image, with the light implant 1 activated, allows, if the light implant 1 is perfectly functional, to highlight the contribution to the signal or the measured image of the photons coming from the intracerebral implant and diffused in the tissues.

[0034] Other operating modes can of course be considered, depending on the means available and implemented.

[0035] In a first embodiment illustrated by the Figure 2, the mechanical support is in the form of an optical plate 30 on which the receiver 31, for example the camera, is fixed opposite one of the two eyes (for example the eye 20) of the living being. The optical plate 30 can be movable on several axes in order to be able to adapt the position of the camera opposite the targeted eye. It can be equipped with a chin rest (not shown) to stabilize the head of the living being opposite the system.

[0036] Advantageously, on this optical plate 30, a point light source 33 will be positioned in front of the other eye 21, to ensure that the living being maintains its gaze immobile: the living being fixes this point of light with one eye 21, and the camera observes the other eye 20.

[0037] In this first embodiment, for example, an intracerebral light implant 1 is used, made in the form of an optical fiber implanted in the brain 2, so that the end of the optical fiber is located between the two black substances, at the level of the midbrain and therefore close to the optic chiasm. The light implant 1 has, for example, a peak power of 15 mW, the light being pulsed with a duty cycle of 8%. Dilation of the pupil is not necessary. The room is completely dark, and the patient is positioned on the chin rest of the support.

[0038] The distance between the fixed light source 33 (to maintain fixed gaze) and the receiver 31 (detector or camera) is adjusted to correspond to the interocular distance of the patient. In a particular example, the camera is a 16-bit, 2750x2200 pixel, binning 2, 4.54µm pixel camera, cooled to -12°C and positioned approximately 5 cm from the eye. The exposure time is set to 20 seconds. All surrounding light sources are blocked, and the intracerebral implant is switched off. As already described above, the operating mode is for example as follows: With light implant 1 deactivated, a first image is acquired which must be "black", that is to say with only the contribution of the internal noise to the camera. Light implant 1 is then switched on and the operation is repeated which highlights a diffuse spot corresponding to the photons coming from the intracerebral light implant 1.

[0039] Advantageously, the light source 33 allowing the gaze to be fixed emits at a certain wavelength (green for example, 550 nm) while the receiver 31 (camera or detector) observing the other eye 20 is only sensitive to the emission wavelength of the light implant 1 (for example by means of a high-pass filter which would only allow wavelengths greater than 600 nm to pass).

[0040] According to an embodiment variant shown in the Figure 3 , the mechanical support comes in the form of a mask 34 to be applied around the head of the living being.

[0041] The mask 34 carries two glasses 340, 341 intended to be placed respectively opposite the two eyes 20, 21 of the living being, one glass carrying the receiver 31 (detector or camera) and one glass carrying the light source 33 used to capture the gaze of the living being. The mask 34 comprises occultation means 342, used to create a channel isolated from any light pollution between the first eye 20 of the living being and the capture zone of the receiver 31 and between the light source 33 and the second eye 21 of the living being.

[0042] This embodiment may have an adapter to allow the light source 33 and the receiver 31 to be interchanged, and thus to be able to observe the right eye or the left eye of the living being. Alternatively, both the transmitter and the sensor may be on the same eye, or even on both eyes. In addition, the distance between the light source and the point detector could be adjusted to adapt to the interocular distance of the patient.

[0043] The operating principle of this second embodiment is identical to that described above for the first embodiment.

[0044] Advantageously, it is possible to perform synchronous detection, in order to increase the signal-to-noise ratio: the pulsed signal from the optical stimulation device (for example detected electrically by induction on the laser power cable, or optically with a photodetector at the level of the skull, or digitally in RF) is then used as an external source to exacerbate the optical signal measured via the eye. The external source can also come from a second optical detector placed on the patient's skull, at the level of the pulsed light source, on the scalp. A detector measures the signal diffused via the scalp, this signal acting as a carrier to increase the signal-to-noise ratio of the detector observing the eye, as for synchronous detection.

[0045] The invention thus presents numerous advantages, including: Ease of implementation; A non-invasive solution; A solution that uses commonly available components;

Claims

1. Method for determining the operating state of a light-emitting implant (1) implanted in the brain (2) of a living being, said light-emitting implant (1) comprising a light source (10) responsible for emitting light into the brain of the living being, said method using a diagnosing device (3) that comprises a receiver (31) of a light signal transmitted through a first eye (20) of the living being and means for determining the operating state of the light-emitting implant (1) based on the received transmitted light signal, characterized in that it comprises: - a step of positioning the receiver (31) of the diagnosing device facing the first eye (20) of the living being, - a step of measuring a light signal received by the receiver (31) when the light-emitting implant (1) is activated, - a step of comparing data representative of the light signal received by the receiver (31) and at least one reference datum, - a step of determining the operating state of the light-emitting implant (1) between a functional state and a non-functional state given the result of the comparing step.

2. Method according to Claim 1, characterized in that said reference datum is stored beforehand or acquired in a step of calibrating the diagnosing device (3).

3. Method according to Claim 2, characterized in that the calibrating step consists in a step of measuring a reference light signal, carried out when the light-emitting implant (1) is deactivated.

4. Method according to one of Claims 1 to 3, characterized in that the step of determining the operating state of the light-emitting implant (1) consists in determining at least one difference between said reference datum and a datum of said data representative of the received light signal and in comparing said difference with a predetermined threshold value.

5. Method according to one of Claims 1 to 4, characterized in that it comprises a step of positioning a point light source (33) facing a second eye (21) of the living being and a step of activating said point light source (33).

6. Diagnosing device (3) used to implement the method such as defined in one of Claims 1 to 5, characterized in that it comprises a mechanical mount (30, 34) to which said receiver (31) is fastened and means (32) for determining the operating state of said light-emitting implant (1), said means being connected to said receiver (31) and configured to process data delivered by said receiver.

7. Device according to Claim 6, characterized in that the receiver (31) is a camera.

8. Device according to Claim 6, characterized in that the receiver (31) comprises one or more photodiodes.

9. Device according to one of Claims 6 to 8, characterized in that it comprises a point light source (33) fastened to said mount and intended to be arranged facing a second eye (21) of the living being, in parallel with the receiver (31).

10. Diagnosing device according to Claim 6, characterized in that the mechanical mount comprises an optical platform (30) provided with a chin rest, and to which said receiver (31) is fastened.

11. Device according to Claim 6, characterized in that the mechanical mount comprises a headset (34) to be placed around the head of the living being.

12. Device according to Claim 11, characterized in that the headset (34) comprises two eyeglasses, a first eyeglass (340) accommodating said receiver (31) and a second eyeglass (341) accommodating a point light source (33).