WO2012171131A1 - Method and device for measuring intraocular pressure - Google Patents
Method and device for measuring intraocular pressure Download PDFInfo
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- WO2012171131A1 WO2012171131A1 PCT/CH2012/000133 CH2012000133W WO2012171131A1 WO 2012171131 A1 WO2012171131 A1 WO 2012171131A1 CH 2012000133 W CH2012000133 W CH 2012000133W WO 2012171131 A1 WO2012171131 A1 WO 2012171131A1
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- eyeball
- intraocular pressure
- measuring
- laser beam
- frequency
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/16—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for measuring intraocular pressure, e.g. tonometers
- A61B3/165—Non-contacting tonometers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02083—Interferometers characterised by particular signal processing and presentation
- G01B9/02084—Processing in the Fourier or frequency domain when not imaged in the frequency domain
Definitions
- the present invention relates to a method for measuring the intraocular pressure of an eye, without contact with the eyeball * in which the eyeball is placed in vibration, a laser beam is sent by an interferometer on said eyeball and the intraocular pressure is deduced from data from the reflected beam.
- It also relates to a device for measuring the intraocular pressure of an eye, without contact with the eyeball, comprising vibratory means for putting the eyeball in vibration, an interferometer for sending a laser beam on said eyeball, and measuring means for determining the intraocular pressure of data from the reflected beam for the implementation of the above method.
- Previous techniques consist mainly of measuring the intraocular pressure by applying directly to the surface of the eyeball, a pressure sensor that performs this measurement.
- This operation is uncomfortable for the patient because the surface of the eyeball is extremely sensitive so that the patient reacts spontaneously and almost uncontrollably in direct contact with an instrument. This results in tearing and blinking of the eye making the measurement even more delicate. The process is particularly difficult for children, especially young children.
- the international patent application WO 03/0820087 A1 relates to a non-contact tonometer that makes it possible to measure the intraocular pressure of an eye, part of which has been previously vibrated by means of an acoustic wave, this measurement being made on the basis of the speed of the wave.
- US patent application 2007/012 120 A1 which describes an apparatus for performing a number of measurements on the eye of a patient, vibrated by a piezoelectric device in contact with any part the patient's body, including the skin or bones. As for the previous device, the measurement is based on the speed of the vibratory wave.
- the present invention aims to overcome the disadvantages of the prior art by proposing an indirect measurement, without contact with the eyeball, which facilitates the operation of a speaker and avoids the inconvenience for the patient and based on the use of a laser beam transmitted on the eye previously vibrated in a controlled manner.
- the method as defined in the preamble is characterized in that a mechanical vibration of the eyeball is generated and said laser beam is divided into a first half-beam projected on the surface of the eyeball previously set in motion. vibration and a second half-beam which is used as reference, projected on a mirror, in that said two half-beams are recombined to generate a network of interferences due to the phase difference between the two half-beams, in that said interference network is analyzed and in that the vibration modes of the eyeball, which depend on the intraocular pressure, are deduced by the processing of the signal corresponding to said interferences.
- said mechanical vibration can be generated by means of a resonator applied against a bone element near the eyeball.
- said mechanical vibration can be obtained by applying an electromechanical transducer in direct contact with the patient's skin and a bone part of the skull, substantially close to said eyeball.
- said signal processing may consist in producing a frequency spectrum of the demodulated phase of the response signal of the eyeball.
- said signal processing may consist in using a recursive method that minimizes the error between the measured signal and a known theoretical function and in deducing the resonance frequency of the eyeball.
- said relationships linking said resonant frequency to said intraocular pressure can be established experimentally.
- the method as defined in the preamble is characterized in that said vibratory means comprise a resonator arranged to vibrate a bone part near the eyeball which is to measure the intraocular pressure, in that it comprises a generator laser beam, in that said interferometer is a Michelson interferometer arranged to generate a network of interferences between a half-laser beam emitted by said generator and a half-laser beam emitted by said generator and reflected by said eyeball and said measurement means are arranged to interpret said interferences and to deduce the intraocular pressure of said eyeball.
- said vibratory means comprise a resonator arranged to vibrate a bone part near the eyeball which is to measure the intraocular pressure, in that it comprises a generator laser beam
- said interferometer is a Michelson interferometer arranged to generate a network of interferences between a half-laser beam emitted by said generator and a half-laser beam emitted by said generator and reflected by said eyeball and said measurement
- said measuring means comprise means for establishing a frequency spectrum of the eyeball response signal and means for measuring at least one frequency to deduce the pressure of said eyeball according to relationships linking this spectrum to this pressure.
- said means for interpreting said interference comprises an optoelectronic device equipped with a photo detector arranged to interpret these interferences in order to derive a frequency spectrum of the measured signal.
- the measuring device preferably comprises a control and measurement unit connected on the one hand to the resonator to activate the latter at the desired frequency and on the other hand to the generator for controlling the emission of the laser beam.
- FIG. 1 represents a schematic view illustrating the operating phases of the method of the invention
- Figure 2 shows a view of the block diagram illustrating the device for implementing the method according to the invention
- Figure 3 is a view of the frequency spectrum of the signal picked up by a detector. Best ways to achieve the invention
- FIG. 1 represents a schematic diagram illustrating the phases of the method of the invention.
- This process consists firstly in vibrating the eyeball 10 of a person or an animal 11, inside its orbit by means of a resonator 12 which is excited by a module 13 called a control unit and measurement.
- the eyeball is equivalent to a mass suspended from springs and the excitation caused by the resonator generates vibrations of this suspended mass.
- the resonator is applied to a bone structure near the eye, so that the vibrations generated are communicated by its support, ie the orbit, to the eyeball.
- FIG. 2 illustrates a schematic embodiment of a device for measuring intraocular pressure, without contact with the eyeball for implementing the method of the invention as defined above.
- the device 20 comprises a generator 21 which emits a laser beam 22 towards the interferometer, which is in this case a Michelson interferometer 15.
- the Michelson interferometer 15 comprises a beam splitter 23 which breaks down the laser beam 22 in two half beams 22a and 22b.
- the half-beam 22a corresponds to the beam 14 mentioned above and called incident beam in the description of the method with reference to FIG. 1.
- the half-beam 22b is deflected on a total reflection plane mirror 24.
- the incident beam 14 (FIG. half-beam 22a) generates a beam 16 reflected by the eyeball 10 and which is returned to the beam splitter 23.
- This beam splitter reflects it in the form of a beam that carries eyeball-specific data, in particular as regards the intraocular pressure of the latter.
- the half-beam 22b reflected by the mirror 24 passes through the beam splitter in the form of a beam 17 which combines with the reflected beam 16 to generate an interference pattern.
- An optoelectronic device 25 comprising a photo detector interprets these interferences to derive a frequency spectrum of the measured signal.
- a control and measurement unit 26 is on the one hand connected to the resonator 12 to activate the latter at the desired frequency and on the other hand to the generator 21 to control the emission of the laser beam 22.
- Figure 3 represents said spectrum.
- the information sought namely the intraocular pressure is obtained through an interpretation of this spectrum.
- the spectrum may be a frequency spectrum of the eyeball response signal, or a frequency spectrum of the demodulated phase of the eyeball response signal.
- the measured frequency may be the resonance frequency.
- the fundamental frequency F is the first order harmonic as detected by a signal processing algorithm. It can be used to attenuate the lower frequencies of the signal during the analysis.
- the dominant frequency D is the one that offers the best response from the eye. It can be distinguished from the forced vibration of the eye E for example if the forced excitation causes other vibratory modes close to the resonance.
- a digital high pass filter whose cutoff frequency has been determined experimentally has been applied to eliminate low frequency noise.
- Intraocular pressure is defined by relationships between these frequencies and pressure. Note that these relationships are based on experimental measurements and simplified physical models of the human or animal eye.
- the interference pattern provides an analog signal which is digitized and processed and the demodulated phase of this signal allows to deduce the vibration modes of the eyeball.
- the variation of the frequency of the resonator makes it possible to obtain a loop of measurements corresponding to a forced response of the eye.
- the variation of the excitation frequency of the resonator makes it possible to establish a diagram of the representation of the corresponding vibration of the globe eyepiece, this diagram can be used to establish a diagnosis.
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Abstract
The invention relates to a device for measuring the intraocular pressure of an eye of a human or animal, having a resonator (12) designed to cause vibration of the eyeball (10) in which the intraocular pressure is to be measured, a generator (21) for generating a laser beam to be sent to said eyeball, and an interferometer (15) for producing a network of interferences between a laser half-beam (17) emitted by the generator (21) and a laser half-beam (16) reflected by said eyeball, and means for interpreting said interferences in order to deduce therefrom the intraocular pressure of said eyeball. The measuring method involves analyzing said network of interferences caused by the phase shift between the two half-beams, and deducing the modes of vibration of the eyeball, which depend on the intraocular pressure, by processing the signal corresponding to said interferences.
Description
PROCEDE ET DISPOSITIF DE MESURE DE LA PRESSION INTRAOCULAIRE METHOD AND DEVICE FOR MEASURING INTRAOCULAR PRESSURE
Domaine technique Technical area
La présente invention concerne un procédé de mesure de la pression intraoculaire d'un il, sans contact avec le globe oculaire* dans lequel l'on met le globe oculaire en vibration, l'on envoie un faisceau laser par un interféromètre sur ledit globe oculaire et l'on déduit la pression intraoculaire de données issues du faisceau réfléchi. The present invention relates to a method for measuring the intraocular pressure of an eye, without contact with the eyeball * in which the eyeball is placed in vibration, a laser beam is sent by an interferometer on said eyeball and the intraocular pressure is deduced from data from the reflected beam.
Elle a également pour objet un dispositif de mesure de la pression intraoculaire d'un œil, sans contact avec le globe oculaire, comportant des moyens vibratoires pour mettre le globe oculaire en vibration, un interféromètre pour envoyer un faisceau laser sur ledit globe oculaire et des moyens de mesure pour déterminer la pression intraoculaire de données issues du faisceau réfléchi pour la mise en œuvre du procédé ci-dessus. It also relates to a device for measuring the intraocular pressure of an eye, without contact with the eyeball, comprising vibratory means for putting the eyeball in vibration, an interferometer for sending a laser beam on said eyeball, and measuring means for determining the intraocular pressure of data from the reflected beam for the implementation of the above method.
Technique antérieure Prior art
Les techniques antérieures consistent principalement à mesurer la pression intraoculaire en appliquant directement sur la surface du globe oculaire, un capteur de pression qui effectue cette mesure. Cette opération est désagréable pour le patient parce que la surface du globe oculaire est extrêmement sensible de sorte que le patient réagit spontanément et de façon quasi incontrôlable lors d'un contact direct avec un instrument. Ceci se traduit par des larmoiements et des clignotements de l'œil rendant la mesure encore plus délicate. La démarche est particulièrement difficile chez des enfants et notamment des enfants en bas âge. Previous techniques consist mainly of measuring the intraocular pressure by applying directly to the surface of the eyeball, a pressure sensor that performs this measurement. This operation is uncomfortable for the patient because the surface of the eyeball is extremely sensitive so that the patient reacts spontaneously and almost uncontrollably in direct contact with an instrument. This results in tearing and blinking of the eye making the measurement even more delicate. The process is particularly difficult for children, especially young children.
Il existe néanmoins des appareils de mesure qui permettent d'effectuer la mesure de la pression intraoculaire sans contact direct avec le globe oculaire. Ces appareils ont fait l'objet des brevets ou demandes de brevets ci-après :
Le brevet français 00 12957, publié sous le N° 2 814 935 décrit un procédé et un dispositif pour déterminer les modes de vibration d'un œil par interférométrie laser en vue de mesurer la pression intraoculaire de cet œil. On notera que la mise en vibration de l'œil est effectuée par un cillement de la paupière, ce qui ne permet pas d'effectuer un contrôle précis de cette mise en vibration et que la détermination de la pression intraoculaire est effectuée au moyen d'un interférométre de Fabry-Pérot selon un principe optique spécifique qui ne permet pas d'obtenir une mesure précise, notamment à partir d'une vibration qui peut être considérée comme aléatoire. However, there are measuring devices that can measure the intraocular pressure without direct contact with the eyeball. These devices have been the subject of the following patents or patent applications: French Patent No. 00 12957, published under No. 2,814,935, describes a method and a device for determining the modes of vibration of an eye by laser interferometry in order to measure the intraocular pressure of this eye. It should be noted that the vibration of the eye is effected by a flick of the eyelid, which does not make it possible to carry out an accurate control of this setting in vibration and that the determination of the intraocular pressure is carried out by means of a Fabry-Perot interferometer according to a specific optical principle which does not make it possible to obtain an accurate measurement, in particular from a vibration which can be considered random.
La demande de brevet internationale WO 03/0820087 A1 concerne un tonomètre sans contact qui permet d'effectuer une mesure de la pression intraoculaire d'un œil, dont une partie a été préalablement mise en vibration au moyen d'une onde acoustique, cette mesure étant faite sur la base de la vitesse de l'onde. The international patent application WO 03/0820087 A1 relates to a non-contact tonometer that makes it possible to measure the intraocular pressure of an eye, part of which has been previously vibrated by means of an acoustic wave, this measurement being made on the basis of the speed of the wave.
La demande de brevet américain US 2007/012 120 A1 qui décrit un appareil permettant d'effectuer un certain nombre de mesures sur l'œil d'un patient, mis en vibration par un dispositif piézo-électrique en contact avec n'importe quelle partie du corps du patient, notamment la peau ou les os. Comme pour le dispositif précédent, la mesure est basée sur la vitesse de l'onde vibratoire. US patent application 2007/012 120 A1 which describes an apparatus for performing a number of measurements on the eye of a patient, vibrated by a piezoelectric device in contact with any part the patient's body, including the skin or bones. As for the previous device, the measurement is based on the speed of the vibratory wave.
La demande de brevet américain US 2003/0078486 A1 qui décrit un appareil de mesure de la pression intraoculaire d'un œil utilisant un interférométre et représentant un transducteur en contact avec la peau d'un patient. US patent application US 2003/0078486 A1 which describes an apparatus for measuring the intraocular pressure of an eye using an interferometer and representing a transducer in contact with the skin of a patient.
Le brevet américain US 5, 148,807 qui décrit un tonomètre sans contact et non invasif pour déterminer la pression intraoculaire de l'œil d'un patient, excité par des ondes acoustiques de haute fréquence et utilisant un interférométre de Michelson ou de Mach-Zehnder.
Exposé de l'invention US Patent 5,148,807 which discloses a non-contact, non-invasive tonometer for determining the intraocular pressure of a patient's eye, excited by high frequency acoustic waves and using a Michelson or Mach-Zehnder interferometer. Presentation of the invention
La présente invention vise à pallier les inconvénients de l'art antérieur en proposant une mesure indirecte, sans contact avec le globe oculaire, ce qui facilite l'opération d'un intervenant et évite les désagréments pour le patient et basée sur l'utilisation d'un faisceau laser transmis sur l'œil préalablement mis en vibration de façon contrôlée. The present invention aims to overcome the disadvantages of the prior art by proposing an indirect measurement, without contact with the eyeball, which facilitates the operation of a speaker and avoids the inconvenience for the patient and based on the use of a laser beam transmitted on the eye previously vibrated in a controlled manner.
Dans ce but, le procédé tel que défini en préambule est caractérisé en ce que l'on génère une vibration mécanique du globe oculaire et l'on divise ledit faisceau laser en un premier demi-faisceau projeté sur la surface du globe oculaire préalablement mis en vibration et en un deuxième demi-faisceau qui sert de référence, projeté sur un miroir, en ce que l'on recombine lesdits deux demi-faisceaux pour générer un réseau d'interférences dues au déphasage entre les deux demi-faisceaux, en ce que l'on analyse ledit réseau d'interférences et en ce que l'on déduit les modes de vibrations du globe oculaire qui dépendent de la pression intraoculaire, par le traitement du signal correspondant audites interférences. For this purpose, the method as defined in the preamble is characterized in that a mechanical vibration of the eyeball is generated and said laser beam is divided into a first half-beam projected on the surface of the eyeball previously set in motion. vibration and a second half-beam which is used as reference, projected on a mirror, in that said two half-beams are recombined to generate a network of interferences due to the phase difference between the two half-beams, in that said interference network is analyzed and in that the vibration modes of the eyeball, which depend on the intraocular pressure, are deduced by the processing of the signal corresponding to said interferences.
Selon un mode de réalisation préféré, l'on peut générer ladite vibration mécanique au moyen d'un résonateur appliqué contre un élément osseux à proximité du globe oculaire. According to a preferred embodiment, said mechanical vibration can be generated by means of a resonator applied against a bone element near the eyeball.
De manière avantageuse, l'on peut obtenir ladite vibration mécanique en appliquant un transducteur électromécanique en contact direct avec la peau du patient et une partie osseuse du crâne, sensiblement à proximité dudit globe oculaire. Advantageously, said mechanical vibration can be obtained by applying an electromechanical transducer in direct contact with the patient's skin and a bone part of the skull, substantially close to said eyeball.
Selon un mode de mise en œuvre préférée, l'on peut établir un spectre en fréquence du signal de réponse du globe oculaire et l'on mesure au moins une fréquence pour déduire la pression dudit globe oculaire selon des relations liant ce spectre à cette pression.
Selon une première forme de réalisation, ledit traitement du signal peut consister à produire un spectre en fréquence de la phase démodulée du signal de réponse du globe oculaire. Selon une seconde forme de réalisation ledit traitement du signal peut consister à utiliser une méthode récursive minimisant l'erreur entre le signal mesuré et une fonction théorique connue et à en déduire la fréquence de résonnance du globe oculaire. D'une manière préférentielle, lesdites relations liant ladite fréquence de résonance à ladite pression intraoculaire peuvent être établies expérimentalement. According to a preferred embodiment, it is possible to establish a frequency spectrum of the response signal of the eyeball and at least one frequency is measured to deduce the pressure of said eyeball according to relations linking this spectrum to this pressure. . According to a first embodiment, said signal processing may consist in producing a frequency spectrum of the demodulated phase of the response signal of the eyeball. According to a second embodiment, said signal processing may consist in using a recursive method that minimizes the error between the measured signal and a known theoretical function and in deducing the resonance frequency of the eyeball. Preferably, said relationships linking said resonant frequency to said intraocular pressure can be established experimentally.
Dans ce but également, le procédé tel que défini en préambule est caractérisé en ce lesdits moyens vibratoires comportent un résonateur agencé pour faire vibrer une partie osseuse à proximité du globe oculaire dont on veut mesurer la pression intraoculaire, en ce qu'il comporte un générateur de faisceau laser, en ce que ledit interféromètre est un interféromètre de Michelson agencé pour générer un réseau d'interférences entre un demi-faisceau laser émis par ledit générateur et un demi-faisceau laser émis par ledit générateur et réfléchi par ledit globe oculaire et en ce que lesdits moyens de mesure sont agencés pour interpréter lesdites interférences et en déduire la pression intraoculaire dudit globe oculaire. Avantageusement lesdits moyens de mesure comprennent des moyens pour établir un spectre en fréquence du signal de réponse du globe oculaire et des moyens pour mesurer au moins une fréquence pour déduire la pression dudit globe oculaire selon des relations liant ce spectre à cette pression.
De façon préférentielle, lesdits moyens pour interpréter lesdites interférences comportent un dispositif optoélectronique équipé d'un photo détecteur agencé pour interpréter ces interférences en vue d'en déduire un spectre en fréquence du signal mesuré. For this purpose also, the method as defined in the preamble is characterized in that said vibratory means comprise a resonator arranged to vibrate a bone part near the eyeball which is to measure the intraocular pressure, in that it comprises a generator laser beam, in that said interferometer is a Michelson interferometer arranged to generate a network of interferences between a half-laser beam emitted by said generator and a half-laser beam emitted by said generator and reflected by said eyeball and said measurement means are arranged to interpret said interferences and to deduce the intraocular pressure of said eyeball. Advantageously, said measuring means comprise means for establishing a frequency spectrum of the eyeball response signal and means for measuring at least one frequency to deduce the pressure of said eyeball according to relationships linking this spectrum to this pressure. Preferably, said means for interpreting said interference comprises an optoelectronic device equipped with a photo detector arranged to interpret these interferences in order to derive a frequency spectrum of the measured signal.
Le dispositif de mesure comporte de préférence une unité de contrôle et de mesures connecté d'une part au résonateur pour activer ce dernier à la fréquence souhaitée et d'autre part au générateur pour commander l'émission du faisceau laser. The measuring device preferably comprises a control and measurement unit connected on the one hand to the resonator to activate the latter at the desired frequency and on the other hand to the generator for controlling the emission of the laser beam.
Description sommaire des dessins Brief description of the drawings
La présente invention et ses avantages apparaîtront mieux dans la description suivante d'un mode de réalisation donné à titre d'exemple non limitatif, en référence aux dessins annexés, dans lesquels: la figure 1 représente une vue schématique illustrant les phases opératoires du procédé de l'invention, la figure 2, représente une vue du schéma de principe illustrant le dispositif qui permet de mettre en œuvre le procédé selon l'invention, et la figure 3 est une vue du spectre en fréquence du signal capté par un , détecteur. Meilleures manières de réaliser l'invention The present invention and its advantages will appear better in the following description of an embodiment given by way of non-limiting example, with reference to the appended drawings, in which: FIG. 1 represents a schematic view illustrating the operating phases of the method of the invention, Figure 2, shows a view of the block diagram illustrating the device for implementing the method according to the invention, and Figure 3 is a view of the frequency spectrum of the signal picked up by a detector. Best ways to achieve the invention
La figure 1 représente un schéma de principe qui illustre les phases du procédé de l'invention. Ce procédé consiste tout d'abord à faire vibrer le globe oculaire 10 d'une personne ou d'un animal 11 , à l'intérieur de son orbite au moyen d'un résonateur 12 qui est excité par un module 13 appelé unité de contrôle et de mesure. Le globe oculaire est équivalent à une masse suspendue à des ressorts et l'excitation provoquée par le résonateur engendre des vibrations de
cette masse suspendue. Dans la pratique le résonateur est appliqué à une structure osseuse à proximité de l'œil, de telle manière que les vibrations engendrées soient communiquées par son support, c'est-dire l'orbite, au globe oculaire. FIG. 1 represents a schematic diagram illustrating the phases of the method of the invention. This process consists firstly in vibrating the eyeball 10 of a person or an animal 11, inside its orbit by means of a resonator 12 which is excited by a module 13 called a control unit and measurement. The eyeball is equivalent to a mass suspended from springs and the excitation caused by the resonator generates vibrations of this suspended mass. In practice, the resonator is applied to a bone structure near the eye, so that the vibrations generated are communicated by its support, ie the orbit, to the eyeball.
Ce procédé consiste ensuite à envoyer un faisceau laser appelé faisceau incident 14 sur le globe oculaire 10 mis en vibration, ce faisceau incident étant émis par un interféromètre, par exemple un interféromètre de Michelson 5 ou similaire, et à capter le faisceau réfléchi 16 par un photo détecteur 17 pour établir le spectre en fréquence du signal de réponse de l'œil. La fréquence de résonance permet de déduire la pression intraoculaire grâce à des relations liant cette fréquence à la pression, ces relations étant établies à partir de mesures expérimentales et de modèles physiques simplifiés de l'œil. La figure 2 illustre une forme de réalisation schématique d'un dispositif de mesure de la pression intraoculaire, sans contact avec le globe oculaire pour la mise en œuvre du procédé de l'invention tel que défini ci-dessus. Le dispositif 20 comporte un générateur 21 qui émet un faisceau laser 22 vers l'interféromètre, qui est dans ce cas un interféromètre de Michelson 15. L'interféromètre de Michelson 15 comporte un diviseur de faisceau 23 qui décompose le faisceau laser 22 en deux demi-faisceaux 22a et 22b. Le demi- faisceau 22a correspond au faisceau 14 mentionné ci-dessus et appelé faisceau incident dans la description du procédé en référence à la figure 1. Le demi-faisceau 22b est dévié sur un miroir plan à réflexion totale 24. Le faisceau incident 14 (demi-faisceau 22a) génère un faisceau 16 réfléchi par le globe oculaire 10 et qui est renvoyé sur le diviseur de faisceau 23. Ce diviseur de faisceau le réfléchit sous la forme d'un faisceau qui est porteur de données propres au globe oculaire, notamment en ce qui concerne la pression intraoculaire de ce dernier. Par ailleurs le demi-faisceau 22b réfléchi par le miroir 24 traverse le diviseur de faisceau sous la forme d'un faisceau 17 qui se combine au faisceau réfléchi 16 pour générer une figure d'interférences.
Un dispositif optoélectronique 25 comportant un photo détecteur interprète ces interférences pour en déduire un spectre en fréquence du signal mesuré. Une unité de contrôle et de mesures 26 est d'une part connecté au résonateur 12 pour activer ce dernier à la fréquence souhaitée et d'autre part au générateur 21 pour commander l'émission du faisceau laser 22. This method then consists in sending a laser beam called an incident beam 14 to the vibrated eyeball 10, this incident beam being emitted by an interferometer, for example a Michelson interferometer or the like, and sensing the reflected beam 16 by a detector photo 17 to establish the frequency spectrum of the response signal of the eye. The resonance frequency allows to deduce the intraocular pressure thanks to the relations linking this frequency to the pressure, these relations being established from experimental measurements and simplified physical models of the eye. FIG. 2 illustrates a schematic embodiment of a device for measuring intraocular pressure, without contact with the eyeball for implementing the method of the invention as defined above. The device 20 comprises a generator 21 which emits a laser beam 22 towards the interferometer, which is in this case a Michelson interferometer 15. The Michelson interferometer 15 comprises a beam splitter 23 which breaks down the laser beam 22 in two half beams 22a and 22b. The half-beam 22a corresponds to the beam 14 mentioned above and called incident beam in the description of the method with reference to FIG. 1. The half-beam 22b is deflected on a total reflection plane mirror 24. The incident beam 14 (FIG. half-beam 22a) generates a beam 16 reflected by the eyeball 10 and which is returned to the beam splitter 23. This beam splitter reflects it in the form of a beam that carries eyeball-specific data, in particular as regards the intraocular pressure of the latter. Furthermore, the half-beam 22b reflected by the mirror 24 passes through the beam splitter in the form of a beam 17 which combines with the reflected beam 16 to generate an interference pattern. An optoelectronic device 25 comprising a photo detector interprets these interferences to derive a frequency spectrum of the measured signal. A control and measurement unit 26 is on the one hand connected to the resonator 12 to activate the latter at the desired frequency and on the other hand to the generator 21 to control the emission of the laser beam 22.
La figure 3 représente ledit spectre. L'information recherchée, à savoir la pression intraoculaire est obtenue grâce à une interprétation de ce spectre. Le spectre peut être un spectre en fréquence du signal de réponse du globe oculaire, ou un spectre en fréquence de la phase démodulée du signal de réponse du globe oculaire. La fréquence mesurée peut être la fréquence de résonnance. Dans l'exemple représenté, la fréquence fondamentale F est l'harmonique de premier ordre telle que détectée par un algorithme de traitement du signal. Elle peut être utilisée pour atténuer les fréquences plus basses du signal lors de l'analyse. La fréquence dominante D est celle qui offre la meilleure réponse de la part de l'œil. Elle peut se distinguer de la vibration forcée de l'œil E par exemple si l'excitation forcée provoque d'autres modes vibratoires proches de la résonnance. Un filtre passe-haut numérique dont la fréquence de coupure a été déterminée expérimentalement a été appliqué pour permettre d'éliminer le bruit en basse fréquence. A partir du spectre de la figure 3 et grâce à un algorithme de traitement du signal, il est possible de déterminer la réponse de l'œil et la fréquence de résonance. La pression intraoculaire est définie grâce à des relations liant ces fréquences à la pression. On notera que ces relations sont établies à partir de mesures expérimentales et de modèles physiques simplifiés de l'œil humain ou animal. Figure 3 represents said spectrum. The information sought, namely the intraocular pressure is obtained through an interpretation of this spectrum. The spectrum may be a frequency spectrum of the eyeball response signal, or a frequency spectrum of the demodulated phase of the eyeball response signal. The measured frequency may be the resonance frequency. In the example shown, the fundamental frequency F is the first order harmonic as detected by a signal processing algorithm. It can be used to attenuate the lower frequencies of the signal during the analysis. The dominant frequency D is the one that offers the best response from the eye. It can be distinguished from the forced vibration of the eye E for example if the forced excitation causes other vibratory modes close to the resonance. A digital high pass filter whose cutoff frequency has been determined experimentally has been applied to eliminate low frequency noise. From the spectrum of Figure 3 and using a signal processing algorithm, it is possible to determine the response of the eye and the resonant frequency. Intraocular pressure is defined by relationships between these frequencies and pressure. Note that these relationships are based on experimental measurements and simplified physical models of the human or animal eye.
La figure d'interférences fournit un signal analogique qui est numérisé et traité et la phase démodulée de ce signal permet de déduire les modes de vibrations du globe oculaire. La variation de la fréquence du résonateur permet d'obtenir une boucle de mesures correspondant à une réponse forcée de l'œil. La variation de la fréquence d'excitation du résonateur permet d'établir un diagramme de la représentation de la vibration correspondante du globe
oculaire, ce diagramme pouvant être utilisé en vue de l'établissement d'un diagnostic. The interference pattern provides an analog signal which is digitized and processed and the demodulated phase of this signal allows to deduce the vibration modes of the eyeball. The variation of the frequency of the resonator makes it possible to obtain a loop of measurements corresponding to a forced response of the eye. The variation of the excitation frequency of the resonator makes it possible to establish a diagram of the representation of the corresponding vibration of the globe eyepiece, this diagram can be used to establish a diagnosis.
Possibilités d'application industrielle Possibilities of industrial application
II ressort clairement de cette description que l'invention permet d'atteindre les buts fixés, à savoir déduire de mesures faites sans contact avec le globe oculaire, la pression intraoculaire de l'œil. L'instrumentation pourrait être différente, notamment d'autres types d'interféromètres pourraient être utilisés. Différentes variantes de réalisation pourraient être envisagées dans le cadre des caractéristiques de l'invention telles qu'identifiées par les revendications.
It is clear from this description that the invention achieves the goals set, namely to deduce from measurements made without contact with the eyeball, the intraocular pressure of the eye. The instrumentation could be different, especially other types of interferometers could be used. Various alternative embodiments could be envisaged within the scope of the features of the invention as identified by the claims.
Claims
1. Procédé de mesure de la pression intraoculaire d'un œil, sans contact avec le globe oculaire, dans lequel l'on met le globe oculaire en vibration, l'on envoie un faisceau laser par un interféromètre sur ledit globe oculaire et l'on déduit la pression intraoculaire de données issues du faisceau réfléchi, caractérisé en ce que en ce que l'on génère une vibration mécanique du globe oculaire et l'on divise ledit faisceau laser en un premier demi-faisceau projeté sur la surface du globe oculaire préalablement mis en vibration et en un deuxième demi-faisceau qui sert de référence, projeté sur un miroir, en ce que l'on recombine lesdits deux demi-faisceaux pour générer un réseau d'interférences dues au déphasage entre les deux demi-faisceaux, en ce que l'on analyse ledit réseau d'interférences et en ce que l'on déduit les modes de vibrations du globe oculaire qui dépendent de la pression intraoculaire, par le traitement du signal correspondant audites interférences. 1. A method for measuring the intraocular pressure of an eye, without contact with the eyeball, in which the eyeball is placed in vibration, a laser beam is sent by an interferometer on said eyeball and the the intraocular pressure is deduced from data from the reflected beam, characterized in that a mechanical vibration of the eyeball is generated and said laser beam is divided into a first half-beam projected on the surface of the eyeball. previously vibrated and in a second half-beam which serves as a reference, projected on a mirror, in that said two half-beams are recombined to generate an interference network due to the phase shift between the two half-beams, in that said interference network is analyzed and in that the vibration modes of the eyeball which depend on the intraocular pressure are deduced by the processing of the corresponding interfering signal. ences.
2. Procédé de mesure selon la revendication 1 , caractérisé en ce que l'on génère ladite vibration mécanique au moyen d'un résonateur appliqué contre un élément osseux à proximité du globe oculaire. 2. Measuring method according to claim 1, characterized in that said mechanical vibration is generated by means of a resonator applied against a bone element near the eyeball.
3. Procédé de mesure selon la revendication 2, caractérisé en ce que l'on obtient ladite vibration mécanique en appliquant un transducteur électromécanique en contact direct avec la peau du patient et une partie osseuse du crâne, sensiblement à proximité dudit globe oculaire. 3. Measuring method according to claim 2, characterized in that said mechanical vibration is obtained by applying an electromechanical transducer in direct contact with the skin of the patient and a bone part of the skull, substantially in the vicinity of said eyeball.
4. Procédé de mesure selon la revendication 1 , caractérisé en ce que l'on établit un spectre en fréquence du signal de réponse du globe oculaire et l'on mesure au moins une fréquence pour déduire la pression dudit globe oculaire selon des relations liant ce spectre à cette pression. 4. Measuring method according to claim 1, characterized in that a frequency spectrum of the response signal of the eyeball is established and at least one frequency is measured to deduce the pressure of said eyeball according to relations linking this eyeball. spectrum at this pressure.
5. Procédé de mesure selon la revendication 1 , caractérisé en ce que ledit traitement du signal consiste à produire un spectre en fréquence de la phase démodulée du signal de réponse du globe oculaire. 5. Measuring method according to claim 1, characterized in that said signal processing consists in producing a frequency spectrum of the demodulated phase of the response signal of the eyeball.
6. Procédé de mesure selon la revendication 1 , caractérisé en ce que ledit traitement du signal consiste à utiliser une méthode récursive minimisant l'erreur entre le signal mesuré et une fonction théorique connue et d'en déduire la fréquence de résonnance du globe oculaire. 6. Measuring method according to claim 1, characterized in that said signal processing consists in using a recursive method minimizing the error between the measured signal and a known theoretical function and in deducing the resonance frequency of the eyeball.
7. Procédé de mesure selon la revendication 4, caractérisé en ce que lesdites relations liant ladite fréquence de résonance à ladite pression intraoculaire sont établies expérimentalement. 7. Measuring method according to claim 4, characterized in that said relations linking said resonant frequency to said intraocular pressure are established experimentally.
8. Dispositif de mesure de la pression intraoculaire d'un œil, sans contact avec le globe oculaire, comportant des moyens vibratoires pour mettre le globe oculaire en vibration, un interféromètre pour envoyer un faisceau laser sur ledit globe oculaire et des moyens de mesure pour déterminer la pression intraoculaire de données issues du faisceau réfléchi, caractérisé en ce que lesdits moyens vibratoires comportent un résonateur (12) agencé pour faire vibrer une partie osseuse à proximité du globe oculaire (10) dont on veut mesurer la pression intraoculaire, en ce qu'il comporte un générateur (21) de faisceau laser, en ce que ledit interféromètre est un interféromètre de Michelson (15) agencé pour générer un réseau d'interférences entre un demi- faisceau laser (17) émis par ledit générateur (21) et un demi-faisceau laser (16) émis par ledit générateur (21) et réfléchi par ledit globe oculaire et en ce que lesdits moyens de mesure sont agencés pour interpréter lesdites interférences et en déduire la pression intraoculaire dudit globe oculaire. 8. Device for measuring the intraocular pressure of an eye, without contact with the eyeball, comprising vibratory means for putting the eyeball in vibration, an interferometer for sending a laser beam on said eyeball and measuring means for determining the intraocular pressure of data from the reflected beam, characterized in that said vibratory means comprise a resonator (12) arranged to vibrate a bone part near the eyeball (10) whose intraocular pressure is to be measured, in that it comprises a laser beam generator (21), in that said interferometer is a Michelson interferometer (15) arranged to generate an interference network between a half-laser beam (17) emitted by said generator (21) and a half-laser beam (16) emitted by said generator (21) and reflected by said eyeball and in that said measuring means are arranged to interp to reiterate said interferences and to deduce the intraocular pressure of said eyeball.
9. Dispositif de mesure selon la revendication 8, caractérisé en ce que lesdits moyens de mesure comprennent des moyens pour établir un spectre en fréquence du signal de réponse du globe oculaire et des moyens pour mesurer au moins une fréquence pour déduire la pression dudit globe oculaire selon des relations liant ce spectre à cette pression. 9. Measuring device according to claim 8, characterized in that said measuring means comprise means for establishing a frequency spectrum of the response signal of the eyeball and means for measuring at least one frequency for deriving the pressure of said eyeball in relationships relating that spectrum to that pressure.
10. Dispositif de mesure selon la revendication 9, caractérisé en ce que lesdits moyens pour interpréter lesdites interférences comportent un dispositif optoélectronique (25) équipé d'un photo détecteur agencé pour interpréter ces interférences en vue d'en déduire un spectre en fréquence du signal mesuré. 10. Measuring device according to claim 9, characterized in that said means for interpreting said interference comprises an optoelectronic device (25) equipped with a photo detector arranged to interpret these interferences in order to deduce a frequency spectrum of the signal. measured.
11. Dispositif de mesure selon la revendication 8, caractérisé en ce qu'il comporte une unité de contrôle et de mesures (26) connecté d'une part au résonateur (12) pour activer ce dernier à la fréquence souhaitée et d'autre part au générateur (21) pour commander l'émission du faisceau laser (22). 11. Measuring device according to claim 8, characterized in that it comprises a control and measurement unit (26) connected on the one hand to the resonator (12) to activate the latter at the desired frequency and secondly the generator (21) for controlling the emission of the laser beam (22).
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| CH1021/11 | 2011-06-16 | ||
| CH01021/11A CH705167A1 (en) | 2011-06-16 | 2011-06-16 | Method and apparatus for measuring intraocular pressure. |
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| WO2012171131A1 true WO2012171131A1 (en) | 2012-12-20 |
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| Application Number | Title | Priority Date | Filing Date |
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| PCT/CH2012/000133 WO2012171131A1 (en) | 2011-06-16 | 2012-06-18 | Method and device for measuring intraocular pressure |
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| WO (1) | WO2012171131A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110859592A (en) * | 2019-11-27 | 2020-03-06 | 电子科技大学 | Non-invasive non-contact measurement method and device for coherent intraocular pressure and intracranial pressure |
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