Non-contact tonometer and method for measuring intraocular pressure value

Abstract

A non-contact tonometer (100, 200, 302, 502) is disclosed. The invention relates to a non-contact tonometer comprising an excitation and measurement unit (102, 202, 300, 504) comprising an electromagnetic exciter (104, 204, 306, 400, 506) comprising: at least one electrical coil (106, 206, 304, 404, 508) powered with a variable current (i) and arranged to generate a variable magnetic field (416, 500); at least one magnetic armature (108, 208, 210, 212, 510) arranged to direct a variable magnetic field toward the eye (110, 214, 303, 418, 512) to at least partially pass through the cornea (112, 216, 301, 402) of the eye. The invention discloses a method for measuring an intraocular pressure value.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a non-contact tonometer. The present disclosure also relates to a method of measuring an intraocular pressure value of an eye. BACKGROUND

[0002] A tonometer is a medical instrument used to measure the internal pressure of an eye, also known as intraocular pressure (IOP). Generally, an eye pressure measurement is a quick, painless and non-invasive test, usually performed during a comprehensive eye examination. There are different types of tonometers according to different working principles. There is a known type of tonometer which applies a vibratory excitation to the eye and measures the vibratory response. Furthermore, the tonometer measures the resulting corneal vibrations and calculates the intraocular pressure (IOP) of the eye from the measurements.

[0003] There are some techniques which describe a correlation between the resonant frequency of an eye and the intraocular pressure of the eye. This correlation makes it possible to calculate the intraocular pressure of an eye using the measured resonant frequency of the eye. In this regard, such techniques use a sound wave excitation and a laser Doppler velocimeter to measure the eye. The resonant frequency at which a first peak of the observed corneal flutter amplitude is determined. The sound excitation is applied using a loudspeaker. Furthermore, the loudspeaker is mounted on a soft cup which is then pressed against the face of the subject in contact with an annular region surrounding the eye in order to improve the efficiency of the power transfer from the loudspeaker to the eye. This enables the vibrations of the loudspeaker membrane to be transmitted to the eye by means of the variable air pressure within the chamber defined by the loudspeaker membrane, the soft cup and the face of the subject. The variable air pressure exerts a variable force on the cornea of the eye which induces vibrations of the eye. By varying the frequency of the air pressure applied to the eye, it is possible to measure the resonant frequency of the eye.

[0004] However, this technique is not contactless. Furthermore, since the soft cup is pressed against the skin of the subject, there is a considerable risk of transmitting a disease (such as covid-19) from a subject to another subject. Furthermore, in some cases, the soft cup is disinfected before being used for another subject. However, the disinfection act requires human intervention and therefore cannot completely rule out the risk of disease transmission. Furthermore, the disinfection act also increases the time and cost of the operation.

[0005] Further, variable pressure has the disadvantage of exerting a variable force even on the annular region surrounding the eye. In this regard, the intraocular pressure is then determined by using the vibrational response of the eye. However, this technique does not accurately measure the intraocular pressure of the eye. The main reason is that the pressure change is exerted not only on the cornea but also simultaneously on the eye and the annular region surrounding the eye. The pressure change causes the desired oscillation of the cornea of the eye, which is related to the intraocular pressure, while causing an undesired secondary oscillation of the entire eye along with the volume of the tissue surrounding the eye. The secondary oscillation depends on the stiffness of the tissue surrounding the eye and the volume of the tissue and not on the intraocular pressure. Thus, the secondary oscillation interferes with the measurement, making the relationship between the intraocular pressure and the measured corneal vibrational response less accurate.

[0006] Therefore, in view of the foregoing discussion, there is a need to overcome the aforementioned drawbacks associated with the prior art techniques for measuring intraocular pressure and the devices associated therewith. SUMMARY

[0007] The present disclosure seeks to provide a non-contact tonometer. The present disclosure also seeks to provide a method of measuring an intraocular pressure value of an eye. The object of the present disclosure is to provide a solution that at least partially overcomes the problems encountered in the prior art.

[0008] In one aspect, embodiments of the present disclosure provide a non-contact tonometer, comprising: an excitation and measurement unit, the excitation and measurement unit comprising: an electromagnetic exciter, the electromagnetic exciter comprising: at least one electric coil powered with a variable electric current (i) and arranged to generate a variable magnetic field, and at least one magnetic armature arranged to direct the variable magnetic field towards the eye to at least partially pass through the cornea of the eye.

[0009] In another aspect, embodiments of the present disclosure provide a method of measuring an intraocular pressure value of an eye, the method comprising: vibrating the cornea of the eye by providing a variable magnetic field, varying the frequency of the variable magnetic field in a predefined frequency range, measuring at least a peak amplitude value of the vibration of the cornea of the eye, finding a lowest value of the frequency corresponding to the peak amplitude value to find a resonance frequency value of the cornea of the eye, and calculating the intraocular pressure value of the eye using the resonance frequency.

[0010] The embodiments of the present disclosure substantially eliminate or at least partially solve the above mentioned problems in the prior art and achieve an improved, simple, compact, accurate, reliable and efficient non-contact tonometer. Advantageously, the non-contact tonometer employs an electromagnetic exciter to support the application of an excitation force on the cornea in a non-contact manner. Furthermore, the excitation force is limited to a desired portion of the cornea so as to be able to measure the intraocular pressure with better accuracy.

[0011] Additional aspects, advantages, features and objects of the present disclosure will become apparent to those skilled in the art from the detailed description of illustrative embodiments, taken in conjunction with the accompanying drawings.

[0012] It should be understood that the features of the present disclosure can be combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0013] The above summary of the present disclosure, as well as the following detailed description of illustrative embodiments, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the present disclosure are shown in the drawings. However, the present disclosure is not limited to the specific methods and instrumentalities disclosed herein. Moreover, one skilled in the art will understand that the drawings are not drawn to scale. Where possible, like elements have been designated with the same numerals.

[0014] Embodiments of the present disclosure will now be described, by way of example only, with reference to the following drawings in which: Figure 1A is a view of a first preferred embodiment of a non-contact tonometer according to an embodiment of the present disclosure; Figure 1B and Figure 1C is a view of a first preferred embodiment of an excitation and measurement unit according to an embodiment of the present disclosure; Figure 2A and Figure 2C is a view of a second preferred embodiment of a non-contact tonometer according to an embodiment of the present disclosure; Figure 2B and Figure 2D is a view of a second preferred embodiment of an excitation and measurement unit according to an embodiment of the present disclosure; Figure 3A and Figure 3B is a view of a third preferred embodiment of an excitation and measurement unit according to an embodiment of the present disclosure; Figure 3C is a view of a third preferred embodiment of a non-contact tonometer according to an embodiment of the present disclosure; Figure 4 is another view of a third preferred embodiment of an electromagnetic exciter according to an embodiment of the present disclosure; Figure 5Ais a view of a variable magnetic field generated towards an eye using a non-contact tonometer according to a first preferred embodiment of the present disclosure; Figure 5B and Figure 5C is a view of a first preferred embodiment of an electric current induced by a variable magnetic field inside an eye according to the first and second preferred embodiments of the present disclosure; Figure 6A and Figure 6B is a further view of a variable magnetic field generated towards an eye using a non-contact tonometer according to a third preferred embodiment of the present disclosure; and Figure 7 is a flowchart depicting steps of a method of measuring an intraocular pressure value of an eye according to an embodiment of the present disclosure.

[0015] In the drawings, underlined numerals denote elements or components, which are in the drawings designated with the underlined numerals. Un-underlined numerals refer to elements identified by the un-underlined numerals in the line linking the un-underlined numerals to the elements. When a numeral is un-underlined and accompanied by an associated arrow, the un-underlined numeral is used to identify the general element to which the arrow is pointing. DETAILED DESCRIPTION

[0016] The following detailed description shows embodiments of the present disclosure and ways in which they can be implemented. While some modes of implementing the present disclosure have been disclosed, those skilled in the art will recognize that other embodiments for implementing or practicing the present disclosure are possible.

[0017] In one aspect, embodiments of the present disclosure provide a non-contact tonometer, comprising: an excitation and measurement unit, the excitation and measurement unit comprising: an electromagnetic exciter, the electromagnetic exciter comprising: at least one electric coil, the at least one electric coil being powered with a variable electric current (i) and being arranged to generate a variable magnetic field, and at least one magnetic armature, the at least one magnetic armature being arranged to direct the variable magnetic field towards an eye to at least partially pass through a cornea of the eye.

[0018] In another aspect, embodiments of the present disclosure provide a method of measuring an intraocular pressure value of an eye, the method comprising: causing a cornea of the eye to vibrate by providing a variable magnetic field, varying a frequency of the variable magnetic field within a predefined frequency range, measuring at least a peak amplitude value of the vibration of the cornea of the eye, finding a lowest value of the frequency corresponding to the peak amplitude value to find a resonance frequency value of the cornea of the eye, and The resonant frequency is used to calculate the intraocular pressure of the eye.

[0019] This disclosure provides a simple, compact, robust, accurate, reliable, and user-friendly non-contact tonometer and method. Advantageously, the non-contact tonometer employs an electromagnetic actuator, which enables the application of excitation force to the cornea in a non-contact manner. Furthermore, the non-contact tonometer eliminates the risk of disease transmission from one subject to another. Additionally, the non-contact tonometer employs an electromagnetic actuator having at least one electrical coil and at least one magnetic armature, the at least one magnetic armature cooperating with each other to determine the eye's vibrational response and the intraocular pressure associated with that response.

[0020] According to embodiments of this disclosure, the term "non-contact tonometer" as used herein refers to an instrument used to measure the intraocular pressure (IOP) of the eye in a non-contact manner. As used herein, the term "internal pressure" (i.e., intraocular pressure (IOP)) refers to the fluid pressure within the eye. IOP exerts force on every part of the eye. It should be understood that the cornea, being the surface of the eye, is well-suited for measuring IOP. Measurement of IOP on the cornea can be easier and more accurate than IOP on other eye surfaces, such as the sclera. Notably, the measurement of IOP is crucial for maintaining overall eye health and function. It should be understood that non-contact tonometers can be used to measure intraocular pressure. Typically, such measurements enable the diagnosis and treatment of ocular hypertension before the development of eye-related conditions such as glaucoma.

[0021] A non-contact tonometer comprises an excitation and measurement unit. As used herein, the term "excitation and measurement unit" refers to a device used to excite the cornea of ​​the eye and also to measure the corneal vibration response to measure its intraocular pressure. In this document, excitation refers to the process of applying a variable force to the cornea of ​​the eye. The excitation and measurement unit includes an electromagnetic exciter. As used herein, the term "electromagnetic exciter" refers to a device that generates an electromagnetic force applied to the anterior segment of the eye, which is capable of causing mechanical movement of the cornea. In this sense, the electromagnetic force is the excitation force that causes mechanical movement such as oscillation or vibration of the cornea. In this example, the eye is considered as a thin-walled elastic container filled with pressurized fluid. Therefore, the eye exhibits mechanical vibration behavior and resonant frequencies.

[0022] The electromagnetic exciter includes at least one electric coil powered by a variable current (i) and arranged to generate a variable magnetic field. As used herein, the term "electric coil" refers to an electrical conductor in the shape of a coil (spiral or helix), such as an electrical wire. Optionally, the at least one electric coil consists of one or more turns of wire. Optionally, the shape and number of the at least one electric coil may vary depending on its application. Optionally, the at least one electric coil is made using insulated copper wire. Typically, the at least one electric coil is wound on a core. The electrical terminals of the coil are connected to a power source to receive current therefrom. In this document, the current is variable, preferably alternating current. It should be understood that, during operation, the electric coil is powered with a variable current to generate a variable magnetic field. Furthermore, the amount of current can be changed by increasing or decreasing the power supplied by the power source.

[0023] The electromagnetic actuator includes at least one magnetic armature. As used herein, the term "magnetic armature" refers to a structure made of ferromagnetic material associated with a winding (or set of windings) of at least one electric coil. Optionally, the at least one magnetic armature is a U-shaped magnetic armature having a first arm with a first end and a second arm with a second end. It should be understood that the at least one magnetic armature is capable of directing a variable magnetic field toward the eye, regardless of the shape of the at least one magnetic armature.

[0024] It should be understood that at least one electric coil and at least one magnetic armature are mounted together such that the at least one magnetic armature is operable to guide a variable magnetic field generated by the at least one electric coil toward the cornea of ​​the eye. Furthermore, the variable magnetic field is guided such that it can at least partially penetrate the cornea of ​​the eye. The variable magnetic field induces an electric current in the cornea and aqueous humor, which are conductive materials of the eye. The interaction between the induced current and the variable magnetic field generates a variable axial force on the cornea. The variable axial force applied to the cornea causes mechanical tremors of the cornea. The frequency of the alternating current supplying the electric coil is equal to the changing frequency of the variable magnetic field generated by the electric coil, also equal to the frequency of the variable electromagnetic force applied to the cornea, and also equal to the frequency of the mechanical tremors of the cornea.

[0025] Optionally, the at least one magnetic armature includes an inner magnetic armature, an outer magnetic armature, and a rear magnetic armature. Optionally, the inner magnetic armature has a tapered shape with an inner hole that may be substantially tapered. Optionally, the number and shape of the magnetic armatures may vary depending on the application. Optionally, the at least one electrical coil is placed inside the outer magnetic armature. Optionally, the at least one electrical coil is placed around the inner magnetic armature.

[0026] Optionally, the electromagnetic actuator further includes at least one permanent magnet. Optionally, the permanent magnet is a neodymium magnet or a samarium cobalt magnet, which are well-known types of strong magnets. Optionally, the electromagnetic actuator includes one or more permanent magnets that, together with a magnetic armature, apply a strong constant magnetic field to the cornea. Advantageously, the at least one permanent magnet is used to generate a constant magnetic field with a high magnetic induction value inside the eye, compared to the magnetic induction value of a variable magnetic field generated when only one coil is used in a non-contact tonometer.

[0027] In this respect, when a variable current is supplied to the coil, the variable magnetic field generated by the coil is added to the constant magnetic field generated by the permanent magnet. The resulting magnetic field exhibits a change in magnetic induction near a constant value of magnetic induction. This change in magnetic induction within the anterior segment of the eye generates a variable current in the cornea and aqueous humor, which are conductive materials. The interaction between the variable current and the strong constant component of the magnetic field generated by the permanent magnet produces a variable electromagnetic force, which is higher than the electromagnetic force obtained in the previous preferred embodiment without a permanent magnet. This higher electromagnetic force value improves the efficiency of corneal vibration excitation.

[0028] Optionally, the excitation and measurement unit also includes an optical displacement sensor. As used herein, the term "optical displacement sensor" refers to a displacement sensor that measures the distance between the sensor and an object using optical elements and a light beam. Optionally, the optical displacement sensor is positioned between the first and second arms of at least one U-shaped magnetic armature to detect corneal tremors. It should be understood that the optical displacement sensor is positioned appropriately to accurately detect corneal tremors. Optionally, the distance between the first and second arms is minimized towards the first and second ends closest to the eye. In this respect, this geometry enables effective measurement of corneal tremors.

[0029] Optionally, the optical displacement sensor is selected as at least one of a confocal chromatic displacement sensor and a laser Doppler vibrometer. As used herein, the term "confocal chromatic displacement sensor" refers to an instrument that works by focusing light (typically white light) with a broad wavelength band onto a target surface (such as the eye) using a high-dispersion objective lens. It should be understood that the confocal chromatic displacement sensor is used to resolve displacements of tens of nanometers measured at measurement frequencies of tens of kilohertz (kHz). Optionally, the confocal chromatic displacement sensor is used to measure distances from a few millimeters to tens of millimeters between the confocal chromatic displacement sensor and the eye. Advantageously, the confocal chromatic displacement sensor can be customized to make it cost-effective.

[0030] As used herein, the term "laser Doppler vibrometer" refers to a class of sensors used for non-contact vibration measurement of target surfaces, such as the eye. In this process, a laser beam from the laser Doppler vibrometer is directed towards the target surface, and the vibration amplitude and frequency are extracted from the Doppler shift of the reflected laser beam frequency caused by surface motion. Typically, the output of the laser Doppler vibrometer is a continuous analog voltage proportional to the target velocity component along the laser beam direction. Furthermore, laser Doppler vibrometers support precise measurement of corneal vibration amplitude.

[0031] Optionally, the confocal chromatic displacement sensor can be designed to operate using an infrared beam for measurement. In this regard, the confocal chromatic displacement sensor uses broadband infrared light as the measurement beam to measure the displacement of the cornea of ​​the eye. Advantageously, infrared light is invisible to the eyes of subjects such as patients. In this case, the inducement for blinking in the subject is reduced during the initial phase, for example, when the correct relative position is established between the non-contact tonometer and the eye. Optionally, infrared light is used to reduce the final blinking of the eye during its measurement. Furthermore, infrared light is unlikely to cause damage to the eye being measured. In addition, the beam of the confocal chromatic sensor is oriented perpendicular to the cornea. Optionally, a significant tilt of the beam axis relative to the normal direction of the eye is easily tolerated by the confocal chromatic displacement sensor. Therefore, the measurement may not be affected even if the non-contact tonometer is handheld and not properly tilted or oriented.

[0032] Alternatively, the optical displacement sensor can be operated to measure at least one of the following: The amplitude of tremor at at least one point on the cornea; The thickness of the cornea at at least one point; and The distance between the cornea and the excitation and measurement unit.

[0033] In this regard, the excitation and measurement unit includes an optical displacement sensor positioned near the cornea of ​​the eye, along with an electromagnetic exciter. Optionally, the optical displacement sensor is operable to measure the tremor amplitude of at least one point on the cornea. In this regard, the tremor amplitude of at least one point on the cornea refers to the difference between the maximum and minimum distances between the optical sensor and the cornea during corneal tremors. Optionally, the tremor amplitude is measured to determine the movement or deviation of the at least one point during a blink or another eye movement. It should be understood that the confocal chromatic displacement sensor can perform thousands of observations per second at a resolution of tens of nanometers, and thus enables precise measurement of the tremor amplitude of at least one point on the cornea. Optionally, the tremor amplitude of at least one point on the cornea is used to determine the resonant frequency of the cornea. In this regard, when the cornea is excited by a variable force, the cornea is forced to tremble at the frequency of the variable force. Furthermore, the tremor amplitude of the cornea has a peak when the frequency of the variable force equals the resonant frequency of the cornea. Furthermore, by scanning the frequency of the electromagnetic force that excites the cornea within a frequency range, the resonant frequency of the cornea can be identified as the frequency corresponding to the peak value of the corneal tremor amplitude. The resonant frequency of the cornea, depending on the intraocular pressure and corneal thickness, is typically in the range of 100-500 Hz.

[0034] Optionally, the optical displacement sensor is operable to measure corneal thickness at at least one point. Advantageously, a confocal chromatic displacement sensor is used to measure thickness because it has the ability to simultaneously measure the positions of both the outer and inner surfaces of the cornea. Corneal thickness characterizes corneal stiffness, which is a distracting factor when measuring intraocular pressure. Furthermore, when measuring corneal thickness, its value can be used to apply corrections when calculating intraocular pressure. This allows for the calculation of intraocular pressure with improved accuracy.

[0035] Optionally, an optical displacement sensor can be operated to measure the distance between the front of the non-contact tonometer and the cornea. It should be understood that this measured distance is used as feedback (such as visual or acoustic feedback) during the initial phase of the measurement. Furthermore, the measured distance indicates the correct position of the non-contact tonometer relative to the eye.

[0036] Optionally, when the non-contact tonometer is handheld, the measured distance can be used to provide feedback to the operator to confirm that the non-contact tonometer is placed in the correct position relative to the eye, or to indicate that a change in position is needed. Alternatively, the measured distance can be used as feedback in an automatic position control system. In this regard, the automatic position control system includes at least one actuator for changing the relative position of the non-contact tonometer relative to the eye. In this case, the actuator is controlled by using the measured distance as feedback. Optionally, at least one coil is used as a sensor by measuring the change in impedance of at least one coil caused by corneal tremors. In this regard, the maximum value of the coil's impedance corresponds to the peak value of the corneal tremor amplitude.

[0037] Alternatively, in a non-contact tonometer: The permanent magnet has a substantially annular shape and has a first pole and a second pole on opposite surfaces; The electromagnetic actuator has a proximal end and a distal end, and the electromagnetic actuator further includes a spatial volume extending along a centerline of the electromagnetic actuator from the proximal end to the distal end; and The at least one magnetic armature includes: An internal magnetic armature is arranged to at least partially surround the spatial volume in the proximal end and is magnetically coupled to the first pole of the permanent magnet via the second end. An external magnetic armature is arranged to at least partially surround the electric coil and is magnetically coupled to the second pole of the permanent magnet; And among them, The coil is arranged to at least partially surround the internal magnetic armature.

[0038] In this document, "ring-shaped" refers to a ring-shaped geometric pattern. Optionally, the permanent magnet has a ring shape with an inner hole that may have a cylindrical shape. Optionally, the permanent magnet has a first pole and a second pole located on opposite faces of the permanent magnet. Optionally, the electromagnetic actuator includes a proximal end and a distal end. In this respect, the proximal end is closer to the cornea of ​​the eye than the distal end, which is farther away from the eye. Optionally, the electromagnetic actuator also includes a spatial volume extending from the proximal end to the distal end along the centerline of the electromagnetic actuator. Optionally, the at least one magnetic armature includes the internal magnetic armature. In this document, the internal magnetic armature is arranged such that it at least partially surrounds the spatial volume at the proximal end. Furthermore, the internal magnetic armature is arranged such that it can be magnetically coupled to the first pole of the permanent magnet via a second end.

[0039] Optionally, the at least one magnetic armature includes the outer magnetic armature. In this document, the outer magnetic armature is arranged such that it at least partially surrounds the coil. Furthermore, the at least one outer magnetic armature is magnetically coupled to the permanent magnet. Optionally, the coil is arranged to at least partially surround the inner magnetic armature. It should be understood that the above arrangement supports improved measurement of the intraocular pressure of the eye's cornea. Optionally, the electromagnetic actuator can function even if at least one coil only surrounds the inner magnetic armature. Optionally, even without a permanent magnet, the electromagnetic actuator can function with a single coil and a coaxial configuration of at least one magnetic armature and coil.

[0040] Optionally, the optical displacement sensor is arranged within the spatial volume. In this regard, the aforementioned arrangement supports placing the optical displacement sensor near or at least partially within the internal magnetic armature. In this case, the light beam emitted by the optical displacement sensor can pass through the internal magnetic armature and reach the cornea of ​​the eye, enabling the measurement of its displacement.

[0041] This disclosure also relates to the method described above. Various embodiments and variations disclosed above are adapted to this method with necessary modifications.

[0042] Optionally, the variable magnetic field is generated by a coil powered by a variable current (i), and a frequency scan of the variable current is performed within the frequency range.

[0043] Optionally, the method further includes: Measure the thickness of the cornea of ​​the eye at at least one point; Measuring the resonant frequency of the cornea; and The intraocular pressure of the eye is calculated using both the resonant frequency of the cornea and the thickness of the cornea.

[0044] Optionally, the method further includes: The distance between the cornea and the excitation and measurement unit is measured, and The measured distance value is used as a feedback signal to place the excitation and measurement unit at the desired position relative to the cornea.

[0045] Optionally, the impedance of the coil is continuously measured during the frequency sweep of the variable current (i). In this case, the resonant frequency of the cornea is measured as the lowest frequency of the current (i) that causes the peak amplitude of the coil impedance.

[0046] In this regard, at least one electrical coil is used to measure the peak amplitude of corneal tremor. In this case, an induced current (I) passes through the anterior segment of the eye's tremor and causes a change in the impedance of at least one electrical coil. Furthermore, when the corneal tremor reaches its peak amplitude, the impedance of at least one electrical coil reaches its maximum value. Therefore, the initial peak amplitude of the corneal tremor can be determined by measuring the fluctuations in the impedance of at least one electrical coil using various electrical devices. The impedance of at least one electrical coil is continuously measured throughout the current frequency scan to complete the measurement. The lowest frequency of the current that causes the peak in the impedance of at least one coil is identified as the resonant frequency of the corneal tremor.

[0047] Detailed description of the attached figures refer to Figure 1A , Figure 1A This is a preferred embodiment of the non-contact tonometer 100 according to embodiments of the present disclosure. Reference Figure 1B and Figure 1C The diagram shows a perspective view of a first preferred embodiment of the excitation and measurement unit 102 according to embodiments of the present disclosure. The non-contact tonometer 100 includes an excitation and measurement unit 102 comprising an electromagnetic exciter 104. The electromagnetic exciter 104 includes at least one coil 106 powered by a variable current (i) (not shown) and arranged to generate a variable magnetic field (not shown). Furthermore, the electromagnetic exciter 104 includes at least one magnetic armature 108 arranged to direct the variable magnetic field toward the eye 110 to at least partially penetrate the cornea 112 of the eye 110. The excitation and measurement unit 102 also includes an optical displacement sensor 114 positioned together with the electromagnetic exciter 104 near the cornea 112 of the eye 110.

[0048] like Figure 1C The figure shows a perspective view of the excitation and measurement unit 102. As shown, at least one magnetic armature 108 is a U-shaped magnetic armature having a first arm 116 having a first end and a second arm 118 having a second end. As shown, at least one electrical coil 106 is mounted on the first arm 116 and the second arm 118 of the U-shaped magnetic armature. Additionally, the non-contact tonometer 100 includes an electrical terminal 120 for supplying power to the at least one electrical coil 106.

[0049] Figure 1A , Figure 1B and Figure 1C These are merely examples and should not unduly limit the scope of the claims. Those skilled in the art will recognize numerous variations, alternatives, and modifications to the embodiments of this disclosure.

[0050] refer to Figure 2A and Figure 2CA view of a second preferred embodiment of a non-contact tonometer 200 according to embodiments of the present disclosure is shown. (Reference) Figure 2B and Figure 2D This diagram shows a view of a second preferred embodiment of the excitation and measurement unit 202 according to embodiments of the present disclosure. The non-contact tonometer 200 includes the excitation and measurement unit 202. The excitation and measurement unit 202 includes an electromagnetic actuator 204. The electromagnetic actuator 204 includes at least one electric coil 206 powered by a variable current (i) and arranged to generate a variable magnetic field. Furthermore, the electromagnetic actuator 204 includes at least one magnetic armature, such as 208, 210, 212, arranged to guide the variable magnetic field toward the eye 214 to at least partially penetrate the cornea 216 of the eye 214. The electromagnetic actuator 204 also includes at least one permanent magnet, such as 218 and 220. The magnetic field guided toward the eye by the at least one magnetic armature has a tangential component (Bt) of magnetic induction within the eye. In this document, Figure 2A A top view of the non-contact tonometer 200 is depicted, and Figure 2B A perspective view of the non-contact tonometer 200 is depicted. As shown, the excitation and measurement unit 202 also includes an optical displacement sensor 222 positioned near the cornea 216 of the eye 214, together with the electromagnetic exciter 204.

[0051] In this article, Figure 2C A top view of the non-contact tonometer 200 is depicted, and Figure 2D A perspective view of the excitation and measurement unit 202 is depicted. As shown, at least one magnetic armature, such as 208, 210, and 212, is a U-shaped magnetic armature having a first arm with a first end and a second arm with a second end. Additionally, the non-contact tonometer 200 includes an electrical terminal 224 for supplying power to at least one electrical coil 206.

[0052] Figure 2A , Figure 2B , Figure 2C and Figure 2D These are merely examples and should not unduly limit the scope of the claims. Those skilled in the art will recognize numerous variations, alternatives, and modifications to the embodiments of this disclosure.

[0053] refer to Figure 3A and Figure 3B This image shows a view of a third preferred embodiment of the excitation and measurement unit 300 according to embodiments of the present disclosure. (See reference...) Figure 3C A view is shown of a third preferred embodiment of a non-contact tonometer 302 according to embodiments of the present disclosure. Figure 3AThe diagram shows a longitudinal section of the excitation and measurement unit 300 at its operating position near the cornea 301 of the eye 303. The excitation and measurement unit 300 has at least one electrical coil 304. The excitation and measurement unit 300 includes an electromagnetic actuator 309 having a proximal end 308 and a distal end 310, the electromagnetic actuator 309 also including a spatial volume extending from the proximal end 308 to the distal end 310 along the centerline of the electromagnetic actuator 306. At least one magnetic armature including an internal magnetic armature 312 is shown, the internal magnetic armature being arranged to at least partially surround the spatial volume in the proximal end 308. An external magnetic armature 314 is shown, which is arranged to at least partially surround at least one electrical coil 304 and is magnetically coupled to at least one permanent magnet 316. The at least one permanent magnet 316 has a substantially annular shape and has a first pole and a second pole on opposite faces. The at least one permanent magnet 316 is an optional component of the excitation and measurement unit 300 and is used to improve its efficiency. At least one electrical coil 304 is arranged to at least partially surround an internal magnetic armature 312. Additionally, the excitation and measurement unit 300 includes electrical terminals 318 for supplying power to the at least one electrical coil 304. Figure 3C As shown, the non-contact tonometer 300 includes an optical displacement sensor 320. (As...) Figure 3B As shown, it is a perspective view of the excitation and measurement unit 300 at its operating position near the eye 303. Figure 3C As shown, it is a top view of the non-contact tonometer 300 in its operating position near the eye 303.

[0054] Figure 3A , Figure 3B and Figure 3C These are merely examples and should not unduly limit the scope of the claims herein. Those skilled in the art will recognize numerous variations, alternatives, and modifications to the embodiments of this disclosure.

[0055] refer to Figure 4 This image shows another view of a third preferred embodiment of the electromagnetic actuator 400 according to embodiments of the present disclosure. In this document, Figure 4A coaxial version of the electromagnetic actuator 400 is shown. The figure shows a cross-sectional view of the electromagnetic actuator 400 applying vibrational excitation to the cornea 402. The electromagnetic actuator 400 includes at least one electric coil 404 and at least one magnetic armature. The at least one magnetic armature comprises an inner magnetic armature 406, an outer magnetic armature 408, and a rear magnetic armature 410. Herein, the inner magnetic armature 406 has a conical shape with an inner hole that may be substantially conical. Optionally, at least one electric coil 404 is placed inside the outer magnetic armature 408 and at least partially surrounds the inner magnetic armature 406. Optionally, the electromagnetic actuator 400 has at least one permanent magnet 412. Additionally, the electromagnetic actuator 400 includes an electrical terminal 414 for supplying power to the at least one electric coil 404. Furthermore, the at least one electric coil 404 is powered by a variable current (i) and arranged to generate a variable magnetic field 416. Here, the variable magnetic field 416 is a toroidal magnetic field. In addition, the electromagnetic actuator 400 includes at least one magnetic armature arranged to direct a variable magnetic field 416 toward the eye 418 to at least partially pass through the cornea 402 of the eye 418.

[0056] Figure 4 These are merely examples and should not unduly limit the scope of the claims herein. Those skilled in the art will recognize many variations, substitutions, and modifications to the embodiments of this disclosure.

[0057] refer to Figure 5A This image shows a view of a variable magnetic field 500 generated using a non-contact tonometer 502 according to a first preferred embodiment of the present disclosure. Figure 5A As shown, a first preferred embodiment of the non-contact tonometer 502 includes an excitation and measurement unit 504. The excitation and measurement unit 504 includes an electromagnetic actuator 506, which includes at least one coil 508 powered by a variable current (i) and arranged to generate a variable magnetic field 500. Furthermore, the electromagnetic actuator 506 includes at least one magnetic armature 510 arranged to guide the variable magnetic field 500 toward the eye 512 to at least partially penetrate the cornea 514 of the eye 512.

[0058] refer to Figure 5B and Figure 5C This illustrates a first preferred embodiment of a current induced by a variable magnetic field within an eye 512. Here, the variable magnetic field is generated by an electromagnetic exciter along with an induced current (I) and a generated electromagnetic force (Fem) applied to the cornea 514 of the eye 512. The variable magnetic field has a tangential component (Bt) of magnetic induction. Furthermore, the interaction between the induced current and the tangential component of the variable magnetic field generates an electromagnetic force.

[0059] Figure 5A , Figure 5B and Figure 5C These are merely examples and should not unduly limit the scope of the claims herein. Those skilled in the art will recognize numerous variations, alternatives, and modifications to the embodiments of this disclosure.

[0060] refer to Figure 6A and Figure 6B This illustrates another view of the variable magnetic field generated using a non-contact tonometer (not shown) according to a third preferred embodiment of this disclosure. Figure 6A and Figure 6B As shown, the variable magnetic field is generated by an electromagnetic exciter (not shown) along with an induced current and applied to the eye. Figure 1A The cornea described as 110 in the text ( Figure 1A The electromagnetic force (Fem) generated on the cornea 514 of the eye 512 is generated together with the induced current (I). The variable magnetic field is generated by an electromagnetic exciter together with the induced current (I) and the generated electromagnetic force (Fem) applied to the cornea 514 of the eye 512. The constant magnetic field of at least one permanent magnet (not shown) together with the variable magnetic field generated by at least one electric coil (not shown) is guided to the cornea of ​​the eye by at least one magnetic armature and at least partially through the corneal closure. In this document, the constant magnetic field generated by at least one permanent magnet 412 inside the eye has a radial component (Br) of magnetic induction. The interaction between the induced current (I) and the radial component (Br) of magnetic induction generates the electromagnetic force (Fem).

[0061] Figure 6A and Figure 6B These are merely examples and should not unduly limit the scope of the claims herein. Those skilled in the art will recognize numerous variations, alternatives, and modifications to the embodiments of this disclosure.

[0062] refer to Figure 7 A flowchart 700 depicting the steps of a method for measuring the intraocular pressure of an eye according to an embodiment of the present disclosure is shown. In step 702, the cornea of ​​the eye is vibrated by providing a variable magnetic field. In step 704, the frequency of the variable magnetic field is varied within a predefined frequency range. In step 706, at least the peak amplitude value of the corneal vibration is measured. In step 708, the lowest value of the frequency corresponding to the peak amplitude value is found to determine the resonant frequency value of the cornea. In step 710, the intraocular pressure of the eye is calculated using the resonant frequency.

[0063] Steps 702, 704, 706, 708, and 710 are illustrative only, and other alternatives may be provided, such as adding one or more steps, removing one or more steps, or providing one or more steps in a different order, without departing from the scope of the claims herein.

[0064] Modifications may be made to the embodiments of the present disclosure described above without departing from the scope of the present disclosure as defined by the appended claims. Expressions such as “comprising,” “including,” “incorporated,” “having,” and “are” used to describe and claim the present disclosure are intended to be interpreted in a non-exclusive manner, that is, allowing for the presence of elements, components, or elements not explicitly described. References to the singular should also be interpreted to refer to the plural.

Claims

1. A non-contact tonometer (100, 200, 302, 502), comprising: Excitation and measurement units (102, 202, 300, 504), wherein the excitation and measurement units include: Electromagnetic actuators (104, 204, 306, 400, 506), wherein the electromagnetic actuators include: At least one electric coil (106, 206, 304, 404, 508), said at least one electric coil is powered by a variable current (i) and is arranged to generate a variable magnetic field (416, 500), and At least one magnetic armature (108, 208, 210, 212, 510) is arranged to direct the variable magnetic field toward the eye (110, 214, 303, 418, 512) to pass at least partially through the cornea of ​​the eye (112, 216, 301, 402).

2. The non-contact tonometer (100, 200, 302, 502) as described in claim 1, wherein, The electromagnetic actuators (104, 204, 306, 400, 506) also include at least one permanent magnet (218, 220, 316, 412).

3. The non-contact tonometer (100, 200, 302, 502) as described in claim 1 or 2, wherein, The excitation and measurement units (102, 202, 300, 504) also include optical displacement sensors (114, 222, 320).

4. The non-contact tonometer (100, 200, 302, 502) as described in claim 3, wherein, The optical displacement sensors (114, 222, 320) are selected as at least one of the following: a confocal chromatic displacement sensor, a laser Doppler vibrometer.

5. The non-contact tonometer (100, 200, 302, 502) as described in claim 4, wherein, The confocal chromaticity shift sensor is operable to perform measurements using an infrared beam.

6. The non-contact tonometer (100, 200, 302, 502) as described in any one of claims 3 to 5, wherein, The optical displacement sensors (114, 222, 320) are operable to measure at least one of the following: The amplitude of the flutter at at least one point of the cornea (112, 216, 301, 402), The thickness of the cornea at at least one point; The distance between the cornea and the excitation and measurement units (102, 202, 300, 504).

7. The non-contact tonometer (100, 200, 302, 502) according to any one of the preceding claims, wherein, The at least one magnetic armature (108, 208, 510) is a U-shaped magnetic armature, which has a first arm (116) having a first end and a second arm (118) having a second end.

8. The non-contact tonometer (100, 200, 302, 502) as described in claim 7, wherein, The optical displacement sensors (114, 222, 320) are arranged between the first arm (116) and the second arm (118).

9. The non-contact tonometer (100, 200, 302, 502) as described in claim 7 or 8, wherein, The distance between the first arm (116) and the second arm (118) decreases toward the first end and the second end.

10. The non-contact tonometer (100, 200, 302, 502) as described in any one of claims 2 to 6, wherein, The permanent magnets (218, 220, 304, 412) have a substantially annular shape and a first pole and a second pole on opposite surfaces; The electromagnetic actuators (104, 204, 306, 400, 506) have a proximal end (308) and a distal end (310), and the electromagnetic actuators further include a spatial volume extending along the centerline of the electromagnetic actuator from the proximal end to the distal end; and The at least one magnetic armature (108, 208, 210, 212, 510) includes: An internal magnetic armature (312, 406) is arranged to at least partially surround the spatial volume and is magnetically coupled to the first pole of the permanent magnet via the second end. An external magnetic armature (314, 408) is arranged to at least partially surround the electric coil (106, 206, 316, 404, 508) and is magnetically coupled to the second pole of the permanent magnet; And among them, The coil is arranged to at least partially surround the internal magnetic armature.

11. The non-contact tonometer (100, 200, 302, 502) as described in claim 10, wherein, The optical displacement sensors (114, 222, 320) are arranged within the spatial volume.

12. A method for measuring the internal pressure of an eye (110, 214, 303, 418, 512), the method comprising: By providing variable magnetic fields (416, 500), the cornea of ​​the eye (112, 216, 301, 402) vibrates. The frequency of the variable magnetic field can be changed within a predefined frequency range. Measure at least the peak amplitude of the corneal tremor of the eye. Find the lowest value of the frequency corresponding to the peak amplitude value to find the resonant frequency value of the cornea of ​​the eye, and The resonant frequency is used to calculate the intraocular pressure of the eye.

13. The method according to claim 12, wherein, The variable magnetic field (416, 500) is generated by a coil powered by a variable current (i), and the frequency scan of the variable current is performed within the frequency range.

14. The method of claim 12 or 13, further comprising: Measure the thickness of the cornea (112, 216, 301, 402) of the eyes (110, 214, 303, 418, 512) at at least one point; Measure the resonant frequency value of the cornea; as well as The intraocular pressure of the eye is calculated using both the resonant frequency of the cornea and the thickness of the cornea.

15. The method of claims 12 to 14, further comprising: The distance between the cornea (112, 216, 301, 402) and the excitation and measurement units (102, 202, 300, 504) was measured, and... The measured distance value is used as a feedback signal to place the excitation and measurement unit at the desired position relative to the cornea.

16. The method according to any one of claims 13 to 15, wherein, The impedance of the coil is continuously measured during the frequency scan of the variable current (i), and the resonant frequency value is the lowest frequency of the current (i) that causes the peak amplitude value of the impedance of the coil.

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