Apparatus and related methods for measuring the characteristics of the eye

Abstract

A device for measuring the characteristics of the eye (100, 300, 400). The device comprises an execution unit (102, 202) comprising an impact means (104) configured to impact the cornea of ​​the eye, a firing means (114), and a solid probe (116); a measurement unit (106) comprising a confocal chromatic displacement sensor (108); and a controller (110) connected to the execution unit and the measurement unit. The controller is configured to operate the execution unit to impact the cornea of ​​the eye using the impact means, and to operate the measurement unit to measure the displacement of the cornea caused by the impact multiple times over a predetermined time period. The firing means is operable to fire at least one solid probe toward the eye and impact it.

Description

Technical Field

[0001] The disclosure of the present application (hereinafter referred to as the present disclosure) relates to an apparatus for measuring the characteristics of an eye. The present disclosure also relates to a method for measuring the characteristics of an eye. Background

[0002] A tonometer (ophthalmotonometer) is a device for measuring the pressure in the eye (e.g., intraocular pressure (IOP)). A device for measuring the central corneal thickness (CCT) is called a pachymeter. These devices are used to measure various characteristics of a subject's eye.

[0003] The measurement results can be used, for example, for diagnosis or to track changes over time in specific characteristics or parameters of the eye. As an example, the measured eye characteristics (such as IOP and CCT) are useful for the diagnosis and management of various eye diseases including glaucoma. Glaucoma can lead to vision loss if left untreated. In particular, there are various types of tonometers and various types of pachymeters that operate on different principles. A rebound tonometer is an example. A rebound tonometer can be used to determine an index of intraocular pressure (IOP) by firing a probe towards the eye and measuring the velocity profile when the probe collides with the surface of the eye. The IOP can be determined using this velocity profile. For example, a smaller change in velocity (dv / dt, i.e., acceleration) indicates a lower intraocular pressure. On the other hand, a faster change in velocity during impact suggests a higher intraocular pressure. An example of a pachymeter is a pachymeter using a confocal microscope. Another example is a pachymeter that measures the characteristics of the eyeball using ultrasonic waves. Currently, there is a problem that tonometers and pachymeters are separate devices. The operability and usability of two separate devices are inferior to those of a single device having both functions. Also, the cost of a single device may be lower than that of multiple separate devices.

[0004] A further problem with measuring intraocular pressure using a rebound tonometer is that the elastic properties of the eyeball can be a function of the central corneal thickness (CCT). Therefore, conventional intraocular pressure measurements may yield at least partially inaccurate values.

[0005] Another method for measuring intraocular pressure involves vibrating the surface of the eye (specifically the cornea) and measuring the frequency of the free vibrations of the cornea caused by impact. The frequency of these corneal free vibrations can be used to determine the intraocular pressure value. Currently, there is no readily available and convenient device for obtaining (or calculating) intraocular pressure using the frequency of corneal free vibrations caused by impact. Summary

[0006] This disclosure aims to provide a device for measuring the characteristics of the eye. One of the characteristics to be measured is intraocular pressure (IOP). According to this disclosure, the measurement is performed by applying an impact to the cornea of ​​the eye. This impact causes the cornea to begin vibrating at the frequency of the corneal free vibration (also called the natural frequency) caused by the impact. It has been found that the frequency of the corneal free vibration caused by the impact is a function of intraocular pressure. In this disclosure, a measurement unit is used to measure the displacement of the cornea caused by the impact. The measurement is performed over a predetermined time period. This allows the measurement unit to measure the frequency of the corneal free vibration caused by the impact. The frequency of the corneal free vibration caused by the impact is equal to or very close to the corneal resonant frequency (or natural frequency). However, if the vibration amplitude is large at the time of impact or immediately after impact, there may be a slight difference between the frequency of the corneal vibration caused by the impact and the corneal resonant frequency. On the other hand, if the amplitude is small, the cornea vibrates at its resonant frequency.

[0007] In one aspect, embodiments of the present disclosure provide an apparatus for measuring the characteristics of the eye. This apparatus is An execution unit comprising an impact means positioned to deliver an impact to the cornea of ​​the eyeball, the execution unit comprising a firing means and at least one solid probe; • A measurement unit including at least one confocal chromatic displacement sensor; The controller connected to the execution unit and the measurement unit; It has, The controller is configured to operate the execution unit to apply an impact to the cornea of ​​the eye using the impact means, and to operate the measurement unit to measure the displacement of the cornea caused by the impact multiple times over a predetermined period of time; The firing means is operable to fire the at least one solid probe toward the eye and deliver an impact.

[0008] In another aspect, embodiments of the present disclosure provide a method for measuring the characteristics of the eye. This method is • To generate an impact on the cornea of ​​the eye using an execution unit provided in the device; This includes: measuring the displacement of the cornea caused by the impact multiple times over a predetermined period of time using a measuring unit; The measurement unit comprises at least one confocal chromatic displacement sensor; The impact is generated by firing at least one solid probe, provided in the execution unit, toward the eye.

[0009] Embodiments of this disclosure substantially eliminate, or at least partially solve, the aforementioned problems of the prior art, and provide an improved device for measuring eye properties that is simple, compact, accurate, reliable, and cost-effective. Advantageously, the device delivers an impact only to the cornea of ​​the eye, thereby inducing the desired vibrations only within the cornea. Furthermore, the device employs at least one confocal chromatic displacement sensor, enabling measurement of eye properties with greater precision.

[0010] Further aspects, advantages, features, and objectives of what is disclosed herein will be revealed by the accompanying drawings and the detailed description of exemplary embodiments, which shall be interpreted together with the accompanying claims.

[0011] It will also be understood that a feature of this disclosure is that it can be combined in various ways without departing from the scope defined by the attached claims. [Brief explanation of the drawing]

[0012] The above summary and the following detailed description of exemplary embodiments will be better understood in conjunction with the accompanying drawings. For illustrative purposes of this disclosure, exemplary configurations of this disclosure are shown in the drawings. However, this disclosure is not limited to the specific methods and apparatus disclosed herein. The scale of the drawings is not accurate. Similar elements are indicated by the same number whenever possible. Hereinafter, embodiments of the present disclosure will be described only as examples, with reference to the following drawings. [Figure 1A] This is a block diagram of an apparatus for measuring eye characteristics according to one embodiment of the present disclosure. [Figure 1B] This is a block diagram of an execution unit of an apparatus according to one embodiment of the present disclosure. [Figure 2] This is a block diagram of an execution unit of the apparatus according to another embodiment of the present disclosure. [Figure 3] This is a block diagram of an apparatus according to another embodiment of the present disclosure. [Figure 4] This is a block diagram of an apparatus according to another embodiment of the present disclosure. [Figure 5] This is a graphical representation of frequency against intraocular pressure values ​​according to a first preferred embodiment of the present disclosure. [Figure 6] This flowchart shows the steps of a method for measuring eye characteristics according to one embodiment of the present disclosure. [Figure 7] An example according to one embodiment of the present disclosure is shown. In the accompanying drawings, underlined numbers are used to represent the item at the location of the number or the item adjacent to that number. Detailed description of the embodiment

[0013] The following detailed description illustrates embodiments of the present disclosure and methods by which they may be implemented. Although several embodiments for implementing the present disclosure have been disclosed, those skilled in the art will recognize that other embodiments for implementing the present disclosure are also possible.

[0014] According to one aspect, embodiments of the present disclosure provide an apparatus for measuring the characteristics of an eye. The apparatus includes · an execution unit including impact means arranged to apply an impact to the cornea of the eye, the execution unit including launching means and at least one solid probe; · a measurement unit including at least one confocal chromatic displacement sensor; · a controller connected to the execution unit and the measurement unit; and the controller is configured to operate the execution unit to apply an impact to the cornea of the eye using the impact means and to operate the measurement unit to measure the displacement of the cornea caused by the impact a plurality of times during a predetermined time period; the launching means is operable to launch the at least one solid probe towards the eye to apply an impact.

[0015] According to another aspect, embodiments of the present disclosure provide a method for measuring the characteristics of an eye. The method includes · generating an impact on the cornea of the eye using an execution unit provided in the apparatus; · measuring the displacement of the cornea caused by the impact a plurality of times during a predetermined time period using a measurement unit; and the measurement unit includes at least one confocal chromatic displacement sensor; the impact is generated by launching at least one solid probe provided in the execution unit towards the eye.

[0016] This device can be used to measure the characteristics of the eye. One of the characteristics to be measured is the corneal displacement as a function of time. The displacement as a function of time provides information that can be used to determine further characteristics. The device provides an impact by means of emission means on the cornea of the eye. As an example, electromagnetic force is used to eject a solid probe towards the eye. After the collision, the probe bounces back. During and after the collision, the displacement of the cornea is measured by a confocal chromatic sensor. For example, the natural vibration frequency of the cornea can be identified using the displacement as a function of time. This frequency is correlated with the intraocular pressure (IOP).

[0017] One of the advantages of measuring both IOP and CCT with the same device is that the CCT value can be used to apply a correction when calculating the IOP, and thus a more accurate IOP value can be obtained. Also, another advantage of performing both measurements with the same device is that a single device is easier to operate and less costly than measuring IOP and CCT separately with two devices.

[0018] The present disclosure provides a device for measuring the characteristics of the eye. This device includes an execution unit equipped with impact means. The applied impact causes the cornea to start vibrating. Thereafter, the device measures the vibration behavior of the cornea using a measurement unit. The measurement unit uses a confocal chromatic displacement sensor (CCS) as the measurement means. Specifically, the CCS intermittently measures the displacement of the cornea caused by the impact over a certain period of time.

[0019] This series of corneal displacements at a given time can be used to identify the natural vibration frequency of the cornea caused by the impact. In fact, the measured displacement can be used to identify the natural vibration frequency of the cornea caused by the impact, and further can be used to calculate the intraocular pressure based on the natural vibration frequency of the cornea caused by the impact.

[0020] A further advantage of using CCS as a measurement method is that the device not only measures pressure (tonometer function) but also corneal thickness (pachymeter function). Corneal thickness measurement is possible because CCS can simultaneously measure the positions of the outer and inner surfaces of the cornea. Therefore, this device can be considered a multi-functional device that simultaneously measures two characteristics of the eye (CCT and IOP).

[0021] As a further advantage, the measured CCT values ​​can be used to apply corrections to calculations in order to improve the accuracy of IOP value calculations. The device employs at least one confocal chromatic displacement sensor to precisely measure the characteristics of the eye.

[0022] In the embodiments of this disclosure, the term “apparatus” as used herein refers to an instrument used to measure various characteristics of the eye. In this regard, characteristics refer to physiological parameters related to the eye. Depending on the embodiment, characteristics such as intraocular pressure (i.e., the pressure value inside the eyeball) (IOP) and central corneal thickness (CCT) can be measured with the apparatus. A further advantage of the (multi-function) apparatus is that it can be used as a non-contact device for measuring central corneal thickness.

[0023] As used herein, the term “execution unit” refers to a configuration used to deliver an impact to the cornea of ​​the eye during use. As used herein, the term “impact means” refers to means used to deliver an impact to a surface. The impact means is provided within the execution unit. An impact means is a means that can be used to deliver an impact to a surface. As an example, an impact means may include an electric coil and a magnetic probe. The magnetic probe has an elongated body. In this example, the electric coil is used to accelerate the probe toward the eye. Thus, the probe is fired / projected from the execution unit toward the eye and collides with the eye. As an example, this impact means is used to deliver an impact to the surface of the eyeball. To cause local vibration of the cornea, the impact means is configured to deliver an impact only to the cornea of ​​the eyeball.

[0024] In this specification, “measurement unit” refers to a component used to measure vibrations of the cornea of ​​the eye. An example of a measurement unit is a measurement unit comprising at least one confocal chromatic displacement sensor (CCS). The confocal chromatic displacement sensor is positioned in the device so that it can be used to measure vibrations caused by an impact. Further advantages of using a confocal chromatic displacement sensor are its fast response speed and high accuracy. The corneal displacement values ​​due to the applied impact are less than millimeters. Because the confocal chromatic displacement sensor can measure displacement with a resolution of tens of nanometers, it can even measure corneal vibrations caused by very weak impacts. A high measurement frequency is required to take a sufficient number of measurements within a predetermined time and to know the frequency of the vibration. That is, the measurement frequency should be at least twice (3 times, 5 times, 10 times, etc.) the frequency of the corneal vibration, based on the Nyquist sampling theorem. A CCS may have a measurement frequency of several thousand times per second, which is high compared to the typical frequency of free vibration of the cornea (several hundred hertz). For this reason, a CCS can be used to directly measure the vibrational behavior of the cornea after impact.

[0025] As used herein, the term “confocal chromatic displacement sensor (CCS)” refers to an instrument that operates by focusing a light beam having a broadband wavelength (typically white light) onto the surface of a target (e.g., the eye) using a high-dispersion objective lens. The measurement unit comprises at least one confocal chromatic displacement sensor, which is positioned appropriately to accurately identify corneal vibrations. In some embodiments, the light beam is directed perpendicular to the cornea. Advantageously, the confocal chromatic displacement sensor has the ability to tolerate large inclinations of the beam axis relative to the normal direction of the measurement surface (including reaching tens of degrees). As a result, measurements may not be affected even if the device is handheld and not properly centered or oriented. The confocal chromatic displacement sensor can be used for displacement measurements with a measurement frequency of tens of kilohertz (kHz) and a resolution of tens of nanometers. The confocal chromatic displacement sensor enables precise measurement of the position of at least one point on the cornea. Advantageously, confocal chromatic displacement sensors can be customized to identify only the vibration frequency of the cornea, in order to improve cost efficiency. In some embodiments, at least one confocal chromatic displacement sensor uses infrared (IR) light as the measurement beam. Advantageously, infrared light is invisible to the patient's eye. This reduces the subject's urge to blink during the initial stages of setting the appropriate relative position between the device and the eye. Furthermore, infrared light is less likely to damage the eye being measured. Advantageously, confocal chromatic phase difference sensors have the ability to simultaneously measure the positions of both the outer and inner surfaces of the cornea, making it possible to measure corneal thickness. Corneal thickness can be calculated as the difference between the positions of the outer and inner surfaces of the cornea multiplied by the refractive index of the cornea. Confocal chromatic displacement sensors have high resolution and can detect even minute values ​​of corneal vibration amplitude. Typically, CCS is configured to measure at a single point on the cornea. In addition, confocal chromatic displacement sensors do not require contact with the cornea, reducing the risk of infection and discomfort to the subject.Furthermore, confocal chromatic displacement sensors enable high-speed measurement of eye characteristics. Confocal chromatic displacement sensors make the device user-friendly and do not require advanced training to operate. This increases their usability by healthcare professionals in a variety of environments.

[0026] The term "controller" refers to a computer device capable of operating to control the overall operation of a device. During operation, the controller performs tasks such as using execution units, using measurement units, responding to and processing information, etc. However, the tasks it performs are not limited to these. For example, the controller may include an embedded microcontroller or microprocessor. The controller is also combined with the measurement units and execution units. The controller may be implemented as an internal component of the device, as an external component of the device, or as a combination of these.

[0027] The controller is configured to operate the execution unit by supplying power to it. The execution unit is powered to deliver an impact to the cornea of ​​the eye. The eyeball is considered a thin-walled elastic vessel filled with pressurized fluid. Therefore, the eyeball has mechanical vibrational behavior and a resonant frequency. In this disclosure, the frequency of the free vibration of the cornea caused by the impact is measured. This represents the resonant frequency well and can therefore be used to determine intraocular pressure (IOP). When the cornea is impacted, it deforms and then rapidly returns to its original shape. This creates vibrations in the position of the cornea. These vibrations are temporal changes (displacements) in the position of the cornea.

[0028] The controller is further configured to operate the measurement unit. The measurement unit is used to measure the displacement of the cornea caused by impact multiple times over a predetermined time period. Here, multiple measurements refer to a series of measurements of corneal displacement over a predetermined time period. The multiple measurements provide displacement information as a function of time, which can be used to determine the vibration frequency. In addition, the measurements provide information about the amplitude of the vibration. Depending on the embodiment, multiple measurements make it possible to track the progression of corneal displacement over time and to gain a deeper understanding of the impact on the cornea. Here, displacement refers to the change in position caused by corneal vibration. Measurements are taken at a frequency sufficient to identify corneal vibration. For example, since the frequency of free vibration is usually less than 400 Hz, the number of measurements by the displacement sensor may be 800 times per second. The typical expected frequency of corneal vibration is in the range of 240 Hz to 400 Hz. That is, taking multiple measurements means taking about 800 measurements per second. To obtain more precise information regarding vibration, the sampling rate (number of measurements) of corneal displacement may be set to 1000 or more times per second (e.g., 2000 times). The predetermined time for sampling corneal displacement can be, for example, the time required until the corneal vibration stops (or decreases to a predetermined amplitude level).

[0029] Depending on the embodiment, the apparatus further comprises a computing unit connected to the controller. This computing unit is • Using multiple corneal displacement measurements, the frequency of free vibration of the cornea due to impact is calculated. • Calculate the value of intraocular pressure as a function of the frequency of free vibration of the cornea caused by impact. It can behave in that way.

[0030] In this specification, “calculation unit” refers to electronic hardware or software algorithms used to perform mathematical operations to convert raw data into meaningful measurements. The calculation unit is associated with a controller to allow for greater flexibility and customization based on the design of the device. In some embodiments, the calculation unit is integrated into the controller. The calculation unit can operate to calculate the frequency of corneal free vibrations induced by impact, based on a series of measurements performed. The calculation unit can further operate to use the calculated frequency of corneal free vibrations caused by impact and determine intraocular pressure using the value of the frequency of said corneal free vibrations. The cornea performs free vibrations while decreasing amplitude and eventually stops. The frequency of corneal free vibrations due to impact correlates with intraocular pressure. In an alternative embodiment, the calculation unit can be located away from the device. For example, it can be implemented in a smartphone that is connected to the device. Alternatively, the calculation unit can be implemented in a server system located away from the device. In this scenario, measurements from the measurement unit are provided to the server (or possibly the smartphone), and the calculation of intraocular pressure and other possible parameters is performed on the server. Essentially, the capability can be distributed between the device and an external computing unit. One method for calculating intraocular pressure from free vibrations is to build a physiological model of the eye and use the vibration frequency, (probe) impact value, etc., as input to calculate the pressure. Another method for calculating intraocular pressure is to use a lookup table that provides intraocular pressure values ​​associated with vibration frequencies.

[0031] As used herein, the term “intraocular pressure (IOP)” refers to the fluid pressure within the eyeball. Depending on the embodiment, the calculation unit may apply various mathematical models, such as regression analysis and curve fitting, to the raw data to obtain the most accurate and reliable measurements of IOP values. Depending on the embodiment, the calculation unit may perform other functions such as error correction, data storage, and data analysis. IOP is used to diagnose the overall health and function of the eyeball. In some cases, the eyeball behaves like a mass-spring system, and IOP represents the spring constant. In some cases, the cornea, when displaced from its natural position by an external force, vibrates as a damped harmonic oscillator at a frequency related to IOP. Since IOP modulates the stiffness of the eyeball and cornea, the vibration frequency increases with increasing IOP. Measuring IOP values ​​allows for the diagnosis and treatment of ocular hypertension before the onset of eye-related diseases.

[0032] In some embodiments, the measuring unit is configured to measure the corneal thickness at at least one point on the cornea. That is, the measuring unit can measure the corneal thickness at one or more points on the cornea. Advantageously, the measuring unit has the ability to simultaneously measure the location of both the outer and inner surfaces of the cornea, thus allowing the measurement of corneal thickness. Corneal thickness characterizes corneal rigidity and therefore affects the frequency of corneal free vibrations due to impact and intraocular pressure (IOP). The technical benefit of including the thickness value when determining IOP from the frequency of corneal free vibrations due to impact is that it makes the determined value more accurate.

[0033] In some embodiments, the calculation unit can be operated to apply a correction to the intraocular pressure (IOP) value calculated based on the measured corneal thickness value. Corneal thickness characterizes corneal stiffness, which is an interfering factor in IOP measurement. When corneal thickness is measured, this value can be used to apply a correction when calculating the IOP value. For example, corneal thickness correlates with the frequency of free vibration of the cornea due to impact, and this frequency is used in the calculation of the IOP value. This improves the accuracy of the IOP calculation. As an example, if central corneal thickness is measured, the values ​​in Table 1 (below) can be used as a basis for the correction calculation. For example, if the thickness is 485 micrometers, the IOP value is corrected by adding 3 mmHg. If the measurement point is not central, the values ​​in the table need to be modified. This table can be used as a lookup table, and it is also possible to derive correction values ​​as a function of corneal thickness, for example, from these values. The technical effect obtained from this is that it enables more accurate measurement of intraocular pressure. [Table 1]

[0034] The execution unit comprises a launching means and at least one solid probe. The launching means is operable to launch at least one solid probe toward the eye and generate (or in other words, deliver) an impact.

[0035] As used herein, the term “launching means” refers to a mechanical element used to launch (i.e., project, throw, eject) at least one solid probe from an execution unit at a predetermined speed and in a predetermined direction. The launching means enables efficient and precise movement of the solid probe during use. In some embodiments, the launching means partially encloses the solid probe. The solid probe may include, for example, an elongated magnetic body and a tip provided at its end. Here, the launching means is configured as a solenoid having a series of loops capable of moving at least one solid probe. The launching means moves the solid probe when an electric current is supplied to it (due to the electromagnetic force exerted by the magnetic field on the elongated magnetic body of the probe). In some embodiments, the launching means ejects the elongated magnetic probe and simultaneously ejects at least one solid probe toward the eye at a predetermined speed. As the probe is ejected toward the eye, the tip of the probe eventually strikes the eye, causing the cornea of ​​the eye to vibrate. The frequency of this vibration is the frequency of the free vibration of the cornea caused by the impact. After the impact, the probe bounces back from the eye. The firing mechanism can further be configured to retract the probe into the execution unit or inside the firing mechanism in preparation for the next measurement. The firing mechanism and at least one solid probe work together to deliver a precise impact to the cornea of ​​the eye. That is, the probe velocity is the desired velocity and the impact is delivered to the appropriate location on the cornea. The examples of solid probes and electromagnetic firing mechanisms described are not the only possible forms of solid probes and firing mechanisms. It is also possible to use other types of solid probes and firing mechanisms based on different operating principles.

[0036] Impact to the cornea by a solid probe generates multiple corneal vibrations during the period from the impact to the cessation of vibration. Using a CCS (Corneocentric Stimulus Spectroscopy), it is possible to obtain a set of displacement measurements over a time range that includes some or all of the complete free vibrations induced / generated by the impact. This technique is less susceptible to measurement errors compared to known rebound tonometers because the frequency of the corneal free vibrations induced by the impact can be calculated as an average value over a long period that includes multiple complete periods of corneal vibration. In contrast, known rebound tonometers measure only during a much shorter time, approximately half a period of corneal vibration, i.e., only at the time of impact. The frequency of corneal free vibrations induced by the impact and measured by the CCS is related to intraocular pressure, enabling the calculation of intraocular pressure. Therefore, this disclosure provides a more precise solution.

[0037] This device enables precise identification of the intraocular stimulation site. By firing at least one solid probe towards the eye and applying an impact, the cornea is stimulated (or displaced), forming a stimulation site. Therefore, the stimulation site can be accurately identified. Displacement measurement at the stimulation site is performed with high precision and reliability. The solid probe collides with the cornea, and measurement is performed at the stimulation site. By applying the impact realized by the firing mechanism, corneal displacement over a predetermined time period can be measured consistently and reproducibly using a confocal chromatic displacement sensor. With this configuration, it is possible to calculate basic parameters such as the frequency of corneal free vibration and determine the intraocular pressure value based on them. Because the probe is solid and has predetermined dimensions (such as the area of ​​the tip that contacts the surface of the eyeball), the impact (and the force and pressure of the impact) can be precisely controlled. If it is necessary to change the impact value (Newton-seconds), the probe speed can be adjusted accordingly. It is also possible to change to probes with different weights and geometric dimensions. For example, even if the probe speed and weight at impact are the same, reducing the tip area will cause greater pressure to act on the eyeball over a smaller area. This may result in a vibration pattern that is easier to measure than when the tip is larger. Depending on the embodiment, the execution unit may comprise a firing means and at least one drop of liquid. The firing means operates to fire at least one drop of liquid towards the eye and generate (i.e., add) an impact.

[0038] The term "launching means" as used herein refers to a separate mechanical element used to release or project one or more drops of liquid towards the eye in order to strike the cornea of ​​the eyeball. An example of a launching means for projecting one or more drops of liquid may include a pressurized liquid container with an electrically controlled valve and a nozzle directed towards the eye when in use. When the valve is controlled, the liquid drops are projected from the nozzle. Alternatively, the liquid may be sprayed using, for example, a piston mechanism. In some embodiments, the at least one drop of liquid is selected from at least one of water, saline solution, or physiological saline. In some embodiments, the at least one drop of liquid is water. In some embodiments, the water droplet may be used as a non-irritating liquid that can be sprayed without causing damage or discomfort to the eye. In some embodiments, the at least one drop of liquid is saline solution. Typically, the saline solution is a solution of sterile water and salt and is used for various purposes, such as eye washing. Eye washing is the process of rinsing the eye with a flow of fluid to remove foreign objects, irritants, or chemicals that have entered the eye. In some embodiments, the at least one drop of liquid is physiological saline (a solution of salts, approximately 0.9% sodium chloride solution), which may contain other salts, and is essentially isotonic with tissue fluid or blood. In this embodiment, the controller is configured to operate the execution unit so that, during operation, the associated firing means fires at least one drop of liquid towards the eye to generate impact and vibration to the cornea. The frequency of corneal free vibration after impact indicates the value of intraocular pressure (IOP). In particular, high IOP indicates increased rigidity of the eyeball, and therefore an increase in the frequency of corneal free vibration after impact is observed in the measurement. Conversely, low IOP indicates decreased rigidity of the eyeball, and therefore a decrease in the frequency of corneal free vibration after impact is observed.

[0039] As described above, in some embodiments, the device ejects at least one drop of liquid onto the cornea, generating an impact. The impact of the liquid on the ocular surface generates vibrations. It is possible to measure the vibrational behavior of the cornea over a time range that includes multiple corneal free vibrations induced by the impact. This type of measurement allows for the calculation of the frequency of the corneal free vibrations induced by the impact, which is related to intraocular pressure. An advantage of using a liquid droplet as the impact means is that the possibility of disease transmission can be eliminated. When using liquid, sterile liquid can be stored in the device's container and dispensed from the device without the risk of contamination.

[0040] In some embodiments, the at least one solid probe is designed to contain at least one droplet, and the launching means is operable to launch the at least one solid probe toward the eye, causing the at least one droplet to reach the cornea of ​​the eye and produce an impact. Alternatively, the droplet launching mechanism may include an open container filled with an appropriate amount of liquid. This container is pushed toward the cornea at a predetermined speed and stopped just before contact with the cornea, thereby ejecting the droplet from the container. The droplet continues its motion toward the cornea due to inertia, eventually impacting the cornea. One problem when spraying small amounts of liquid is the surface tension of the liquid. In this regard, one means of supplying liquid toward the eye is to use a piston that ejects the droplet through an opening. This type of configuration has been found to supply droplets of a constant size and speed.

[0041] Regardless of the technique used to apply impact to the cornea (impact with a solid probe or impact with a droplet), the presence of a CCS sensor, used to measure the vibrational behavior of the cornea after impact, also enables the measurement of central corneal thickness (CCT). This allows the device to perform not only tonometer function (IOP measurement) but also pachymeter function (CCT measurement).

[0042] Depending on the embodiment, the apparatus may further • At least one sensor element capable of measuring the distance between the cornea of ​​the eye and the device; A feedback element connected to at least one of the aforementioned sensor elements, which provides feedback based on the measured distance; Equipped with, The aforementioned feedback is selected from at least one of visual feedback or acoustic feedback.

[0043] Here, the sensor element refers to a device capable of measuring the position of the cornea and converting the positional information into a measurable or processable electrical or digital signal. Depending on the embodiment, the at least one sensor element may be an internal or external component of the device. Depending on the embodiment, the at least one sensor element may be used alone or in combination with other sensors to provide complex and detailed measurements of the environment or system being monitored. As used herein, the term “feedback element” refers to means for generating a feedback signal using the output signal provided by the at least one sensor element. The feedback element may be used to provide information useful for the user to correctly position the device relative to the eye and to establish the timing for performing measurements.

[0044] The at least one sensor operates in conjunction with the feedback element to assist a human operator in correctly positioning the device relative to their eyes when the device is a handheld unit. In some embodiments, the feedback is provided as visual feedback. For example, the measured distance is displayed on the device's screen. In some embodiments, the visual feedback is expressed in the form of text or graphic information, or as an LED light that turns on / off or changes color. In some embodiments, the feedback is provided as acoustic feedback. For example, the feedback is provided to the operator of the device as audio feedback via a speaker associated with the device. The visual or acoustic feedback is used to assist a human operator in correctly positioning the device relative to their eyes.

[0045] Depending on the embodiment, the apparatus may further • At least one sensor element capable of measuring the distance between the eye and the device; A control unit connected to at least one of the sensor elements, providing a command signal based on the measured distance, and automatically controlling the relative position between the device and the eye; • At least one actuator connected to the control unit and capable of operating to change the relative position between the device and the eye based on the command signals received from the control unit; It is equipped with.

[0046] Here, “actuator” refers to a component that receives a command signal and, based on the received signal, performs an action to change the relative position of the device and the eye. Depending on the embodiment, this may include moving the device closer to or further away from the eye, or adjusting its angle or orientation. Examples of actuators include motors, solenoids, piezoelectric devices, etc. The device is positioned relative to the eye by at least one actuator. The command signal applied to the actuator is based on position feedback obtained by measuring the distance between the device and the eye by the sensor element. For example, if the measured distance exceeds a desired distance, the control unit compares the measured distance value with the desired distance value, calculates the position error, and transmits a command signal to the actuator based on the position error. The actuator executes the command and moves the device to a desired position relative to the eyeball. The desired position may be a predetermined distance and direction relative to the eyeball or pupil. The predetermined distance depends on the operating range of the impact means from the device and the operating distance of the measuring unit. The operating range of the impact means is, for example, the distance range between the device and the cornea in which the solid probe can be launched toward the cornea at a predetermined speed when using a solid probe, and where it is guaranteed that the solid probe, after impact, will be recaptured within the launch means. For example, the predetermined distance can be 5 mm to 20 mm, or from 5 mm, 10 mm, 15 mm to 10 mm, 15 mm, 20 mm. The direction can be, for example, ±10 degrees with respect to the normal to the corneal surface in the measurement direction.

[0047] Depending on the embodiment, the at least one sensor element capable of measuring the distance between the eye and the device is selected from one or more of a confocal chromatic displacement sensor, a laser position sensor, and an ultrasonic position sensor.

[0048] The advantage of using a confocal chromatic displacement sensor lies in its ability to perform all necessary measurements. Specifically, it can perform a series of corneal position measurements, corneal thickness measurements, and distance measurements between the device and the cornea necessary to correctly position the device relative to the eye, which are required to determine the corneal vibration frequency necessary for calculating intraocular pressure (IOP).

[0049] Alternative or additional position sensors (in addition to CCS) include laser position sensors and ultrasonic position sensors. The advantages of these sensors are their lower complexity compared to CCS, and therefore lower cost. Furthermore, distance measurement does not require the same level of precision as vibration measurement.

[0050] The advantage of introducing additional sensors is that, if the CCS sensor is designed to meet specific requirements (low cost, high accuracy, infrared use, miniaturization), its distance measurement range can be very narrow (a few millimeters).

[0051] In this case, there is a benefit to introducing other types of low-cost additional sensors, such as laser position sensors or ultrasonic position sensors. These additional sensors may have a wider measurement range than the CCS sensor, making them useful as an aid in positioning the device relative to the eyeball before the cornea enters the measurement range of the CCS sensor. The presence of these additional sensors makes it possible to use a CCS sensor with a reduced measurement range. This leads to cost reductions and improved measurement accuracy of the CCS sensor. In this case, the additional distance sensor is used to provide a position feedback signal when the device is relatively far from the measurement position relative to the eye, such as in the initial stages of an eye examination, while the cornea is outside the measurement range of the CCS sensor. After the device has finally reached the measurement position relative to the eye, position feedback can be continuously obtained from the measurements of the auxiliary position sensor, using the CCS sensor, or a combination of both. Thus, by adding low-cost position sensors, the measurement range of the CCS sensor can be reduced, resulting in significant cost savings without compromising the usability of the device.

[0052] In some embodiments, the device is a tonometer. In some embodiments, the device may be a rebound tonometer.

[0053] This disclosure also relates to the method described above. Various embodiments and modifications disclosed above with respect to the first aspect described above are applicable to this method.

[0054] Depending on the embodiment, the method may further be: • Using a computing unit, calculate the frequency of free vibration of the cornea due to impact using multiple corneal displacement measurements; • Calculating the value of intraocular pressure using the frequency of free vibration of the cornea caused by impact; Includes.

[0055] Depending on the embodiment, the method includes measuring the corneal thickness at at least one point on the cornea using a measuring unit.

[0056] Depending on the embodiment, the calculation unit may be used to apply a correction to the calculated intraocular pressure value based on the measured thickness value.

[0057] Depending on the embodiment, the method may further be: • Measuring the distance between the cornea of ​​the eye and the device; • Using the measured distance as feedback to position the execution unit in a predetermined location relative to the cornea; This includes the following. The predetermined position refers to a position desirable from the viewpoint of obtaining good measurement results. This could be, for example, 15 to 20 mm from the eyeball.

[0058] In some embodiments, the impact is generated by firing at least one solid probe provided in the execution unit toward the eye.

[0059] In some embodiments, the impact on the cornea is generated by firing at least one drop of liquid towards the eye. This liquid is stored in an execution unit.

[0060] In summary, the disclosed apparatus and method are for measuring characteristics of the eye, including intraocular pressure (IOP) and / or central corneal thickness (CCT). This measurement is performed by applying an impact to the cornea using an impact device to generate free vibrations in the cornea. These vibrations can be measured using a measurement unit equipped with at least one confocal chromatic displacement sensor. By performing multiple displacement measurements (by multiple samplings) over a period of time, the frequency of the corneal vibrations generated by the impact can be calculated. This frequency value can be used to calculate intraocular pressure. The calculation can be performed using a pre-set formula or based on a lookup table. Detailed description of the drawings

[0061] Referring to Figure 1A, a block diagram is shown illustrating an apparatus 100 for measuring the characteristics of the eye according to an embodiment of the present disclosure. As shown in the figure, the apparatus 100 includes an execution unit 102 having an impact means 104 configured to impact the cornea of ​​the eye. Furthermore, the tonometer 100 includes a measurement unit 106 having at least one confocal chromatic displacement sensor 108, and a controller 110 connected to the execution unit 102 and the measurement unit 106. In some embodiments, the controller 110 may be the same as a "control unit" used to provide visual or auditory feedback to an operator, or a "control unit" that gives commands to an actuator. The controller 110 is configured to operate the execution unit 102 to impact the cornea of ​​the eye using the impact means 104, and to operate the measurement unit 106 to measure the corneal displacement caused by the impact multiple times over a predetermined time period. Furthermore, the apparatus 100 may include a calculation unit 112 connected to the controller 110. In some embodiments, this calculation unit may be part of the controller. Essentially, functions such as receiving measurement signals from sensors, calculating frequency and intraocular pressure, providing feedback signals to the operator or outputting commands to actuators, displaying information to the operator, and storing information can be implemented in various configurations (including configurations located away from the device), and may operate to calculate the frequency of corneal free vibration due to impact using multiple corneal displacement measurements, and to calculate the value of intraocular pressure as a function of the frequency of corneal free vibration due to impact.

[0062] Referring to Figure 1B, a block diagram is shown depicting the execution unit 102 of the apparatus 100 according to an embodiment of the present disclosure. As shown in the figure, the execution unit 102 comprises a firing means 114 and at least one solid probe 116. The firing means 114 is operable to fire the solid probe 116 toward the eye to generate an impact.

[0063] Figures 1A and 1B are for illustrative purposes only and do not unduly limit the scope of the claims of this application. Those skilled in the art will be able to recognize many variations, alternatives, and modifications of the embodiments of this disclosure.

[0064] Referring to Figure 2, a block diagram is shown depicting an execution unit 202 of the apparatus according to another embodiment of the present disclosure. As shown in the figure, the execution unit 202 further comprises a firing means 204 and at least one drop of liquid 206, the firing means 204 being operable to fire at least one drop of liquid 206 toward the eye to generate an impact.

[0065] Referring to Figure 3, a block diagram is shown illustrating an apparatus 300 according to another embodiment of the present disclosure. In some embodiments, the apparatus 300 includes at least one sensor element 302 capable of measuring the distance between the cornea of ​​the eye and the apparatus 300, and a control unit 304 connected to the sensor element 302 and providing feedback based on the measured distance. In some embodiments, the feedback is selected from at least one of visual feedback and acoustic feedback.

[0066] Referring to Figure 4, a block diagram is shown illustrating the apparatus 400 according to another embodiment of the present disclosure. In some embodiments, the apparatus 400 further comprises at least one sensor element 402 capable of measuring the distance between an eye (not shown) and the apparatus 400, and a control unit 404 connected to the sensor element 402, which provides command signals based on the measured distance and is capable of automatically controlling the relative position between the apparatus 400 and the eye. Furthermore, the apparatus 400 further comprises at least one actuator 406 connected to the control unit 404. The actuator 406 is operable to receive command signals from the control unit 404 and change the relative position of the apparatus 400 with respect to the eye.

[0067] Referring to Figure 5, a graph representation 500 is shown showing the frequency of corneal free vibration due to impact against the value of intraocular pressure, according to an embodiment of the present disclosure. As shown in the figure, the y-axis 502 represents the frequency of corneal free vibration due to impact, calculated by measuring corneal displacement multiple times. The x-axis 504 shows the value of intraocular pressure against the frequency of corneal free vibration due to impact. The value of intraocular pressure is correlated with the frequency of corneal free vibration.

[0068] Figure 6 shows a flowchart illustrating the steps of a method for measuring eye characteristics according to one embodiment of the present disclosure. In step 602, an impact is generated on the cornea using an execution unit incorporated in the apparatus. In step 604, the displacement of the cornea caused by the impact is measured multiple times over a predetermined time period using a measurement unit. Here, the measurement unit comprises at least one confocal chromatic displacement sensor, and the impact is generated by firing at least one solid probe provided in the execution unit toward the eye.

[0069] Figure 7 shows the operation of a device 700 for measuring the characteristics of an eye 740. The device 700 comprises an execution unit 702. The execution unit 702 comprises an impact means 704. In the provided example, the impact means 704 is a probe comprising an elongated magnetic body and a tip, as shown in the figure. The device 700 has a measuring unit 706 comprising a confocal chromatic displacement sensor 708. A controller 710 is connected to the execution unit 702 and the measuring unit 706. As illustrated, at least a portion of the execution unit 702 is located inside the body of the device 700. The measuring unit 706 is located (connected) to the same end of the device body from which the impact means 705 is fired toward the eyeball 740. This allows the confocal chromatic displacement sensor 708 to measure the free vibration of the cornea 742 caused by the impact. In other words, the confocal chromatic displacement sensor is positioned toward the cornea of ​​the eyeball. Preferably, it is positioned toward the impact location of the impact means.

[0070] Figure 7 shows steps S1, S2, and S3 related to the operation of the device during use. In step S1, the device 700 is positioned at a predetermined distance from the cornea 742 of the patient's (user's) eye 740. In step S2, the controller 710 supplies a control signal to the execution unit 702, ejecting the impact means 704 (probe in this example) to impact the cornea 742 of the eyeball 740. The direction of movement is indicated by an arrow. As shown in step S3, the impact means (probe) bounces back (or is pulled back). The cornea 742 vibrates at the frequency of free vibration caused by the impact (indicated by vibration 750). These vibrations correspond to the displacement of the cornea (surface) caused by the impact. These displacements are measured by the measurement unit 706 within a predetermined time after the impact. This makes it possible to identify the vibration frequency. Since the measurement unit is equipped with a confocal chromatic displacement sensor 708, it is possible to measure the corneal thickness simultaneously or after the vibration stops.

[0071] The steps described above are merely illustrative, and alternative steps may also be included. That is, one or more steps may be added, one or more steps may be omitted, or one or more steps may be performed in a different order without departing from the scope of the attached claims.

[0072] It is possible to modify the embodiments of this disclosure described above without departing from the scope defined by the attached claims. Expressions such as “includes,” “equip,” “incorporates,” “possesses,” and “is” used to describe and claim this disclosure are intended to be interpreted non-exclusively, that is, to allow for the existence of items, parts, or components not expressly described. The absence of explicit indication that an element is plural does not preclude the existence of multiple such elements.

Claims

1. A device for measuring the characteristics of the eye, An execution unit comprising an impact means positioned to deliver an impact to the cornea of ​​the eyeball, the execution unit comprising a firing means and at least one solid probe; A measurement unit including at least one confocal chromatic displacement sensor; - The controller connected to the execution unit and the measurement unit; It has, The controller is configured to operate the execution unit to apply an impact to the cornea of ​​the eye using the impact means, and to operate the measuring unit to measure the displacement of the cornea caused by the impact multiple times over a predetermined period of time; The firing means is operable to fire the at least one solid probe toward the eye and deliver an impact; Device.

2. The controller is connected to a computing unit, and the computing unit is - Using multiple corneal displacement measurements, calculate the frequency of free vibration of the cornea due to impact. - The value of intraocular pressure is calculated using the frequency of free vibration of the cornea caused by impact. The apparatus according to claim 1, which can operate in such a manner.

3. The apparatus according to claim 1 or 2, wherein the measuring unit is configured to measure the corneal thickness value at at least one point on the cornea.

4. The apparatus according to claim 2 or 3, wherein the calculation unit is operable to apply a correction to the calculated intraocular pressure value based on the measured corneal thickness value.

5. - At least one sensor element capable of measuring the distance between the cornea of ​​the eye and the device; - A control unit connected to at least one of the sensor elements and providing feedback based on the measured distance; The apparatus according to any of the preceding claims, comprising, wherein the feedback is selected from at least visual feedback and acoustic feedback.

6. - At least one sensor element capable of measuring the distance between the eye and the device; - A control unit connected to at least one of the sensor elements, which provides a command signal based on the measured distance and automatically controls the relative position between the device and the eye; - At least one actuator connected to the control unit and capable of operating to change the relative position between the device and the eye based on the command signals received from the control unit; The apparatus according to any one of claims 1 to 5, comprising:

7. The apparatus according to claim 5 or 6, wherein the at least one sensor element is selected from a confocal chromatic displacement sensor, a laser position sensor, and / or an ultrasonic position sensor.

8. The apparatus according to any of the preceding claims, which is a rebound tonometer.

9. A method for measuring the characteristics of the eye, - To generate an impact on the cornea of ​​the eye using the execution unit of the device; - Using the measuring unit of the apparatus, the displacement of the cornea caused by the impact is measured multiple times during a predetermined time period; Includes, The measurement unit comprises at least one confocal chromatic displacement sensor; The impact is generated by firing at least one solid probe provided in the execution unit toward the eye; method.

10. - Using a calculation unit, calculate the frequency of free vibration of the cornea due to impact using multiple corneal displacement measurements; - Calculating the value of intraocular pressure using the frequency of free vibration of the cornea caused by impact; The method according to claim 9, including the method described in claim 9.

11. The method according to claim 9 or 10, further comprising measuring the corneal thickness at at least one point on the cornea using the measuring unit of the apparatus.

12. The method according to claim 11, further comprising applying a correction to the calculated intraocular pressure value based on the measured thickness value using the calculation unit.

13. - To measure the distance between the cornea of ​​the eye and the device; - Using the measured distance as feedback, position the execution unit of the device at a predetermined location relative to the cornea; The method according to any one of claims 9 to 12, including the method described above.

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