Tonometer and related methods for measuring the characteristics of the eye

Abstract

Tonometers (100, 200, 300, 400, 900) for measuring the characteristics of an eye (960). The tonometer comprises an execution unit (102, 202, 902) including impact means (104, 904) configured to impact the cornea (962) of the eye when in use; a measuring unit (106, 906) including at least one optical sensor (108, 908); and a controller (110, 910) connected to the execution unit and the measuring unit, wherein the controller is configured to operate the execution unit to impact the cornea of ​​the eye using the impact means during use, and to operate the at least one optical sensor to measure the displacement of the cornea caused by the impact multiple times over a predetermined period of time.

Description

Technical Field

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

[0002] A tonometer is a medical device designed to examine the eyes of a subject. The eye is examined by measuring its various characteristics. An example of such a characteristic is the pressure inside the eye known as Intra-Ocular Pressure (IOP). The measured eye characteristics are useful for the diagnosis and management of various eye diseases, including glaucoma, which can lead to vision loss if untreated. A tonometer can be used to measure intraocular pressure. Usually, a tonometer is a fast, painless, and non-invasive medical device.

[0003] There are various types of tonometers operating on different principles, such as the Goldmann applanation tonometer and the rebound tonometer. The Goldmann applanation tonometer is used as the gold standard for intraocular pressure measurement. However, this measurement method requires a relatively long contact with the cornea, thus necessitating the use of anesthetic drugs in the eye. In fact, the measurement by the Goldmann applanation tonometer may cause discomfort and potential damage to the corneal surface. The rebound tonometer is superior to the Goldmann applanation tonometer in that it does not require anesthesia of the eye. In rebound intraocular pressure measurement, a probe or a similar device is ejected towards the cornea of the eye. The velocity profile of the probe is measured, and the intraocular pressure value is determined based on that measurement.

[0004] In view of these circumstances, it is necessary to overcome the above-mentioned drawbacks existing in the existing technologies and devices related to measuring the characteristics of the eye. Summary

[0005] The present disclosure aims to provide a tonometer for measuring the characteristics of the eye. The present disclosure also aims to provide a method for measuring the characteristics of the eye. The objective of the present disclosure is to provide a solution that at least partially overcomes the problems encountered in the prior art.

[0006] In one aspect, embodiments of the present disclosure provide a tonometer for measuring the properties of the eye. This tonometer is An execution unit equipped with an impact mechanism configured to deliver an impact to the cornea of ​​the eye during use; • A measuring unit including at least one optical sensor; The controller connected to the execution unit and the measurement unit; The controller is equipped with, The execution unit is operated to apply an impact to the cornea of ​​the eye using the aforementioned impact means. The at least one optical sensor is operated to measure the displacement of the cornea caused by the impact multiple times during a predetermined time period. It is configured in this way.

[0007] In another aspect, embodiments of the present disclosure provide a method for measuring the characteristics of the eye. This method is • To cause an impact to the cornea of ​​the eye using an impact method, The measurement unit is used to measure the displacement of the cornea caused by the impact multiple times over a predetermined period of time; Includes.

[0008] Embodiments of the present disclosure substantially eliminate, or at least partially solve, the aforementioned problems of the prior art, resulting in an improved tonometer that is simple, compact, accurate, reliable, and cost-effective. This is achieved by vibrating the cornea using an impact means and measuring the vibration using at least one optical sensor. Intraocular pressure can be determined using vibration parameters such as the frequency of the vibration. The tonometer employs the at least one optical sensor to enable measurement of eye characteristics with greater precision.

[0009] Further aspects, advantages, features, and objectives of what is disclosed herein will be made clearer by the accompanying drawings and the detailed description of exemplary embodiments, as to be interpreted in conjunction with the accompanying claims.

[0010] 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]

[0011] 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 illustrating a tonometer for measuring the characteristics of the eye, according to one embodiment of the present disclosure. [Figure 1B] This is a block diagram of a tonometer execution unit according to one embodiment of the present disclosure. [Figure 2] This is a block diagram of a tonometer execution unit according to another embodiment of the present disclosure. [Figure 3] This is a block diagram of a tonometer according to another embodiment of the present disclosure. [Figure 4] This is a block diagram of a tonometer according to another embodiment of the present disclosure. [Figure 5] This is a block diagram of an optical sensor according to another 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] This diagram shows the vibration of the cornea caused by the impact of an impact device. [Figure 8]This diagram shows the relationship between the vibration frequency of the eye and intraocular pressure. [Figure 9] This is a schematic diagram of a tonometer and its use according to an embodiment of the present disclosure. [Figure 10] This figure shows the relationship between the attenuation coefficient and intraocular pressure. In the attached figure, underlined numbers are used to represent the item at the location of that number or an item adjacent to that number. Ununderlined numbers are associated with the item identified by the line extending from that number. When a number is written without an underline and accompanied by an arrow, that number is used to identify the general item indicated by the arrow. Detailed description of the embodiment

[0012] The following detailed description illustrates embodiments of the disclosure and methods by which they may be implemented. While several forms for implementing the disclosure have been disclosed, those skilled in the art will recognize that other forms for implementing the disclosure are also possible.

[0013] In one aspect, embodiments of the present disclosure provide a tonometer for measuring the properties of the eye. This tonometer is An execution unit equipped with an impact mechanism configured to deliver an impact to the cornea of ​​the eye during use; • A measuring unit including at least one optical sensor; The controller connected to the execution unit and the measurement unit; The controller is equipped with, The execution unit is operated to apply an impact to the cornea of ​​the eye using the aforementioned impact means. The at least one optical sensor is operated to measure the displacement of the cornea caused by the impact multiple times during a predetermined time period. It is configured in this way.

[0014] In another aspect, embodiments of the present disclosure provide a method for measuring the characteristics of the eye. This method is • To cause an impact to the cornea of ​​the eye using an impact method, · Using a measurement unit, measuring the displacement of the cornea caused by the impact a plurality of times during a predetermined time period; comprising.

[0015] The present disclosure provides the aforementioned tonometer and the aforementioned method, which are simple, cost-effective, robust, accurate, reliable, and user-friendly. The impact means contacts the cornea of the eye, but the contact time is very short. The contact time is shorter than the time required for a person to blink. This tonometer employs at least one optical sensor, thereby measuring the characteristics of the eye in a highly accurate and cost-effective manner.

[0016] According to an embodiment of the present disclosure, the term "tonometer" as used herein refers to a device used to measure various characteristics of the eye. In this regard, characteristics refer to physiological parameters related to the eye. In some embodiments, the parameter of the eye measured by the tonometer is intraocular pressure.

[0017] As used herein, the term “execution unit” refers to a configuration used to apply force (impact) to the cornea of ​​the eye. As used herein, the term “impact means” refers to means used to impact a surface. The impact means is considered part of the execution unit. As an example, the impact means is used to impact the surface of the cornea of ​​the eye. The impact means is configured to impact only the cornea of ​​the eye without impacting the entire eye or the surrounding tissues. The typical duration of the impact ranges from 0.1 to 5 milliseconds, depending on the velocity and weight of the impact means, as well as the characteristics of the eye (e.g., intraocular pressure and elasticity of the ocular surface). The duration can be set from milliseconds, 0.1 milliseconds, 0.5 milliseconds, 1.0 milliseconds, 1.5 milliseconds, 2.0 milliseconds, 2.5 milliseconds, 3.0 milliseconds, 3.5 milliseconds, 4.0 milliseconds, 5.0 milliseconds to 0.5 milliseconds, 1.0 milliseconds, 1.5 milliseconds, 2.0 milliseconds, 2.5 milliseconds, 3.0 milliseconds, 3.5 milliseconds, 4.0 milliseconds, 5.0 milliseconds, 6.0 milliseconds. The impact means is applied by firing the impact means toward the surface of the eye. Thus, impact refers to the rapid contact / strike / application of an instantaneous force (impulse) to the cornea of ​​the eye. The impact is applied to the cornea of ​​the eye to cause the cornea to vibrate. The vibration of the eyeball due to the applied short-duration impact is called free vibration of the cornea. The duration of the impact is in the range of 1 to 5 milliseconds. Depending on the embodiment, the tonometer is implemented as a rebound tonometer. Measuring vibrations caused by the impact of a rebound tonometer probe provides accurate measurement of intraocular pressure (IOP). This method allows for the measurement of IOP using two means: the probe velocity profile and vibrations caused by impact.

[0018] In this specification, “measurement unit” refers to a component used to measure the free vibration of the cornea of ​​the eye. The measurement unit has at least one optical sensor. This optical sensor is used to measure the displacement of the cornea caused by an impact over a predetermined time period. The impact causes the cornea to vibrate. Displacement refers to the displacement of the corneal surface from its “normal” level. Specifically, multiple measurements of corneal displacement (e.g., in nanometers) are taken using the optical sensor over a predetermined time period. This collects a set of displacement values ​​(displacement from the 0 level) as a function of time over at least a predetermined time period. The predetermined time interval can be the time from the start of the impact to the end of the vibration. (Typically, the vibration attenuates to a negligible level about 50 milliseconds after impact.) The predetermined time interval can also be started during or after the impact. Ideally, the predetermined time interval is long enough to collect enough data points to determine the frequency of the vibration. The frequency of the vibration is expected to be about 100 to 500 Hz. In other words, from this perspective, the predetermined time should be in the range of at least 1 to 10 vibrations (1 / 500 to 10 / 100 seconds). Depending on the embodiment, the predetermined time period may be at least 0.001 seconds, 0.005 seconds, 0.01 seconds, 0.015 seconds, 0.020 seconds, 0.025 seconds, 0.030 seconds, 0.05 seconds, 0.1 seconds, 0.15 seconds, 0.2 seconds, 0.3 seconds, 0.5 seconds, 1.0 seconds, or 2.0 seconds. Since the frequency range is up to 500 Hz, the optical sensor should be configured to operate within a measurement range of 500 × 2-10 times per second. That is, it should be configured to perform 1000-5000 measurements per second in order to obtain sufficient sampling from the displacement. Another method of measuring displacement is to measure a "zero value" at the time of impact (or immediately before) and determine a binary value when the distance value "passes" the zero value. For example, a value of 1 is determined when the corneal surface is closer to the retina than the 0 level, and a value of 0 is determined when the corneal surface is further away from the retina than the 0 level. This method allows for the detection of vibrations moving from 0 towards the retina and away from the retina. As used herein, the term “optical sensor” refers to a device that operates by shining a light beam toward the eye.The light beam is reflected off the surface of the eye, and the corneal displacement during measurement is detected by analyzing this reflection. As mentioned above, multiple measurements are taken to collect sufficient data to make a judgment based on the measured vibration frequency.

[0019] Measuring displacement multiple times over time using optical sensors offers various advantages, including precise characterization of rapid and transient changes in displacement with high temporal resolution, dynamic analysis capabilities for behavior and response, displacement pattern recognition, noise reduction and improved displacement data quality, quantitative measurement of variability, stability, and statistical significance, leading to deeper insights. These advantages include statistical analysis, performance optimization, stability maintenance, adaptive control enabling real-time response to changing conditions, and long-term monitoring of displacement trends and patterns.

[0020] In rebound tonometers, the contact time between the probe and the eyeball is usually extremely short, allowing corneal vibration to occur freely following contact, without external interference from the contact element (impact medium such as the probe). In contact vibration measurement, the weight and external force of the contact element itself are transmitted to the cornea, potentially interfering with the vibration characteristics of the eyeball and impairing the accuracy of the measurement results. Also, the long contact time with the cornea and the long measurement time can cause discomfort to the patient. Since rebound tonometers only contact the eyeball for 0.1 to 5 milliseconds, measuring corneal vibration non-contact using an optical sensor improves measurement accuracy, shortens measurement time, and allows for a more comfortable measurement for the patient. Measuring corneal vibration rather than simple rebound improves accuracy compared to current rebound tonometers. This is because more data on the characteristics of the eyeball can be obtained in a single measurement.

[0021] Depending on the embodiment, the at least one optical sensor may be selected from a chromatic confocal sensor, a laser Doppler vibrometer, or a laser displacement sensor. A "laser Doppler vibrometer" here refers to a type of sensor used to measure the distance between a tonometer and the cornea of ​​the eye. A laser beam from the laser Doppler vibrometer is directed towards the cornea, and the amplitude and frequency of the vibration are extracted from the Doppler shift of the reflected laser beam frequency due to corneal movement. Typically, the output of a laser Doppler vibrometer is a continuous analog voltage directly proportional to the target velocity component along the laser beam direction. This target velocity component can be used to derive corneal displacement as a measured value.

[0022] As used herein, the term “laser displacement sensor” refers to a device that uses a laser beam to measure the distance between two objects. Laser displacement sensors may be designed using time-of-flight (TOF) measurement techniques. In some embodiments, the laser displacement sensor is used to transmit a laser pulse toward the cornea and measure the time it takes for the pulse to reflect back from the cornea. The time of flight of the laser pulse is used to measure the distance, or displacement, between the laser displacement sensor and the cornea.

[0023] A "chromatic confocal displacement sensor" is a device that uses a high-dispersion objective lens to irradiate the surface of a target (e.g., the eyeball) with a light beam having a broadband wavelength (usually white light). The reflected light is analyzed by a spectrometer, and wavelengths that show a peak in the spectrum within the broadband wavelength range are identified. This peak wavelength corresponds to the distance between the sensor and the reflective surface (eyeball surface). As in the example above, by performing multiple consecutive measurements, a sufficient dataset of corneal displacement as a function of time can be collected. This data can be used to determine the vibration frequency of the eyeball. For example, the number of measurements per second can be 1,000 to 5,000 or more, depending on the accuracy requirements, as mentioned above. For example, 10,000 to 20,000 measurements per second are possible.

[0024] The measurement unit comprises one or more optical sensors. Depending on the embodiment, the measurement unit may be equipped with multiple optical sensors to improve the accuracy of intraocular pressure measurement. For example, different regions of the cornea may have different biomechanical properties. In such cases, multiple optical sensors can measure the cornea from multiple angles or positions, providing more information to be used to measure the characteristics of the eye.

[0025] In some embodiments, the at least one optical sensor comprises at least one light-emitting diode (LED) and at least one photosensor, where the photosensor is selected from either a phototransistor or a photodiode. As used herein, the term “light-emitting diode” refers to a semiconductor device that emits light when an electric current flows through it. The at least one optical sensor includes an LED as its light source. Photons emitted from the LED are directed toward an object, such as the cornea of ​​the eye. When the photons strike the cornea, some of the photons are reflected toward the optical sensor. In some embodiments, the amount of light reflected back to the at least one optical sensor depends on the reflectivity of the cornea of ​​the eye. An advantage of using an LED instead of a laser is that LEDs emit non-monochromatic light. Monochromatic light from a laser can have adverse effects on the retina. LEDs provide light with a relatively broad spectrum (compared to lasers).

[0026] As used herein, the term “phototransistor” refers to a type of semiconductor device used to detect light. Each of the at least one optical sensors includes a phototransistor that operates in conjunction with an LED. As used herein, the term “photosensor” refers to a device that detects light and converts it into an electrical signal. The photosensor operates in conjunction with the LED present in each of the at least one optical sensors. In some embodiments, the photosensor is a photodiode, which is a light-sensitive semiconductor device. Both phototransistors and photodiodes are high-speed components and are therefore suitable for accurately measuring fast transient phenomena or, for example, pulsed light sources. In some embodiments, the corneal displacement to be measured does not need to be an absolute value (e.g., in nanometers), but it is sufficient to understand the temporal change in the displacement. In this regard, by using an LED-photosensor pair, a photocurrent as a function of time can be obtained as an output. This photocurrent does not provide direct information about the actual amount of displacement (in meters). However, the photocurrent as a function of time can be considered to represent the relative displacement between different points in time and can be used for further data processing to determine the frequency of the vibration. Furthermore, the LED and photodiode combination is non-invasive and can be comfortably placed near the eye without causing discomfort or interfering with normal vision. An additional advantage of using LEDs and photosensors / phototransistors is that these components are inexpensive.

[0027] The photosensor is positioned appropriately to accurately identify corneal vibrations. Preferably, the optical sensor is positioned near the execution unit, and more preferably, to measure from the same direction in which the impact means is applied to the cornea of ​​the eye. In some embodiments, the light beam is preferably directed perpendicular to the cornea. Advantageously, the optical sensor has the ability to tolerate a large inclination of the beam axis with respect to the normal direction of the measurement surface (including reaching tens of degrees). The optical sensor is used for a resolution that can measure displacements of tens of nanometers and for the ability to measure at frequencies of tens of kilohertz (kHz). Advantageously, at least one optical sensor is customized to identify the corneal vibration frequency for cost-effectiveness. In some embodiments, at least one optical sensor uses infrared (IR) as the measurement beam. Advantageously, infrared light is invisible to the subject's eye, thus reducing the incentive for the subject to blink.

[0028] The term "controller" refers to a computer device capable of operating to control the overall operation of a tonometer. During operation, the controller performs tasks such as using the execution unit, using the measurement unit, and responding to and processing information. However, the tasks it performs are not limited to these. For example, the controller may be an embedded microcontroller, a microprocessor, etc. The controller is also combined with the measurement unit and the execution unit. The controller may be implemented as an internal component of the tonometer, as an external component of the tonometer, or as a combination of these.

[0029] The controller is configured to operate by supplying power to the execution unit. The execution unit is powered to apply an impact, or force, to the cornea of ​​the eye. The eyeball is considered a thin-walled elastic vessel filled with pressurized fluid. Therefore, the eyeball has mechanical vibration behavior and resonant frequencies. When the cornea is impacted, it deforms and then rapidly returns to its original shape. This creates vibrations on the surface of the cornea. Vibration refers to the process by which the displacement of the corneal surface changes over time. The term displacement refers to the amplitude of the vibration.

[0030] Multiple measurements refer to a series of measurements of corneal displacement over a predetermined time period. Multiple measurements allow for the consideration of variations and inconsistencies in the measured values, thus providing more accurate and reliable data. Depending on the embodiment, multiple measurements can track the progression of corneal displacement over time, leading to 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.

[0031] The controller is configured to control or power the measurement unit. The controller operates the measurement unit, which has at least one optical sensor, to measure corneal displacement. For example, the photosensor includes an LED as a light-emitting element. The LED of the optical sensor emits a light beam toward the cornea, and the corresponding photodetector (such as at least one photosensor) measures the amount of light reflected back from the cornea to measure corneal displacement. In this example, when the impact means hits the cornea, the cornea deforms slightly. This changes the distance between the LED and the photosensor, causing a change in the amount of light reflected back to the photosensor. The change in the amount of reflected light can be used as a displacement measurement result (displacement value from the 0 level of the corneal surface, e.g., X meters (e.g., -150 to 150 micrometers)) or as a change in the current of the photosensor. The measurement unit is used to measure the corneal displacement caused by the impact multiple times over a predetermined time period.

[0032] In some embodiments, the tonometer further comprises a computing unit connected to a controller. This computing unit is • To calculate the frequency of free vibration of the cornea caused by impact, the measured displacement is used. • To calculate the intraocular pressure of the eyeball, the frequency of free vibration of the cornea is used. It can behave in that way.

[0033] Here, it can be assumed that the internal pressure value depends on the frequency of the free vibration of the cornea caused by the impact. In fact, the displacement measured as a function of time (e.g., amplitude from zero level) provides a means of determining the vibration frequency. The frequency of free vibration can be calculated by determining the periodicity of the measurements (e.g., the time difference between two peaks, or the time difference between multiple pairs of peaks) and calculating their average. The frequency is the reciprocal of the calculated average time difference (1 / s = Hz). The internal pressure of the eyeball can be determined from the calculated frequency of free vibration (vibration without disturbance), for example, using a lookup table that has a correlation table between frequency and intraocular pressure (IOP). That is, the frequency of the free vibration of the cornea is used to calculate the internal pressure value of the eyeball. Another calculation method is to use a mathematical model of eye vibration and use frequency as its input value.

[0034] In some embodiments, the tonometer further comprises a computing unit connected to a controller. This computing unit is • To calculate the damping coefficient of the free vibration of the cornea caused by impact, the measured displacement is used. The internal pressure value of the eyeball is calculated using the aforementioned damping coefficient. It can behave in that way.

[0035] In addition, the tonometer is configured to adjust the internal pressure value as follows. • The intraocular pressure value calculated using the frequency of free vibration is adjusted using the damping coefficient and the calculated intraocular pressure value. Or, The intraocular pressure value of the eyeball, calculated using the damping coefficient, is adjusted using the frequency of free vibration and the calculated intraocular pressure value of the eye.

[0036] As used herein, the term “computation unit” refers to electronic hardware or software algorithms used to perform mathematical operations to convert raw data into meaningful measurements. The computation unit is associated with a controller to allow for greater flexibility and customization based on the tonometer design. In some embodiments, the computation unit is integrated into the controller (i.e., is part of the controller). In some embodiments, the computation unit is implemented as a cloud service. The computation unit can calculate the frequency of corneal free vibration using the measured displacement (displacement value or index). Free vibration refers to the resonant frequency or natural vibration frequency of the cornea induced by impact. In practice, the cornea undergoes free vibration at a frequency equal to (or close to) its resonant frequency, stopping as the amplitude decreases. One method for calculating the frequency is to use the inverse Fourier transform. Since the frequency of free vibration correlates with intraocular pressure, the intraocular pressure (IOP) value can be measured by determining / measuring the frequency. Another frequency calculation method is to compare “zero level” passages obtained by optical sensors. This simplifies the process. This is because it is easy to calculate the values ​​1 (indicating a state where the corneal surface is closer to the retina than usual) and 0 (indicating a state where the corneal surface is further away from the retina than usual), as well as the time it takes to change from 1 to 0.

[0037] As mentioned above, the cornea vibrates at the frequency of free vibration. The amplitude of the vibration decreases over time (from a few milliseconds to about 100 milliseconds). This decrease in amplitude can be described using the damping coefficient of the vibration. To calculate the internal pressure of the eyeball, multiple displacement values ​​measured (as a function of time) can be used. In this way, by measuring corneal displacement due to impact multiple times, it becomes possible to (indirectly) measure intraocular pressure (IOP) through the damping coefficient. Generally, the eyeball can be considered a harmonic oscillator. The basic equations for a harmonic oscillator are as follows: TIFF2026514854000002.tif28170 Here, x is the measured displacement value (from the normal level), i.e., amplitude, t is time, ω is frequency, and ζ is the damping coefficient. By solving this, we can find the displacement x(t) as a function of time. TIFF2026514854000003.tif28170 By measuring multiple displacement values ​​over a certain period, multiple data points x(t) can be obtained. These can then be used to calculate the frequency and damping coefficient.

[0038] To define the intraocular pressure of the eyeball, a damping coefficient can be used in addition to frequency, based on experiments. This can be done, for example, using curve fitting, lookup tables, or predefined formulas. Using a damping coefficient is advantageous because the range of error in determining the damping coefficient is small. Another method for calculating the damping coefficient is to determine the peak maximum and minimum values ​​of each vibration from multiple displacement measurements. The peak maximum and minimum values ​​can then be used to calculate the damping, for example, by comparing two different peak maximum values.

[0039] In another embodiment, the intraocular pressure of the eyeball is calculated using the frequency of free vibration, and its value is adjusted based on an internal pressure value calculated using a damping coefficient. In yet another embodiment, the intraocular pressure of the eyeball is calculated using a damping coefficient, and its value is adjusted based on an internal pressure value calculated using the frequency of free vibration of the cornea. This can improve measurement accuracy.

[0040] As used herein, the term “intraocular pressure (IOP)” refers to the fluid pressure within the eyeball. In some embodiments, 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. In some embodiments, the calculation unit may perform other functions such as error correction, data storage, and data analysis. In particular, intraocular pressure is measured to maintain the overall health and function of the eyeball. In some embodiments, the eyeball exhibits 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. Furthermore, dimensions are determined for the diagnosis of ocular growth regulation, and tactile sensitivity is determined for the treatment of eye diseases such as conjunctivitis, corneal infections, glaucoma, and dry eye.

[0041] The frequency and damping coefficient of corneal free vibration provide useful information for IOP assessment based on the biomechanical properties of the cornea. These biomechanical properties include corneal stiffness and elasticity, which influence the corneal response to IOP changes. Corneal thickness, in particular, varies from person to person and can affect the accuracy of IOP measurement. By considering corneal biomechanical properties such as frequency and damping coefficient, it becomes possible to obtain IOP estimates that are less dependent on corneal thickness using a simple tonometer, and improved accuracy is expected, especially in patients with abnormal corneal thickness. Furthermore, calculating IOP based on the frequency and damping coefficient of corneal free vibration allows for a more comprehensive understanding of factors contributing to ocular pathology and enables the development of individualized treatment strategies accordingly. For example, monitoring changes in corneal biomechanics, including changes in corneal vibration frequency and damping coefficient, over a long period goes beyond conventional IOP measurement, providing additional indicators of eye health, disease progression, and treatment effectiveness, and can support the early detection and management of glaucoma and corneal ectasia. This ultimately improves clinical judgment and patient care.

[0042] In some embodiments, the impact means of the execution unit is a solid probe, and the execution unit further comprises a firing means. The firing means is operable to fire the solid probe toward the eye and generate an impact.

[0043] The term “launching means” as used herein refers to a mechanical element used to eject at least one solid probe from the execution unit toward (or toward) the eye. In this respect, the launching means enables efficient and precise movement of the solid probe during use. As an example, the solid probe may be an elongated probe having an elongated magnetic body and a biocompatible tip. In this example, the launching means partially surrounds the elongated magnetic body of the solid probe. Here, the launching means is configured as a group of loops (of an electric coil) capable of moving at least one solid probe. The launching means moves at least one solid probe when current is supplied to the group of loops. The current generates a magnetic field in the loops, which moves the probe. (This is because the probe has an elongated magnetic body, and at least a portion of it is located within the loops.) The launching means ejects the solid probe toward the eye at a speed that is a function of the current supplied to the loops of the launching means and the magnetization of the solid probe body. The launching means and at least one solid probe work together to deliver a precise impact to the cornea of ​​the eye, i.e., to the appropriate location on the cornea.

[0044] In some embodiments, the impact means of the execution unit is at least one drop of liquid, and the execution unit further comprises a firing means. The firing means is operable to fire at least one drop of liquid towards the eye to generate an impact.

[0045] The term "launching means" here 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. 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 droplet can be a non-irritating liquid that can be projected towards the eye without causing harm 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. In this embodiment, the controller is configured to operate the execution unit so that, during operation, the associated launching means fires at least one drop of liquid towards the eye in order to generate vibrations in the cornea. As mentioned above, the frequency of the vibration is related to the value of intraocular pressure (IOP). In particular, high IOP suggests increased rigidity of the eyeball, and consequently, an increase in the resonant frequency of the cornea. In another or additional embodiment, the liquid is a drug, and the tonometer is configured to administer the drug. (By detecting the presence or absence of corneal movement due to the administered drug with an optical sensor,) the measurement can be used to detect whether or not the drug has been administered.

[0046] In some embodiments, the at least one drop of liquid is stored in a hollow container. In some embodiments, the hollow container is located within at least one solid probe associated with the launching means. The launching means works in conjunction with the at least one solid probe to deliver the at least one drop of liquid to the cornea in an optimal amount. Advantageously, when the at least one drop of liquid is delivered in an optimal amount, it produces a precise impact on the cornea of ​​the eye.

[0047] Advantageously, applying at least one drop of liquid to the eye is a non-invasive method for inducing corneal vibration without causing discomfort or harm to the patient, and minimizing the risk of adverse effects. Furthermore, the application of at least one drop of liquid to induce corneal vibration is standardizable and reproducible across different patients, ensuring the consistency of experimental protocols and facilitating comparisons between studies. Moreover, by controlling the volume and composition of the droplet, the amplitude and frequency of corneal vibration induced in the eyeball can be adjusted. This allows for precise manipulation of experimental conditions, such as external stimuli and fluctuations in eye condition, enabling studies on the effects on intraocular pressure dynamics in conditions like glaucoma. It also contributes to the identification of biomarkers and patterns indicating disease progression and treatment response.

[0048] Depending on the embodiment, the tonometer may further include: • At least one sensor element capable of measuring the distance between the eye and the tonometer; A feedback element connected to at least one of the aforementioned sensor elements, which provides feedback based on the measured distance; Equipped with, The feedback is selected from at least one of visual feedback, acoustic feedback, or a feedback signal.

[0049] Here, a sensor element refers to a device that detects and responds to physical changes in its environment. The tonometer comprises at least one sensor used to convert physical phenomena such as light and motion into measurable or processable electrical or digital signals. Depending on the embodiment, the at least one sensor may be an internal or external component of the tonometer. 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. Here, the term “feedback element” refers to an electronic component that provides information indicating the output of a sensor and allows adjustment to the input or output of the sensor accordingly. Depending on the embodiment, the feedback element may be a physical component such as a potentiometer or a digital component such as a microcontroller. The feedback element is used to improve the accuracy and reliability of the at least one sensor element by detecting errors or discrepancies between a desired distance value and a measured distance value and making adjustments to correct them.

[0050] In this regard, during operation, at least one sensor element is operable to measure the distance between the cornea and the tonometer and provide the measured distance as feedback to a coupled feedback element. The feedback element compares the distance measured by at least one sensor element to a reference value (such as a desired distance or an optimal distance), and the controller adjusts the input to the sensor based on the difference between the two values. If the tonometer is a handheld unit, at least one sensor and the feedback element work together to accurately position the tonometer relative to the eye. 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. Furthermore, the feedback is provided as acoustic feedback. For example, the feedback is provided to the tonometer operator as audio feedback via a speaker associated with the tonometer. Preferably, visual or acoustic feedback is used to assist in the correct positioning of the tonometer relative to the eye. Furthermore, the feedback may be provided as a feedback signal. A feedback signal is an electrical signal (such as a command, voltage value, or bitstream) that is provided to other electrical components to control them or provide them with control commands.

[0051] In some embodiments, the tonometer further includes at least one actuator capable of automatically changing the relative position of the tonometer to the cornea of ​​the eye based on a feedback signal.

[0052] In this context, "actuator" refers to a component that automatically changes the relative position of the tonometer to the eye based on feedback signals received from a feedback element. Depending on the embodiment, this may include moving the tonometer closer to or further away from the eye, or adjusting its angle and orientation. Examples of actuators include motors, solenoids, and piezoelectric devices. The tonometer is positioned relative to the eye by at least one actuator. A position feedback signal is obtained by measuring the distance between the tonometer and the eye using at least one sensor element. For example, if the measured distance exceeds a desired distance, the feedback element provides a feedback signal to the actuator, which then moves the tonometer to the optimal position relative to the eyeball.

[0053] In some embodiments, at least one sensor element is selected from laser displacement sensors. In this regard, the tonometer is associated with one or more sensor elements useful for providing positional feedback. Positional feedback is provided at least in the initial stages of positioning the tonometer relative to the cornea and before the cornea enters the measurement area of ​​a given optical sensor. In some embodiments, once the cornea enters the measurement area of ​​a given optical sensor, it is possible to obtain positional feedback using the given optical sensor or to continue using the laser displacement sensor. Advantageously, laser displacement sensors are low-cost sensors.

[0054] The disclosed tonometer enables the measurement of corneal displacement over all or part of the free oscillation period to determine the accurate intraocular pressure of the eye by using a tonometer implemented as a contact tonometer, i.e., a rebound tonometer. This tonometer uses an execution unit equipped with an impact means configured to apply an impact (0.1 to 5 milliseconds) to the cornea of ​​the eye when the tonometer is used, and a measurement unit equipped with at least one optical sensor. When a rebound tonometer is used, the probe of the rebound tonometer strikes the cornea of ​​the eye, causing corneal displacement. Free oscillation is then measured. However, the time the probe is in contact with the cornea of ​​the eye is short, and the contact time is not long enough to measure corneal oscillations to obtain an accurate intraocular pressure value of the eye. On the other hand, measurement using an optical sensor allows for more accurate measurement because corneal displacement can be measured over a long period without contact with the eyeball, resulting in a more accurate intraocular pressure value of the eyeball. Furthermore, the use of optical sensors solves the technical problems of methods for measuring corneal displacement over the entire free oscillation period in order to determine the accurate intraocular pressure of the eye using a rebound tonometer (i.e., a contact tonometer) without requiring a non-contact tonometer.

[0055] 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.

[0056] In some embodiments, the characteristics of the eye are measured by applying an impact to the cornea of ​​the eye using an impact means. This impact causes the cornea to vibrate. In this method, the displacement associated with the corneal vibration is measured multiple times during a predetermined time period (e.g., the duration of the vibration). This predetermined time period is, for example, the duration of the vibration. The multiple measurements are performed to collect the displacement (value / index) as a function of time. The impact can be generated using the impact means of an execution unit. The measurement of the displacement can be performed using at least one optical sensor.

[0057] Depending on the embodiment, the method may further be: • Calculating the frequency of free vibration of the cornea due to impact using multiple corneal displacement measurements; • Calculating the value of intraocular pressure from the frequency of free vibration of the cornea caused by impact; This includes the intraocular pressure, which is a function of the measured frequency. This value can be determined using a (device-specific) function or a lookup table.

[0058] Depending on the embodiment, multiple measurements of displacement are performed using at least one optical sensor. The at least one optical sensor is selected from a confocal chromatic sensor, a laser Doppler vibrometer, and a laser displacement sensor.

[0059] In some embodiments, the at least one optical sensor comprises at least one light-emitting diode (LED) and at least one photosensor. Here, the photosensor is selected from either a phototransistor or a photodiode.

[0060] Depending on the embodiment, the method may further be: • Measuring the distance between the cornea and the tonometer, • The measured distance is used as a feedback signal to move the execution unit to a desired position relative to the cornea, Includes.

[0061] In some embodiments, the impact is generated by emitting at least one solid probe provided in the execution unit toward the eye.

[0062] Depending on the embodiment, the method described above may be • Calculate the damping coefficient of corneal free vibration due to impact using multiple corneal displacement measurements; • Calculate the intraocular pressure using the calculated damping coefficient; Includes.

[0063] In some embodiments, a tonometer for measuring the characteristics of the eye is provided. The tonometer is An execution unit comprising impact means configured to apply an impact of 0.1 milliseconds to 5 milliseconds to the cornea of ​​the eye when the tonometer is in use; A measuring unit comprising at least one of the aforementioned optical sensors; • Computation units and; The execution unit and the controller connected to the measurement unit and the calculation unit; The controller is equipped with, The execution unit is operated to apply an impact to the cornea of ​​the eye using the aforementioned impact means. The at least one optical sensor is operated to measure the displacement of the cornea caused by the impact multiple times during a predetermined time period. The calculation unit is operated to use the measured displacement to calculate the frequency of the free vibration of the cornea caused by the impact, and to use the frequency of the free vibration to calculate the intraocular pressure, The measured displacement is used to calculate the damping coefficient of the free vibration of the cornea caused by the impact, and the calculation unit is operated to use the damping coefficient to calculate the intraocular pressure. It is configured in such a way, The impact means of the execution unit is a solid probe, and the execution unit further comprises a firing means. The firing means is operable to fire the solid probe toward the eye and generate an impact. Alternatively, the intraocular pressure can be calculated using a combination of the free vibration frequency and damping coefficient. Detailed description of the drawings

[0064] Referring to Figure 1A, a block diagram is shown illustrating a tonometer 100 for measuring the characteristics of the eye according to an embodiment of the present disclosure. As shown in the figure, the tonometer 100 includes an execution unit 102 having an impact means 104 configured to apply an impact to the cornea of ​​the eye. Furthermore, the tonometer 100 includes a measurement unit 106 having at least one optical sensor 108, and a controller 110 connected to the execution unit 102 and the measurement unit 106. The controller 110 is configured to operate the execution unit 102 to apply an impact to the cornea of ​​the eye using the impact means 104, and to operate at least one optical sensor 108 to measure the displacement of the cornea caused by the impact multiple times over a predetermined time period. Furthermore, the tonometer 100 includes a calculation unit 112 connected to the controller 110. The calculation unit 112 may operate to calculate the frequency of free vibration of the cornea due to impact using multiple measurements of corneal displacement, and to calculate the intraocular pressure as a function of the frequency of free vibration of the cornea due to impact.

[0065] Referring to Figure 1B, a block diagram is shown depicting the execution unit 102 of the tonometer 100 according to an embodiment of the present disclosure. As shown in the figure, the execution unit 102 comprises a launching means 114 and at least one solid probe 116. The launching means 114 is operable to launch the solid probe 116 toward the eye to generate an impact.

[0066] 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.

[0067] Referring to Figure 2, a block diagram is shown depicting an execution unit 202 of a tonometer 200 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.

[0068] Referring to Figure 3, a block diagram is shown illustrating a tonometer 300 according to another embodiment of the present disclosure. In some embodiments, the tonometer 300 comprises at least one sensor element 302 capable of measuring the distance between the cornea of ​​the eye and the tonometer 300, and a feedback element 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 visual feedback, acoustic feedback, and a feedback signal.

[0069] Referring to Figure 4, a block diagram is shown illustrating a tonometer 400 according to another embodiment of the present disclosure. In some embodiments, the tonometer 400 further comprises at least one sensor element 402 capable of measuring the distance between an eye (not shown) and the tonometer 400. In some embodiments, the tonometer 400 further comprises at least one actuator 404 capable of operating to automatically change the relative position of the tonometer 400 with respect to the cornea of ​​the eye. The distance measured between the tonometer 400 and the cornea is used as a feedback signal to automatically control the relative position between the tonometer 400 and the cornea.

[0070] Referring to Figure 5, a block diagram is shown illustrating at least one optical sensor 500 according to an embodiment of the present disclosure. As shown in the figure, the at least one optical sensor 500 includes at least one LED 502 and at least one photosensor 504. Depending on the embodiment, the at least one photosensor 504 is selected from a phototransistor and a photodiode.

[0071] Figures 2 to 5 are for illustrative purposes only and should not unduly limit the scope of the claims herein. Those skilled in the art will be able to recognize many variations, alternatives, and modifications of embodiments of the present disclosure.

[0072] Figure 6 shows a flowchart illustrating the steps of a method for measuring the characteristics of the eye according to one embodiment of the present disclosure. In step 602, an impact is generated on the cornea using an impact means of an execution unit provided in the tonometer. 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.

[0073] Figure 7 shows the measurement results of corneal displacement caused by impact (within a predetermined time). The X-axis represents time (units are arbitrary). The Y-axis represents displacement (units are arbitrary). It can be seen that the frequency of the first measurement group 764A (solid line) is lower than the frequency of the second measurement group 764B (dotted line). This graph is obtained by measuring the displacement as a function of time multiple times. For example, if the total time of the predetermined period is 50 milliseconds, the number of measurements within that time could be 20, 50, 100, 1000, or 10000. These measurements can be used to determine the frequency of vibration.

[0074] Figure 8 shows the correlation between frequency (Hz) and intraocular pressure (mmHg). It can be seen that the higher the frequency, the higher the intraocular pressure, and vice versa. Figure 9 shows the procedure for using the tonometer 900 according to an embodiment of the present disclosure. The tonometer 900 includes an execution unit 902. The execution unit includes an impact means 904. In the figure, the impact means is a solid probe whose tip 930 is connected to an elongated magnetic body 932. The elongated magnetic body is partially surrounded by an electrical loop 903 of the execution unit 902.

[0075] The measuring unit 906 is mounted on the body of the tonometer 900 and positioned to face the eye 960 when the tonometer is in use. The measuring unit includes at least one optical sensor 908. The controller 910 is connected to the execution unit 902 and the measuring unit 906. In step S1, the controller operates the execution unit 902. In this example, the electrical loop 903 is energized. The current flowing through the electrical loop 903 generates an electric field, which creates a magnetic force on the elongated magnetic body 932 of the impact means 904. This force propels the impact means toward the cornea 962 of the eye 960 (as indicated by the arrow). In step S2, the impact means 904 is shown to impact the cornea 962; that is, the tip 930 collides with the cornea 962 of the eye 960.

[0076] Due to the elasticity of the eyeball 960, the impact means 904 bounces back after impact (indicated by the arrow in step S3). In another embodiment, the execution unit 902 can be configured to actively pull back the impact means 904 after impact. This can be achieved by reversing the direction of the current in the electrical loop 903 with respect to the direction of emission. After impact, the cornea 962 vibrates. The vibration 964 is shown by a thick line in the figure. The optical sensor 908 of the measurement unit 906 measures the displacement of the vibration caused by the impact multiple times within a predetermined time. The measured values ​​are stored in the memory of the controller 910 for further data processing. The controller may have a built-in computing unit (or a separate computing unit may exist). The computing unit uses the stored measured values ​​to calculate the frequency of free vibration (by Fourier analysis, etc.). Furthermore, it calculates the intraocular pressure value from this frequency (using a lookup table or equation).

[0077] Figure 10 shows the relationship between the vibration damping coefficient (decrease in amplitude over time) obtained from a series of experiments. The x-axis of the graph represents intraocular pressure (in mmHg), and the y-axis represents the damping coefficient. It can be seen that the damping coefficient can estimate intraocular pressure with good reliability, especially in the low intraocular pressure range (below 20 mmHg). In fact, the damping coefficient can provide good adjustment (calibration / correction) for intraocular pressure identified by frequency, compared to the high intraocular pressure range. Depending on the embodiment, when the intraocular pressure is less than 15 mmHg, 20 mmHg, 25 mmHg, 30 mmHg, or 40 mmHg, the damping coefficient is used as the intraocular pressure value or to adjust for intraocular pressure values ​​measured using the free vibration frequency. Beneficially, the disclosed tonometer can be calibrated periodically to ensure accuracy, maintain measurement reliability, and guarantee that the tonometer is functioning correctly.

[0078] 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.

[0079] 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 tonometer for measuring the characteristics of the eye, An execution unit equipped with an impact mechanism configured to deliver an impact to the cornea of ​​the eye during use; A measuring unit including at least one optical sensor; - The controller connected to the execution unit and the measurement unit; The controller is equipped with, The execution unit is operated to apply an impact to the cornea of ​​the eye using the aforementioned impact means. The at least one optical sensor is operated to measure the displacement of the cornea caused by the impact multiple times during a predetermined time period. A tonometer configured in such a way.

2. The controller is connected to a computing unit, and the computing unit is - To calculate the frequency of free vibration of the cornea caused by the impact, the measured displacement is used. - The frequency of corneal free vibration is used to calculate the intraocular pressure of the eyeball. A tonometer according to claim 1, which can operate in such a manner.

3. The controller is connected to a computing unit, and the computing unit is - To calculate the damping coefficient of the free vibration of the cornea caused by impact, the measured displacement is used. - The aforementioned damping coefficient is used to calculate the internal pressure value of the eyeball. A tonometer according to claim 1, which can operate in such a manner.

4. - Is the intraocular pressure value calculated using the frequency of free vibration adjusted using the damping coefficient, or is it adjusted using the calculated intraocular pressure value? - The intraocular pressure value of the eyeball, calculated using the damping coefficient, is adjusted using the frequency of free vibration and the calculated intraocular pressure value of the eye. The tonometer according to claim 2 or 3.

5. The tonometer according to any of the preceding claims, wherein the at least one optical sensor is selected from a chromatic confocal sensor, a laser Doppler vibrometer, and a laser displacement sensor.

6. The tonometer according to any one of claims 1 to 4, wherein the at least one optical sensor comprises at least one light-emitting diode and at least one photosensor, the photosensor being selected from either a phototransistor or a photodiode.

7. The tonometer according to any of the preceding claims, wherein the impact means of the execution unit is a solid probe, and the execution unit further comprises a firing means, the firing means operable to fire the solid probe toward the eye and generate an impact.

8. A tonometer according to any one of claims 1 to 6, The impact means of the execution unit is at least one drop of liquid, The execution unit is equipped with a firing means, The firing means may operate to fire at least one drop of liquid towards the eye and generate an impact.

9. The tonometer according to claim 8, wherein the at least one drop of liquid is selected from at least one of water, saline solution, or physiological saline.

10. - At least one sensor element capable of measuring the distance between the eye and the tonometer; - A feedback element connected to at least one of the sensor elements and providing feedback based on the measured distance; A tonometer according to any of the preceding claims, further comprising the above, wherein the feedback is selected from at least visual feedback, acoustic feedback, and a feedback signal.

11. The tonometer according to claim 10, comprising at least one actuator capable of operating to automatically change the relative position of the tonometer to the cornea of ​​the eye based on a feedback signal.

12. The tonometer according to claim 10 or 11, wherein at least one of the sensor elements is a laser displacement sensor.

13. The tonometer according to any of the preceding claims, wherein the duration of the impact is 0.1 milliseconds to 5 milliseconds.

14. A method for measuring the characteristics of the eye, - Generating an impact to the cornea of ​​the eye using an impact mechanism; - The displacement of the cornea caused by the impact is measured multiple times over a predetermined period of time; Methods that include...

15. - Calculating the frequency of free vibration of the cornea due to impact using multiple corneal displacement measurements; - Calculating the value of intraocular pressure from the frequency of free vibration of the cornea caused by impact; The method according to claim 14, further comprising:

16. - Calculate the damping coefficient of the free vibration of the cornea due to impact using multiple corneal displacement measurements; - Calculate the intraocular pressure using the calculated damping coefficient; The method according to claim 14, further comprising:

17. The method according to claims 14 to 16, wherein the multiple measurements are performed using at least one optical sensor, and the at least one optical sensor is selected from a confocal chromatic sensor, a laser Doppler vibrometer, and a laser displacement sensor.

18. The method according to claims 14 to 17, wherein the multiple measurements are performed using at least one optical sensor comprising at least one light-emitting diode and at least one photosensor, the at least one photosensor being selected from either a phototransistor or a photodiode.

19. - Measuring the distance between the cornea of ​​the eye and the tonometer; - The measured distance is used as a feedback signal to move the tonometer to a desired position relative to the cornea, The method according to any one of claims 14 to 18, further comprising:

20. The method according to any one of claims 14 to 19, wherein the impact means is a solid probe or at least one drop of liquid.

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