System and method for measuring eye property value

Abstract

Disclosed is system (104) for measuring eye property value (EPV). System comprises bio signal measurement device (106) configured to measure heart rate related signal (112) and determine therefrom start time of heartbeat cycle (114A, 114B) and cycle time (tc) thereof; tonometer (108) configured to measure plurality of intraocular pressure (IOP) values, wherein plurality of measurements is done within time range from start time to start time added with integer times tc; and computing arrangement (110) configured to calculate, from measured plurality of IOP values and tc, EPV from at least one of: average IOP (116), diastolic IOP (118) (DIOP), systolic IOP (120) (SIOP) or ocular pulse peak-to-peak amplitude value (122).

Description

[0001] SYSTEM AND METHOD FOR. MEASURING EYE PROPERTY VALUE

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to systems for measuring eye property values. Moreover, the present disclosure relates to methods of measuring eye property values.

[0004] BACKGROUND

[0005] Intraocular pressure (IOP) inside an eye of a subject, is not a constant value but rather exhibits pulsatile components that are influenced by a cardiac cycle of the subject. Notably, the traditional methods of measuring IOP, such as applanation tonometry, rely on direct contact with a cornea of the eye and provide a single value representing an average IOP at a given moment. However, said methods fail to capture the dynamic nature of the IOP, which changes as a function of a heartbeat. Conventionally, a rebound tonometer is used for measuring the IOP. The working principle of the rebound tonometer involves ejecting a probe towards an eye's surface and measuring a velocity change profile of the probe during its impact. In this regard, the rebound tonometer calculates the IOP value corresponding to the moment of measurement by analysing the velocity change profile.

[0006] Typically, the contact time between the probe and the eye's surface lasts between 2 to 5 milliseconds (0.002 s - 0.005 s). Generally, a resting heartbeat for a subject is in a range of 40bpm (beats per minute) to lOObmp. This corresponds to a cycle time (tc) of 0.6 to 1.5 seconds between the two heartbeats. However, said short duration of the probeeye contact in comparison to the cycle time of the heartbeat results in a situation where the measured IOP value may fall anywhere between the average IOP minus half of the difference between diastolic IOP (lower bound during the cardiac cycle) and systolic IOP (upper bound during the cardiac cycle), to the average IOP plus half of the same difference. Said uncertainty arises due to the timing of the probe's impact with respect to the phase of the heartbeat.

[0007] Moreover, the variation in a heart rate and timing between the two consecutive heartbeats, known as heart rate variability, may introduce further fluctuations in the IOP measurements. Furthermore, the inaccuracies in the IOP measurement have significant implications for the subjects, particularly in the diagnosis and monitoring of conditions such as glaucoma. In an example, an elevated IOP and an ocular pulse peak- to-peak amplitude (OPA) has emerged as a parameter for the glaucoma assessment.

[0008] Existing devices for measuring the IOP suffer from limitations stemming from the delay or difference in a pulse arrival time when comparing measurements taken at various places in the subject's body to those within the eye. The pulsation of the heart introduces substantial shortterm variations to IOP measurements, leading to unwanted variability. Additionally, factors such as blood pressure can affect the rebound time of the probe during tonometry, further complicating accurate IOP measurements.

[0009] Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks.

[0010] SUMMARY

[0011] The aim of the present disclosure is to provide systems and methods to measure eye property values. The aim of the present disclosure is achieved by a system and a method for (of) measuring an eye property value as defined in the appended independent claims to which reference is made to. Advantageous features are set out in the appended dependent claims. Throughout the description and claims of this specification, the words "comprise" , "include", "have", and "contain" and variations of these words, for example "comprising" and "comprises" , mean "including but not limited to", and do not exclude other components, items, integers or steps not explicitly disclosed also to be present. Moreover, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0012] BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1A is an illustration of an environment illustrating a user using a system for measuring an eye property value, in accordance with an embodiment of the present disclosure;

[0014] FIG. IB is an illustration of a heart rate related signal measured by the bio signal measurement device, in accordance with an embodiment of the present disclosure;

[0015] FIG. 1C is an illustration of a graphical representation depicting eye property values with respect to time, in accordance with an embodiment of the present disclosure;

[0016] FIGs. 2A and 2B are graphical representations depicting intraocular pressure value with respect to a relative phase, in accordance with an embodiment of the present disclosure; and

[0017] FIG. 3 is an illustration of a flowchart depicting steps of a method of measuring an eye property value, in accordance with an embodiment of the present disclosure.

[0018] DETAILED DESCRIPTION OF EMBODIMENTS

[0019] The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practising the present disclosure are also possible.

[0020] In a first aspect, the present disclosure provides a system for measuring an eye property value, the system comprising:

[0021] - a bio signal measurement device configured to measure a heart rate related signal and determine from the heart rate related signal a start time of a heartbeat cycle and a cycle time of the heartbeat cycle;

[0022] - a tonometer configured to measure a plurality of intraocular pressure values, wherein the plurality of the measurements is done within a time range from the start time to the start time added with an integer times the cycle time of the heartbeat cycle; and

[0023] - a computing arrangement configured to calculate, from the measured plurality of intraocular pressure values and the cycle time of the heartbeat cycle, the eye property value which is at least one of: an average intraocular pressure value, a diastolic intraocular pressure value, a systolic intraocular pressure value or an ocular pulse peak-to-peak amplitude value.

[0024] According to the first aspect of the present disclosure, there is provided the aforementioned system having various components that work together synergistically to achieve several advantages in the measurement of the eye property values. In this regard, the system employs the bio signal measurement device to measure the heart rate related signal and determine the start time and the cycle time of the heartbeat cycle. The system employs the tonometer to perform a series of IOP measurements within a specific time range that corresponds to the heartbeat cycle. It will be appreciated that the start time and the cycle time of the heartbeat cycle, are crucial for coordinating with the timing of the tonometer's measurements. Thus, by aligning the measurements with specific points in the cardiac cycle, the system can capture the influence of heart rate and fluctuations in the intraocular pressure more effectively.

[0025] The system employs the computing arrangement that processes the collected intraocular pressure values and calculates the eye property values such as the average intraocular pressure value, diastolic intraocular pressure value, systolic intraocular pressure value, or ocular pulse pea k-to- peak amplitude value. Advantageously, said comprehensive analysis provides a more detailed understanding of the eye's condition and dynamics, allowing for a more precise assessment of ocular health and potential abnormalities.

[0026] In a second aspect, the present disclosure provides a method of measuring an eye property value, the method comprising

[0027] - measuring, using a bio signal measurement device, a heart rate related signal and determining from the heart rate related signal a start time of a heartbeat cycle and a cycle time of the heartbeat cycle;

[0028] - measuring, using a tonometer, a plurality of intraocular pressure values within a time range from the start time to the start time added with an integer times the cycle time of the heartbeat cycle; and

[0029] - calculating, using a computing arrangement, from the measured plurality of intraocular pressure values and the cycle time of the heartbeat cycle, the eye property value which is at least one of: an average intraocular pressure value, a diastolic intraocular pressure value, a systolic intraocular pressure value or an ocular pulse peak-to-peak amplitude value.,

[0030] According to the second aspect of the present disclosure, the method combines the measurement of the plurality of intraocular pressure values with the timing of the heartbeat cycle to determine various eye property values. The method allows for precise timing of the plurality of intraocular pressure measurements within a specific time range by determining the start time and cycle time of the heartbeat cycle. Said synergistic approach enables the calculation of eye property values such as the average intraocular pressure, the diastolic intraocular pressure, the systolic intraocular pressure, or the ocular pulse pea k-to- peak amplitude. It will be appreciated that the synchronized measurement of the plurality of intraocular pressure values with the heartbeat cycle provides a comprehensive understanding of the eye's physiological characteristics, allowing for a more accurate assessment of its overall health and functioning.

[0031] The term "eye property value" as used herein refers to quantitative measurements or characteristics associated with the eye's physiological state or behaviour. Notably, the eye property values provide insights into various aspects of the eye's function and health. In this regard, the eye property values include the average intraocular pressure, the diastolic intraocular pressure, the systolic intraocular pressure or an ocular pulse peak-to-peak amplitude. It will be appreciated that the system facilitates the calculation of the eye property values selected from at least one of: the eye property values include the average intraocular pressure, the diastolic intraocular pressure, the systolic intraocular pressure or an ocular pulse peak-to-peak amplitude.

[0032] Herein, the term intraocular pressure refers to a fluid pressure inside the eye of the subject such as a human. Herein, the term average intraocular pressure value represents a mean intraocular pressure measured during the specified time range. Herein, the term diastolic pressure refers to a lowest pressure level reached during a relaxation phase of the heart of the subject. Herein, the term diastolic intraocular pressure indicates a minimum pressure recorded during the given time range. Herein, the term systolic pressure refers to highest pressure level reached during a contraction phase of the heart. Herein, the term systolic intraocular pressure represents the maximum pressure measured within the given time range. Herein, the term ocular pulse peak-to-peak amplitude refers to a difference between the systolic intraocular pressure value and the diastolic intraocular pressure value. Moreover, the ocular pulse peak-to- peak amplitude reflects a fluctuation or a pulsatile nature of the intraocular pressure value during the heartbeat cycle and provides insights into the eye's ability to regulate the intraocular pressure changes.

[0033] The term "bio signal measurement device" as used herein refers to a device that is capable of capturing and measuring electrical or mechanical signals associated with the beating of the heart. Optionally, the bio signal measurement device consists of several components that work together to capture and measure the heart rate-related signal. Optionally, the components of the bio signal measurement device include a plurality of sensors, a signal processing unit, a processor, and so forth. Optionally, the plurality of sensors is used to detect the electrical activity or mechanical movements associated with the beating of the heart. Optionally, the signal processing unit is responsible for amplifying, filtering, and analyzing the heart rate related signal. Optionally, the processor is used to control the overall operation of the bio signal measurement device. Optionally, if the heart rate related signal is analog in nature, the bio signal measurement device may include the analog-to- digital converter to convert the analog signal into a digital format, enabling further digital processing and analysis of the heart rate related signal. Optionally, the bio signal measurement device may include a communication interface to transmit the heart rate related data to external devices. Optionally, the communication interface may be wired (such as a USB or serial port) or wireless (such as Bluetooth® or Wi-Fi®), allowing for data exchange with the external devices.

[0034] In this regard, the heart rate related signal provides information about the timing and frequency of the beats of the heart. Moreover, by analyzing the heart rate related signal, the bio signal measurement device identifies the beginning of a heartbeat cycle, which marks the start time. Optionally, the heart rate related signal could be analyzed by detecting specific patterns or features in the heart rate related signal that indicate the onset of a heartbeat. The term "cycle time" as used herein refers to a duration between consecutive heartbeats and provides a basis for synchronizing the subsequent measurements of the plurality of intraocular pressure values. The bio signal measurement device further calculates the cycle time of the heartbeat cycle.

[0035] The technical effect of employing the bio signal measurement device is that it enables the system to align the measurements of the plurality of intraocular pressure values with the specific phases of the heartbeat cycle, ensuring that the measurements are performed at consistent time intervals.

[0036] Optionally, the cycle time of the heartbeat cycle is determined from the heart rate related signal by calculating a time difference between two heartbeats. In this regard, the heart rate related signal provides information about a temporal pattern of heartbeats, and by calculating the time difference between two heartbeats, the cycle time is determined. Optionally, the time difference is calculated by measuring the time between the onset of two successive R-peaks in an electrocardiogram (ECG) signal. Optionally, the cycle time may be calculated by determining the time interval between the R-peaks. Optionally, the cycle time of the heartbeat cycle serves as a fundamental parameter for understanding a timing and rhythm of physiological events related to the heart. Optionally, the system may establish a time reference for measuring the plurality of intraocular pressure values and perform calculations related to eye property values by accurately calculating the cycle time. Optionally, the cycle time of the heartbeat cycle may provide an insight into the heart's functioning and cardiovascular dynamics.

[0037] Optionally, the bio signal monitoring device is configured to determine a heart rate variability and use the heart rate variability to select moments of time for making the measurements of the intraocular pressure values. The term "heart rate variability" as used herein refers to a variation in the time intervals between consecutive heartbeats. Notably, the heart rate variability encompasses the differences in beat-to-beat intervals, which can be measured and analyzed to gain insights into the cardiac state of the subject. Optionally, the bio signal monitoring device is capable of utilizing the heart rate variability to select specific moments in time for making measurements of the plurality of intraocular pressure values. Optionally, by analyzing the heart rate variability, the bio signal monitoring device may identify periods of time characterized by specific patterns or levels of autonomic modulation. For example, the bio signal monitoring device may prioritize moments of higher heart rate variability, that typically indicate increased sympathetic and parasympathetic influence on the heart rate. Optionally, said moments may correspond to specific phases of the cardiac cycle, such as the systolic or diastolic phases. Optionally, by selecting the moments of time with higher heart rate variability, the bio signal measurement device aims to capture intraocular pressure values during periods when the eye's physiological conditions are more representative.

[0038] Optionally, the bio signal measurement device is a heart rate monitor. The term "heart rate monitor" as used herein refers to a device that is used to detect the heart related signals and then process the heart related signals to calculate the heart rate and provide other related information. Typically, the heart rate monitor includes sensors, electrodes, or optical devices that are placed in contact with the subject. In this regard, the heart rate monitor detects and measure the heart's electrical signals, or the pulse generated by the heart's contractions. The technical effect of using the heart rate monitor as the bio signal measurement device is that it provides a dedicated and specialized device for accurately measuring the heart rate related signal. Optionally, the accuracy and reliability of the heart rate-related signal measurement are enhanced by utilizing the heart rate monitor as the bio signal measurement device in the system. Pursuant to the embodiments of the present disclosure, the term "tonometer" as used herein refers to an instrument that is used for measuring an internal pressure value of an eye. Typically, the intraocular pressure exerts forces on every part of the eye. Notably, the cornea is a surface of the eye that is suitable to measure the intraocular pressure. Optionally, the measurement of the intraocular pressure on the cornea could be made easier and with better precision than on other eye surfaces, such as the sclera. Notably, the measurement of the intraocular pressure is of vital importance to maintain overall eye health and function. Typically, the said measurement enables a diagnosis and treatment of ocular hypertension before the development of eye-related condition such as glaucoma.

[0039] The technical effect of using the tonometer is to measure the plurality of intraocular pressure values over a defined period aligned with the heart's activity. It will be appreciated that by synchronizing the timing of the measurements of the intraocular pressure values with the heartbeat cycle, the tonometer may obtain more reliable and representative intraocular pressure values. Optionally, the tonometer's synchronization with the heartbeat cycle ensures that the measurements are consistently taken at predetermined intervals. It will be appreciated that the tonometer's synchronization promotes consistency in data collection, making it easier to compare and analyze the intraocular pressure values over time.

[0040] Optionally, the tonometer could minimize the potential interference caused by external factors or artifacts by aligning the measurements with the heartbeat cycle. Optionally, the tonometer could reduce the need for repeated measurements at various time points and streamlines the process, saving time for both the subject and the healthcare professional. Optionally, the tonometer is a rebound tonometer, a corneal tonometer or an oscillation-based tonometer. The term "rebound tonometer" as used herein refers to a tonometer that measures the intraocular pressure by utilizing a rebound principle. In this regard, the rebound tonometer works by projecting a small probe onto the cornea, and upon contact, the probe rebounds or bounces back. The rebound tonometer measures the speed and changes in the probe's rebound, which are directly related to the intraocular pressure. The technical effect of implementing the tonometer as the rebound tonometer is that the rebound tonometer offers noncontact measurements, making them more comfortable and hygienic for the subjects such as patients. Optionally, the rebound tonometer is user friendly and may provide quick measurements without the need for anesthesia or contact with the cornea. Additionally, rebound tonometers are portable and suitable for various clinical settings, enabling convenient intraocular pressure monitoring.

[0041] The term "corneal tonometer" as used herein refers to a tonometer that measures intraocular pressure by assessing the biomechanical properties of the cornea. Optionally, the corneal tonometer may use different techniques, such as applanation or indentation, to evaluate the response of the cornea to the applied force by the probe. The technical effect of using the corneal tonometer is that it provides direct contact measurements, allowing for precise assessment of the intraocular pressure value. Typically, the corneal tonometer takes into account factors such as a corneal thickness and biomechanical characteristics, which may influence intraocular pressure measurements.

[0042] The term "oscillation-based tonometer" as used herein refers to a tonometer that utilizes the principle of corneal resonance or natural frequency of the eye to estimate intraocular pressure. Typically, the oscillation-based tonometer applies a small oscillating force to the cornea and measures the response or vibrations caused by this force. The technical effect of using the oscillation-based tonometer is that it offers a non-contact method for measuring the intraocular pressure. Optionally, the oscillation-based tonometer may provide rapid and reproducible measurements without the need for anesthesia or corneal contact. Optionally, the oscillation-based tonometer is suitable for screening purposes and may be particularly useful in situations where contact tonometry may be challenging or undesirable, such as while examining the subjects such as children.

[0043] The term "computing arrangement" as used herein refers to a component that is used for performing computational tasks and calculations. Typically, the computing arrangement includes hardware and software components that work together to process and analyze data. Optionally, the computing arrangement may include various elements, such as processors, memory, algorithms, and software programs. Optionally, the computing arrangement may be designed to receive an input data, perform calculations or computations on that data, and generate meaningful output or results.

[0044] In this regard, the computing arrangement receives the measured intraocular pressure values and the cycle time of the heartbeat cycle as input data. The computing arrangement then utilizes the input data to calculate the desired eye property values, such as the average intraocular pressure value, the diastolic intraocular pressure value, the systolic intraocular pressure value, or the ocular pulse peak-to-peak amplitude value.

[0045] Optionally, the computing arrangement may employ statistical methods, signal processing techniques, or other mathematical models to derive meaningful insights from the input data provided by the bio signal measurement device and the tonometer. Optionally, the eye property values may guide a selection of appropriate treatments and monitoring strategies. For example, knowing the average intraocular pressure value may help determine the overall pressure level, while diastolic and systolic values provide insights into the pressure during specific phases of the cardiac cycle. Said information enables healthcare professionals to tailor interventions based on individual patient needs.

[0046] Optionally, the calculation comprises:

[0047] - fitting the plurality of measured intraocular pressure values to a periodic function having a periodicity of the cycle time of the heartbeat cycle;

[0048] - determining from the periodic function a maximum value and a minimum value of the periodic function; and

[0049] - using the maximum value and the minimum value of the periodic function as the systolic intraocular pressure value and the diastolic intraocular pressure value, respectively.

[0050] Optionally the calculation performed by the computing arrangement includes several steps. In this regard, the computing arrangement is used to fit the plurality of measured intraocular pressure values to the periodic function that has the periodicity corresponding to the cycle time of the heartbeat cycle. Said fitting process involves analyzing the plurality of measured intraocular pressure values and determining the best-fitting periodic function that accurately represents the pressure variations over the cardiac cycle. Once the periodic function is established, the computing arrangement proceeds to determine the maximum value and the minimum value from the periodic function. Optionally, the maximum value and the minimum value correspond to specific points in the cardiac cycle, representing the systolic and diastolic phases of the intraocular pressure, respectively. Optionally, the computing arrangement can provide valuable insights into the dynamic changes in the intraocular pressure by utilizing the maximum value as the systolic intraocular pressure value and the minimum value as the diastolic intraocular pressure value. A technical effect of calculating the eye property value from the measured plurality of intraocular pressure values and the cycle time of the heartbeat cycle, is to provide valuable insights into the pressure during specific phases of the cardiac cycle. In this regard, the maximum value is utilized as the systolic intraocular pressure value and the minimum value is utilized as the diastolic intraocular pressure value by calculating the systolic intraocular pressure value and the diastolic intraocular pressure value based on the period function that fits the measured plurality of intraocular pressure values, which is novel and inventive over the conventional systems for measuring eye property value. Further technical effect of starting the measurements at the start time of the heartbeat cycle is, that this way we ensure to obtain relevant samples of intraocular pressure values to find variations which are associated with different phases of the heartbeat cycle.

[0051] Moreover, with the measurement method (like rebound tonometer) it is difficult to obtain intraocular pressure values at tight enough time intervals and the comprehensive ocular pulse amplitude (OPA) information containing the systolic intraocular pressure values and diastolic intraocular pressure values. For example, the heart rate is around 60-100 beats per minute, thus 2-3 rebound intraocular pressure measurements can be made during one cardiac cycle. Therefore, the intraocular pressure measurements occur at some points of the OPA that may not be the points with the systolic intraocular pressure or diastolic intraocular pressure values. However, beneficially, by fitting the measured plurality of intraocular pressure values to the periodic function, the periodic function can be used to find the actual systolic intraocular pressure values and diastolic intraocular pressure values as well as the average intraocular pressure.

[0052] Optionally, the calculation is carried out by solving d and p from: xi = dfi (wti) + p X2 = dfi (Wt ) + P wherein xi is a first intraocular pressure value from the measured plurality of intraocular pressure values, X2 is a second intraocular pressure value from the measured plurality of intraocular pressure values, d is the ocular pulse peak-to-peak amplitude value, p is the average intraocular pressure value, fi is a first periodic function having a period w, which the period (w) is associated with the cycle time and wherein ti is different from t2 by integer times the cycle time added with an offset time.

[0053] In this regard, the computing arrangement implements the aforementioned calculation to calculate the ocular pulse peak-to-peak amplitude (d) and the average intraocular pressure value (p) using a set of intraocular pressure values (x). The equations xi = dfi (wti) + p and X2 = dfi (wt2) + p, relate the intraocular pressure values (xi and X2) to the ocular pulse peak-to-peak amplitude (d), the average intraocular pressure value (p), and other variables. It will be appreciated that the aforementioned calculation considers the fact that the intraocular pressure fluctuates over time, leading to more accurate calculations of the ocular pulse peak-to-peak amplitude (d) and the average intraocular pressure value (p). Optionally, the computing arrangement implements the calculation in order to make the system less susceptible to noise and other errors, increasing reliability thereof. Optionally, the periodic function fi is typically a sine wave. Optionally, the offset time represents the delay between the peak of the ocular pulse peak-to-peak amplitude value and the time of intraocular pressure measurement.

[0054] Optionally, the diastolic intraocular pressure is calculated by subtracting from the average intraocular pressure value (p)1 / 2 of the ocular pulse peak-to-peak amplitude (d) and the systolic intraocular pressure is calculated by adding to the average intraocular pressure value (p)1 / 2 of the ocular pulse peak-to-peak amplitude (d). In this regard, the computing arrangement may implement an algorithm that takes into account a mathematical calculation for calculating the diastolic intraocular pressure. Optionally, the mathematical calculation uses the ocular pulse peak-to-peak amplitude value for determining the diastolic and the systolic intraocular pressures more accurately. Notably, the ocular pulse peak-to-peak amplitude value reflects the fluctuations in pressure caused by the pulsatile nature of blood flow within the eye. Thus, by incorporating the ocular pulse peak-to-peak amplitude value into the mathematical calculation, the resulting diastolic and systolic intraocular pressure values provide insights into the pressure variations throughout the cardiac cycle. Additionally, the mathematical calculation may aid in enhancing the understanding of ocular hemodynamics and contribute to the evaluation of other ocular conditions influenced by intraocular pressure fluctuations.

[0055] Optionally, the system further comprises:

[0056] - a respiration measurement device configured to measure a breathing related signal and determine from the breathing related signal a breathing cycle time (tb) between inhales cycles; and

[0057] - the computing arrangement that is further configured to use, in calculation of the breathing cycle time.

[0058] The term "respiration measurement device" as used herein refers to a component of the system that is specifically designed to measure and capture a breathing-related signal. Optionally, the respiration measurement device is responsible for monitoring the respiratory pattern of the subject. Optionally, the respiration measurement device typically consists of sensors or transducers that can detect and record the breathing-related signal. Optionally, the respiration measurement device is connected to the system either directly or wirelessly. Optionally, the connection allows the device to transmit the measured breathing-related signal to the computing arrangement for further analysis and calculation. Optionally, the breathing-related signal may include parameters such as a respiratory rate, an airflow, or chest movements. Optionally, the respiration measurement device identifies the time interval between consecutive inhalations to determine the breathing cycle time (tb) between inhalation cycles.

[0059] The technical effect of employing the respiration measurement device in the system is to provide a more comprehensive evaluation of the intraocular pressure dynamics. Optionally, the respiration measurement device is connected to the computing arrangement, which is responsible for processing and analyzing the received breathing-related signal. Optionally, the computing arrangement uses the measured breathing cycle time in the calculation process to incorporate the effects of respiration on intraocular pressure.

[0060] Optionally, the calculation is carried out by solving p, P, d and D using equation: xi = dfi (wti) +P + D f2(wbti) + P x2= dfi (wt ) + p + D f2(wbt2) + P

[0061] X3 = dfi (wts) + p + D f2(wbts) + P

[0062] X4 = dfi (Wt4) + p + D f2(wbt4) + P wherein D is contribution of the breathing to the ocular pulse peak-to- peak amplitude value, P is contribution of the breathing to the average intraocular pressure value, wb is periodicity of the breathing, and xi, X2, X3, X4 are measured intraocular pressure values from the measured plurality of intraocular pressure values at respective moments of time.

[0063] In this regard, the computing arrangement performs the calculation by solving the equation for the unknowns p, P, d, and D using the measured intraocular pressure values and the provided weights. Optionally, the system may estimate the contributions of breathing to both the average intraocular pressure value and the ocular pulse peak-to-peak amplitude value by finding the values of p, P, d, and D that satisfy the equation for all given measurements.

[0064] Optionally, the aforementioned equation allows for the incorporation of the effects of breathing on the intraocular pressure values calculations. Optionally, the aforementioned equation considers the relationship between breathing-related factors (D, P, and the weights associated with breathing functions) and intraocular pressure measurements (xi, X2, X3, X4). Optionally, by solving for the unknowns, the system can provide a more accurate estimation of the intraocular pressure values, accounting for the influence of respiration. The technical effect of using the aforementioned equation is the improved accuracy in assessing the intraocular pressure value by considering the contributions of breathing.

[0065] The present disclosure also relates to the method of measuring an eye property value as described above. Various embodiments and variants disclosed above, with respect to the aforementioned system for measuring an eye property value, apply mutatis mutandis to the method of measuring an eye property value.

[0066] Optionally, the calculation comprises:

[0067] - fitting the measured plurality of intraocular pressure values to a periodic function having a periodicity of the cycle time of the heart beat cycle;

[0068] - determining from the periodic function a maximum value and a minimum value of the periodic function; and

[0069] - using the maximum value and the minimum value of the periodic function as the systolic intraocular pressure value and the diastolic intraocular pressure value, respectively.

[0070] Optionally, the calculation is carried out by solving d and p from: xi = dfi (wti) + p X2 = dfi (Wt2) + p wherein xi is a first intra ocular pressure value from the measured plurality of intraocular pressure values, X2 is a second intra ocular pressure value from the measured plurality of intraocular pressure values, d is the ocular pulse pea k-to- peak amplitude value, p is average intraocular pressure value, fi is a first periodic function having a period w, which the period (w) is associated with the cycle time and wherein ti is different from t by integer times the cycle time added with an offset time.

[0071] Optionally, the diastolic intraocular pressure is calculated by subtracting from the average intraocular pressure value (p)1 / 2 of the ocular pulse peak-to-peak amplitude (d) and the systolic intraocular pressure is calculated by adding to the average intraocular pressure value (p)1 / 2 of the ocular pulse peak-to-peak amplitude value (d).

[0072] Optionally, the method further comprises:

[0073] - measuring, using a respiration measurement device, a breathing related signal;

[0074] - determining, using the respiration measurement device, from the breathing related signal, a breathing cycle time (tb) between inhales cycles; and

[0075] - using in calculation of the breathing cycle time.

[0076] Optionally, the calculation is carried out by solving p, P, d and D using equation: xi = dfi (wti) 4-p + D f2(wbti) + P x2= dfi (Wt2) + p + D f2(wbt2) + P

[0077] X3 = dfi (wts) + p + D f2(wbts) + P

[0078] X4 = dfi (Wt4) + p + D f2(wbt4) + P wherein D is contribution of the breathing to the ocular pulse peak-to- peak amplitude value, P is contribution of the breathing to the average intraocular pressure value, wb is periodicity of the breathing, and xi, X2, X3, X4 are measured intraocular pressure values from the measured plurality of intraocular pressure values at respective moments of time.

[0079] DETAILED DESCRIPTION OF THE DRAWINGS

[0080] Referring to FIG. 1A, there is shown an environment 100 illustrating a user 102 using a system 104 for measuring an eye property value, in accordance with an embodiment of the present disclosure. As shown, the system 104 comprises a bio signal measurement device 106, a tonometer 108 and a computing arrangement 110. It will be appreciated that the bio signal measurement device 106, the tonometer 108 and the computing arrangement 110 work in conjunction with each other to measure the eye property value. The bio signal measurement device 106 is configured to measure a heart rate related signal 112 (as depicted below in FIG. IB) and determine from the heart rate related signal 112 a start time of a heartbeat cycle 114A and 114B and a cycle time tc of the heartbeat cycle 114A and 114B (as depicted below in FIG. IB). The tonometer 108 is configured to measure a plurality of intraocular pressure values, wherein the plurality of the measurements is done within a time range from the start time to the start time added with an integer times the cycle time tc of the heartbeat cycle 114A and 114B. The computing arrangement 110 is configured to calculate, from the measured plurality of intraocular pressure values and the cycle time tc of the heartbeat cycle 114A and 114B, the eye property value which is at least one of: an average intraocular pressure value 116 (as depicted below in FIG. 1C), a diastolic intraocular pressure value 118 (as depicted below in FIG. 1C), a systolic intraocular pressure value 120 (as depicted below in FIG. 1C) or an ocular pulse peak-to-peak amplitude value 122 (as depicted below in FIG. 1C). Moreover, the calculation comprises fitting the measured plurality of intraocular pressure values to a periodic function having a periodicity of the cycle time tc of the heartbeat cycle 114A and 114B; determining from the periodic function a maximum value and a minimum value of the periodic function; and using the maximum value and the minimum value of the periodic function as the systolic intraocular pressure value 120 and the diastolic intraocular pressure value 118, respectively.

[0081] Referring to FIG. IB, there is shown a heart rate related signal 112 measured by the bio signal measurement device 106 (as depicted below in FIG. 1A), in accordance with an embodiment of the present disclosure. As shown, the heart rate related signal 112 includes a start time of a heartbeat cycle 114A and 114B and a cycle time tc of the heartbeat cycle 114A and 114B. Optionally, the cycle time tc of the heartbeat cycle 114A and 114B is determined from the heart rate related signal 112 by calculating a time difference between two heartbeats.

[0082] Referring to FIG. 1C, there is shown a graphical representation 124 depicting eye property values with respect to time, in accordance with an embodiment of the present disclosure. As shown, an x-axis 126 is depicting the eye property values such as intraocular pressure values that are measured at various instances of time. The y-axis 128 depicts the time at which corresponding intraocular pressure value of an eye is measured. Moreover, there is shown the average intraocular pressure value 116, the diastolic intraocular pressure value 118, the systolic intraocular pressure value 120 and the ocular pulse pea k-to- peak amplitude value 122. Furthermore, there is shown a first intraocular pressure value 130 measured at time ti and a second intraocular pressure value 132 measured at time tz = [(ti + N x tc) + offset], where in N is an integer and offset is a value which is different from cycle time tc. For example, herein the N is 2.

[0083] Referring to FIGs. 2A and 2B, shown are graphical representations 200A and 200B depicting intraocular pressure value with respect to a relative phase, in accordance with an embodiment of the present disclosure. There is shown an x-axis 202 depicting the intraocular pressure value values that are measured at various instances of time. The y-axis 204 is depicting the time at which the corresponding IOP value of an eye is measured. As shown in FIG. 2A, a heart rate related signal 206 that is constructed using the randomly measured plurality of intraocular pressure values (such as A-F). As shown in FIG. 2B, an x-axis 208 depicting the intraocular pressure value and a y-axis 210 depicting a relative phase. Moreover, there is shown the measured plurality of intraocular pressure values A-F that are fitted to a periodic function having a periodicity of the cycle time of the heartbeat cycle. Optionally, the maximum value and a minimum value of the periodic function is determined. Optionally, the maximum value and the minimum value of the periodic function is used as the systolic intraocular pressure value and the diastolic intraocular pressure value, respectively.

[0084] Referring to FIG. 3, shown is a flowchart depicting steps of a method of measuring an eye property value, in accordance with an embodiment of the present disclosure. At step 302, a heart rate related signal is measured using a bio signal measurement device, and a start time of a heartbeat cycle and a cycle time of the heartbeat cycle is determined from the heart rate related signal. At step 304, a plurality of intraocular pressure values within a time range from the start time to the start time added with an integer times the cycle time of the heartbeat cycle is measured using a tonometer. At step 306, the eye property value which is at least one of: an average intraocular pressure value, a diastolic intraocular pressure value, a systolic intraocular pressure value or an ocular pulse pea k-to- peak amplitude value is calculated, using a computing arrangement, from the measured plurality of intraocular pressure values and the cycle time of the heartbeat cycle. Moreover, the calculation comprises fitting the measured plurality of intraocular pressure values to a periodic function having a periodicity of the cycle time of the heartbeat cycle; determining from the periodic function a maximum value and a minimum value of the periodic function; and using the maximum value and the minimum value of the periodic function as the systolic intraocular pressure value and the diastolic intraocular pressure value, respectively.

[0085] The aforementioned steps are only illustrative and other alternatives can also be provided where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.

Claims

CLAIMS1. A system (104) for measuring an eye property value, the system comprising:- a bio signal measurement device (106) configured to measure a heart rate related signal (112) and determine from the heart rate related signal a start time of a heartbeat cycle and a cycle time (tc) of the heartbeat cycle (114A, 114B);- a tonometer (108) configured to measure a plurality of intraocular pressure values, wherein the plurality of the measurements is done within a time range from the start time to the start time added with an integer times the cycle time of the heartbeat cycle; and- a computing arrangement (110) configured to calculate, from the measured plurality of intraocular pressure values and the cycle time of the heartbeat cycle, the eye property value which is at least one of: an average intraocular pressure value (116), a diastolic intraocular pressure value (118), a systolic intraocular pressure value (120) or an ocular pulse pea k-to- peak amplitude value (122).

2. A system (104) according to claim 1, wherein the cycle time (tc) of the heartbeat cycle (114A, 114B) is determined from the heart rate related signal (112) by calculating a time difference between two heartbeats.

3. A system (104) according to any of the preceding claims, wherein the bio signal monitoring device (106) is configured to determine a heart rate variability and use the heart rate variability to select moments of time for making the measurements of the plurality of intraocular pressure values.

4. A system (104) according to any of the preceding claims, wherein the calculation comprises:- fitting the measured plurality of intraocular pressure values to a periodic function having a periodicity of the cycle time of the heartbeat cycle;- determining from the periodic function a maximum value and a minimum value of the periodic function; and- using the maximum value and the minimum value of the periodic function as the systolic intraocular pressure value and the diastolic intraocular pressure value, respectively.

5. A system (104) according to any of the preceding claims, wherein the calculation is carried out by solving d and p from: xi = dfi (wti) + p X2 = dfi (wt ) + p wherein xi is a first intraocular pressure value from the measured plurality of intraocular pressure values , X2 is a second intraocular pressure value from the measured plurality of intraocular pressure values, d is the ocular pulse pea k-to- peak amplitude, p is average intraocular pressure value, fi is a first periodic function having a period w, which the period (w) is associated with the cycle time (tc) and wherein ti is different from t2 by integer times the cycle time added with an offset time.

6. A system (104) according to claim 5, wherein the diastolic intraocular pressure value (118) is calculated by subtracting from the average intraocular pressure value (116) (p)1 / 2 of the ocular pulse peak-to-peak amplitude (d) (122) and the systolic intraocular pressure (120) is calculated by adding to the average intraocular pressure value (p)1 / 2 of the ocular pulse peak-to-peak amplitude (d).

7. A system (104) according to any of the preceding claims, wherein the system further comprises- a respiration measurement device configured to measure a breathing related signal and determine from the breathing related signal a breathing cycle time (tb) between inhales cycles; and- the computing arrangement (110) that is further configured to use, in calculation of the breathing cycle time.

8. A system (104) according to claim 6, wherein the calculation is carried out by solving p, P, d and D using equation: xi = dfi (wti) +p + D f2(wbti) + P x2= dfi (wt ) + p + D f2(wbt2) + PX3 = dfi (wts) + p + D f2(wbts) + PX4 = dfi (Wt4) + p + D f2(wbt4) + P wherein D is contribution of the breathing to the ocular pulse peak-to- peak amplitude value (122), P is contribution of the breathing to the average intraocular pressure value (116), wb is periodicity of the breathing, and xi, X2, X3, X4 are measured intraocular pressure values from the measured plurality of intraocular pressure values at respective moments of time.

9. A system (104) according to any of the preceding claims, wherein the bio signal measurement device (116) is a heart rate monitor.

10. A system (104) according to any of the preceding claims, wherein the tonometer (108) is a rebound tonometer, a corneal tonometer or an oscillation-based tonometer.

11. A method of measuring an eye property value, the method comprising- measuring, using a bio signal measurement device (106), a heart rate related signal (112) and determining from the heart rate related signal a start time of a heartbeat cycle and a cycle time (tc) of the heartbeat cycle (114A, 114B);- measuring, using a tonometer (108), a plurality of intraocular pressure values within a time range from the start time to the start time added with an integer times the cycle time of the heartbeat cycle; and- calculating, using a computing arrangement (110), from the measured plurality of intraocular pressure values and the cycle time of the heartbeat cycle, the eye property value which is at least one of: an average intraocular pressure value (116), a diastolic intraocular pressure value(118), a systolic intraocular pressure value (120) or an ocular pulse peak- to-peak amplitude value (122).

12. A method according to claim 11, wherein the calculation comprises:- fitting the measured plurality of intraocular pressure values to a periodic function having a periodicity of the cycle time of the heartbeat cycle;- determining from the periodic function a maximum value and a minimum value of the periodic function; and- using the maximum value and the minimum value of the periodic function as the systolic intraocular pressure value and the diastolic intraocular pressure value, respectively.

13. A method according to any of the preceding claims 11-12, wherein the calculation is carried out by solving d and p from: xi = dfi (wti) + p X2 = dfi (wt ) + p wherein xi is a first intraocular pressure value from the measured plurality of intraocular pressure values, X2 is a second intraocular pressure value from the measured plurality of intraocular pressure values, d is the ocular pulse peak-to-peak amplitude, p is average intraocular pressure value, fi is a first periodic function having a period w, which the period (w) is associated with the cycle time and wherein ti is different from t2 by integer times the cycle time added with an offset time.

14. A method according to claim 13, wherein the diastolic intraocular pressure value (118) is calculated by subtracting from the average intraocular pressure value (116) (p)1 / 2 of the ocular pulse peak-to-peak amplitude (d) (122) and the systolic intraocular pressure (120) is calculated by adding to the average intraocular pressure value (p)1 / 2 of the ocular pulse peak-to-peak amplitude (d).

15. A method according to any of the preceding claims 10 to 12, wherein the method further comprises- measuring, using a respiration measurement device, a breathing related signal;- determining, using the respiration measurement device, from the breathing related signal, a breathing cycle time (tb) between inhales cycles; and- using in calculation of the breathing cycle time.

16. A method according to claim 15, wherein the calculation is carried out by solving p, P, d and D using equation: xi = dfi (wti) +p + D f2(wbti) + P x2= dfi (wt ) + p + D f2(wbt2) + PX3 = dfi (wts) + p + D f2(wbts) + PX4 = dfi (Wt4) + p + D f2(wbt4) + P wherein D is contribution of the breathing to the ocular pulse peak-to- peak amplitude, P is contribution of the breathing to the average intraocular pressure value, wb is periodicity of the breathing, and xi, X2, X3, X4 are measured intraocular pressure values from the measured plurality of intraocular pressure values at respective moments of time.

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