Method and device for measuring in-vivo human cornea biomechanics

Abstract

The invention discloses a method and device for measuring biomechanics of an in-vivo human cornea, and relates to the technical field of biomechanics nondestructive detection.The method comprises the steps that the cornea is excited for the first time to trigger cornea deformation, and a first vibration displacement field of the cornea is synchronously collected; the rebound process of the cornea is tracked in real time, and the deformation quantity of the cornea is determined; when the deformation quantity of the cornea meets a set condition, triggering second excitation, and synchronously collecting a second vibration displacement field of the cornea; performing deformation analysis on the first vibration displacement field and the second vibration displacement field to generate a relative elastic modulus distribution diagram; and superposing the relative elastic modulus distribution diagram on the OCT structure image to obtain a biomechanical characteristic distribution diagram of the cornea. According to the invention, the confounding factors can be eliminated, so that the accuracy of cornea biomechanical measurement is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biomechanical non-destructive testing, in particular to a method and device for measuring the biomechanics of a human cornea in vivo. BACKGROUND

[0002] The cornea is the most important component of the human eye, accounting for 1 / 6 of the fibrous membrane, and provides about 70% of the refractive power of the entire eye, which provides key support for clear imaging and protection of the human eye from external damage. The biomechanical properties of the cornea play an indispensable role in maintaining the shape and imaging of the eyeball and normal eye function, and changes in biomechanics will directly affect the refractive system of the entire eye and even vision.

[0003] Studies have shown that corneal biomechanical testing has double medical value: at the disease level, it can identify mechanical abnormality diseases such as blinding glaucoma, keratoconus, and Fuchs' corneal dystrophy at an early stage; in the treatment dimension, it provides direct evidence support for preoperative parameter design of corneal refractive surgery, potential keratoconus screening, intraoperative complications and postoperative effect evaluation, and can provide a basis for the treatment effect of corneal cross-linking to prevent the progression of keratoconus. This mechanical-guided precision medicine strategy significantly ensures the safety threshold of surgery and reduces the occurrence of corneal blindness.

[0004] Optical coherence elastography (OCE) is an advanced imaging technique that combines optical coherence tomography (OCT) and biomechanical measurement. It quantitatively evaluates the elastic properties of tissues by detecting their small deformations under mechanical excitation. The core principle of OCE is the combination of high-resolution optical interference technology based on OCT and the dynamics of elastic wave propagation: near-infrared light (wavelength usually 800-1300 nm) is used to irradiate biological tissues, and the microstructure of the tissues is analyzed through interference signals, while a controllable mechanical excitation (such as air pulse, acoustic radiation force or piezoelectric vibration) is applied to excite internal elastic waves in the tissues, and a high-speed camera is used to capture the displacement response.

[0005] The current commonly used corneal biomechanical measurement method mostly relies on single air pulse excitation OCE technology. For example, in the Chinese patent application CN110974148A known to the inventors, the mixed factors cannot be eliminated, the single measurement is affected by different subject mixed factors (such as intraocular pressure difference), and the subject with weak corneal biomechanics but high intraocular pressure may be measured as a subject with strong corneal biomechanics but low intraocular pressure, and the phase gradient distortion caused by non-uniform deformation cannot be eliminated. Moreover, the physiological interference is uncontrollable: the intraocular pressure fluctuation (about 1-5 mmHg / min), the blood vessel pulsation (frequency range 0.8-2 Hz) and other low-frequency physiological signals partially overlap with the elastic wave frequency band (50-500 Hz), and the single measurement cannot effectively separate the real elastic response. In another Chinese patent application CN116725475A known to the inventors, the contact type excitation head easily causes micro-damage (indentation depth > 5 μm) on the corneal surface, and cannot realize the synchronous measurement of multi-mode excitation at the same position.

[0006] Based on the above description, the traditional single air pulse excitation OCE technology has the following defects: (1) mixed factor interference. For example, intraocular pressure interference, different intraocular pressure measurements will cause the biomechanical properties characterized by OCE measurement to change, and the higher the intraocular pressure, the higher the OCE measurement elastic modulus, which will cause the subject with low corneal elastic modulus but high intraocular pressure to be incorrectly classified as a strong biomechanics state, and vice versa. (2) Transient interference (such as blinking, nystagmus) causes distortion of single measurement data, corneal viscoelasticity causes the tissue to not fully recover after excitation, affecting the consistency of repeated measurements, and physiological pulsation (heart rate, intraocular pressure fluctuation) introduces low-frequency noise.

[0007] In summary, the precision and accuracy of the existing method and technology are affected by the limitation of single excitation, and the mixed factors cannot be eliminated, so that the measured corneal biomechanical properties are not accurate enough. SUMMARY

[0008] The purpose of the present application is to provide a method and device for measuring in-vivo human corneal biomechanics, which can eliminate mixed factors and improve the accuracy of corneal biomechanics measurement.

[0009] To achieve the above-mentioned purpose, the present application provides the following solutions:

[0010] In a first aspect, the present application provides a method for measuring in-vivo human corneal biomechanics, comprising:

[0011] Firstly, the cornea is excited to trigger the deformation of the cornea, and the first vibration displacement field of the cornea is synchronously collected;

[0012] The rebound process of the cornea is tracked in real time, and the deformation amount of the cornea is determined;

[0013] When the deformation of the cornea meets the set conditions, a second excitation is triggered, and the second vibration displacement field of the cornea is collected simultaneously.

[0014] Deformation analysis was performed on the first and second vibration displacement fields to generate a relative elastic modulus distribution map.

[0015] The relative elastic modulus distribution map is superimposed on the OCT structural image to obtain the biomechanical property distribution map of the cornea; the OCT structural image is a corneal image obtained using OCT technology.

[0016] Optionally, during the first stimulation of the cornea, a low-pressure, short-pulse-width method is used to induce micron-level deformation of the cornea; the low-pressure, short-pulse-width method refers to a pulse where both the pressure and pulse width are within a set range.

[0017] Optionally, when performing a second stimulation on the cornea, the pressure gradient and pulse width are adjusted based on the pulse used in the first stimulation.

[0018] Optionally, the corneal rebound process is tracked in real time, and the corneal deformation is determined, including:

[0019] The thickness of the corneal apex is obtained during real-time tracking of corneal rebound.

[0020] The deformation recovery rate is determined based on the initial thickness of the cornea and the thickness of the corneal apex.

[0021] The deformation recovery rate is used as the deformation of the cornea.

[0022] Optionally, the corneal rebound process is tracked in real time, and the corneal deformation is determined, including:

[0023] The thickness of the cornea is determined in real time while tracking the rebound of the cornea.

[0024] The determined thickness of the cornea is used as the deformation of the cornea.

[0025] Optionally, when the deformation of the cornea is the deformation recovery rate, the corneal deformation satisfies the set condition by the deformation recovery rate being greater than or equal to the set rate value.

[0026] When the deformation of the cornea is a given corneal thickness, the corneal deformation satisfies the set condition if the given corneal thickness is less than the set thickness value.

[0027] Optionally, the time interval between two stimulations of the cornea is calculated using formula T. interval =t recovery +t delay Dynamic adjustments are made; where t recovery For the actual recovery time, tdelay In response to the delay, the T interval The time interval is dynamically adjusted.

[0028] Optionally, a M-B hybrid scanning mode is adopted to track the rebound process of the cornea in real time and determine the deformation of the cornea.

[0029] Optionally, the first vibration displacement field and the second vibration displacement field are deformed to generate a relative elastic modulus distribution map, including:

[0030] The first vibration displacement field and the second vibration displacement field are aligned by using a cross-correlation algorithm to obtain registration data;

[0031] The registration data is subjected to band-pass filtering to extract a Lamb wave main frequency component;

[0032] The elastic modulus and displacement of the first excitation and the elastic modulus and displacement of the second excitation are determined based on the Lamb wave main frequency component;

[0033] The displacement response difference of the two excitations is determined based on the elastic modulus and displacement of the first excitation and the elastic modulus and displacement of the second excitation;

[0034] The relative elastic modulus change rate is determined based on the displacement response difference of the two excitations;

[0035] The relative elastic modulus change rate is reconstructed into a relative elastic modulus distribution map by using a spatial interpolation algorithm.

[0036] In a second aspect, the application provides a device for measuring in-vivo corneal biomechanics, comprising: a double excitation system, a PhS-OCT imaging module, a signal synchronization control module and a data processing unit;

[0037] The double excitation system and the PhS-OCT imaging module are respectively connected with the signal synchronization control module and the data processing unit; the signal synchronization control module and the data processing unit are connected;

[0038] The double excitation system is used to excite the cornea twice under the control of the signal synchronization control module; the PhS-OCT imaging module is used to synchronously collect the vibration displacement field of the cornea under the two excitations; the data processing unit is used to implement the method for measuring in-vivo corneal biomechanics provided above based on the vibration displacement field of the cornea under the two excitations, generate the control basis of the signal synchronization control module, and complete the biomechanics measurement of the cornea.

[0039] According to the specific embodiments provided by the application, the application has the following technical effects:

[0040] The application provides a method and device for measuring corneal biomechanics of an in-vivo human eye, which maintains short-interval excitation consistency to offset mixed factors by twice differential excitation of the cornea. Based on deformation analysis on twice vibration displacement field data collected synchronously, a relative elastic modulus distribution map is generated, which can improve displacement detection accuracy and avoid the influence of individual anatomical differences on absolute modulus. Based on this, the relative elastic modulus distribution map is superimposed on an OCT structure image, which can break through the technical bottleneck of traditional single excitation OCE technology which is easily affected by physiological interference and residual deformation superposition, and provide a reliable tool for early diagnosis of keratoconus and evaluation of corneal crosslinking therapy, thereby promoting the transformation of ophthalmic diagnosis and treatment from morphology to quantitative evaluation of biomechanics, and having important clinical value. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0042] Figure 1 A flowchart of a method for measuring corneal biomechanics of an in-vivo human eye according to an embodiment of the present application is shown in the figure.

[0043] Figure 2 A device architecture diagram for measuring corneal biomechanics of an in-vivo human eye according to an embodiment of the present application is shown in the figure.

[0044] Figure 3 A timing control logic diagram according to an embodiment of the present application is shown in the figure.

[0045] Figure 4 A dynamic deformation analysis flowchart according to an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0047] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0048] In an exemplary embodiment, the present application provides a method for measuring corneal biomechanics of an in-vivo human eye, as shown in the figure. Figure 1As shown, the method includes:

[0049] Step 100: Apply the first excitation to the cornea to trigger corneal deformation and simultaneously collect the first vibration displacement field of the cornea.

[0050] Step 101: Track the corneal rebound process in real time and determine the corneal deformation.

[0051] Step 102: When the deformation of the cornea meets the set conditions, the second excitation is triggered, and the second vibration displacement field of the cornea is collected simultaneously.

[0052] Step 103: Perform deformation analysis on the first and second vibration displacement fields to generate a relative elastic modulus distribution map.

[0053] Step 104: Overlay the relative elastic modulus distribution map onto the OCT structural image to obtain a distribution map of the biomechanical properties of the cornea. The OCT structural image is a corneal image obtained using OCT technology.

[0054] By implementing steps 100 to 104 above, this application combines timing- and intensity-controllable dual-pulse jet excitation with optical coherence tomography (OCT) to eliminate confounding interference in in vivo elastic modulus measurements by utilizing the dynamic response difference between two interval excitations. The core principle is as follows: the initial micro-air pulse excitation induces dynamic deformation of the cornea and simultaneously acquires displacement field data. After the corneal morphology recovers to its initial state through real-time monitoring, a second differential excitation is applied, and data acquisition is repeated. Based on the two displacement field data after spatiotemporal registration, common-mode noise and confounding factors (such as intraocular pressure and vascular pulsation) are suppressed differentially. Compared with existing technologies, this application solves the problem of eliminating confounding factors in single-measurement in vivo corneal elastic modulus measurements through a dual-excitation method, thereby achieving more accurate and comprehensive corneal biomechanical measurements.

[0055] In another exemplary embodiment of this application, in order to achieve differentiated mechanical loading, during the first stimulation of the cornea in step 100 above, a low-pressure, short-pulse-width (typical values: pressure P1 is 20mBar-50mBar, pulse width τ1 is 1ms-3ms) can be used to induce micron-level deformation of the cornea (deformation d1 is approximately 5μm-15μm). Low-pressure, short-pulse-width refers to a pulse where both pressure and pulse width are within a set range.

[0056] In step 102, when the cornea is stimulated a second time, the pressure gradient and pulse width are adjusted based on the pulse used in the first stimulation to change the applied energy. For example, during the adjustment process, the pressure gradient ΔP = P2 - P1 or the pulse width Δτ = τ2 - τ1. Wherein, P2 is the pressure of the first stimulation, P2 is the pressure of the second stimulation, τ1 is the pulse width of the first stimulation, and τ2 is the pulse width of the second stimulation.

[0057] In another exemplary embodiment of this application, in order to accurately determine the corneal deformation and thus achieve precise control of the second excitation, step 101 can be implemented in two ways. The first is: during real-time tracking of corneal rebound, the thickness of the corneal apex is obtained. The deformation recovery rate is determined based on the initial corneal thickness and the thickness of the corneal apex. The deformation recovery rate is used as the corneal deformation. The second is: during real-time tracking of corneal rebound, the corneal thickness is determined in real time. The determined corneal thickness is used as the corneal deformation.

[0058] The formula for determining the deformation recovery rate is expressed as follows:

[0059]

[0060] In the formula, R(t) is the deformation recovery rate, h0 is the initial thickness of the cornea, and h(t) is the thickness of the corneal apex.

[0061] Based on the two methods for determining corneal deformation given above, when the corneal deformation is the deformation recovery rate, in step 102 above, the corneal deformation meeting the set condition means that the deformation recovery rate is greater than or equal to the set rate value. For example, when R(t) ≥ 95%, it is determined that the recovery is complete, and a second excitation is performed.

[0062] When the corneal deformation is a defined corneal thickness, in step 102 above, the corneal deformation meeting the set condition means that the defined corneal thickness is less than a set thickness value. For example, d residual <0.05d max Among them, d residual Given the currently determined corneal thickness, d max This is the maximum thickness of the cornea.

[0063] In another exemplary embodiment of this application, in order to ensure strict synchronization between excitation and data acquisition, this application may also use formula T to specify the time interval between two excitations of the cornea. interval =t recovery +t delay Dynamic adjustments are made. Where t... recovery For the actual recovery time, t delayFor the response delay (approximately 2ms), T interval This is the dynamically adjusted time interval.

[0064] In another exemplary embodiment of this application, in order to provide a more accurate data basis, a hybrid MB scanning mode can be used to track the corneal rebound process in real time and determine the corneal deformation.

[0065] In another exemplary embodiment of this application, to avoid the influence of individual anatomical differences on the absolute modulus, a dynamic analytical model of the elastic modulus based on Lamb wave propagation can be established, and a relative elastic mapping algorithm can be developed by introducing phase unfolding wrapping technology to improve displacement detection accuracy. Based on this, in this embodiment, as... Figure 4 As shown, the process of dynamic deformation analysis in step 103 of this application can be described as follows:

[0066] 1) Spatiotemporal registration: The first and second vibration displacement fields are aligned using a cross-correlation algorithm to obtain registration data. Taking the registration of the second vibration displacement field as an example, the cross-correlation algorithm is used to align the displacement fields of the two excitations:

[0067] D′2(x,t)=D2(x+Δx,t+Δt).

[0068] In the formula, D′2(x,t) is the second vibration time-series displacement coordinate, D2(x+Δx,t+Δt) is the second vibration time-series displacement coordinate after registration, x is the spatial position coordinate on the cornea, t is the time variable, and Δx and Δt are the registration offsets, which are determined by maximizing the cross-correlation function C(D1,D2).

[0069] 2) Elastic wave separation and noise suppression: Apply bandpass filtering (e.g., 50-500Hz) to the registration data and extract the Lamb wave main frequency component.

[0070] 3) Differential processing: Based on the Lamb wave dominant frequency component, determine the elastic modulus and displacement of the first excitation and the elastic modulus and displacement of the second excitation. Based on the elastic modulus and displacement of the first excitation and the elastic modulus and displacement of the second excitation, determine the difference in displacement response between the two excitations.

[0071] A Lamb wave is a model of elastic waves propagating in thin samples (such as the cornea). When the sample is thin, elastic waves propagating within it encounter the upper and lower boundaries and are reflected, resulting in a Lamb wave. The thickness of normal human corneal tissue is less than 1 mm, close to the wavelength of an elastic wave. Therefore, the propagation of corneal elastic waves is affected by the upper and lower surfaces of the cornea, causing corneal elastic waves to primarily propagate in the form of Lamb waves. Lamb wave velocity V L The relationship between the elastic modulus of the cornea (i.e., Young's modulus) E and the elastic modulus of the cornea is as follows:

[0072]

[0073] In the formula, f is the propagation frequency, h is the corneal thickness, and ρ is the corneal density.

[0074] The relationship between wave velocity V and phase difference ΔФ is:

[0075]

[0076] In the formula, Δx represents the spatial displacement on the cornea. V = V L .

[0077] The phase difference ΔФ is typically within the range of 0 to 2π and can be corrected using a phase unfolding method. When the sample is subjected to a load, the displacement d of the sample can be determined by the phase difference, as follows:

[0078]

[0079] In the formula, n' is the average refractive index of the cornea (approximately 1.376).

[0080] 4) Determination of the relative elastic modulus change rate: The relative elastic modulus change rate is determined based on the difference in displacement response between the two excitations. It should be noted that under single-pulse excitation, when the cornea deforms, confounding factors such as intraocular pressure included in the corneal elastic modulus E cannot be eliminated by the above formula. Therefore, this application defines the measured corneal elastic modulus E and the confounding factor elastic modulus E0. c The following relationships exist:

[0081] E = E t +E c .

[0082] In the formula, E t This represents the actual elastic modulus of the cornea.

[0083] By recording the elastic moduli E1 and E2 under two time-controlled dual-pulse excitations, the mixed-factor elastic moduli E under short-interval corneal excitation were determined. c To maintain consistency. After determining the relationship between the corneal elastic modulus E and the displacement d, the relative elastic modulus change rate ΔE can be calculated by calculating the difference in corneal elastic modulus and the difference in displacement under two excitations, resulting in:

[0084]

[0085] Under the rate of change equation, the common-mode noise E shared by the two excitations is suppressed. c The relative elastic modulus change rate ΔE is obtained, which is used to compare and evaluate the differences in the relative elastic modulus of the subjects.

[0086] Based on the above description, and considering the difference in displacement response between the two excitations, the calculated rate of change of the relative elastic modulus can be expressed as:

[0087]

[0088] In the formula, E1(x) is the elastic modulus at spatial coordinate x on the cornea under the first excitation, E2(x) is the elastic modulus at spatial coordinate x on the cornea under the second excitation, ΔE(x) is the rate of change of the relative elastic modulus at spatial coordinate x on the cornea, d2(x) is the displacement at spatial coordinate x on the cornea under the first excitation, and d2(x) is the displacement at spatial coordinate x on the cornea under the second excitation. <d ref >The average deformation of a healthy cornea is used as a reference displacement for normalization.

[0089] 5) The spatial interpolation algorithm is used to reconstruct the relative elastic modulus change rate ΔE(x) into a relative elastic modulus distribution map (i.e., a two-dimensional distribution map), and the visualization output is performed.

[0090] After overlaying the obtained relative elastic modulus distribution map onto the OCT structural image, pseudo-color coding can be used to represent the relative elastic values. The red area corresponds to a decrease in modulus (pathological softening), and the blue area represents normal mechanical properties. The specific color representation is only for illustrating the measurement effect of this application and is not intended to limit the scope of this application.

[0091] Based on the above description, this application has the following advantages over the prior art:

[0092] (1) Dual excitation with time and intensity control: In practical application, this application can be excited by two micro-jet jets with controllable intervals. The first excitation induces tissue response, and the second differentiated excitation obtains two corneal elastic moduli after eliminating interference.

[0093] (2) Differential signal extraction: This application utilizes the difference in mechanical response between two excitations to eliminate common-mode noise (such as systemic vascular pulsation, intraocular pressure fluctuations, etc.).

[0094] (3) Relative modulus mapping: This application can avoid the dependence of absolute measurement on individual anatomical parameters through normalization.

[0095] Based on the same inventive concept, this application also provides an apparatus for measuring in vivo human corneal biomechanics using the methods described above. The solution provided by this apparatus is similar to the implementation described in the methods above. Therefore, the specific limitations of one or more apparatus embodiments for measuring in vivo human corneal biomechanics provided below can be found in the limitations of the methods for measuring in vivo human corneal biomechanics described above, and will not be repeated here.

[0096] In one exemplary embodiment, such as Figure 2 As shown, a device for measuring the biomechanics of the human cornea in vivo is provided, comprising: a dual excitation system, a PhS-OCT imaging module, a signal synchronization control module, and a data processing unit. Figure 2 In the diagram, solid arrows represent signal flow, and dashed arrows represent control flow.

[0097] Both the dual-excitation system and the PhS-OCT imaging module are connected to the signal synchronization control module and the data processing unit, respectively.

[0098] The dual-excitation system is used to apply two intervals of micro-air pulse excitation with controllable intensity to the surface of the target cornea, during which the cornea recovers to its initial shape.

[0099] The signal synchronization control module is used to coordinate the timing of the jet excitation of the dual-excitation system and the OCT scan of the PhS-OCT imaging module, ensuring strict synchronization between the two excitation signals and data acquisition. For example, the signal synchronization control module can achieve microsecond-level timing synchronization through an FPGA, triggering precise linkage between the jet valve and the OCT scan.

[0100] The PhS-OCT imaging module dynamically responds to synchronous acquisition, simultaneously acquiring corneal vibration displacement signals generated by two excitations through the OCT system, obtaining the first vibration displacement field D1(x,t) and the second vibration displacement field D2(x,t). The data processing unit, based on the corneal vibration displacement fields under the two excitations, implements the aforementioned method for measuring in vivo human corneal biomechanics, generates the control basis for the signal synchronization control module, and completes the corneal biomechanical measurement.

[0101] As an optional implementation, the data processing unit may include: a dynamic recovery monitoring module, a dynamic deformation analysis module, and a relative elastic modulus mapping module. The dynamic deformation analysis module includes a spatiotemporal registration unit, an elastic wave separation unit, and a visualization output unit.

[0102] The dynamic recovery monitoring module continuously monitors the corneal morphological recovery process during the interval between two excitations using OCT until the deformation drops to less than 5% of the initial state.

[0103] The relative elastic modulus mapping module eliminates common-mode interference by using a differential algorithm based on the difference in displacement response between two excitations, and outputs a relative elastic modulus distribution map of the cornea.

[0104] As an optional implementation, the dual-excitation system can consist of a pneumatic system. This pneumatic system includes a high-pressure gas storage unit. The high-pressure gas storage unit employs dual gas tanks, one for the primary pulse and the other for the secondary pulse. The high-pressure gas storage unit achieves independent control of the pulse width and pressure gradient via piezoelectric ceramic valves.

[0105] As an optional implementation, the PhS-OCT imaging module is an optical coherence tomography (OCT) module. Based on this, a dual-excitation system can be integrated with the OCT module. The dual-excitation system and the OCT module are assembled at an angle. For example, the dual-excitation system and the OCT probe in the PhS-OCT imaging module are installed at a 30°-45° angle to avoid airflow interference with the imaging optical path. The PhS-OCT imaging module uses a swept-frequency light source with a center wavelength of 1310nm, an axial resolution of less than or equal to 8μm, and a scan rate of greater than or equal to 100kHz.

[0106] As an optional implementation method, phase-sensitive OCT (PhS-OCT) uses MB scanning mode to detect corneal displacement and deformation.

[0107] (1) M-scan: A-scan signals are continuously acquired at a fixed transverse position with a time resolution of 10 μs to capture the propagation process of elastic waves.

[0108] (2) B scan: A transverse scan is performed along the curvature of the cornea, with a spatial coverage of ≥8mm, to reconstruct the three-dimensional displacement field of the cornea.

[0109] Perform phase difference-displacement conversion. Based on the phase difference ΔΦ(x,z,t) of the interference signal, calculate the displacement of each point on the cornea:

[0110]

[0111] In the formula, d(x,z,t) represents the displacement of each point on the cornea, (x,z,t) represents the corneal point, and n c λ is the effective refractive index of the cornea (approximately 1.376), and λ is the center wavelength of the light source.

[0112] In an exemplary embodiment, the workflow of the device structure described above in this application is as follows:

[0113] (1) The first micro air pulse triggers corneal deformation, and the PhS-OCT imaging module simultaneously acquires the first vibration displacement field D1(x,t).

[0114] (2) The dynamic recovery monitoring module tracks the corneal rebound process in real time, and when the residual deformation d residual <0.05d max A secondary stimulus is triggered at that time.

[0115] (3) After the second differential pulse is applied, the second vibration displacement field D2(x,t) is collected.

[0116] (4) The dynamic deformation analysis module performs spatiotemporal registration and differential processing on the two vibration displacement field data and outputs the relative elastic modulus distribution map ΔE(x,y).

[0117] Based on the above description, the dynamic recovery monitoring logic of the device provided in this application is as follows: when R(t)≥95%, the recovery is determined to be complete.

[0118] Furthermore, during the measurement of corneal biomechanics, a signal synchronization control timing design was implemented. (See attached document.) Figure 3 As shown, the synchronization control timing is divided into five stages:

[0119] (1) Pre-triggering phase (-10ms to 0ms): OCT scan starts 10ms in advance to establish baseline phase reference.

[0120] (2) Initial excitation acquisition phase (0ms~T1): The jet valve is in the Nth phase of the OCT scan. trigger Frame-time activation ensures strict synchronization between stimulus and data acquisition.

[0121] (3) Dynamic recovery monitoring phase (T1~T2). In this phase, the interval between the two excitations needs to be dynamically adjusted.

[0122] (4) Secondary excitation acquisition stage (T2~T3).

[0123] (5) Delay compensation (T3~T delay ).

[0124] In summary, this application addresses the technical challenges of measuring the elastic modulus of the human cornea by proposing a non-contact detection method and device based on the fusion of dual-pulse temporal excitation and optical coherence tomography (OCT). The cornea is differentially excited by two micro-air pulses, and displacement field data is simultaneously acquired using phase-sensitive OCT. Dynamic recovery monitoring (deformation recovery >95%) ensures complete tissue repositioning, and a differential algorithm is employed to eliminate common-mode noise such as intraocular pressure fluctuations and vascular pulsation, thereby constructing a relative elastic modulus distribution map.

[0125] This application pioneers a dual-pulse timing control mechanism, achieving synchronous cancellation of confounding factors through short-interval excitation consistency maintenance. A dynamic analytical model of elastic modulus based on Lamb wave propagation is established, and phase unfolding wrapping technology is introduced to improve displacement detection accuracy. A relative elastic mapping algorithm is developed to avoid the influence of individual anatomical differences on the absolute modulus. Based on these advancements, this application overcomes the technical bottlenecks of traditional single-excitation OCE technology, which is susceptible to physiological interference and residual deformation superposition. It provides a reliable tool for early diagnosis of keratoconus and evaluation of the efficacy of corneal cross-linking surgery, promoting the transformation of ophthalmic diagnosis and treatment from morphological to biomechanical quantitative assessment, and has significant clinical value.

[0126] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0127] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for measuring the biomechanics of the human cornea in vivo, characterized in that, include: The cornea is first stimulated to trigger corneal deformation, and the first vibrational displacement field of the cornea is simultaneously acquired. The corneal rebound process is tracked in real time, and the deformation of the cornea is determined. When the deformation of the cornea meets the set conditions, a second excitation is triggered, and the second vibration displacement field of the cornea is collected simultaneously. Deformation analysis was performed on the first and second vibration displacement fields to generate a relative elastic modulus distribution map. The relative elastic modulus distribution map is superimposed on the OCT structural image to obtain the biomechanical property distribution map of the cornea; the OCT structural image is a corneal image obtained using OCT technology.

2. The method for measuring in vivo human corneal biomechanics according to claim 1, characterized in that, During the initial stimulation of the cornea, a low-pressure, short-pulse-width method is used to induce micron-level deformation in the cornea; the low-pressure, short-pulse-width method refers to a pulse where both the pressure and pulse width are within a set range.

3. The method for measuring in vivo human corneal biomechanics according to claim 2, characterized in that, When performing a second stimulation on the cornea, the pressure gradient and pulse width are adjusted based on the pulse used in the first stimulation.

4. The method for measuring in vivo human corneal biomechanics according to claim 1, characterized in that, Real-time tracking of corneal rebound and determination of corneal deformation, including: The thickness of the corneal apex is obtained during real-time tracking of corneal rebound. The deformation recovery rate is determined based on the initial thickness of the cornea and the thickness of the corneal apex. The deformation recovery rate is used as the deformation of the cornea.

5. The method for measuring in vivo human corneal biomechanics according to claim 1, characterized in that, Real-time tracking of corneal rebound and determination of corneal deformation, including: The thickness of the cornea is determined in real time while tracking the rebound of the cornea. The determined thickness of the cornea is used as the deformation of the cornea.

6. The method for measuring in vivo human corneal biomechanics according to claim 4 or 5, characterized in that, When the deformation of the cornea is the deformation recovery rate, the deformation of the cornea satisfies the set condition if the deformation recovery rate is greater than or equal to the set rate value. When the deformation of the cornea is a given corneal thickness, the corneal deformation satisfies the set condition if the given corneal thickness is less than the set thickness value.

7. The method for measuring in vivo human corneal biomechanics according to claim 1, characterized in that, The time interval between two corneal stimulations is calculated using formula T. interval =t recovery +t delay Dynamic adjustments are made; where t recovery For the actual recovery time, t delay To respond to delay, T interval This is the dynamically adjusted time interval.

8. The method for measuring in vivo human corneal biomechanics according to claim 1, characterized in that, The MB hybrid scanning mode is used to track the corneal rebound process in real time and determine the corneal deformation.

9. The method for measuring in vivo human corneal biomechanics according to claim 1, characterized in that, Deformation analysis was performed on the first and second vibration displacement fields to generate relative elastic modulus distribution maps, including: The first and second vibration displacement fields were aligned using a cross-correlation algorithm to obtain registration data; A bandpass filter is applied to the registration data to extract the Lamb wave dominant frequency component; The elastic modulus and displacement of the first excitation and the elastic modulus and displacement of the second excitation are determined based on the Lamb wave dominant frequency components. The difference in displacement response between the two excitations is determined based on the elastic modulus and displacement of the first excitation and the elastic modulus and displacement of the second excitation. The rate of change of relative elastic modulus is determined based on the difference in displacement response between two excitations; The relative elastic modulus change rate is reconstructed into a relative elastic modulus distribution map using a spatial interpolation algorithm.

10. A device for measuring the biomechanics of the human cornea in vivo, characterized in that, include: Dual excitation system, PhS-OCT imaging module, signal synchronization control module and data processing unit; The dual-excitation system and the PhS-OCT imaging module are both connected to the signal synchronization control module and the data processing unit, respectively; the signal synchronization control module and the data processing unit are connected. The dual-excitation system is used to excite the cornea twice under the control of the signal synchronization control module; the PhS-OCT imaging module is used to synchronously acquire the vibration displacement field of the cornea under the two excitations; the data processing unit is used to implement the method for measuring the biomechanics of the in vivo human cornea as described in any one of claims 1-9 based on the vibration displacement field of the cornea under the two excitations, generate the control basis of the signal synchronization control module, and complete the biomechanical measurement of the cornea.

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