An ultrasound-excited elastography device and detection method for measuring the mechanical properties of the cornea and retina.

Abstract

An ultrasound-excited elastography device and detection method for measuring the mechanical properties of the cornea and retina are disclosed. The ultrasound excitation module uses three-dimensionally localizable focused ultrasound waves to excite elastic waves in the cornea or retina. Its transducer axis is angled to the OCT optical axis, and the sound wave path is deflected by an obliquely placed acoustic reflector. The OCT module dynamically captures the spatiotemporal displacement signals of the tissue induced by the elastic waves through a dual-scan mode, achieving high-resolution imaging of the anterior segment and fundus. The eye cup fitting module, combined with a biocompatible structure, adapts to the eye contour and coordinates the incident angle of the sound waves to optimize the acoustic-optical coupling efficiency. The data processing module derives the Young's modulus distribution of the tissue using an elastography algorithm. The detection method achieves high-precision quantitative analysis of the mechanical properties of the cornea and retina through non-invasive ultrasound-OCT co-excitation and signal acquisition, combined with a motion platform to compensate for eye movement deviations in real time. This invention provides a reliable tool for assisting in the diagnosis of ophthalmic diseases.

Description

Technical Field

[0001] This invention relates to the fields of optics, physiology and medicine, and computer science, and in particular to an ultrasound-excited elastography device and detection method for measuring the mechanical properties of the cornea and retina. Background Technology

[0002] As a transparent refractive barrier at the front of the eye, the cornea, through its unique hyperboloid structure, achieves an optical power output of approximately 43D, undertaking about two-thirds of the refractive function. Its biomechanical stability not only maintains intraocular pressure balance but also directly affects the prognosis of corneal refractive surgery and the pathological progression of diseases such as keratoconus. Modern biomechanical research reveals that the mechanical properties of the cornea are closely related to its microfiber structure—a five-layered heterogeneous structure composed of stratified squamous epithelium, Bowman's membrane, stroma, Descemet's membrane, and simple endothelium. The stroma, accounting for 90% of the total thickness, contains over 300 layers of orthogonally arranged collagen lamellae. These lamellae exhibit a highly interwoven network structure in the anterior region, gradually transitioning to a parallel arrangement in the posterior region. Experimental data show that the tangential elastic modulus of the central cornea can reach 2.3 times that of the peripheral region, and the viscoelastic property parameter η of the anterior stroma (0-200 μm depth) is 58% ± 6% higher than that of deeper tissues. The disruption of this mechanical gradient has been proven to be strongly correlated with the development of corneal bulging diseases. In recent years, with the popularization of femtosecond laser-assisted corneal surgery, how to quantify corneal anisotropic mechanical parameters in real time without contact has become a key technical bottleneck in improving surgical safety and developing individualized treatment plans.

[0003] As the core photosensitive tissue at the back of the eye, the retina plays a crucial role in converting light signals into neural electrical signals. Its intricate layered structure directly determines the efficiency of visual information processing. Retinal detachment, macular edema, and other diseases not only cause visual distortions but can also lead to irreversible vision loss. This makes in-depth analysis of the biomechanical properties of the retina a significant breakthrough in ophthalmological diagnosis and treatment. Studies have shown that a normal retina consists of 10 intricate layers, from the internal limiting membrane to the pigment epithelium. The radial arrangement of the nerve fiber layer and the retinal network of the blood vessel layer form a unique mechanical coupling system. Notably, there are significant differences in the viscoelastic modulus of the extracellular matrix in each layer; for example, the viscosity coefficient of the inner nuclear layer is about 40% higher than that of the outer nuclear layer. This mechanical heterogeneity directly affects the retina's response to shear stress. For metabolic eye diseases such as diabetic retinopathy, quantifying the dynamic mechanical parameters of each retinal layer has become a key basis for early diagnosis and treatment planning.

[0004] However, existing detection methods have some fundamental flaws, resulting in insufficient measurement accuracy and depth, and making it even more difficult to measure retinal mechanics. Non-contact intraocular pressure analyzers (ORA) induce corneal planarization using air pulses (peak pressure ≥25 kPa), record corneal deformation using infrared sensors, and derive corneal hysteresis and resistance factors based on a first-order dynamic model. However, they can only output overall mechanical parameters and cannot distinguish the mechanical gradient differences between the central and peripheral corneas. Corvis ST uses air jets to induce corneal deformation and captures the dynamic deformation process using a high-speed Scheimpflug camera. Based on a linear regression model, it converts parameters such as deformation amplitude and velocity into a stiffness index (SSI), relying on statistical correlation and failing to analyze the layered mechanical properties of the cornea. Furthermore, measurement repeatability is affected by blink reflexes. Additionally, clinical intraocular pressure testing uses Goldmann planarization tonometers or pneumatic tonometers to measure the corneal resistance to external pressure deformation. This simplifies biomechanical characteristics to a single pressure parameter and cannot decouple the inherent corneal stiffness from the contribution of intraocular pressure. Brillouin microscopy is based on the principle of Brillouin scattering. By detecting the spectral shift of the laser beam when it is scattered in the tissue, a direct relationship is established between the spectral shift and the longitudinal elastic modulus of the tissue, thereby obtaining the three-dimensional spatial distribution of the elastic modulus of the eye tissue. However, the point-by-point scanning mode results in a slow imaging speed and relies on empirical models to invert elastic parameters, making parameter decoupling very complicated.

[0005] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The main objective of this invention is to overcome the deficiencies in the aforementioned background technology and provide an ultrasound-excited elastography device and detection method for measuring the mechanical properties of the cornea and retina, achieving high-precision multidimensional analysis of the mechanical properties of ocular tissues through acoustic-optical synergy technology.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An ultrasound-excited elastography device for measuring the mechanical properties of the cornea and retina, comprising:

[0009] An ultrasound excitation module is used to generate three-dimensionally localizable focused ultrasound waves to excite ocular tissues to produce elastic waves.

[0010] The OCT observation module is used to capture the spatiotemporal displacement signal of the tissue induced by the elastic wave through optical coherence tomography (OCT) technology.

[0011] The eye cup adaptation module, with its biocompatible structure, adapts to the eye contour and is used to couple the optical and acoustic paths of the ultrasound excitation module and the OCT observation module.

[0012] The data processing module is used to process the spatiotemporal displacement signal using an elastic imaging mechanics algorithm to derive the Young's modulus distribution of the eye tissue;

[0013] The ultrasonic transducer axis of the ultrasonic excitation module is angularly geometrically related to the optical axis of the OCT observation module, and the acoustic path is deflected by an acoustic path deflection device. The eye cup fitting module works with the ultrasonic excitation module to control the incident angle of the acoustic wave. The data processing module converts the spatiotemporal displacement signal into a biomechanical parameter map through wave model inference.

[0014] A detection method using the aforementioned ultrasonically excited elastography device includes the following steps:

[0015] S1. Fix the eye to be tested using the eye cup adapter module, and start OCT scanning to obtain tissue spatial coordinates;

[0016] S2. The ultrasonic excitation module dynamically adjusts the focal position according to the target area, and the motion platform calibrates the angle of the acoustic reflective glass plate.

[0017] The S3 and OCT observation modules switch scanning modes to capture the spatiotemporal displacement signals induced by elastic waves.

[0018] S4. The data processing module executes the elastic imaging algorithm to generate a Young's modulus distribution map.

[0019] The method utilizes the synergistic effect of ultrasound and OCT to achieve non-invasive quantitative detection of the mechanical properties of the cornea and retina, thereby improving measurement accuracy.

[0020] Furthermore, the elasticity imaging algorithm in step S4 specifically includes:

[0021] (a) Obtain tissue reflection signals in complex form by OCT scanning, and construct a two-dimensional matrix by separating the real and imaginary parts of the data;

[0022] (b) Calculate the phase difference based on the complex conjugate product of adjacent signal frames to generate an elastic wave Doppler phase map;

[0023] (c) Combine the light source wavelength and the refractive index of the medium to convert the phase difference into a tissue spatiotemporal displacement distribution map;

[0024] (d) Low-frequency physiological motion noise is eliminated by high-pass filtering to extract high signal-to-noise ratio displacement signals;

[0025] (e) Perform a two-dimensional frequency domain transformation on the displacement signal, analyze the wavenumber-frequency domain spectrum, and extract the wavenumber corresponding to the maximum intensity at each frequency;

[0026] (f) Calculate the phase velocity based on the relationship between wavenumber and frequency, and construct a phase velocity distribution map of the tissue;

[0027] (g) Based on tissue density, Poisson's ratio and wave velocity, establish an elastic wave propagation model and derive the initial Young's modulus estimate;

[0028] (h) Input the phase velocity distribution map and the initial modulus estimate into the deep learning model, fuse tissue morphology features to perform modulus correction, and output the final biomechanical parameter map.

[0029] Furthermore, in step S2, the ultrasound excitation module compensates for the incident angle deviation caused by eye movement in real time using a forward kinematics algorithm. The forward kinematics algorithm specifically includes:

[0030] A three-dimensional coordinate system is established with the center of the reflector as the origin to define the position of the ultrasonic transmitter and the target tissue.

[0031] The incident vector and the reflection vector are normalized to obtain the normalized incident vector and the normalized reflection vector, respectively.

[0032] The normal direction of the mirror is calculated based on the sum of the incident and reflected vectors;

[0033] The rotation angles around the x-axis and y-axis are calculated based on the component relationships of the normal vector in the coordinate system. The deflection attitude of the acousto-optic coupling glass is dynamically adjusted to compensate for the incident angle deviation and accurately guide the ultrasonic excitation focus.

[0034] The present invention has the following beneficial effects:

[0035] This invention provides an ultrasound-excited elastography system and detection method for measuring the mechanical properties of the cornea and retina. Through the synergistic innovation of ultrasound excitation and optical coherence tomography (OCT) technology, it realizes the measurement of Young's modulus of multiple tissues, which solves the limitations of traditional detection technology in terms of the depth and accuracy of mechanical parameter analysis. It achieves high-precision multidimensional analysis of the mechanical properties of ocular tissues through acoustic-optical synergy technology. Its technical advantages are as follows: The ultrasound excitation module and OCT module adopt an angular geometric layout design, dynamically adjusting the sound wave path through an obliquely placed acoustic reflector to avoid interference between acoustic and optical signals, achieving non-invasive elastic wave excitation and high-sensitivity displacement detection; The eye cup fitting module combines biocompatible structure and acoustic-optical coupling optimization, improving sound wave transmission efficiency and optical path stability while adapting to the eye contour, and compensating for the incident angle deviation caused by eye movement in real time through a motion platform to ensure accurate positioning of the excitation focus; The OCT module supports dual scanning modes, which can seamlessly switch between anterior segment and fundus imaging, taking into account the multi-scale analysis of corneal layered mechanical properties and retinal mechanical response; The data processing module integrates elastic wave propagation model and deep learning algorithm, extracting key parameters such as phase difference and phase velocity from spatiotemporal displacement signals, and combining tissue morphology characteristics to correct modulus calculation, overcoming the shortcomings of traditional methods that rely on single parameters or empirical models, and achieving high-precision, multi-dimensional biomechanical property mapping. This system can provide biomechanical parameter maps that are compatible with all eyes, and has the advantages of full eye compatibility, high signal-to-noise ratio processing capability and dynamic adaptability. It provides a comprehensive solution for the quantitative analysis of the mechanical properties of the cornea and retina, and provides an important tool for assisting the early diagnosis of eye diseases.

[0036] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of corneal biomechanical ultrasound elasticity measurement using an ultrasound-excited elastography system according to an embodiment of the present invention.

[0038] Figure 2 This is a schematic diagram of retinal biomechanics and ultrasonic elasticity measurement using an ultrasonic-excited elastography system according to an embodiment of the present invention.

[0039] Figure 3 This is a schematic diagram of the multi-layer composite acoustic reflection structure of the acoustic reflective glass sheet according to an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the steps of the ultrasonic-excited elastography method according to an embodiment of the present invention. Detailed Implementation

[0041] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0042] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for fixing, coupling, or communication.

[0043] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0045] See Figure 1 and Figure 2 This invention provides an ultrasound-excited elastography device for measuring the mechanical properties of the cornea and retina, comprising an ultrasound excitation module, an OCT observation module, an eye cup fitting module 18, and a data processing module. The ultrasound excitation module generates three-dimensionally localizable focused ultrasound waves to excite ocular tissues to produce elastic waves. The OCT observation module captures the spatiotemporal displacement signal of the tissue induced by the elastic waves using optical coherence tomography (OCT). The eye cup fitting module 18 adapts to the ocular contour through a biocompatible structure and couples the optical and acoustic paths of the ultrasound excitation module and the OCT observation module. The data processing module processes the spatiotemporal displacement signal using an elastography mechanics algorithm to derive the Young's modulus distribution of the ocular tissue. The ultrasound transducer axis of the ultrasound excitation module is angularly geometrically related to the optical axis of the OCT observation module, and the acoustic path is deflected by an acoustic path deflection device. The eye cup fitting module 18, in conjunction with the ultrasound excitation module, regulates the incident angle of the acoustic waves. The data processing module converts the spatiotemporal displacement signal into a biomechanical parameter map through wave model inference.

[0046] In a preferred embodiment, the axis of the ultrasonic transducer in the ultrasonic excitation module is orthogonal to the optical axis of the OCT observation module. Complementing this, as an example of an acoustic path deflection device, the acoustic wave path can be controlled by an obliquely placed reflector. The orthogonal layout reduces interference between the acoustic and optical signals, adapting to collaborative measurement requirements. The ultrasonic excitation module includes an array of ultrasonic transducers 11, a dynamic phase control unit, and a motion platform. The ultrasonic transducer 11 is composed of multiple independent piezoelectric crystals. The dynamic phase control unit adjusts the excitation timing of each crystal to achieve three-dimensional positioning of the ultrasonic focus and switching of the corneal / retinal excitation area. The motion platform is driven by piezoelectric ceramics to achieve translation and deflection, compensating for ultrasonic incident angle deviations in real time.

[0047] In a preferred embodiment, the OCT observation module adopts a dual-threaded interferometric architecture, including a swept-frequency laser 2, a beam splitter (such as a 70:30 beam splitter 3), a circulator (a first circulator 4 and a second circulator 7), a galvanometer scanning unit 9, and a balance detector 20; the galvanometer scanning unit 9 is used for two-dimensional grating scanning, and the balance detector 20 adopts an InGaAs array to detect nanoscale displacement changes; the module is configured with anterior segment mode and fundus mode, and high-resolution imaging of the cornea and retina is achieved by switching the objective lens focal length and scanning depth, respectively.

[0048] In a preferred embodiment, the acoustic path deflection device includes an acoustic reflective glass plate 12 placed at an angle (e.g., 45° angle), and the bottom of the eye cup adapter module 18 integrates a gradient acoustic-optic coupling window, which includes a four-layer transition structure of titanium-aluminum-quartz-polymer to improve the ultrasonic wave transmittance and OCT optical path transmittance; a two-dimensional adjustment platform is provided below the coupling window to locate the spatial coordinates of the ultrasonic transducer 11 and the acoustic reflective glass plate 12.

[0049] like Figure 3 As shown, in a preferred embodiment, the acoustic reflective glass sheet 12 adopts a multi-layer composite acoustic reflective structure, which includes a quartz layer, a tantalum pentoxide layer, and a magnesium fluoride layer. The thickness of the tantalum pentoxide layer and the magnesium fluoride layer is 1 / 4 of the ultrasonic wavelength. An anti-reflection film is deposited on the surface of the quartz layer to further suppress optical path return loss.

[0050] In a preferred embodiment, the reference arm of the OCT observation module is equipped with an adjustable optical path compensation mechanism, which enables seamless switching between the anterior segment mode and the fundus mode by synchronously extending the optical path, and the polarization controller automatically loads a preset matrix to optimize the backscattering efficiency of different tissues.

[0051] See Figure 4 The present invention also provides a detection method using the ultrasonically excited elastography device, comprising the following steps:

[0052] Step S1: Fix the eye to be tested using the eye cup adapter module 18, and start OCT scanning to obtain tissue spatial coordinates;

[0053] Step S2: The ultrasonic excitation module dynamically adjusts the focal position according to the target area, and the motion platform calibrates the angle of the acoustic reflective glass plate 12.

[0054] Step S3: The OCT observation module switches to the scanning mode to capture the spatiotemporal displacement signal induced by the elastic wave;

[0055] Step S4: The data processing module executes the elastic imaging algorithm to generate a Young's modulus distribution map.

[0056] The method utilizes the synergistic effect of ultrasound and OCT to achieve non-invasive quantitative detection of the mechanical properties of the cornea and retina, thereby improving measurement accuracy.

[0057] In a preferred embodiment, the elastic imaging algorithm in step S4 specifically includes: acquiring complex tissue reflection signals through OCT scanning, separating the real and imaginary parts of the data to construct a two-dimensional matrix; calculating the phase difference based on the complex conjugate product of adjacent signal frames (the phase difference can be achieved through standard algorithms such as cross-correlation of adjacent frame signals), generating an elastic wave Doppler phase map; converting the phase difference into a tissue spatiotemporal displacement distribution map by combining the light source wavelength and the refractive index of the medium; eliminating low-frequency physiological motion noise through high-pass filtering and extracting high signal-to-noise ratio displacement signals; performing a two-dimensional frequency domain transformation on the displacement signals, analyzing the wavenumber-frequency domain spectrum and extracting the wavenumber corresponding to the maximum intensity at each frequency; calculating the phase velocity according to the relationship between wavenumber and frequency, and constructing a tissue phase velocity distribution map; establishing an elastic wave propagation model based on tissue density, Poisson's ratio, and wave velocity (for example, the model can be matched with the wave velocity type by adapting the corresponding modulus derivation formula according to the wave type such as Rayleigh wave / Lamb wave), deriving the initial Young's modulus estimate; inputting the phase velocity distribution map and the initial modulus estimate into a deep learning model, fusing tissue morphology features for modulus correction, and outputting the final biomechanical parameter spectrum.

[0058] In a preferred embodiment, the ultrasound excitation module compensates for the incident angle deviation caused by eye movement in real time in step S2 using a forward kinematics algorithm. The forward kinematics algorithm specifically includes: establishing a three-dimensional coordinate system with the center of the reflector as the origin, defining the position of the ultrasound transmitter and the target tissue; normalizing the incident vector and the reflection vector to obtain the normalized incident vector and the normalized reflection vector, respectively; calculating the normal vector direction of the reflector based on the vector sum of the incident vector and the reflection vector; calculating the rotation angle around the x-axis and y-axis according to the component relationship of the normal vector in the coordinate system, and dynamically adjusting the deflection attitude of the acousto-optic coupling glass to compensate for the incident angle deviation and accurately guide the ultrasound excitation focus.

[0059] The following describes specific embodiments of the present invention.

[0060] like Figure 1 and Figure 2 As shown, an ocular biomechanical detection system mainly includes an ultrasound excitation module, an OCT observation module, and an eye cup fitting module 18.

[0061] The ultrasonic excitation module includes a host unit 1, an ultrasonic transducer 11, an acoustic reflective glass plate 12 and its motion platform, a function generator 16, a power amplifier 17, and an impedance matching circuit. The host unit 1 is connected to the function generator 16 via a data cable. The output of the function generator 16 is connected in series with the impedance matching circuit via the power amplifier 17, ultimately driving the ultrasonic transducer 11 to generate focused ultrasonic waves. The ultrasonic transducer 11 is fixed inside the side wall cavity of the eye cup adapter module 18, and its radiating surface is completely immersed in the eye cup medium. The transducer axis is orthogonal to the OCT optical axis at 90°, and the acoustic reflective glass plate 12 is set at a 45° angle at its front end. The acoustic reflective glass plate 12 is fixed inside the eye cup by a motion platform device controlled by a motion control card 15. The motion platform device achieves 0.1mm-level translation and ±15° dynamic deflection through a preset motion trajectory to control the incident path of the ultrasonic waves.

[0062] The OCT observation module employs a dual-threaded interferometric architecture, comprising a swept laser 2, a 70:30 beam splitter 3, dual circulators (first circulator 4 and second circulator 7), a polarization controller 8, a galvanometer scanning unit 9, and a balanced detector 20. The output beam from the swept laser 2 is split into a reference arm and a sample arm by the 70:30 beam splitter 3. The reference arm beam passes sequentially through the first circulator 4 and collimating lens group 5 to reach the adjustable reference mirror 6, with the reflected light returning to the first circulator 4 via the original path. The sample arm beam passes through the second circulator 7, and its polarization state is adjusted by the polarization controller 8. A two-dimensional grating scan at a scanning frequency of 10 kHz is achieved by the galvanometer, and then focused onto the tested eye tissue by the objective lens group 10. The two returning beams generate an interference signal at the 50:50 beam combiner 19, which is differentially detected by the balanced detector 20. After eliminating environmental noise through a 0.1-1.5 MHz bandpass filter 13, the signal is acquired and processed by a 1.25 GS / s high-speed data card 14. Finally, Young's modulus inference is performed using an elastic imaging mechanics algorithm, i.e., a deep learning model. The specific algorithm flow is as follows:

[0063] (1) In the OCT scanning method, one scan yields B-scansize A-scans, which, according to the previous acquisition logic, constitutes a complete B-scan. The data is selected from the fifth storage format in the data card: 'FFT complex data', which includes the real and imaginary parts of each location. The first half of the data format stores the real parts of all complex data, arranged in a two-dimensional matrix with dimensions of width × height = A-scanSize × B-scanSize. The imaginary parts of all complex data are stored, arranged in the same way as the real parts, with the same dimensions of A-scanSize × B-scanSize. It is stored in a bin file format, containing one complete B-scan.

[0064] (2) To obtain the elastic wave Doppler phase map, each OCT data image (size A-scanSize × B-scanSize) needs to be processed to obtain the phase value at each point. The phase calculation formula is as follows:

[0065]

[0066] in, This represents the arctangent function, used to calculate angles. Representing complex numbers and conjugate The imaginary part after multiplication. Represents the real part of the result.

[0067] (3) To obtain the Doppler spatiotemporal displacement map, it is necessary to solve the Doppler phase shift formula to generate the Doppler phase shift map. The calculation formula is as follows:

[0068]

[0069] in, Indicates the wavelength of the OCT light source. This represents the refractive index of the medium (which could be the cornea or retina). Its Doppler phase shift.

[0070] (4) In order to obtain a high signal-to-noise ratio spatiotemporal displacement map and remove motion artifacts of the human body, a high-pass filter can be used to remove low-frequency artifact displacements caused by heartbeat and breathing.

[0071] (5) Apply 2D Fast Fourier Transform to the spatiotemporal displacement map to transform the high signal-to-noise ratio spatiotemporal displacement map into a wavenumber-frequency domain spectrum. The calculation formula is as follows:

[0072]

[0073] (6) In order to extract the phase velocity dispersion curve, the wave value with the maximum intensity at each frequency of the wavenumber-frequency domain spectrum is selected, i.e., according to To determine the wave number, the wave velocity is calculated using the following formula:

[0074]

[0075] in Select the current frequency. This is the wavenumber corresponding to the maximum intensity at this frequency.

[0076] (7) In order to obtain the phase velocity distribution map, it is necessary to calculate the phase velocity of each region. Extract the phase shift change of a certain position over time in the spatiotemporal displacement map, and use 1D fast Fourier transform to obtain its frequency domain map. Observe the frequency domain map and select the position of maximum intensity as its dominant frequency, and select the phase velocity corresponding to the dominant frequency from the phase velocity dispersion curve as the final phase velocity at that position.

[0077] (8) Using the wave model, the preliminary inference of the tissue Young's modulus and the mechanical calculation formulas for the cornea and retina are as follows:

[0078]

[0079]

[0080] in, For material density, Poisson's ratio, and For Lamb wave and Rayleigh wave speed, and These are the estimated moduli of corneal and retinal mechanics, respectively.

[0081] (9) The estimated modulus is corrected by combining the features of the tissue phase velocity distribution image. The method is to use the estimated modulus and the generated tissue phase velocity distribution map as model inputs. The tissue phase velocity distribution map is input into ResNet-50 to extract tissue morphology and phase velocity distribution information. This image information is then fused with the estimated modulus, and the corrected mechanical modulus is finally output. The training data for this model comes from gel phantom experimental data. The training data can be extended to in vitro tissue experiments or finite element simulation data, thereby improving the model's adaptability to real tissues.

[0082] The eye cup adapter module 18 is made of biocompatible silicone, and its cup shape conforms to the structure around the human eye socket, ensuring a tight seal and comfort when it is fitted onto the eye socket. The bottom of the eye cup integrates an acoustic-optical coupling window, composed of BK7 optical glass and a calcium fluoride composite layer, with a transmittance of >92% at a wavelength of 1060nm, while ensuring an ultrasonic reflectivity of <5%, thus guaranteeing its airtightness. A 2D adjustment platform is located below the coupling window, which can precisely position the spatial coordinates of the ultrasonic transducer and the acoustic glass plate, ensuring controllable ultrasonic focal point position.

[0083] Furthermore, the ultrasonic transducer adopts an array design, consisting of a ring array of multiple piezoelectric crystals. Each crystal is independently connected to an impedance matching circuit to achieve three-dimensional focal point positioning, facilitating automatic switching between corneal and retinal ultrasound excitation. Ultrasonic parameters (such as a center frequency of 1-3MHz and Ispta < 720mW / cm²) can be set according to ophthalmic diagnostic safety standards, and the system can integrate safety monitoring circuitry.

[0084] Furthermore, to meet the needs of OCT anterior segment and fundus observation, a dual-scanning mode configuration is adopted. In anterior segment scanning, the scanning depth is set to approximately 5mm, objective lens NA=0.3, and axial resolution 8μm. In fundus mode, a longer focal length objective is switched (focal length increased by 2 times), extending the scanning depth to approximately 3cm while maintaining an axial resolution of 12μm. A circular scanning mode is used to penetrate the lens and observe the retina. Both modes share the same interferometric architecture, with the reference arm synchronously extended to compensate for optical path differences. The polarization controller automatically loads a preset matrix to optimize backscattering efficiency in different tissues.

[0085] Furthermore, its balanced detector uses an InGaAs array, which has a responsivity of 0.95 A / W in the 1050 nm band. Combined with a transimpedance amplifier, it achieves a certain dynamic range, which can improve the accuracy of detecting changes in tissue surface displacement.

[0086] Furthermore, the acousto-optic coupling window at the bottom of the eye cup adopts a gradient acoustic impedance design, comprising four layers of titanium-aluminum-quartz-polymer transition layers, achieving a 99.2% transmission efficiency for 1.5MHz ultrasound. A λ / 4 (λ=1060nm) anti-reflection film is deposited at the interface to suppress OCT echo loss.

[0087] Furthermore, its acousto-optic coupling glass plate adopts a three-layer composite structure of magnesium fluoride-tantalum pentoxide-quartz. The magnesium fluoride-tantalum pentoxide coating (facing the transducer) is two layers thicker than 1 / 4 of the ultrasonic wavelength (1.5MHz), and the acoustic impedance gradient design ensures an ultrasonic reflectivity ≥98%. The quartz layer, serving as an acousto-optic compatible substrate, can be 2mm thick and coated with a 1060nm antireflection film, achieving an OCT optical path transmittance >95%. The magnesium fluoride layer (facing the eye tissue) has a thickness of λ / 4 (λ=1060nm), further suppressing OCT return loss. The thickness of the quartz substrate can be selected to match the wavelength characteristics of ultrasound and light waves, reducing interference from acoustic / optical path differences.

[0088] Furthermore, its motion platform employs piezoelectric ceramic drive, providing ±3mm stroke and 500µm resolution positioning capability on the X-axis, and a ±15° deflection range and 0.1° step accuracy on the rotary axis. Real-time dynamic compensation of the ultrasonic incident angle is achieved through a forward kinematics algorithm. The specific algorithm flow is as follows:

[0089] (1) First, define the coordinate system. Set the center of the reflector as the origin O and establish a three-dimensional coordinate system. The position of the ultrasonic transmitter is S, and the position of the target tissue is T.

[0090] (2) Subsequently, the incident vector and the reflection vector are normalized, as shown in the following formula:

[0091]

[0092]

[0093] in Represents the incident normalized vector. This represents the reflection normalized vector.

[0094] (3) Calculate the direction of the mirror's normal vector using the following formula:

[0095]

[0096] in The unit normal vector represents the mirror.

[0097] (4) The rotation angle of the acousto-optic coupling glass plate can be derived from the following formula:

[0098]

[0099]

[0100] in and It is the rotation angle around the x and y axes. They are The components in the x, y, and z directions in coordinate system O. Finally, based on the desired result, the lens is rotated to direct the ultrasound in the desired direction.

[0101] Example

[0102] An ultrasound-excited elastography device for measuring the mechanical properties of the cornea and retina mainly includes an ultrasound excitation module, an OCT observation module, an eye cup fitting module 18, and a data processing module.

[0103] The ultrasonic excitation module comprises a main unit 1, a function generator 16, a power amplifier 17, an impedance matching circuit, an ultrasonic transducer 11, an acoustic reflective glass plate 12, and a motion platform. The main unit 1 is connected to the function generator 16 via a data cable. The output of the function generator 16 is connected in series with the impedance matching circuit via the power amplifier 17, ultimately driving the ultrasonic transducer 11 to generate focused ultrasonic waves. The ultrasonic transducer 11 is fixed within the side wall cavity of the eye cup adapter module 18, with its radiating surface completely immersed in the eye cup medium. The transducer axis is orthogonally aligned with the OCT optical axis at 90°, and a 45° angled acoustic reflective glass plate 12 is positioned at its front end. The acoustic reflective glass plate 12 achieves 0.1mm-level translation and ±15° dynamic deflection via the motion platform, used to control the ultrasonic wave incident path.

[0104] The OCT observation module employs a dual-threaded interferometric architecture, comprising a swept laser 2, a 70:30 beam splitter 3, dual circulators (first circulator 4 and second circulator 7), a polarization controller 8, a galvanometer scanning unit 9, and a balanced detector 20. The output beam from the swept laser 2 is split into a reference arm and a sample arm by the beam splitter 3. The reference arm beam passes through the first circulator 4 and collimating lens group 5 to reach the adjustable reference mirror 6, with the reflected light returning along the same path. The sample arm beam, after its polarization state is adjusted by the second circulator 7 and polarization controller 8, is scanned by the galvanometer at 10kHz using a two-dimensional grating and focused onto the tested eye tissue by the objective lens 10. The two returning beams generate interference signals via a 50:50 beam combiner 19, which are differentially detected by the balanced detector 20. After bandpass filtering (0.1-1.5MHz), the signals are acquired and processed by a 1.25GS / s high-speed data card.

[0105] Eye cup fitting module 18: Made of biocompatible silicone, the cup opening is shaped to fit the structure of the human eye socket, and the bottom integrates an acoustic-optical coupling window and an adjustment platform. The acoustic-optical coupling window is composed of BK7 optical glass and a calcium fluoride composite layer, with a transmittance of >92% and an ultrasonic reflectance of <5% at a wavelength of 1060nm; the adjustment platform can accurately position the spatial coordinates of the ultrasonic transducer and the acoustic glass plate.

[0106] Furthermore, the ultrasonic transducer 11 adopts a ring array design, consisting of multiple independent piezoelectric crystals, each crystal being individually connected to an impedance matching circuit to achieve three-dimensional positioning of the focal point.

[0107] Furthermore, the OCT observation module is configured with dual scanning modes. Anterior segment mode: scanning depth approximately 5mm, objective lens NA=0.3, axial resolution 8μm; Fundus mode: switching to a telephoto objective (focal length increased by 2 times), scanning depth extended to approximately 3cm, axial resolution 12μm, using a ring scan to penetrate the lens and observe the retina. Both modes share the same interferometric architecture, with the reference arm synchronously extended to compensate for optical path difference, and the polarization controller automatically loading a preset matrix to optimize backscattering efficiency.

[0108] Furthermore, the balance detector 20 adopts an InGaAs array, with a responsivity of 0.95 A / W in the 1050 nm band. Combined with a transimpedance amplifier, it achieves a certain dynamic range and can accurately detect tissue displacement changes.

[0109] Furthermore, the acoustic-optic coupling window adopts a gradient acoustic impedance design, including a four-layer transition structure of titanium-aluminum-quartz-polymer, to achieve a 99.2% transmission efficiency of 1.5MHz ultrasound; the interface is coated with a λ / 4 (λ=1060nm) anti-reflection film system to suppress OCT echo loss.

[0110] Furthermore, the acoustic reflective glass sheet 12 adopts a three-layer composite structure of magnesium fluoride-tantalum pentoxide-quartz, wherein the thickness of the magnesium fluoride-tantalum pentoxide coating (facing the transducer side) is two layers of 1 / 4 ultrasonic wavelength (1.5MHz), and the acoustic impedance gradient design makes the ultrasonic reflectivity ≥98%; the quartz layer serves as an acousto-optic compatible substrate with a thickness of 2mm and a 1060nm antireflection film coated on its surface to achieve an OCT optical path transmittance >95%; the magnesium fluoride layer (facing the eye tissue) has a thickness of λ / 4 (λ=1060nm), which further suppresses OCT return loss.

[0111] Furthermore, the motion platform employs piezoelectric ceramic drive, with an X-axis travel of ±3mm and a positioning resolution of 500nm, a rotation axis deflection range of ±15°, and a stepping accuracy of 0.1°. It also incorporates a kinematic forward algorithm to compensate for ultrasonic incident angle deviations in real time. The specific algorithm is as described in the previous section.

[0112] In practice, the detection process is as follows: 1. The user wears the eye cup fitting module, the system starts automatic positioning, and obtains the spatial coordinates of the eye tissue through OCT scanning; 2. The ultrasound excitation module automatically adjusts the focal position according to the target area (cornea / retina), and the motion platform dynamically calibrates the angle of the acoustic reflective glass slide; 3. The OCT observation module switches the scanning mode, and the balanced detector collects interference signals; 4. The data processing card performs 2D FFT transformation, extracts the phase velocity dispersion curve, processes it through elastic imaging mechanics algorithms, generates a spatiotemporal displacement map and Young's modulus distribution, uses wave models and deep learning models for inference, and finally outputs a map of biomechanical parameters of the eye tissue.

[0113] This invention integrates ultrasound and OCT design, achieving interference-free coordination of ultrasound excitation and optical detection through orthogonal layout and optimized acousto-optic coupling window, enabling multi-tissue Young's modulus measurement. Ultrasound focus control utilizes an array transducer, resulting in minimal focus positioning error and shortened switching time. It supports full-eye compatible detection, with dual-scan mode allowing rapid switching between anterior segment (cornea) and fundus (retina), maintaining an axial resolution of 8-12 μm. High signal-to-noise ratio processing, combining a balanced detector and bandpass filter, suppresses signal noise, resulting in displacement detection sensitivity higher than pure ultrasound detection. A wave model combined with a deep learning model is used to correct the mechanical modulus calculation.

[0114] Compared with the prior art, the key features and technical advantages of the embodiments of the present invention are as follows:

[0115] By combining ultrasonic excitation technology with optical coherence tomography (OCT) imaging technology and incorporating an optimized eye cup adapter module, an ocular biomechanical detection system was constructed, achieving high-precision, non-invasive measurement of the biomechanical properties of ocular tissues. The ultrasonic excitation module employs an array transducer, enabling flexible three-dimensional positioning of the ultrasonic focus, improving detection flexibility and significantly enhancing work efficiency. The OCT observation module, with its dual-scanning mode design, allows for high-resolution imaging of the anterior segment and fundus through parameter adjustments without hardware replacement, expanding the system's applicability. Furthermore, the balanced detector uses an InGaAs array, possessing high responsivity and a wide dynamic range, ensuring the accuracy of tissue displacement detection and providing reliable data support for subsequent Young's modulus derivation. The eye cup adapter module is made of biocompatible silicone, combined with a gradient acoustic impedance-designed acousto-optic coupling window and a composite acousto-optic coupling glass plate, improving the transmission efficiency of the ultrasonic and OCT beams and preventing the ultrasonic transducer from obstructing the OCT optical path. The motion platform, driven by piezoelectric ceramics, provides high-precision translation and deflection capabilities. Combined with a forward kinematics algorithm, it achieves real-time dynamic compensation of the ultrasonic wave incident angle, ensuring the accuracy and stability of ultrasonic excitation. Wave model algorithms are integrated with deep learning model training to correct the accuracy of Young's modulus calculation. These innovative designs work together to enable the system to accurately capture tissue responses during detection and derive the Young's modulus of ocular tissue through elastic imaging mechanics algorithms.

[0116] This invention enables multifunctional detection of ocular biomechanical properties, providing an important tool for assisting in the early diagnosis of ophthalmic diseases and possessing significant clinical application value.

[0117] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. An ultrasound-excited elastography device for measuring the mechanical properties of the cornea and retina, characterized in that, include: An ultrasonic excitation module is used to generate three-dimensionally localizable focused ultrasound waves to excite ocular tissues to produce elastic waves. The ultrasonic excitation module includes an array-type ultrasonic transducer, a dynamic phase control unit, and a motion platform. The array-type ultrasonic transducer is composed of multiple independent piezoelectric crystals. The dynamic phase control unit adjusts the excitation timing of each crystal to achieve three-dimensional localization of the ultrasonic focus and switching of the corneal / retinal excitation area. The motion platform realizes translation and deflection to compensate for the deviation of the ultrasonic incident angle in real time. The OCT observation module is used to capture the spatiotemporal displacement signal of tissue induced by the elastic wave through optical coherence tomography (OCT). The OCT observation module is configured with anterior segment mode and fundus mode, and high-resolution imaging of the cornea and retina is achieved by switching the objective lens focal length and scanning depth, respectively. The eye cup adaptation module, with its biocompatible structure, adapts to the eye contour and is used to couple the optical and acoustic paths of the ultrasound excitation module and the OCT observation module. The data processing module is used to process the spatiotemporal displacement signal using an elastic imaging mechanics algorithm to derive the Young's modulus distribution of the eye tissue; The ultrasonic transducer axis of the ultrasonic excitation module is angularly geometrically related to the optical axis of the OCT observation module, and the acoustic wave path is deflected by the obliquely placed acoustic reflective glass plate of the acoustic path deflection device. The eye cup fitting module works with the ultrasonic excitation module to control the incident angle of the acoustic wave. The data processing module converts the spatiotemporal displacement signal into a biomechanical parameter spectrum through wave model inference.

2. The device according to claim 1, characterized in that, The ultrasonic transducer axis of the ultrasonic excitation module is orthogonal to the optical axis of the OCT observation module; the motion platform is driven by piezoelectric ceramics.

3. The device according to claim 1, characterized in that, The OCT observation module adopts a dual-threaded interferometric architecture, which includes a swept laser, a beam splitter, a circulator, a galvanometer scanning unit, and a balance detector. The galvanometer scanning unit is used for two-dimensional grating scanning, and the balance detector adopts an InGaAs array to detect nanoscale displacement changes.

4. The device according to any one of claims 1 to 3, characterized in that, The bottom of the eye cup adapter module integrates a gradient acoustic-optical coupling window, which includes a four-layer transition structure of titanium-aluminum-quartz-polymer to improve the ultrasonic wave transmittance and OCT optical path transmittance; a two-dimensional adjustment platform is set below the coupling window to locate the spatial coordinates of the ultrasonic transducer and the acoustic reflective glass plate.

5. The device according to claim 4, characterized in that, The acoustic reflective glass sheet adopts a multi-layer composite acoustic reflective structure, which includes a quartz layer, a tantalum pentoxide layer and a magnesium fluoride layer. The thickness of the tantalum pentoxide layer and the magnesium fluoride layer is 1 / 4 of the ultrasonic wavelength. An anti-reflection film is deposited on the surface of the quartz layer to further suppress optical path return loss.

6. The device according to any one of claims 1 to 3, characterized in that, The data processing module is configured to perform the following elastic imaging processing: (a) Obtain tissue reflection signals in complex form by OCT scanning, and construct a two-dimensional matrix by separating the real and imaginary parts of the data; (b) Calculate the phase difference based on the complex conjugate product of adjacent signal frames to generate an elastic wave Doppler phase map; (c) Combine the light source wavelength and the refractive index of the medium to convert the phase difference into a tissue spatiotemporal displacement distribution map; (d) Low-frequency physiological motion noise is eliminated by high-pass filtering to extract high signal-to-noise ratio displacement signals; (e) Perform a two-dimensional frequency domain transformation on the displacement signal, analyze the wavenumber-frequency domain spectrum, and extract the wavenumber corresponding to the maximum intensity at each frequency; (f) Calculate the phase velocity based on the relationship between wavenumber and frequency, and construct a phase velocity distribution map of the tissue; (g) Based on tissue density, Poisson's ratio and wave velocity, establish an elastic wave propagation model and derive the initial Young's modulus estimate; (h) Input the phase velocity distribution map and the initial modulus estimate into the deep learning model, fuse tissue morphology features to perform modulus correction, and output the final biomechanical parameter map.

7. The device according to any one of claims 1 to 3, characterized in that, The reference arm of the OCT observation module is equipped with an adjustable optical path compensation mechanism, which enables seamless switching between the anterior segment mode and the fundus mode by synchronously extending the optical path. In addition, the polarization controller automatically loads a preset matrix to optimize the backscattering efficiency of different tissues.

8. A detection method using the apparatus according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Fix the eye to be tested using the eye cup adapter module, and start OCT scanning to obtain tissue spatial coordinates; S2. The ultrasonic excitation module dynamically adjusts the focal position according to the target area, and the motion platform calibrates the angle of the acoustic reflective glass plate. The S3 and OCT observation modules switch scanning modes to capture the spatiotemporal displacement signals induced by elastic waves. S4. The data processing module executes the elasticity imaging algorithm to generate a Young's modulus distribution map. The detection method achieves non-invasive quantitative detection of the mechanical properties of the cornea and retina through the synergistic effect of ultrasound-OCT.

9. The method according to claim 8, characterized in that, The elastic imaging algorithm in step S4 specifically includes: (a) Obtain tissue reflection signals in complex form by OCT scanning, and construct a two-dimensional matrix by separating the real and imaginary parts of the data; (b) Calculate the phase difference based on the complex conjugate product of adjacent signal frames to generate an elastic wave Doppler phase map; (c) Combine the light source wavelength and the refractive index of the medium to convert the phase difference into a tissue spatiotemporal displacement distribution map; (d) Low-frequency physiological motion noise is eliminated by high-pass filtering to extract high signal-to-noise ratio displacement signals; (e) Perform a two-dimensional frequency domain transformation on the displacement signal, analyze the wavenumber-frequency domain spectrum, and extract the wavenumber corresponding to the maximum intensity at each frequency; (f) Calculate the phase velocity based on the relationship between wavenumber and frequency, and construct a phase velocity distribution map of the tissue; (g) Based on tissue density, Poisson's ratio and wave velocity, establish an elastic wave propagation model and derive the initial Young's modulus estimate; (h) Input the phase velocity distribution map and the initial modulus estimate into the deep learning model, fuse tissue morphology features to perform modulus correction, and output the final biomechanical parameter map.

10. The method according to claim 8 or 9, characterized in that, In step S2, the ultrasound excitation module compensates for the incident angle deviation caused by eye movement in real time using a forward kinematics algorithm. The forward kinematics algorithm specifically includes: A three-dimensional coordinate system is established with the center of the reflector as the origin to define the position of the ultrasonic transmitter and the target tissue. The incident vector and the reflection vector are normalized to obtain the normalized incident vector and the normalized reflection vector, respectively. The normal direction of the mirror is calculated based on the sum of the incident and reflected vectors; The rotation angles around the x-axis and y-axis are calculated based on the component relationships of the normal vector in the coordinate system. The deflection attitude of the acousto-optic coupling glass is dynamically adjusted to compensate for the incident angle deviation and accurately guide the ultrasonic excitation focus.

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