Cornea elastic modulus measuring equipment and method based on magnetic nanoparticle excitation

Abstract

The invention discloses a corneal elastic modulus measuring device and method based on magnetic nanoparticle excitation. The corneal elastic modulus measuring device comprises a soft magnetic nanoparticle contact lens, an electromagnetic excitation module, an OCT module and a data processing module. The soft contact lens is attached to the cornea surface by wrapping magnetic nanoparticles with the sealing film, and generates mechanical response under a controllable magnetic field generated by the electromagnetic coil; the OCT module synchronously captures dynamic deformation images before and after excitation, and an optical path of the OCT module is coaxially matched with the annular electromagnetic structure to guarantee synchronization of imaging and excitation. And the data processing module extracts displacement information through multi-stage signal processing, compensates the influence of cornea geometric parameters in combination with a magnetic field acting force and a correction coefficient, and generates a high-resolution two-dimensional elastic modulus map. According to the system, real-time regionalization measurement of corneal mechanical characteristics is achieved with micron-level resolution, discomfort of millimeter-level deformation in the prior art is avoided, detection precision, safety and comfort are remarkably improved, and the system is suitable for precise diagnosis and treatment evaluation of clinical corneal diseases.

Description

Technical Field

[0001] This invention relates to the measurement of corneal mechanical properties, and in particular to a device and method for measuring the corneal elastic modulus based on magnetic nanoparticle excitation. Background Technology

[0002] The cornea, as a vital component of the eye, plays a crucial role in maintaining the shape of the eyeball, protecting the eye from damage, and participating in the eye's refractive function. Therefore, corneal research is of paramount importance. Currently, corneal research mainly focuses on morphology and pathology, while research on the mechanical properties of the cornea is still in its early stages.

[0003] Medical research shows that a normal cornea consists of five layers: the epithelial cell layer (50 μm), the anterior elastic lamina (15 μm), the stroma (450 μm), the descemet's membrane (5 μm), and the endothelial cell layer (5 μm). Each layer is composed of collagen fibers, and the orientation and arrangement of these fibers directly affect the mechanical properties of the cornea. The collagen fibers are denser near the center of the cornea than at the periphery, and the density decreases from front to back. The biomechanics of the cornea determines its shape, which in turn affects its visual function.

[0004] Therefore, accurately, rapidly, and safely measuring the mechanical properties of the corneal stroma and distinguishing differences in mechanical properties across different regions has become crucial. Furthermore, research on corneal mechanical properties can advance the field of corneal mechanics-related diseases. To achieve early diagnosis, patient-specific treatment, and evaluation of its effectiveness, there is an increasing need for high-resolution screening methods capable of sensitively assessing changes in corneal biomechanical space. Simultaneously, accurate knowledge of corneal mechanical properties is essential for identifying risk factors and preventing serious complications before refractive surgery.

[0005] In recent years, with the development of optical coherence tomography (OCT), observing corneal features using OCT has become a reality. Compared with techniques such as atomic force microscopy (AFM) and ultrasound elastography (UE), OCT's relative spatial resolution and penetration depth better meet the needs of corneal observation and detection. However, OCT devices still suffer from frame rate issues. While maintaining clarity, OCT is only suitable for capturing still images and cannot meet the requirements of high frame rate imaging. OCT utilizes the principle of a Michelson interferometer, using the interference information of coherent light to obtain depth information of the sample. Optical coherence elastography (OCE), on the other hand, uses an excitation device to generate excitation, which is then observed using OCT.

[0006] The development of instruments for measuring corneal mechanical properties is of great significance for doctors' preoperative diagnosis and assessment, as well as postoperative treatment planning. However, there is currently no instrument on the market that can directly measure corneal mechanical properties; the more mature instruments are non-contact intraocular pressure analyzers (ORA and Corvis ST). Meanwhile, hospitals often assess corneal mechanical performance by measuring intraocular pressure, but this assessment is not accurate because there is a complex coupling relationship between intraocular pressure and corneal mechanics, and the two cannot be equated.

[0007] Currently, the Corvis ST is the instrument used to assess corneal biomechanics. The Corvis ST utilizes a high-speed (4300 frames / second) Scheimpflug camera to capture air-induced corneal deformation (maximum pressure: 25 kPa). Based on multiple frames of images, various parameters are obtained. Using extensive medical data and regression analysis, a new assessment index, SSI, is proposed. This SSI index is calculated using a linear equation based on parameters from multiple frames. Specifically, the regression data uses corneal stiffness from 50-year-old healthy individuals as the index, defined as SSI=1. The relationship between SSI and 1 is used to determine the patient's corneal stiffness. However, this result has significant inaccuracies. Secondly, the SSI index obtained using the Corvis ST can only assess the overall corneal value, not different regions of the cornea or the depth direction. Furthermore, the Corvis ST requires air blowing to induce millimeter-level corneal deformation, resulting in a poor patient experience. Therefore, it is necessary to develop a more accurate, real-time, safe, and comfortable corneal biomechanical measurement instrument.

[0008] CN110974148A discloses a detection method based on air pulse optical coherence elastography (OCE). Its detection accuracy remains at the millimeter level, and it does not obtain a two-dimensional elastic image of the cornea. Furthermore, current corneal mechanical assessment patents all employ a single-excitation mode, relying on experiments to correct and eliminate the influence of intraocular pressure. This method is prone to errors, thus affecting the accuracy of the results. In addition, in existing magnetic nanoparticle OCE technologies, magnetic nanoparticles are mainly used as contrast agents. Moreover, current OCT detection accuracy cannot reach the nanometer level, making it impossible to detect the displacement of magnetic nanoparticles. Furthermore, there are issues regarding the recovery of magnetic nanoparticles, involving unresolved safety concerns.

[0009] 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

[0010] The main objective of this invention is to overcome the deficiencies in the aforementioned background technology and provide a corneal elastic modulus measurement device and method based on magnetic nanoparticle excitation, thereby achieving high-precision real-time assessment of the spatial distribution of corneal mechanical properties.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: A corneal elastic modulus measurement device based on magnetic nanoparticle excitation, comprising: Soft magnetic nanoparticle contact lenses are made of magnetic nanoparticles wrapped in a sealing film. They are used to attach to the corneal surface and generate a mechanical response through magnetic field excitation. An electromagnetic excitation module, comprising an electromagnetic coil, is used to generate a controllable magnetic field to drive the magnetic nanoparticles to apply a push-pull force. Optical coherence tomography (OCT) module is used to capture real-time images of dynamic corneal deformation before and after excitation; The data processing module is used to extract displacement information based on the dynamic deformation image and calculate the real-time elastic modulus distribution of the cornea by combining stress data and using an elastic modulus algorithm. The electromagnetic coil structure of the electromagnetic excitation module is coaxially adapted with the optical path of the OCT module to enable the magnetic field excitation and optical imaging to be synchronized. The data processing module realizes displacement tracking and strain-stress conversion of dynamic deformation signals through multi-stage signal processing, and generates a two-dimensional map of corneal elastic modulus.

[0012] Furthermore, the sealing film of the soft magnetic nanoparticle contact mirror adopts a double-layer hydrogel structure and is formed by a centrifugal spin coating process. The magnetic nanoparticles have a preset particle size range and paramagnetism to ensure that measurable stress and strain are generated under magnetic field excitation.

[0013] Furthermore, the electromagnetic excitation module adopts a coreless ring coil design, and the inner diameter of the coil is matched with the imaging optical path of the OCT module. The magnetic field strength and heat dissipation performance are ensured through the selection and design of structure and size to avoid overheating of the electromagnet.

[0014] Furthermore, the high frame rate OCT module includes a swept-frequency light source, a beam splitter, a reference arm and a sample arm lens assembly, and a balanced detector; the sample arm lens assembly is conjugate focused with the corneal surface, and the imaging frame rate is increased to more than 200 frames / s by optimizing the light source parameters and the number of scan lines.

[0015] Furthermore, the high frame rate OCT module further includes a high-pass filter for frequency domain filtering of the electrical signal output by the balanced detector to filter out low-frequency physiological motion artifacts below 100Hz; the optical path of the reference arm lens group and the sample arm lens group are matched to ensure synchronous capture of corneal deformation signals at different depths.

[0016] Furthermore, the data processing module is configured to execute the following elastic modulus algorithm: The original image signal is averaged in the time domain to suppress high-frequency noise; The denoised signal is subjected to frequency domain transformation, and low-frequency physiological motion artifacts are separated by high-pass filtering; The phase change of laser speckle is used to track corneal deformation, the phase difference is extracted by autocorrelation analysis, and the displacement distribution is calculated by integration. The local strain is derived based on the displacement difference between the two excitations and the corneal thickness, and the stress distribution is calculated in conjunction with the magnetic field force. A two-dimensional map of corneal elastic modulus is generated by the ratio of strain to stress.

[0017] Furthermore, the elastic modulus algorithm introduces a correction coefficient to compensate for deviations in the calculation results caused by the thickness of the sealing film, corneal curvature, and intraocular pressure.

[0018] Furthermore, the electromagnetic excitation module employs dual-excitation timing control, applying magnetic field excitation twice at intervals and acquiring baseline calibration images to eliminate the interference of intraocular pressure on elastic modulus measurement.

[0019] A method for real-time measurement of corneal elastic modulus based on magnetic nanoparticle excitation includes the following steps: S1. Attach the soft magnetic nanoparticle contact lens to the corneal surface and activate the high frame rate OCT module to acquire a baseline corneal image; S2. Control the electromagnetic excitation module to apply a magnetic field, driving the magnetic nanoparticles to generate a push-pull force excitation on the cornea; S3. Capture dynamic deformation images before and after excitation in real time using a high frame rate OCT module; S4. Perform multi-stage signal processing on the deformation image to extract displacement information and calculate the corneal elastic modulus distribution; The signal processing includes noise suppression, artifact removal, speckle tracking, and strain-stress conversion, ultimately generating a corneal elastic modulus map.

[0020] Furthermore, the signal processing in step S4 specifically includes: (a) Perform time-domain averaging on the original image signal to suppress high-frequency noise; (b) The denoised signal is transformed in the frequency domain and low-frequency physiological motion artifacts are separated by high-pass filtering; (c) Based on the phase change of laser speckle, corneal deformation is tracked, the phase difference is extracted by autocorrelation analysis, and the displacement distribution is calculated by integration; (d) Based on the displacement difference between the two excitations and the corneal thickness, the local strain is derived, and the stress distribution is calculated by combining the magnetic field force and the correction coefficient. The correction coefficient is used to compensate for the effects of the sealing film thickness, corneal curvature and intraocular pressure. (e) A two-dimensional map of corneal elastic modulus is generated by the ratio of strain to stress.

[0021] The present invention has the following beneficial effects: This invention proposes a device and method for measuring corneal elastic modulus based on magnetic nanoparticle excitation. By integrating a soft magnetic nanoparticle contact lens, a ring electromagnetic excitation module, and a high-frame-rate optical coherence tomography (OCT) system, it achieves high-precision real-time measurement of corneal elastic modulus. Its core advantages are: using magnetic nanoparticles as the mechanical excitation source, combined with micron-level resolution high-frame-rate OCT dynamic imaging technology, it can acquire the mechanical properties of different regions of the cornea in a single measurement, and optimizes the use of a dual-excitation mode to eliminate intraocular pressure interference; through a multi-stage signal processing algorithm, it tracks corneal deformation and performs strain-stress conversion, ultimately generating a two-dimensional elastic modulus map; compared with existing technologies, this solution avoids the discomfort caused by millimeter-level deformation excitation, significantly improving the comfort and safety of the test with a non-invasive contact lens and a low-intensity magnetic field. Simultaneously, through dynamic image analysis and regional measurement capabilities, it overcomes the limitations of traditional devices that can only assess overall corneal hardness and rely on empirical regression models, providing a more accurate and real-time means of corneal mechanical assessment for clinical use.

[0022] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a real-time corneal elastic modulus measurement device according to an embodiment of the present invention.

[0024] Figure 2 This is a hardware schematic diagram of an embodiment of the present invention.

[0025] Figure 3 This is a flowchart of the real-time measurement method for corneal elastic modulus of the present invention.

[0026] Figure 4 This is a data processing flowchart of an embodiment of the present invention. Detailed Implementation

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] See Figure 1 and Figure 2 This invention provides a corneal elastic modulus measurement device based on magnetic nanoparticle excitation, comprising: a soft magnetic nanoparticle contact lens, consisting of a magnetic nanoparticle layer 4 wrapped in a sealing film 3, for attaching to the corneal surface of a human eye 5 and generating a mechanical response through magnetic field excitation; an electromagnetic excitation module 2, including an electromagnetic coil, preferably ring-shaped, for generating a controllable magnetic field to drive the magnetic nanoparticles 41 to apply a push-pull force; an optical coherence tomography (OCT) module 1, for capturing real-time images of corneal dynamic deformation before and after excitation; and a data processing module for extracting displacement information based on the dynamic deformation images and calculating the real-time elastic modulus distribution of the cornea using an elastic modulus algorithm in conjunction with stress data; wherein, the electromagnetic coil structure of the electromagnetic excitation module 2 is coaxially adapted with the optical path of the OCT module 1 to ensure that magnetic field excitation and optical imaging are performed synchronously, and the data processing module realizes displacement tracking and strain-stress conversion of dynamic deformation signals through multi-stage signal processing to generate a two-dimensional corneal elastic modulus map.

[0032] See Figure 2In a preferred embodiment, the sealing film 3 of the soft magnetic nanoparticle contact mirror adopts a double-layer hydrogel structure and is formed by a centrifugal spin coating process. The magnetic nanoparticles 41 have a preset particle size range and paramagnetism to ensure that measurable stress and strain are generated under magnetic field excitation.

[0033] In a preferred embodiment, the electromagnetic excitation module 2 adopts a coreless ring coil design, and the inner diameter of the coil is matched with the imaging optical path of the OCT module 1. The magnetic field strength and heat dissipation performance are ensured through the selection and design of structure and size, so as to avoid the electromagnet overheating.

[0034] In some embodiments, the OCT module 1 includes a swept-frequency light source, a beam splitter, a reference arm and a sample arm lens assembly, and a balanced detector; the sample arm lens assembly is conjugate focused with the corneal surface, and the imaging frame rate is increased to more than 200 frames / s by optimizing the light source parameters and the number of scan lines.

[0035] In some embodiments, the OCT module 1 further includes a high-pass filter for frequency domain filtering of the electrical signal output by the balanced detector to filter out low-frequency physiological motion artifacts below 100Hz; the optical path of the reference arm lens group and the sample arm lens group are matched to ensure synchronous capture of corneal deformation signals at different depths.

[0036] In a preferred embodiment, the data processing module is configured to execute the following elastic modulus algorithm: time-domain averaging of the original image signal to suppress high-frequency noise; frequency-domain transformation of the denoised signal, and separation of low-frequency physiological motion artifacts through high-pass filtering; tracking corneal deformation based on the phase change of laser speckle, extracting the phase difference through autocorrelation analysis, and calculating the displacement distribution by integration; deriving local strain based on the displacement difference between the two excitations and corneal thickness, and calculating the stress distribution in conjunction with the magnetic field force; generating a two-dimensional corneal elastic modulus map based on the ratio of strain to stress. In a further preferred embodiment, the elastic modulus algorithm also introduces a correction coefficient to compensate for deviations in the calculation results caused by the thickness of the sealing film, corneal curvature, and intraocular pressure.

[0037] In a preferred embodiment, the electromagnetic excitation module 2 employs dual-excitation timing control, applying magnetic field excitation twice at intervals and acquiring baseline calibration images to eliminate the interference of intraocular pressure on elastic modulus measurement.

[0038] See Figure 3 and Figure 4 This invention also provides a method for real-time measurement of corneal elastic modulus based on magnetic nanoparticle excitation, comprising the following steps: Step S1: Attach the soft magnetic nanoparticle contact lens to the corneal surface and activate OCT module 1 to acquire a baseline corneal image; Step S2: Control the electromagnetic excitation module 2 to apply a magnetic field, driving the magnetic nanoparticles to generate a push-pull force excitation on the cornea; Step S3: Capture dynamic deformation images before and after excitation in real time using OCT module 1; Step S4: Perform multi-stage signal processing on the deformation image to extract displacement information and calculate the corneal elastic modulus distribution; The multi-stage signal processing includes noise suppression, artifact removal, speckle tracking, and strain-stress conversion, ultimately generating a corneal elastic modulus map.

[0039] In a preferred embodiment, the signal processing in step S4 specifically includes: (a) performing time-domain averaging on the original image signal to suppress high-frequency noise; (b) performing frequency-domain transformation on the denoised signal and separating low-frequency physiological motion artifacts through high-pass filtering; (c) tracking corneal deformation based on the phase change of laser speckle, extracting the phase difference through autocorrelation analysis, and calculating the displacement distribution by integration; (d) deriving local strain based on the displacement difference between the two excitations and the corneal thickness, and calculating the stress distribution by combining the magnetic field force and correction coefficient, wherein the correction coefficient is used to compensate for the effects of sealing film thickness, corneal curvature, and intraocular pressure; and (e) generating a two-dimensional map of corneal elastic modulus based on the ratio of strain to stress.

[0040] This invention constructs an innovative corneal biomechanics testing scheme by combining a soft magnetic nanoparticle corneal contact lens module, an electromagnetic excitation module, and an OCT module, achieving safe, accurate, efficient, and real-time measurement of corneal biomechanics. Compared with existing technologies, this invention can achieve safer and more accurate corneal biomechanics measurements. Furthermore, the introduction of magnetic nanoparticles elevates the comfort, safety, and accuracy of corneal biomechanics testing to new heights.

[0041] The following describes specific embodiments of the present invention.

[0042] A real-time corneal elastic modulus measurement device mainly includes: a soft magnetic nanoparticle corneal contact lens module, an electromagnetic excitation module, an OCT module, and a data processing module. The soft magnetic nanoparticle corneal contact lens consists of two layers of hydrogel sealing film encapsulating magnetic nanoparticles. The hydrogel is prepared into a thin layer using centrifugal spin-coating technology and then demolded due to temperature difference. This not only prevents leakage of magnetic nanoparticles to ensure measurement safety, but its thin-layer structure also improves measurement sensitivity and reduces errors. The sealing reliability can be verified through artificial tear immersion and rubbing tests. The magnetic nanoparticles can be selected from biocompatible materials that meet clinical standards (such as clinically approved iron oxide particles). The magnetic nanoparticles must meet specific particle size requirements and possess paramagnetism to ensure sufficient stress and strain under magnetic field conditions. The OCT module employs a high-frame-rate OCT system.

[0043] The electromagnetic excitation module employs a non-ferroic structure composed of a ring magnet coil and wires. This design ensures that the light from high-frame-rate OCT reaches the cornea for imaging without obstruction, while optimizing the structure and size to generate sufficient magnetic field strength while preventing overheating. The high-frame-rate OCT system further enhances the frame rate to 200 frames per second while maintaining resolution through collaborative optimization of light source parameters, imaging field of view, and acquisition line count. It also utilizes components such as a high-pass filter to achieve precise capture of dynamic images.

[0044] When the device is in operation, the contact lens is first attached to the corneal surface. After power is applied, the electromagnetic excitation module generates a pushing and pulling force on the magnetic nanoparticles, and high-frame-rate OCT simultaneously records corneal images before and after excitation. Notably, it employs a dual-excitation mode, eliminating the interference of intraocular pressure on the measurement results through two excitations. The data processing module runs a corneal elasticity imaging algorithm, which comprehensively considers factors such as corneal thickness, curvature, internal pressure, and hydration level. Combining the strain information obtained from detection with the stress data provided by the device, it accurately calculates the real-time elastic modulus of the cornea after multi-stage signal processing and generates a two-dimensional map.

[0045] The specific data processing flow is as follows: Figure 3 and Figure 4 As shown. The electrical signal information of corneal motion is obtained through the data acquisition card, which is the original image. The following processing steps are then performed.

[0046] 1) Denoising: The original image contains a large amount of high-frequency noise. Therefore, the obtained electrical signal needs to be denoised. Specifically, the signal information from 10 time points is averaged to obtain the true information of that point in the previous time period. .Right now:

[0047] in, This represents the electrical signal strength (original image signal) at time t.

[0048] 2) Artifact Removal: Besides the original high-frequency noise introduced by the system, the processed image also contains low-frequency noise caused by factors such as heartbeat, blood vessels, blinking, and unconscious head movements during the detection process. After detection, this noise's frequency domain is <100Hz, which differs from the excitation frequency of 1200Hz. A high-pass filter is used to remove the low-frequency noise. The acquired denoised signal is then subjected to a Fourier transform to obtain the complex signal F(z). That is:

[0049] in, Indicates the signal amplitude. Indicates the signal phase.

[0050] Then, a high-pass filter is used to remove low-frequency signals below 100Hz. The specific formula is:

[0051] in R is the cutoff frequency, R is the set resistance value, and C is the set capacitance value.

[0052] 3) Speckle Tracking: Speckle tracking is based on the laser speckle phenomenon. It tracks and measures the motion or deformation of an object by analyzing changes in the speckle pattern. When a laser beam strikes the surface of an object, the reflected light interferes with each other due to the surface's microscopic roughness, forming a speckle pattern. When the object moves or deforms, the speckle pattern changes accordingly. By capturing and analyzing these changes, the object's motion state, internal stress, displacement, and other information can be inferred.

[0053] 4) Displacement image. The phase information of the signal can be obtained by performing autocorrelation analysis on the complex-valued signal. That is: ,

[0054] in, and They represent the first i Second and third i The complex signal sampled at +1 time can be uniformly converted into a phase-resolved OCT measurement, and phase jumps can be corrected using known phase unwrapping algorithms (such as adjacent pixel threshold correction).

[0055] Therefore, the corneal displacement information d can be obtained through the following formula.

[0056] ,

[0057] in, Indicates the center wavelength of the OCT light source. Indicates the refractive index of corneal tissue. Indicates the time interval for signal acquisition. This represents the time difference between two samplings.

[0058] 5) Modulus image. Based on the displacement information from the two excitations, the displacement difference is obtained as follows: Corneal thickness (CCT). Strain It can be obtained using the following formula: ,

[0059] stress It can be calculated using the following formula: ,

[0060] Among them, the force of the magnetic field on the magnetic nanoparticles is The force exerted on the cornea is The particle size of the magnetic nanoparticles is r. This is a correction factor to adjust for the influence of factors such as sealing film thickness and surface curvature on the actual stress. Magnetic field force. The excitation parameters can be determined through calibration using standard samples (such as PDMS gel) or electromagnetic simulation (such as COMSOL), establishing a correlation between the excitation parameters and the standard. The correspondence. Correction coefficient. It can be broken down into sub-items such as the sealing film and corneal curvature, which are determined respectively through membrane mechanics measurements, surface models, or experimental fitting. Ultimately, the corneal elastic modulus E at a point on the cornea is: .

[0061] Therefore, the accurate Young's modulus of the cornea can be obtained by taking into account corneal thickness, corneal surface curvature, and intraocular pressure.

[0062] Example The overall detection process is as follows: During the test, the patient places their head in the designated position and clicks "Start Positioning." The detection device uses a positioning algorithm to locate the cornea, then moves to align the lens with the cornea, preparing for imaging. Prompts are then given to complete the positioning. The device then places a soft magnetic nanoparticle contact lens onto the cornea. Once ready, the device captures the first baseline image. The excitation mode can be set according to the detection requirements, or the default mode can be selected. After selection, "Start Detection" is clicked. The excitation device generates the first excitation, and the detection device collects the electrical signal for detection, obtaining the first excitation image. After a 0.5-second interval, a second excitation is performed, obtaining the second excitation image. After another 0.5-second interval, a baseline calibration image is acquired. Finally, based on the internal algorithm, the corneal image is reconstructed, corneal mechanical property parameters are corrected, and a corneal elastic topography map of the patient is obtained, facilitating the doctor's assessment.

[0063] Overall, the device of this invention not only improves the accuracy and comfort of detection, but also elevates the comfort, safety, and accuracy of corneal mechanics detection to a new level through the introduction of magnetic nanoparticles. The corneal mechanics measuring instrument of this invention, by introducing key components such as a light source, fiber optic coupler, balanced detector, high-pass filter, and sample and reference armature groups, constructs a precise and novel detection mechanism by applying magnetic nanoparticle excitation. This improves the detection resolution to the micrometer level, significantly enhancing the detection accuracy and efficiency of the instrument. Furthermore, unlike resonant frequency magnetic nanoparticle OCT measurements that can only perform single-point measurements, this device can measure corneal hardness at different locations across the entire cornea in a single measurement, enabling rapid measurement of corneal hardness in different regions. Simultaneously, unlike static image analysis, the high frame rate optical detection module allows for the acquisition of dynamic excitation information, thereby extracting corneal mechanical information from dynamic images. The introduction of magnetic nanoparticles, unlike traditional global measurements, elevates the comfort, safety, and accuracy of corneal mechanics detection to a new level.

[0064] In terms of processing method, the influence of intraocular pressure on corneal rigidity measurement is eliminated. In terms of data processing algorithm, the influence of corneal curvature and thickness on corneal rigidity measurement is interpretably corrected. Furthermore, the influence of corneal thickness on corneal rigidity has been considered from the perspective of the measurement principle and therefore will not affect the measurement results. In summary, this device considers all factors that may affect corneal rigidity measurement, thus obtaining more accurate and interpretable corneal rigidity.

[0065] In summary, the multifunctional corneal detector of the present invention provides a new detection method and integrated diagnostic functions through technological innovation, realizing efficient and accurate corneal biomechanical measurement and greatly facilitating clinical operation.

[0066] 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. A device for measuring the corneal elastic modulus based on magnetic nanoparticle excitation, characterized in that, include: Soft magnetic nanoparticle contact lenses are made of magnetic nanoparticles wrapped in a sealing film. They are used to attach to the corneal surface and generate a mechanical response through magnetic field excitation. An electromagnetic excitation module, comprising an electromagnetic coil, is used to generate a controllable magnetic field to drive the magnetic nanoparticles to apply a push-pull force. Optical coherence tomography (OCT) module is used to capture real-time images of dynamic corneal deformation before and after excitation; The data processing module is used to extract displacement information based on the dynamic deformation image and calculate the real-time elastic modulus distribution of the cornea by combining stress data and using an elastic modulus algorithm. The electromagnetic coil structure of the electromagnetic excitation module is coaxially adapted with the optical path of the OCT module to enable the magnetic field excitation and optical imaging to be synchronized. The data processing module realizes displacement tracking and strain-stress conversion of dynamic deformation signals through multi-stage signal processing, and generates a two-dimensional map of corneal elastic modulus.

2. The device according to claim 1, characterized in that, The sealing film of the soft magnetic nanoparticle contact mirror adopts a double-layer hydrogel structure and is formed by centrifugal spin coating. The magnetic nanoparticles have a preset particle size range and paramagnetism to ensure that measurable stress and strain are generated under magnetic field excitation.

3. The device according to claim 1, characterized in that, The electromagnetic excitation module adopts a coreless ring coil design. The inner diameter of the coil is matched with the imaging optical path of the OCT module. The magnetic field strength and heat dissipation performance are ensured through the selection and design of structure and size to avoid overheating of the electromagnet.

4. The device according to any one of claims 1 to 3, characterized in that, The OCT module includes a swept-frequency light source, a beam splitter, a reference arm and a sample arm lens assembly, and a balanced detector; the sample arm lens assembly is conjugate focused with the corneal surface, and the imaging frame rate is increased to more than 200 frames / s by optimizing the light source parameters and the number of scan lines.

5. The device according to claim 4, characterized in that, The OCT module further includes a high-pass filter for frequency domain filtering of the electrical signal output by the balanced detector to filter out low-frequency physiological motion artifacts below 100Hz; the optical path of the reference arm lens group and the sample arm lens group are matched to ensure synchronous capture of corneal deformation signals at different depths.

6. The device according to any one of claims 1 to 3, characterized in that, The data processing module is configured to execute the following elastic modulus algorithm: The original image signal is averaged in the time domain to suppress high-frequency noise; The denoised signal is subjected to frequency domain transformation, and low-frequency physiological motion artifacts are separated by high-pass filtering; The phase change of laser speckle is used to track corneal deformation, the phase difference is extracted by autocorrelation analysis, and the displacement distribution is calculated by integration. The local strain is derived based on the displacement difference between the two excitations and the corneal thickness, and the stress distribution is calculated in conjunction with the magnetic field force. A two-dimensional map of corneal elastic modulus is generated by the ratio of strain to stress.

7. The device according to claim 6, characterized in that, The elastic modulus algorithm further introduces a correction coefficient to compensate for deviations in the calculation results caused by the thickness of the sealing film, corneal curvature, and intraocular pressure.

8. The device according to any one of claims 1 to 3, characterized in that, The electromagnetic excitation module employs dual-excitation timing control, applying magnetic field excitation twice at intervals and acquiring baseline calibration images to eliminate the interference of intraocular pressure on elastic modulus measurement.

9. A method for real-time measurement of corneal elastic modulus based on magnetic nanoparticle excitation, characterized in that, Includes the following steps: S1. Attach the soft magnetic nanoparticle contact lens to the corneal surface and activate the OCT module to acquire a baseline corneal image; S2. Control the electromagnetic excitation module to apply a magnetic field, driving the magnetic nanoparticles to generate a push-pull force excitation on the cornea; S3. Capture dynamic deformation images before and after excitation in real time using the OCT module; S4. Perform multi-stage signal processing on the deformation image to extract displacement information and calculate the corneal elastic modulus distribution; The signal processing includes noise suppression, artifact removal, speckle tracking, and strain-stress conversion, ultimately generating a corneal elastic modulus map.

10. The method according to claim 9, characterized in that, The signal processing in step S4 specifically includes: (a) Perform time-domain averaging on the original image signal to suppress high-frequency noise; (b) The denoised signal is transformed in the frequency domain and low-frequency physiological motion artifacts are separated by high-pass filtering; (c) Based on the phase change of laser speckle, corneal deformation is tracked, the phase difference is extracted by autocorrelation analysis, and the displacement distribution is calculated by integration; (d) Based on the displacement difference between the two excitations and the corneal thickness, the local strain is derived, and the stress distribution is calculated by combining the magnetic field force and the correction coefficient. The correction coefficient is used to compensate for the effects of the sealing film thickness, corneal curvature and intraocular pressure. (e) A two-dimensional map of corneal elastic modulus is generated by the ratio of strain to stress.

Images