Biomechanical test equipment for multi-muscle coordinated movement of extraocular muscles and test method thereof

Abstract

The invention belongs to the technical field of medical instruments, and particularly relates to biomechanical testing equipment for multi-muscle coordinated movement of extraocular muscles and a testing method thereof.The biomechanical testing equipment comprises an eyeball support, a fixing support, a traction motor, an angular velocity sensor and a force sensor; the eyeball support is used for placing eyeballs and rotates along with the eyeballs; the fixed bracket is movably connected with the eyeball support; the traction motor is connected with extraocular muscles of eyeballs through a traction rope; the angular velocity sensor is arranged on the eyeball support and used for measuring the rotation angle of the eyeball; the force sensor is arranged on the traction rope and used for measuring the force applied to extraocular muscles. Compared with the prior art, the defect that in the prior art, sufficient accuracy is still lacked in the aspects of extraocular muscle strength measurement and simulation and strabismus surgery effect prediction is overcome, the strength and movement of the extraocular muscle are measured and controlled through a more accurate and quantitative method, the implementation of the surgery is assisted, and the operation efficiency is improved. Therefore, the treatment effect of strabismus and other related eye diseases is finally improved.

Description

Technical Field

[0001] The invention belongs to the technical field of medical devices, and in particular relates to a biomechanical testing device for coordinated movement of multiple muscles of extraocular muscles and a testing method thereof. Background Art

[0002] Eye movement control is a vital part of the visual system and relies on the precise coordination of the extraocular muscles. The extraocular muscles include six muscles, which are divided into four rectus muscles and two oblique muscles according to their attachment position on the sclera and the direction of action. These muscles can be divided into antagonist muscles, synergist muscles and partner muscles according to their functions. In normal visual activities, these muscles must maintain a dynamic balance to ensure that the eyeball can accurately align with the visual target. Once the strength of a muscle is abnormal, whether it is weakened or strengthened, it may cause eye deviation and then cause strabismus.

[0003] The occurrence of strabismus not only affects visual beauty, but more importantly, it may lead to impeded vision development. If not treated for a long time, it may develop into functional blindness. Traditionally, the diagnosis and treatment of strabismus rely on clinical experience and subjective evaluation of postoperative effects. This method lacks precise quantitative analysis, which often makes the treatment effect suboptimal. Especially during surgery, the control of extraocular muscle strength and tension is crucial, but traditional technology fails to provide effective measurement methods.

[0004] Traditionally, the diagnosis and treatment of strabismus rely on the doctor's experience and reasoning. Due to the complexity of the motor control and muscle contraction force of the extraocular muscles, as well as the direct effect of the number of muscle fibers on the contraction force, quantitative analysis in this area is particularly difficult. However, with the development of biomechanics and imaging technology, we are now able to measure and analyze the biomechanical properties of the extraocular muscles more accurately. Researchers such as Robinson and Scott have revealed the mechanical properties of extraocular muscles and their application in strabismus surgery through experimental studies. For example, Robinson measured the relationship between the length and tension of the lateral rectus muscle during surgery and found that its changes were significantly position-dependent. The research of Scott et al. provided detailed mechanical data of the extraocular muscles and the restrictive tissues of the eyeball, providing important reference information for surgery.

[0005] For example, CN105455775A discloses an eye position and extraocular muscle strength measurement device and method. The device is a hemispherical structure, and the middle point A is the fixation point and the camera setting position. A test light is arranged inside the hemispherical structure. The design of the test light is as follows: the test light is arranged radially from the midpoint to the periphery, and is arranged at equal distances. The eye position measurement method includes the following steps: step 1: in the initial state, all lights are in the off state; step 2: turn on the lights in each direction in turn and turn them off after taking pictures. The extraocular muscle strength measurement method includes the following steps: step 1: in the initial state, all lights are in the off state; step 2: the test light A in the middle position is always on, turn on light B3 and turn off B3 after taking pictures; turn on light B2 and turn off B2 after taking pictures, turn on light B1 and turn it off after taking pictures. However, this method cannot obtain specific and accurate extraocular muscle strength values ​​and specific and accurate eyeball rotation angle values, and can only determine which one or several extraocular muscles have problems, which cannot meet the measurement requirements.

[0006] For example, CN211264770U discloses a teaching model for simulating eyeball and extraocular muscle movement, including a base, an opaque eye frame fixed on the base, a transparent simulated eye frame fixed on the upper side of the opaque eye frame, one end of the simulated optic nerve is connected to the rear end center of the simulated eyeball through a hinge, the other end of the simulated optic nerve is connected to the upper end of the support rod, the simulated total health ring is fixed on the partial periphery of the simulated optic nerve, one end of the simulated superior rectus muscle, simulated inferior rectus muscle, simulated lateral rectus muscle and simulated medial rectus muscle is respectively located at the periphery of the simulated eyeball, and the other end of the simulated superior rectus muscle, simulated inferior rectus muscle, simulated lateral rectus muscle and simulated medial rectus muscle is respectively connected to the power output end of a rectus muscle drive motor. However, the model can only provide the correlation between the extraocular muscle movement and the eyeball rotation direction, and cannot obtain specific and accurate extraocular muscle force value and eyeball rotation angle, and does not have the basis for further precise research.

[0007] For example, CN117521454A discloses a method for simulating and predicting eye movement based on a finite element model, which includes finite element model construction and surgical dose-effect relationship evaluation; first, the eyeball is geometrically modeled by computer-aided design software, and the material properties of the eyeball model are defined, and a hyperelastic constitutive model is constructed using finite element analysis software, including a retrobulbar fat model and an extraocular muscle model; muscle activation and mechanical response are simulated, the activation amount of muscles in different fibers is simulated, the Piola-Kerckhoff stress is calculated, and the stretching in the fiber direction is evaluated; data analysis is performed to estimate the strength of the extraocular muscles. However, this method is a pure simulation method, and the parameters used are difficult to customize according to the actual situation of the patient, so a lot of preliminary preparation is required for patients with different eye diseases.

[0008] Despite some progress, existing technologies still have limitations in measuring and controlling extraocular muscle strength. Current technologies have difficulty providing continuous, real-time strength measurements and determination of eye rotation angles, and still lack sufficient accuracy in simulating and predicting the effects of strabismus surgery. In addition, existing methods often ignore the effects of neural innervation and mechanical changes after muscle injury. Summary of the invention

[0009] The purpose of the present invention is to provide a biomechanical testing device and a testing method for the coordinated movement of multiple extraocular muscles in order to solve at least one of the above problems, so as to address the shortcomings of the prior art in the measurement and simulation of extraocular muscle strength and the prediction of the effect of strabismus surgery. The present scheme realizes a more accurate and quantitative method to measure and control the strength and movement of the extraocular muscles to assist the implementation of the surgery, thereby ultimately improving the treatment effect of strabismus and other related eye diseases.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] The first aspect of the present invention discloses a biomechanical testing device for coordinated movement of multiple muscles of the extraocular muscles, comprising an eyeball support, a fixing bracket, a pulling motor, an angular velocity sensor and a force sensor;

[0012] The eyeball holder is used to place the (ex vivo) eyeball, and the eyeball holder rotates with the eyeball;

[0013] The fixed bracket is movably connected to the eyeball support;

[0014] The pulling motor is connected to the extraocular muscle of the eyeball via a pulling rope;

[0015] The angular velocity sensor is arranged on the eyeball support and is used to measure the rotation angle of the eyeball;

[0016] The force sensor is arranged on the pulling rope and is used to measure the force applied by the extraocular muscles.

[0017] Preferably, the eyeball tray is connected to the eyeball wall of the eyeball by biocompatible glue or mechanical clamps, and the eyeball tray is a semicircle or inferior arc manufactured by 3D printing; the inner surface of the eyeball tray cooperates with the shape of the eyeball.

[0018] Preferably, the fixing bracket is provided with a bayonet, and the bayonet is used to pass through the extraocular muscles and limit the extraocular muscles.

[0019] Preferably, the bayonet is respectively arranged on the upper side, lower side, left side, right side, upper right side and lower right side of the fixing bracket, and is used to pass through the superior rectus muscle, inferior rectus muscle, medial rectus muscle, lateral rectus muscle, superior oblique muscle and inferior oblique muscle respectively.

[0020] Preferably, six stretching motors are provided, which are used to stretch the superior rectus muscle, inferior rectus muscle, medial rectus muscle, lateral rectus muscle, superior oblique muscle and inferior oblique muscle respectively.

[0021] Preferably, the pulling motor is a servo motor or a stepper motor.

[0022] Preferably, the pulling rope is a steel cable or a steel wire.

[0023] Preferably, the angular velocity sensor comprises a (three-axis) gyroscope, and the force sensor comprises a micro-force sensor.

[0024] Preferably, the biomechanical testing equipment further comprises a control module, which is electrically connected to the traction motor, the angular velocity sensor and the force sensor respectively; the operation of the traction motor is controlled through real-time data fed back by the sensor, and overload protection is implemented.

[0025] The rotation of the eyeball is the result of the coordinated action of six extraocular muscles (i.e., four rectus muscles and two oblique muscles), including the superior rectus, inferior rectus, medial rectus, lateral rectus, superior oblique and inferior oblique muscles, which are responsible for the movement of the eyeball in different directions.

[0026] The eye rotation angle is closely related to the coordinated action of these six muscles:

[0027] 1) Superior rectus (SR): Its main function is to rotate the eyeball upward.

[0028] 2) Inferior rectus (IR): Its main function is to rotate the eyeball downward.

[0029] 3) Medial Rectus (MR): Its main function is to rotate the eyeball inward (toward the nose).

[0030] 4) Lateral Rectus (LR): Its main function is to rotate the eyeball outward (temporally).

[0031] 5) Superior oblique (SO): The main function is to rotate the eyeball inward and downward, and the secondary function includes abduction of the eyeball.

[0032] 6) Inferior Oblique (IO): The main function is to rotate the eyeball outward and upward, and the secondary function includes abduction of the eyeball.

[0033] The rotation of the eyeball in any direction involves the coordinated work of at least two extraocular muscles. The relationship between the specific rotation direction and muscle action is as follows:

[0034] 1) Look up: The superior rectus and inferior oblique muscles contract simultaneously, causing the eyeball to rotate upward.

[0035] 2) Look down: The inferior rectus and superior oblique muscles contract simultaneously, causing the eyeball to rotate downward.

[0036] 3) Look outward: The lateral rectus muscle of the left eye and the medial rectus muscle of the right eye contract at the same time, causing the left eye to rotate to the left and the right eye to rotate to the right.

[0037] 4) Look inward: The lateral rectus muscle of the right eye and the medial rectus muscle of the left eye contract at the same time, causing the right eye to rotate to the right and the left eye to rotate to the left.

[0038] 5) Look to the outside and above: The superior rectus and inferior oblique muscles of the left eye, as well as the superior rectus and inferior oblique muscles of the right eye, contract in a coordinated manner to rotate the eyeball to the upper left.

[0039] 6) Look inward and upward: The superior rectus and inferior oblique muscles of the right eye, as well as the superior rectus and inferior oblique muscles of the left eye, contract in a coordinated manner, causing the eyeball to rotate to the upper right.

[0040] The same applies to other directions.

[0041] Based on the above technical background, the second aspect of the present invention discloses a testing method for a biomechanical testing device for coordinated movement of extraocular muscles as described above, wherein the force applied by the extraocular muscles is obtained based on the rotation angle of the eyeball, and the force balance equation of the eyeball is:

[0042]

[0043] In the above formula, F i is the force exerted by the i-th extraocular muscle, θ m is the component of the eyeball rotation angle in the m direction;

[0044] i: MR is the medial rectus muscle, LR is the lateral rectus muscle, SR is the superior rectus muscle, IR is the inferior rectus muscle, SO is the superior oblique muscle, and IO is the inferior oblique muscle;

[0045] m: x is the component in the x-axis direction, y is the component in the y-axis direction, and z is the component in the z-axis direction;

[0046] The length change of the extraocular muscle is obtained based on the force applied by the extraocular muscle and the elastic stiffness coefficient of the extraocular muscle. The relationship between the force applied by the extraocular muscle and the change in the length of the extraocular muscle is:

[0047] F i =k i ΔL i ;

[0048] In the above formula, k i is the elastic stiffness coefficient of the i-th extraocular muscle, ΔL i is the length change of the i-th extraocular muscle.

[0049] After obtaining the change in the length of the extraocular muscles, the length of the extraocular muscles can be adjusted surgically to change the strength of the extraocular muscles, thereby improving the strabismus of the eye.

[0050] Preferably, obtain several groups (ΔL i ,F i ) data, and the elastic stiffness coefficient of the extraocular muscles was obtained by data fitting.

[0051] The working principle of the present invention is:

[0052] Multiple traction motors independently control each extraocular muscle to apply force to the eyeball through a traction rope, thereby controlling the rotational movement of the eyeball; the target rotation angle of the eyeball is set, and the traction motor is controlled to drive the eyeball to rotate. During this period, the rotation angle of the eyeball and the force value of the traction motor (extraocular muscle) are obtained in real time through the angular velocity sensor and the force sensor.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] By integrating the latest biomechanical research results and advanced technologies, the device will be able to monitor the strength and status of the extraocular muscles in real time, providing doctors with real-time data support to ensure optimization of surgery and treatment.

[0055] After we calculate the strength of the extraocular muscles, the stretching length of the extraocular muscles can be obtained through the force and the material coefficient of the extraocular muscles. With the stretching length of the extraocular muscles, we can adjust the length of the extraocular muscles through surgery to change the strength of the extraocular muscles and thus improve the strabismus of the eye.

[0056] The development of this innovative device not only fills the technical gap in ophthalmic surgery, but also marks the development of ophthalmic surgery towards higher precision and more scientific direction. Through the application of this device, we can expect that the treatment of strabismus and other extraocular muscle-related diseases will be more precise and effective, ultimately improving the visual health and quality of life of patients.

[0057] Since this device uses 6 independent pulling motors to pull 6 extraocular muscles respectively, the feedback equation between muscle force and eye rotation angle can be established to optimize the calculation of the strength of the six muscles, ensuring that different muscles exert appropriate force to achieve the desired eye rotation angle. Similarly, we can also calculate the eye rotation angle synchronously when applying the force of a single or multiple muscles. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a schematic diagram of the front structure of the biomechanical testing equipment;

[0059] Figure 2 It is a schematic diagram of the back structure of the biomechanical testing equipment;

[0060] Figure 3 It is a structural schematic diagram of the eyeball support and the fixed bracket;

[0061] In the figure: 1-eyeball support; 2-fixed bracket; 3-traction motor; 4-traction rope; 5-angular velocity sensor. DETAILED DESCRIPTION

[0062] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0063] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0064] Example 1

[0065] A biomechanical testing device for the coordinated movement of multiple extraocular muscles, such as Figure 1-3 As shown, it includes an eyeball support 1, a fixing bracket 2, a pulling motor 3, an angular velocity sensor 5 and a force sensor;

[0066] The eyeball holder 1 is used to place the eyeball, and the eyeball holder 1 rotates with the eyeball;

[0067] The fixed bracket 2 is movably connected to the eyeball support 1;

[0068] The pulling motor 3 is connected to the extraocular muscle of the eyeball via a pulling rope 4;

[0069] The angular velocity sensor 5 is arranged on the eyeball support 1 and is used to measure the rotation angle of the eyeball;

[0070] The force sensor is arranged on the pulling rope 4 and is used to measure the force applied by the extraocular muscles.

[0071] More specifically, in this embodiment:

[0072] like Figure 1-3As shown, the biomechanical testing equipment mainly includes an eyeball support 1 for placing an eyeball, a fixed bracket 2 movably connected to the eyeball support 1, a traction motor 3 for pulling the extraocular muscles, an angular velocity sensor 5 for measuring the rotation angle of the eyeball (eyeball support 1) and a force sensor for measuring the force applied by the extraocular muscles (traction motor 3), and also includes a control module electrically connected to the traction motor 3, the angular velocity sensor 5 and the force sensor respectively.

[0073] The eyeball support 1 is a 3D printed structure. After the overall model of the eyeball is obtained by CT scanning, a structure matching the eyeball wall of the eyeball is obtained by 3D printing. The eyeball support 1 is a semicircular or inferior arc-shaped structure as a whole. The eyeball support is bonded to the eyeball through commercial cyanoacrylate glue from the back of the eyeball and rotates with the eyeball; the inner side of the eyeball support 1 is a rough surface, and the inner side is partially spherical or partially ellipsoidal, which can match the eyeball wall well. The outer side of the eyeball support 1 is hemispherical or partially spherical, which is convenient for it to be connected with the fixed bracket 2, and at the same time ensures that the rotation angle measured by the angular velocity sensor 5 located on the eyeball support 1 is accurate. According to the size of the normal eyeball, the outer diameter of the eyeball support 1 can be set to 15mm, and the wall thickness can be set to 2-4mm. An opening is opened in the center of the eyeball support 1, which can be used to pass the nerve, and the angular velocity sensor 5 can also be installed.

[0074] The fixed bracket 2 is movably connected to the eyeball support 1 at the center, and the eyeball support 1 can be rotated arbitrarily but not translated. The fixed bracket 2 is made of high-strength metal, such as stainless steel that meets medical conditions or high-strength alloys used in general, and a metal bayonet is also provided on its side for the extraocular muscles on the eyeball to pass through and limit and guide the extraocular muscles. The metal bayonet is respectively located at the upper, lower, left, right, upper right and lower right positions of the fixed bracket 2, corresponding to passing through the superior rectus muscle, inferior rectus muscle, lateral rectus muscle, medial rectus muscle, superior oblique muscle and inferior oblique muscle, respectively, to better simulate the relationship between the eyeball and the eye socket, and to avoid contact between the extraocular muscles and the eyeball support 1.

[0075] The pulling motor 3 is a stepper motor or a servo motor, and its output end is connected to the extraocular muscles through a pulling rope 4 (such as a connecting piece with a certain strength such as a steel wire or a steel cable to avoid damage to the eyeball and the extraocular muscles due to breakage during the pulling process), and then the extraocular muscles are driven to pull the eyeball through the output of the pulling motor 3. There are 6 pulling motors 3, each of which is independently connected to 6 extraocular muscles (superior rectus, inferior rectus, lateral rectus, medial rectus, superior oblique, and inferior oblique) through a pulling rope 4, so as to ensure independent control of a single extraocular muscle and avoid mutual interference, so as to control the rotation of the eyeball with high precision.

[0076] The angular velocity sensor 5 uses a three-axis gyroscope to obtain the specific data of the rotational movement of the eyeball (eyeball holder 1) in real time. The angular velocity sensor 5 is installed on the eyeball holder 1. Since the eyeball holder 1 follows the movement of the eyeball, the real-time movement data of the eyeball holder 1 can be further obtained by measuring the real-time movement data of the eyeball holder 1.

[0077] The force sensor adopts a micro force sensor, which is connected to the pulling rope 4 and can obtain the output pulling force of the pulling motor 3 in real time, which is equivalent to obtaining the pulling force of the corresponding extraocular muscle on the eyeball in real time.

[0078] The control module adopts a PLC control module, which is equipped with a PID feedback control system to accurately control the high-precision rotation of the eyeball based on the measurement data collected in real time. The PID feedback control system preferably adopts adaptive PID control to dynamically adjust and optimize PID parameters according to the measurement data fed back in real time, so as to improve the control accuracy and response speed while ensuring the normal operation of the special environment of eye movement control. The control module also provides overload protection (with an upper limit of pulling force) for the biomechanical testing equipment to avoid the situation where the pulling rope 4 is broken due to excessive tension, thereby protecting the safety of the eyeball and the extraocular muscles.

[0079] Example 2

[0080] A testing method for a biomechanical testing device for coordinated movement of extraocular muscles as described in Example 1 above, in order to express the balance of the pulling force of the six extraocular muscles of the eyeball in the x, y, and z directions under the joint action with a mathematical relationship, and the pulling force of each extraocular muscle acts on the eyeball through a common rotation angle θ, we can decompose the pulling force of each extraocular muscle and establish a force balance equation of the eyeball to obtain the force applied by each extraocular muscle based on the rotation angle of the eyeball:

[0081]

[0082] In the above formula, F i is the force exerted by the i-th extraocular muscle, θ m is the component of the eyeball rotation angle in the m direction;

[0083] i: MR is the medial rectus muscle, LR is the lateral rectus muscle, SR is the superior rectus muscle, IR is the inferior rectus muscle, SO is the superior oblique muscle, and IO is the inferior oblique muscle;

[0084] m: x is the component in the x-axis direction, y is the component in the y-axis direction, and z is the component in the z-axis direction;

[0085] The length change of the extraocular muscle is obtained based on the force applied by the extraocular muscle and the elastic stiffness coefficient of the extraocular muscle. The relationship between the force applied by the extraocular muscle and the change in the length of the extraocular muscle is:

[0086] Fi =k i ΔL i ;

[0087] In the above formula, k i is the elastic stiffness coefficient of the i-th extraocular muscle, ΔL i is the length change of the i-th extraocular muscle.

[0088] More specifically, in this embodiment:

[0089] The rotation of the eyeball is the result of the coordinated action of six extraocular muscles (i.e., four rectus muscles and two oblique muscles), including the superior rectus, inferior rectus, medial rectus, lateral rectus, superior oblique and inferior oblique muscles, which are responsible for the movement of the eyeball in different directions.

[0090] The eye rotation angle is closely related to the coordinated action of these six muscles:

[0091] 1) Superior rectus (SR): Its main function is to rotate the eyeball upward.

[0092] 2) Inferior rectus (IR): Its main function is to rotate the eyeball downward.

[0093] 3) Medial Rectus (MR): Its main function is to rotate the eyeball inward (toward the nose).

[0094] 4) Lateral Rectus (LR): Its main function is to rotate the eyeball outward (temporally).

[0095] 5) Superior oblique (SO): The main function is to rotate the eyeball inward and downward, and the secondary function includes abduction of the eyeball.

[0096] 6) Inferior Oblique (IO): The main function is to rotate the eyeball outward and upward, and the secondary function includes abduction of the eyeball.

[0097] The rotation of the eyeball in any direction involves the coordinated work of at least two extraocular muscles. The relationship between the specific rotation direction and muscle action is as follows:

[0098] 1) Look up: The superior rectus and inferior oblique muscles contract simultaneously, causing the eyeball to rotate upward.

[0099] 2) Look down: The inferior rectus and superior oblique muscles contract simultaneously, causing the eyeball to rotate downward.

[0100] 3) Look outward: The lateral rectus muscle of the left eye and the medial rectus muscle of the right eye contract at the same time, causing the left eye to rotate to the left and the right eye to rotate to the right.

[0101] 4) Look inward: The lateral rectus muscle of the right eye and the medial rectus muscle of the left eye contract at the same time, causing the right eye to rotate to the right and the left eye to rotate to the left.

[0102] 5) Look to the outside and above: The superior rectus and inferior oblique muscles of the left eye, as well as the superior rectus and inferior oblique muscles of the right eye, contract in a coordinated manner to rotate the eyeball to the upper left.

[0103] 6) Look inward and upward: The superior rectus and inferior oblique muscles of the right eye, as well as the superior rectus and inferior oblique muscles of the left eye, contract in a coordinated manner, causing the eyeball to rotate to the upper right.

[0104] The same applies to other directions.

[0105] The force of each extraocular muscle contraction is proportional to its contribution to the eye movement; therefore, the angle of eye rotation depends on the force and precise coordination of these extraocular muscles.

[0106] The magnitude and direction of the force of the extraocular muscles will change according to the angle of rotation. When the rotation angle in a certain direction increases, the extraocular muscles involved in movement in that direction need to generate greater force.

[0107] For example, as the angle of upward gaze increases, the superior rectus and inferior oblique muscles must increase their contraction force to overcome gravity and the eye's own elastic resistance.

[0108] The rotation of the eyeball can be calculated using a mechanical model that takes into account the origin, attachment point, direction and magnitude of the force of each extraocular muscle. These calculations usually involve vector force analysis and three-dimensional geometry to accurately describe the movement of the eyeball.

[0109] In short, the rotation angle of the eyeball is determined by the combined force of the six extraocular muscles. The specific rotation angle is proportional to the force exerted by each muscle, and is also closely related to the degree of coordination between these muscles.

[0110] Based on the above background, the specific mathematical calculation model of muscle force and eye rotation angle is as follows:

[0111] 1. Parameter definition:

[0112] F SR : The tension of the superior rectus (SR) muscle.

[0113] F IR : The tension of the inferior rectus (IR).

[0114] F MR :The tension of the medial rectus muscle (MR).

[0115] F LR: The tension of the lateral rectus (LR).

[0116] F SO : The tension of the superior oblique muscle (SO).

[0117] F IO : The tension of the inferior oblique (IO).

[0118] θ x : The component of the eyeball rotation angle in the x-axis direction (horizontal rotation angle).

[0119] θ y : The component of the eyeball rotation angle in the y-axis direction (vertical rotation angle).

[0120] θ z : The component of the eyeball rotation angle in the z-axis direction (the rotation angle around the front-back axis).

[0121] The pulling force of each extraocular muscle can be decomposed in the x, y, and z directions and expressed by equilibrium conditions.

[0122] 2. The basic relationship between muscle strength and length change:

[0123] L i : The length of the i-th extraocular muscle, i = SR, IR, MR, LR, SO, IO, representing the superior rectus, inferior rectus, medial rectus, lateral rectus, superior oblique and inferior oblique muscles respectively.

[0124] ΔL i : The length change of the ith extraocular muscle, that is, the length difference before and after stretching.

[0125] F i : The force generated by the ith extraocular muscle during stretching.

[0126] k i : The stiffness coefficient (or elastic coefficient, also called elastic stiffness coefficient) of the ith extraocular muscle reflects the elastic properties of the extraocular muscle and represents the force generated by a change in unit length.

[0127] ΔL max : Maximum length change, indicating the maximum stretch of the extraocular muscle when stretched.

[0128] When each extraocular muscle is stretched using the pulling motor 3, its stretched length L can be measured. i , and calculate the length change ΔL i By recording the tension F generated by each extraocular muscle at different stretch lengths i , and obtain a series of (ΔLi ,F i ) data points.

[0129] Experimental steps:

[0130] 1) Fixed initial length: First, measure the initial length L of each extraocular muscle 0i .

[0131] 2) Gradual stretching: Use the traction motor 3 to gradually stretch each extraocular muscle and record the length L of the extraocular muscle after stretching. i .

[0132] 3) Force measurement: Use a force sensor to measure the tension F generated by each extraocular muscle at different stretch lengths i .

[0133] 4) Record data: Change the length of each extraocular muscle by ΔL i =L i -L 0i and the corresponding tension F i Write it down.

[0134] For each muscle, the relationship between length change and force can be approximated by Hooke's Law, assuming that the muscle is linearly elastic within the stretch range:

[0135] F i =k i ΔL i ;

[0136] in:

[0137] F i is the force produced by the ith extraocular muscle when stretched.

[0138] k i is the elastic stiffness coefficient of the ith extraocular muscle, expressed in Newton / meter (N / m).

[0139] ΔL i =L i -L 0i is the change in length of the ith extraocular muscle, where L 0i is the initial length of the ith extraocular muscle.

[0140] The data obtained from the experiment (ΔL i ,F i ) Linear regression or other data fitting methods can be used to fit the relationship between the length change and tension of the extraocular muscles. We can perform linear fitting on the experimental data to obtain the stiffness coefficient k of each extraocular muscle. iBased on the force-length relationship of each extraocular muscle, we further analyzed the effects of these relationships on eye movements at different angles of rotation.

[0141] 3. Force decomposition:

[0142] Assume that the tension of all six extraocular muscles can be decomposed into components in the x, y, and z directions according to the angle. Since the six extraocular muscles are associated with the rotation angle θ of the eyeball, we use sine and cosine functions to represent the components of these tensions.

[0143] 1) Superior rectus (SR):

[0144] The main effect is upward, so the pulling force acts mainly in the y direction.

[0145] F SR,x =0;

[0146] F SR,y =F SR cos(θ y );

[0147] F SR,z =F SR sin(θ z ).

[0148] 2) Inferior rectus muscle (IR):

[0149] The main effect is downward, so the pulling force acts mainly in the y direction.

[0150] F IR,x =0;

[0151] F IR,y =-F IR cos(θ y );

[0152] F IR,z =F IR sin(θ z ).

[0153] 3) Medial rectus muscle (MR):

[0154] The main effect is inwards, so the tension acts mainly in the x-direction.

[0155] F MR,x =-F MR cos(θ x );

[0156] F MR,y =0;

[0157] F MR,z =F MR sin(θz ).

[0158] 4) Lateral rectus muscle (LR):

[0159] The main effect is outward, so the tension acts mainly in the x-direction.

[0160] F LR,x =F LR cos(θ x );

[0161] F LR,y =0;

[0162] F LR,z =F LR sin(θ z ).

[0163] 5) Superior oblique (SO):

[0164] The main effect is internal rotation and downward, so its pulling force has y and z directions.

[0165] F SO,x =-F SO sin(θ x );

[0166] F SO,y =-F SO cos(θ y );

[0167] F SO,z =-F SO cos(θ z ).

[0168] 6) Inferior oblique (IO):

[0169] The main effect is outward rotation and upward, so its pulling force has y and z directions.

[0170] F IO,x =F IO sin(θ x );

[0171] F IO,y =F IO cos(θ y );

[0172] F IO,z =F IO cos(θ z ).

[0173] 4. Equation of force balance condition:

[0174] In order for the eyeball to maintain balance in three-dimensional space, the following three balance conditions must be met. Balance in the x direction:

[0175] F MR,x +F LR,x +F SO,x +F IO,x =0;

[0176] Substituting the tension components of each extraocular muscle, we get:

[0177] -F MR cos(θ x )+F LR cos(θ x )-F SO cos(θ x )+F IO cos(θ x )=0;

[0178] Balance in the y direction:

[0179] F SR,y +F IR,y +F SO,y +F IO,y =0;

[0180] Substituting the tension components of each extraocular muscle, we get:

[0181] F SR cos(θ y )-F IR cos(θ y )-F SO cos(θ y )+F IO cos(θ y )=0;

[0182] Balance in z direction:

[0183] F SR,z +F IR,y +F MR,z +F LR,z +F SO,z +F IO,z =0;

[0184] Substituting the tension components of each extraocular muscle, we get:

[0185] F SR sin(θ z )+F IR sin(θ z )+F MR sin(θ z )+F LRsin(θ z )-F SO cos(θ z )+F IO cos(θ z )=0;

[0186] The pulling force of the six extraocular muscles of the eyeball is exerted through the rotation angle θ x ,θ y ,θ z By decomposing these forces in each direction, we obtain three equilibrium equations, which indicate that the sum of the tensile force components in the x, y, and z directions is zero, thus maintaining the static balance of the eyeball.

[0187] When the biomechanical testing device specifically controls the eyeball:

[0188] 1. First, the biomechanical testing device is connected to the eyeball, including placing the eyeball in the eyeball holder 1, passing the six extraocular muscles through the bayonet, connecting the traction motor 3 to the six extraocular muscles, etc.

[0189] 2. Set the target angle

[0190] Assume that the following target angles are to be achieved:

[0191] Horizontal rotation angle: θ x,target ;

[0192] Vertical rotation angle: θ y,target ;

[0193] Internal rotation / external rotation angle: θ z,target .

[0194] 3. Solve for the force of each extraocular muscle

[0195] Since the equations are a system of linear equations, the force of each extraocular muscle can be obtained by solving them simultaneously.

[0196] 4. Example Application

[0197] Assume that a specific target angle value θ is determined x,target ,θ y,target ,θ z,target Then we can substitute and solve the equations to get the force values ​​of all six extraocular muscles. Combined with the relationship between the force of the extraocular muscles and the change in the length of the extraocular muscles, we can quantitatively change the muscle force of the extraocular muscles by quantitatively changing the length of the extraocular muscles, so that strabismus can be corrected.

[0198] In summary, this embodiment can calculate the force applied by each extraocular muscle based on the specified target eye rotation angle through the force balance equation, and then obtain the extraocular muscle length change value based on the relationship between the extraocular muscle force and the extraocular muscle length change, so that the length of the extraocular muscle can be quantitatively changed through surgery to obtain the required extraocular muscle force, so that strabismus can be corrected.

[0199] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A biomechanical testing device for the coordinated movement of multiple extraocular muscles. It is characterized in that It includes an eyeball support, a fixing bracket, a pulling motor, an angular velocity sensor and a force sensor; The eyeball support is used to place the eyeball, and the eyeball support rotates with the eyeball; The fixed bracket is movably connected to the eyeball support; The pulling motor is connected to the extraocular muscle of the eyeball via a pulling rope; The angular velocity sensor is arranged on the eyeball support and is used to measure the rotation angle of the eyeball; The force sensor is arranged on the pulling rope and is used to measure the force applied by the extraocular muscles.

2. A biomechanical testing device for coordinated movement of extraocular muscles according to claim 1, It is characterized in that The eyeball support is connected to the eyeball wall of the eyeball through biocompatible glue or mechanical clamps. The eyeball support is a semicircle or inferior arc manufactured by 3D printing; the inner side of the eyeball support cooperates with the shape of the eyeball.

3. A biomechanical testing device for coordinated movement of extraocular muscles according to claim 1, It is characterized in that The fixing bracket is provided with a bayonet, and the bayonet is used to pass through the extraocular muscles and limit the extraocular muscles.

4. A biomechanical testing device for coordinated movement of extraocular muscles according to claim 3, It is characterized in that The bayonet is respectively arranged on the upper side, lower side, left side, right side, upper right side and lower right side of the fixing bracket, and is used to pass through the superior rectus muscle, inferior rectus muscle, medial rectus muscle, lateral rectus muscle, superior oblique muscle and inferior oblique muscle respectively.

5. The biomechanical testing device for the coordinated movement of extraocular muscles according to claim 1, It is characterized in that The stretching motors are provided with 6 in number, which are used for stretching the superior rectus muscle, the inferior rectus muscle, the medial rectus muscle, the lateral rectus muscle, the superior oblique muscle and the inferior oblique muscle respectively.

6. A biomechanical testing device for coordinated movement of extraocular muscles according to claim 1, It is characterized in that The pulling motor is a servo motor or a stepping motor.

7. The biomechanical testing device for the coordinated movement of extraocular muscles according to claim 1, It is characterized in that The pulling rope is a steel cable or a steel wire.

8. The biomechanical testing device for the coordinated movement of extraocular muscles according to claim 1, It is characterized in that The angular velocity sensor includes a gyroscope, and the force sensor includes a micro force sensor.

9. A testing method for the biomechanical testing device for the coordinated movement of extraocular muscles according to any one of claims 1 to 8, It is characterized in that Based on the rotation angle of the eyeball, the force exerted by each extraocular muscle is obtained, and the force balance equation of the eyeball is: In the above formula, F i is the force exerted by the i-th extraocular muscle, θ m is the component of the eyeball rotation angle in the m direction; i: MR is the medial rectus muscle, LR is the lateral rectus muscle, SR is the superior rectus muscle, IR is the inferior rectus muscle, SO is the superior oblique muscle, and IO is the inferior oblique muscle; m: x is the component in the x-axis direction, y is the component in the y-axis direction, and z is the component in the z-axis direction; The length change of the extraocular muscle is obtained based on the force applied by the extraocular muscle and the elastic stiffness coefficient of the extraocular muscle. The relationship between the force applied by the extraocular muscle and the change in the length of the extraocular muscle is: F i =k i ·ΔL i ; In the above formula, k i is the elastic stiffness coefficient of the i-th extraocular muscle, ΔL i is the length change of the i-th extraocular muscle.

10. The testing method of the biomechanical testing device for the coordinated movement of extraocular muscles according to claim 9, It is characterized in that Get several groups (ΔL i ,F i ) data, and the elastic stiffness coefficient of the extraocular muscles was obtained by data fitting.

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