Cataract capsulorhexis simulation method and system

Abstract

The present invention provides a cataract capsulorhexis simulation method and system, the method comprising: constructing a capsule membrane model to be torn including an inner capsule membrane and an outer capsule membrane, the inner capsule membrane being connected to the outer capsule membrane through a first constraint point; setting an initial crack on the inner capsule membrane, when a tweezers model clamps and pulls the inner capsule membrane, obtaining the current crack point, and judging whether the current crack point will produce a centripetal fracture; if so, determining the centripetal fracture direction vector of the current crack point based on the clamping movement direction and the current annular fracture direction, and then obtaining the current centripetal fracture distance and the actual crack point; obtaining the crack point to be fractured, determining the predicted crack point based on the current centripetal fracture distance and the centripetal fracture direction vector, and forming a capsulorhexis path through the actual crack point and the predicted crack point. The simulation is realized by using the external parameters of the tweezers model relative to the capsule membrane model to be torn, which saves computing power, avoids many uncertain factors in the physical simulation method, provides a more realistic simulation effect, and improves the teaching accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of simulation teaching, and in particular to a cataract capsulorhexis simulation method and system. Background Art

[0002] Virtual surgery products based on technologies such as virtual reality (VR), augmented reality (AR), and mixed reality (MR) are now increasingly being used in the field of intelligent medical engineering. Phacoemulsification cataract surgery is widely used in basic ophthalmic surgery teaching due to its high incidence and simple operation. Among them, the anterior capsule tear is a key operation of the operation. How to realistically simulate the tearing process in virtual products has become an important indicator for evaluating such teaching products.

[0003] For cataract capsulotomy, the operator needs to tear the capsule into a circle with a diameter of about 5mm. This requires that the path of the capsule tearing, that is, the path of crack extension, should be as smooth as possible, avoiding corners or sudden changes in curvature, so as to prevent the capsule from rupturing at the stress concentration point. During the capsulotomy process, the stress outside the capsule is transmitted within the capsule material. When the stress flow is concentrated in one place, the local stress exceeds the fracture limit of the capsule material, resulting in crack extension.

[0004] The simulation of this process usually involves material mechanics modeling of the capsule membrane and monitoring the stress value at each location in the model in the program. When it is detected that the stress value at a certain location exceeds the threshold, the crack propagation mode when the capsule membrane is torn is simulated according to the stress model. However, this physical simulation method, firstly, requires a large amount of computing resources to achieve the real laws of the capsule membrane at the physical level. Secondly, due to the large number of uncertain factors at the physical level, the simulation effect will deviate from the actual effect, affecting the teaching effect. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a cataract capsulorhexis simulation method and system, aiming to solve the technical problem that the physical simulation method of the prior art simulates the crack propagation mode when the capsule is torn according to the stress mode, which occupies a high amount of computing resources and has many uncertain factors that lead to deviations between the simulation effect and the actual effect, thus affecting the teaching effect.

[0006] In order to achieve the above objectives, in a first aspect, an embodiment of the present application provides a cataract capsulorhexis simulation method, comprising the following steps:

[0007] Constructing a capsule membrane model to be torn, the capsule membrane model to be torn comprising an inner capsule membrane and an outer capsule membrane arranged from outside to inside, a plurality of first constraint points evenly distributed at intervals are arranged around the inner capsule membrane, and the inner capsule membrane is connected to the outer capsule membrane through the first constraint points;

[0008] An initial crack is set at the outer edge of the internal capsule membrane, and two first constraint points corresponding to opposite ends of the initial crack are selected as a first initial crack point and a second initial crack point. When the tweezers model clamps and pulls the internal capsule membrane, a current crack point is obtained, and it is determined whether the current crack point will produce a centripetal fracture;

[0009] If the current crack point will produce a centripetal fracture, determining the centripetal fracture direction vector of the current crack point based on the clamping movement direction of the tweezers model and the current annular fracture direction of the initial crack;

[0010] Acquire a first connecting line between the current crack point and the center of the inner capsule membrane, determine a current centripetal fracture distance corresponding to the current crack point based on the centripetal fracture direction vector, and select an actual crack point on the first connecting line;

[0011] The to-be-broken grain point is obtained, and a second connecting line between the to-be-broken grain point and the center of the circle of the internal capsule membrane is obtained, and a predicted centripetal fracture distance corresponding to the to-be-broken grain point is determined based on the current centripetal fracture distance and the centripetal fracture direction vector, so as to select a predicted crack point on the second connecting line, and a capsulorhexis path is formed through the actual crack point and the predicted crack point to complete the capsulorhexis simulation.

[0012] Compared with the prior art, the beneficial effect of the present invention lies in: by constructing the capsule model to be torn and setting the first constraint point for the internal capsule membrane, during the clamping process of the tweezers model, the circumferential tearing simulation of the initial crack is completed by disconnecting the corresponding first constraint point, and then in the process of circumferential tearing, by detecting the external parameters such as the position, speed, and direction of the tweezers model relative to the capsule model to be torn, it is determined whether centripetal tearing occurs based on the external parameters, and the direction distance of the centripetal tear is obtained to complete the determination of the capsule tearing path. Through this simulation method, simulation of cataract capsule tearing surgery can be achieved, and it only needs to obtain the external parameters associated with the tweezers model, which effectively saves computing power. At the same time, it avoids many uncertain factors in the physical simulation method of monitoring stress, provides a more realistic simulation effect, and improves the accuracy of teaching.

[0013] Furthermore, the step of constructing the capsule model to be torn includes:

[0014] Combining a plurality of triangular facets into a first initial capsule membrane model, and setting a triangular quadratic spring force field for the first initial capsule membrane model to form a second initial capsule membrane model;

[0015] Adding a collision model between adjacent triangular facets in the second initial capsule membrane model, wherein the contact stiffness between the collision model and the triangular facets is 1000, to form a third initial capsule membrane model;

[0016] Adding a plane force field to the upper and lower ends of the third initial capsule model to restrict the up and down floating of the third initial capsule model, and forming a fourth initial capsule model;

[0017] A lens model is arranged at the bottom of the fourth initial capsule model, and the contact stiffness between the lens model and the fourth initial capsule model is 50000 to form a capsule model to be torn.

[0018] Furthermore, the step of obtaining the current crack point and determining whether the current crack point will produce centripetal fracture includes:

[0019] Selecting an extension point from the first initial crack point and the second initial crack point, and obtaining an initial distance between an initial clamping point of the tweezers model and the extension point;

[0020] During the clamping movement of the tweezers model, the disconnection number of the first constraint point is obtained, and the determination distance is obtained according to the initial distance and the disconnection number of the first constraint point;

[0021] The first disconnected constraint point that is farthest from the extension point is selected as the current crack point, and the real-time distance between the current clamping point of the tweezers model and the current crack point is obtained. Based on the real-time distance and the judgment distance, it is determined whether the current crack point will produce centripetal fracture.

[0022] Furthermore, the step of selecting an extension point from the first initial crack point and the second initial crack point comprises:

[0023] Obtaining a first direction extending from the first initial crack point to the second initial crack point and a second direction extending from the second initial crack point to the first initial crack point, and obtaining a line between the first initial crack point and the second initial crack point;

[0024] Obtaining a projection direction of the clamping movement direction of the tweezers model on the connecting line, and determining whether the projection direction is the first direction or the second direction;

[0025] If the projection direction is the first direction, the first initial crack point is selected as the extension point, and if the projection direction is the second direction, the second initial crack point is selected as the extension point.

[0026] Furthermore, the calculation formula for determining the distance is:

[0027] ,

[0028] in, Indicates the judgment distance, represents the initial distance, Indicates the number of disconnections of the first constraint point when the tweezers model is gripping and moving. represents the distance between two adjacent first constraint points, represents a constant factor.

[0029] Furthermore, the step of determining the centripetal fracture direction vector of the current crack point based on the clamping movement direction of the tweezers model and the current annular fracture direction of the initial crack includes:

[0030] Acquire a clamping distance based on an initial clamping point and a current clamping point of the tweezers model, and select a mapping value corresponding to the clamping distance within a mapping range;

[0031] Determine a first weight by the mapping value and the radius of the internal capsule membrane, determine a second weight by the clamping movement direction and the current annular fracture direction, and obtain a total weight according to the first weight and the second weight;

[0032] The centripetal fracture direction vector is determined by the clamping movement vector corresponding to the clamping movement direction, the annular fracture vector corresponding to the current annular fracture direction, and the total weight.

[0033] Furthermore, the mapping range is 0.5-1, and the step of selecting a mapping value corresponding to the clamping distance within the mapping range includes:

[0034] When the clamping distance is 0, the clamping distance is mapped to 0.5;

[0035] When the clamping distance is greater than 1.5 times the radius of the internal capsule membrane, mapping the clamping distance to 1;

[0036] Performing a first data segmentation at a preset interval between 0 and 1.5 times the radius of the inner capsule membrane to obtain a plurality of first value points, and performing a second data segmentation at the preset interval between 0.5 and 1 to obtain a plurality of second value points corresponding to the plurality of first value points one by one;

[0037] When the clipping distance is a first value point, the clipping distance is mapped to a second value point corresponding to the first value point.

[0038] Furthermore, the calculation formula of the first weight is:

[0039] ,

[0040] in, represents the first weight, represents the radius of the internal capsule membrane, represents the mapping value corresponding to the clamping distance;

[0041] The calculation formula of the second weight is:

[0042] ,

[0043] in, represents the second weight, Indicates the angle between the clamping movement direction and the current annular fracture direction;

[0044] The calculation formula of the total weight is:

[0045] ,

[0046] in, represents the total weight, Indicates preset weight;

[0047] The calculation formula of the centripetal fracture direction vector is:

[0048] ,

[0049] in, represents the centripetal fracture direction vector, represents the clamping motion vector, represents the ring break vector.

[0050] Furthermore, the calculation formula for the predicted centripetal fracture distance is:

[0051] ,

[0052] in, represents the predicted centripetal fracture distance, represents a fixed step size, represents the centripetal fracture direction vector, represents the direction vector corresponding to the second connecting line, Indicates the current centripetal fracture distance, represents the cosine function, Represents the upper and lower limit function, whose limit values ​​are [-0.00035, 0.00035].

[0053] In a second aspect, an embodiment of the present application provides a cataract capsulorhexis simulation system, which is applied to the cataract capsulorhexis simulation method as described in the first aspect above, and the system comprises:

[0054] A construction module is used to construct a capsule membrane model to be torn, wherein the capsule membrane model to be torn includes an inner capsule membrane and an outer capsule membrane arranged from the outside to the inside, a plurality of first constraint points evenly distributed at intervals are arranged around the inner capsule membrane, and the inner capsule membrane is connected to the outer capsule membrane through the first constraint points;

[0055] An analysis module, configured to set an initial crack on the outer edge of the internal capsule membrane, select two first constraint points corresponding to opposite ends of the initial crack as a first initial crack point and a second initial crack point, obtain a current crack point when the tweezers model clamps and pulls the internal capsule membrane, and determine whether the current crack point will produce a centripetal fracture;

[0056] A judgment module, for determining the centripetal fracture direction vector of the current crack point based on the clamping movement direction of the tweezers model and the current annular fracture direction of the initial crack if the current crack point will produce a centripetal fracture;

[0057] A selection module, configured to obtain a first connection line between the current crack point and the center of the inner capsule membrane, determine a current centripetal fracture distance corresponding to the current crack point based on the centripetal fracture direction vector, and select an actual crack point on the first connection line;

[0058] An execution module is used to obtain a line point to be broken, and obtain a second connecting line between the line point to be broken and the center of the circle of the internal capsule membrane, determine a predicted centripetal fracture distance corresponding to the line point to be broken based on the current centripetal fracture distance and the centripetal fracture direction vector, select a predicted crack point on the second connecting line, form a capsulorhexis path through the actual crack point and the predicted crack point, and complete the capsulorhexis simulation.

[0059] In a third aspect, an embodiment of the present application provides a computer, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the cataract capsulorhexis simulation method as described in the first aspect above is implemented.

[0060] In a fourth aspect, an embodiment of the present application provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the cataract capsulorhexis simulation method as described in the first aspect above. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a flow chart of the cataract capsulorhexis simulation method in the first embodiment of the present invention;

[0062] Figure 2 It is a structural block diagram of a cataract capsulorhexis simulation system in a second embodiment of the present invention;

[0063] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0064] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0065] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0066] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0067] See also Figure 1 The cataract capsulorhexis simulation method provided by the first embodiment of the present invention comprises the following steps:

[0068] S10: constructing a capsule membrane model to be torn, wherein the capsule membrane model to be torn includes an inner capsule membrane and an outer capsule membrane arranged from outside to inside, and a plurality of first constraint points evenly distributed at intervals are arranged around the inner capsule membrane, and the inner capsule membrane is connected to the outer capsule membrane through the first constraint points;

[0069] In this embodiment, 200 first constraint points are evenly distributed around the inner capsule membrane and are numbered from 1 to 200.

[0070] Specifically, the step S10 includes:

[0071] S110: combining a plurality of triangular facets into a first initial capsule membrane model, and setting a triangular quadratic spring force field for the first initial capsule membrane model to form a second initial capsule membrane model;

[0072] The triangular secondary spring force field is a force field that characterizes the mechanical model. It calculates the stress and strain in each triangular facet, and then calculates the mutual influence between different triangular facets through the finite element method, thereby making the obtained second initial capsule membrane model more simulated.

[0073] S120: adding a collision model between adjacent triangular facets in the second initial capsule model, wherein the contact stiffness between the collision model and the triangular facets is 1000, so as to form a third initial capsule model;

[0074] S130: adding a plane force field to the upper end and the lower end of the third initial capsule model to restrict the up and down floating of the third initial capsule model, and forming a fourth initial capsule model;

[0075] S140: setting a lens model at the bottom of the fourth initial capsule model, wherein the contact stiffness between the lens model and the fourth initial capsule model is 50000, so as to form a capsule model to be torn;

[0076] By setting the lens model, the viscosity of the triangular facet can be increased, and when the capsulotomy simulation is performed later, it can be ensured that the clamping of the tweezers model and the extension of the initial crack are in line with the actual situation.

[0077] S20: setting an initial crack at the outer edge of the internal capsule membrane, selecting two first constraint points corresponding to opposite ends of the initial crack as a first initial crack point and a second initial crack point, and obtaining a current crack point when the tweezers model clamps and pulls the internal capsule membrane, and determining whether the current crack point will produce a centripetal fracture;

[0078] By disconnecting the two first constraint points and the first constraint point between the two, part of the inner capsule membrane is separated from the outer capsule membrane, thereby forming the initial crack. It can be understood that when the two first constraint points corresponding to the two opposite ends of the initial crack are numbered 1 and 2, the first constraint point numbered 1 is the first initial crack point, and the first constraint point numbered 2 is the second initial crack point. When the two first constraint points corresponding to the two opposite ends of the initial crack are numbered 5 and 10, the first constraint point numbered 5 is the first initial crack point, and the first constraint point numbered 10 is the second initial crack point. At the same time, the first constraint points numbered 6, 7, 8, and 9 are all disconnected.

[0079] The step S20 comprises:

[0080] S210: selecting an extension point from the first initial crack point and the second initial crack point, and obtaining an initial distance between an initial clamping point of the tweezers model and the extension point;

[0081] Obtain a first direction extending from the first initial crack point to the second initial crack point and a second direction extending from the second initial crack point to the first initial crack point, and obtain a connecting line between the first initial crack point and the second initial crack point; obtain a projection direction of the clamping movement direction of the tweezers model on the connecting line, and determine whether the projection direction is the first direction or the second direction; if the projection direction is the first direction, select the first initial crack point as an extension point, and if the projection direction is the second direction, select the second initial crack point as an extension point.

[0082] S220: during the clamping movement of the tweezers model, obtaining the number of disconnections of the first constraint point, and obtaining a determination distance according to the initial distance and the number of disconnections of the first constraint point;

[0083] It can be understood that during the clamping and pulling process of the tweezers model, the internal capsule membrane judges whether the next first constraint point adjacent to the extension point will be disconnected based on the set triangular secondary spring force field, the collision model, the plane force field and the lens model, and continues to make this judgment for each first constraint point that is about to be disconnected during the clamping movement.

[0084] The calculation formula of the determination distance is:

[0085] ,

[0086] in, Indicates the judgment distance, represents the initial distance, Indicates the number of disconnections of the first constraint point when the tweezers model is gripping and moving. represents the distance between two adjacent first constraint points, represents a constant factor.

[0087] S230: selecting the first disconnected constraint point farthest from the extension point as the current crack point, acquiring the real-time distance between the current clamping point of the tweezers model and the current crack point, and determining whether the current crack point will produce a centripetal fracture based on the real-time distance and the determination distance;

[0088] Specifically, determine whether the real-time distance is greater than 1.1 times the judgment distance. If the real-time distance is greater than 1.1 times the judgment distance, determine that the first constraint point that is currently disconnected is the current crack point. It should be noted that the centripetal fracture refers to the extension from the current crack point toward the center of the circle of the internal capsule membrane.

[0089] S30: If the current crack point will produce a centripetal fracture, determining a centripetal fracture direction vector of the current crack point based on the clamping movement direction of the tweezers model and the current annular fracture direction of the initial crack;

[0090] The current annular fracture direction refers to the direction in which the initial crack breaks along the outer ring of the inner capsule membrane, that is, the line between the next first constraint point adjacent to the current crack point.

[0091] The step S30 comprises:

[0092] S310: acquiring a clamping distance based on an initial clamping point and a current clamping point of the tweezers model, and selecting a mapping value corresponding to the clamping distance within a mapping range;

[0093] The mapping range is 0.5~1. When the clamping distance is 0, the clamping distance is mapped to 0.5; when the clamping distance is greater than 1.5 times the radius of the internal capsule membrane, the clamping distance is mapped to 1; a first data segmentation is performed at a preset interval between 0 and 1.5 times the radius of the internal capsule membrane to obtain a plurality of first numerical points, and a second data segmentation is performed at the preset interval between 0.5 and 1 to obtain a plurality of second numerical points corresponding one to one to the plurality of first numerical points; when the clamping distance is a first numerical point, the clamping distance is mapped to a second numerical point corresponding to the first numerical point.

[0094] It can be understood that, assuming that 1.5 times the radius of the internal capsule membrane is 5, and the preset interval is 1, there are 4 first numerical points, namely 1, 2, 3, and 4. Then, in the mapping range 0.5 to 1, there are also 4 second numerical points, namely 0.6, 0.7, 0.8, and 0.9. When the clamping distance is 2, the corresponding mapping value is 0.7.

[0095] S320: determining a first weight according to the mapping value and the radius of the internal capsule membrane, determining a second weight according to the clamping movement direction and the current annular fracture direction, and obtaining a total weight according to the first weight and the second weight;

[0096] The calculation formula of the first weight is:

[0097] ,

[0098] in, represents the first weight, represents the radius of the internal capsule membrane, represents the mapping value corresponding to the clamping distance;

[0099] The calculation formula of the second weight is:

[0100] ,

[0101] in, represents the second weight, Indicates the angle between the clamping movement direction and the current annular fracture direction;

[0102] The calculation formula of the total weight is:

[0103] ,

[0104] in, represents the total weight, Indicates the preset weight.

[0105] S330: determining a centripetal fracture direction vector by using a clamping movement vector corresponding to the clamping movement direction, a ring fracture vector corresponding to the current ring fracture direction, and the total weight;

[0106] The calculation formula of the centripetal fracture direction vector is:

[0107] ,

[0108] in, represents the centripetal fracture direction vector, represents the clamping motion vector, It can be understood that the centripetal fracture direction of the current crack point can also be determined by the centripetal fracture direction.

[0109] S40: obtaining a first connecting line between the current crack point and the center of the inner capsule membrane, and determining a current centripetal fracture distance corresponding to the current crack point based on the centripetal fracture direction vector, so as to select an actual crack point on the first connecting line;

[0110] The current centripetal fracture distance is the projection of the product of the centripetal fracture direction vector and the fixed step length on the first connecting line. In this embodiment, the fixed step length is one tenth of the radius of the internal capsule membrane. After obtaining the current centripetal fracture distance, the actual crack point can be obtained on the first connecting line with the current crack point as the starting point, and the initial crack is extended to the actual crack point to start the circular capsulorhexis. It should be noted that when performing this operation, the current crack point is not disconnected.

[0111] S50: obtaining a to-be-broken point, and obtaining a second connecting line between the to-be-broken point and the center of the inner capsule membrane, determining a predicted centripetal fracture distance corresponding to the to-be-broken point based on the current centripetal fracture distance and the centripetal fracture direction vector, selecting a predicted crack point on the second connecting line, and forming a capsulorhexis path through the actual crack point and the predicted crack point, so as to complete the capsulorhexis simulation;

[0112] It can be understood that the crack point to be broken is the next first constraint point of the current crack point along the current annular fracture direction.

[0113] The calculation formula for the predicted centripetal fracture distance is:

[0114] ,

[0115] in, represents the predicted centripetal fracture distance, represents a fixed step size, represents the centripetal fracture direction vector, represents the direction vector corresponding to the second connecting line, Indicates the current centripetal fracture distance, represents the cosine function, Represents the upper and lower limit function, whose limit values ​​are [-0.00035, 0.00035].

[0116] After obtaining the predicted crack point, the line between the actual crack point and the predicted crack point forms the capsulotomy path, and the crack is extended to the predicted crack point. It should be noted that when performing this operation, the crack point to be broken is also not disconnected, and the above-mentioned judgment is repeated for each subsequent first constraint point to finally complete the capsulotomy.

[0117] By constructing the capsule model to be torn and setting the first constraint point for the internal capsule membrane, during the clamping process of the tweezers model, the circumferential tearing simulation of the initial crack is completed by disconnecting the corresponding first constraint point, and then in the process of circumferential tearing, by detecting the external parameters such as the position, speed, and direction of the tweezers model relative to the capsule model to be torn, it is determined whether centripetal tearing occurs based on the external parameters, and the direction distance of the centripetal tear is obtained to complete the determination of the capsule tearing path. This simulation method can be used to realize the simulation of cataract capsule tearing surgery, and it only needs to obtain the external parameters associated with the tweezers model, which effectively saves computing power. At the same time, it avoids many uncertain factors in the physical simulation method of monitoring stress, provides a more realistic simulation effect, and improves the accuracy and efficiency of teaching.

[0118] Preferably, a plurality of second constraint points are arranged around the outer capsule membrane with evenly distributed intervals, and the plurality of second constraint points correspond one-to-one to the plurality of first constraint points.

[0119] After step S50, the method further includes:

[0120] S60: Initialize the world coordinates of the second constraint point, change the world coordinates of the second constraint point corresponding to the current crack point based on the current centripetal fracture distance to form an initial update coordinate, and change the world coordinates of several second constraint points corresponding to several predicted crack points based on several predicted centripetal fracture distances to form several follow-up update coordinates, and update the outer edge position of the outer capsule membrane through the initial update coordinates and several follow-up update coordinates.

[0121] By updating the outer edge position of the external capsule membrane, the morphology of the external capsule membrane can be changed synchronously with the progress of the capsulotomy, so that the process of the capsulotomy is closer to reality and the authenticity of the simulation teaching is improved.

[0122] See also Figure 2 The second embodiment of the present invention provides a cataract capsulorhexis simulation system, which is applied to the cataract capsulorhexis simulation method described in the above embodiment, and will not be repeated hereafter. As used below, the terms "module", "unit", "subunit", etc. may be a combination of software and / or hardware that implements a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and contemplated.

[0123] The system comprises:

[0124] A construction module 10 is used to construct a capsule membrane model to be torn, wherein the capsule membrane model to be torn includes an inner capsule membrane and an outer capsule membrane arranged from the outside to the inside, and a plurality of first constraint points evenly distributed at intervals are arranged around the inner capsule membrane, and the inner capsule membrane is connected to the outer capsule membrane through the first constraint points;

[0125] The building block 10 comprises:

[0126] A first unit is used for combining a plurality of triangular facets into a first initial capsule membrane model, and setting a triangular quadratic spring force field for the first initial capsule membrane model to form a second initial capsule membrane model;

[0127] A second unit is used to add a collision model between adjacent triangular facets in the second initial capsule membrane model, wherein the contact stiffness between the collision model and the triangular facets is 1000, so as to form a third initial capsule membrane model;

[0128] The third unit is used to add a plane force field to the upper end and the lower end of the third initial capsule model to limit the up and down floating of the third initial capsule model and form a fourth initial capsule model;

[0129] The fourth unit is used to set a lens model at the bottom of the fourth initial capsule model, and the contact stiffness between the lens model and the fourth initial capsule model is 50000 to form a capsule model to be torn.

[0130] The analysis module 20 is used to set an initial crack on the outer edge of the internal capsule membrane, select the two first constraint points corresponding to the two opposite ends of the initial crack as the first initial crack point and the second initial crack point, and obtain the current crack point when the forceps model clamps and pulls the internal capsule membrane, and determine whether the current crack point will produce a centripetal fracture;

[0131] The analysis module 20 comprises:

[0132] A fifth unit is used to select an extension point from the first initial crack point and the second initial crack point, and obtain an initial distance between an initial clamping point of the tweezers model and the extension point;

[0133] The fifth unit is specifically used to obtain a first direction extending from the first initial crack point to the second initial crack point and a second direction extending from the second initial crack point to the first initial crack point, and obtain a connecting line between the first initial crack point and the second initial crack point; obtain a projection direction of the clamping movement direction of the tweezers model on the connecting line, and determine whether the projection direction is the first direction or the second direction; if the projection direction is the first direction, the first initial crack point is selected as an extension point, and if the projection direction is the second direction, the second initial crack point is selected as an extension point;

[0134] A sixth unit is used for obtaining the disconnection number of the first constraint point during the clamping movement of the tweezers model, and obtaining the determination distance through the initial distance and the disconnection number of the first constraint point;

[0135] A seventh unit is used to select the first disconnected constraint point farthest from the extension point as the current crack point, obtain the real-time distance between the current clamping point of the tweezers model and the current crack point, and determine whether the current crack point will produce a centripetal fracture based on the real-time distance and the determination distance;

[0136] A judgment module 30, for determining the centripetal fracture direction vector of the current crack point based on the clamping movement direction of the tweezers model and the current annular fracture direction of the initial crack if the current crack point will produce a centripetal fracture;

[0137] The judging module 30 comprises:

[0138] An eighth unit is used to obtain a clamping distance based on an initial clamping point and a current clamping point of the tweezers model, and select a mapping value corresponding to the clamping distance within a mapping range;

[0139] The mapping range is 0.5~1, and the eighth unit is specifically used for mapping the clamping distance to 0.5 when the clamping distance is 0; mapping the clamping distance to 1 when the clamping distance is greater than 1.5 times the radius of the internal capsule membrane; performing a first data segmentation at a preset interval between 0 and 1.5 times the radius of the internal capsule membrane to obtain a plurality of first numerical points, and performing a second data segmentation at the preset interval between 0.5 and 1 to obtain a plurality of second numerical points corresponding to the plurality of first numerical points one by one; when the clamping distance is a first numerical point, mapping the clamping distance to a second numerical point corresponding to the first numerical point;

[0140] A ninth unit is used to determine a first weight according to the mapping value and the radius of the internal capsule membrane, and to determine a second weight according to the clamping movement direction and the current annular fracture direction, and to obtain a total weight according to the first weight and the second weight;

[0141] A tenth unit is used to determine a centripetal fracture direction vector by using a clamping movement vector corresponding to the clamping movement direction, a ring fracture vector corresponding to the current ring fracture direction, and the total weight;

[0142] A selection module 40 is used to obtain a first connection line between the current crack point and the center of the inner capsule membrane, determine a current centripetal fracture distance corresponding to the current crack point based on the centripetal fracture direction vector, and select an actual crack point on the first connection line;

[0143] An execution module 50 is used to obtain a to-be-broken point, and obtain a second connection line between the to-be-broken point and the center of the inner capsule membrane, determine a predicted centripetal fracture distance corresponding to the to-be-broken point based on the current centripetal fracture distance and the centripetal fracture direction vector, select a predicted crack point on the second connection line, form a capsulorhexis path through the actual crack point and the predicted crack point, and complete the capsulorhexis simulation;

[0144] Preferably, the system further comprises:

[0145] The optimization module 60 is used to initialize the world coordinates of the second constraint point, change the world coordinates of the second constraint point corresponding to the current crack point based on the current centripetal fracture distance to form an initial update coordinate, and change the world coordinates of several second constraint points corresponding to several predicted crack points based on several predicted centripetal fracture distances to form several follow-up update coordinates, and update the outer edge position of the outer capsule membrane through the initial update coordinates and several follow-up update coordinates.

[0146] The present invention also provides a computer, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the cataract capsulorhexis simulation method as described in the above technical solution is implemented.

[0147] The present invention also provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the cataract capsulorhexis simulation method as described in the above technical solution is implemented.

[0148] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0149] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A cataract capsulorhexis simulation method, characterized in that: The following steps are involved: Constructing a capsule membrane model to be torn, the capsule membrane model to be torn comprising an inner capsule membrane and an outer capsule membrane arranged from outside to inside, a plurality of first constraint points evenly distributed at intervals are arranged around the inner capsule membrane, and the inner capsule membrane is connected to the outer capsule membrane through the first constraint points; An initial crack is set at the outer edge of the internal capsule membrane, and two first constraint points corresponding to opposite ends of the initial crack are selected as a first initial crack point and a second initial crack point. When the tweezers model clamps and pulls the internal capsule membrane, a current crack point is obtained, and it is determined whether the current crack point will produce a centripetal fracture; If the current crack point will produce a centripetal fracture, determining the centripetal fracture direction vector of the current crack point based on the clamping movement direction of the tweezers model and the current annular fracture direction of the initial crack; Acquire a first connecting line between the current crack point and the center of the inner capsule membrane, determine a current centripetal fracture distance corresponding to the current crack point based on the centripetal fracture direction vector, and select an actual crack point on the first connecting line; The to-be-broken grain point is obtained, and a second connecting line between the to-be-broken grain point and the center of the circle of the internal capsule membrane is obtained, and a predicted centripetal fracture distance corresponding to the to-be-broken grain point is determined based on the current centripetal fracture distance and the centripetal fracture direction vector, so as to select a predicted crack point on the second connecting line, and a capsulorhexis path is formed through the actual crack point and the predicted crack point to complete the capsulorhexis simulation.

2. The cataract capsulorhexis simulation method according to claim 1, characterized in that: The step of constructing a capsule model to be torn comprises: Combining a plurality of triangular facets into a first initial capsule membrane model, and setting a triangular quadratic spring force field for the first initial capsule membrane model to form a second initial capsule membrane model; adding a collision model between adjacent triangular facets in the second initial capsule model to form a third initial capsule model; Adding a plane force field to the upper and lower ends of the third initial capsule model to restrict the up and down floating of the third initial capsule model, and forming a fourth initial capsule model; A lens model is arranged at the bottom of the fourth initial capsule model to form a capsule model to be torn.

3. The cataract capsulorhexis simulation method according to claim 1, characterized in that: The step of obtaining the current crack point and determining whether the current crack point will produce centripetal fracture includes: Selecting an extension point from the first initial crack point and the second initial crack point, and obtaining an initial distance between an initial clamping point of the tweezers model and the extension point; During the clamping movement of the tweezers model, the disconnection number of the first constraint point is obtained, and the determination distance is obtained according to the initial distance and the disconnection number of the first constraint point; The first disconnected constraint point that is farthest from the extension point is selected as the current crack point, and the real-time distance between the current clamping point of the tweezers model and the current crack point is obtained. Based on the real-time distance and the judgment distance, it is determined whether the current crack point will produce centripetal fracture.

4. The cataract capsulorhexis simulation method according to claim 3, characterized in that: The step of selecting an extension point from the first initial crack point and the second initial crack point comprises: Obtaining a first direction extending from the first initial crack point to the second initial crack point and a second direction extending from the second initial crack point to the first initial crack point, and obtaining a line between the first initial crack point and the second initial crack point; Obtaining a projection direction of the clamping movement direction of the tweezers model on the connecting line, and determining whether the projection direction is the first direction or the second direction; If the projection direction is the first direction, the first initial crack point is selected as the extension point, and if the projection direction is the second direction, the second initial crack point is selected as the extension point.

5. The cataract capsulorhexis simulation method according to claim 3, characterized in that: The calculation formula of the determination distance is: ， in, Indicates the judgment distance, represents the initial distance, Indicates the number of disconnections of the first constraint point when the tweezers model is gripping and moving. represents the distance between two adjacent first constraint points, represents a constant factor.

6. The cataract capsulorhexis simulation method according to claim 1, characterized in that: The step of determining the centripetal fracture direction vector of the current crack point based on the clamping movement direction of the tweezers model and the current annular fracture direction of the initial crack comprises: Acquire a clamping distance based on an initial clamping point and a current clamping point of the tweezers model, and select a mapping value corresponding to the clamping distance within a mapping range; Determine a first weight by the mapping value and the radius of the internal capsule membrane, determine a second weight by the clamping movement direction and the current annular fracture direction, and obtain a total weight according to the first weight and the second weight; The centripetal fracture direction vector is determined by the clamping movement vector corresponding to the clamping movement direction, the annular fracture vector corresponding to the current annular fracture direction, and the total weight.

7. The cataract capsulorhexis simulation method according to claim 6, characterized in that: The mapping range is 0.5-1, and the step of selecting a mapping value corresponding to the clamping distance within the mapping range includes: When the clamping distance is 0, the clamping distance is mapped to 0.5; When the clamping distance is greater than 1.5 times the radius of the internal capsule membrane, mapping the clamping distance to 1; Performing a first data segmentation at a preset interval between 0 and 1.5 times the radius of the inner capsule membrane to obtain a plurality of first value points, and performing a second data segmentation at the preset interval between 0.5 and 1 to obtain a plurality of second value points corresponding to the plurality of first value points one by one; When the clipping distance is a first value point, the clipping distance is mapped to a second value point corresponding to the first value point.

8. The cataract capsulorhexis simulation method according to claim 6, characterized in that: The calculation formula of the first weight is: ， in, represents the first weight, represents the radius of the internal capsule membrane, represents the mapping value corresponding to the clamping distance; The calculation formula of the second weight is: ， in, represents the second weight, Indicates the angle between the clamping movement direction and the current annular fracture direction; The calculation formula of the total weight is: ， in, represents the total weight, Indicates preset weight; The calculation formula of the centripetal fracture direction vector is: ， in, represents the centripetal fracture direction vector, represents the clamping motion vector, represents the ring break vector.

9. The cataract capsulorhexis simulation method according to claim 1, characterized in that: The calculation formula for the predicted centripetal fracture distance is: ， in, represents the predicted centripetal fracture distance, represents a fixed step size, represents the centripetal fracture direction vector, represents the direction vector corresponding to the second connecting line, Indicates the current centripetal fracture distance, represents the cosine function, Represents the upper and lower limit function, whose limit values ​​are [-0.00035, 0.00035].

10. A cataract capsulorhexis simulation system, applied to the cataract capsulorhexis simulation method according to any one of claims 1 to 9, characterized in that: The system comprises: A construction module is used to construct a capsule membrane model to be torn, wherein the capsule membrane model to be torn includes an inner capsule membrane and an outer capsule membrane arranged from the outside to the inside, a plurality of first constraint points evenly distributed at intervals are arranged around the inner capsule membrane, and the inner capsule membrane is connected to the outer capsule membrane through the first constraint points; An analysis module, configured to set an initial crack on the outer edge of the internal capsule membrane, select two first constraint points corresponding to opposite ends of the initial crack as a first initial crack point and a second initial crack point, obtain a current crack point when the tweezers model clamps and pulls the internal capsule membrane, and determine whether the current crack point will produce a centripetal fracture; A judgment module, for determining the centripetal fracture direction vector of the current crack point based on the clamping movement direction of the tweezers model and the current annular fracture direction of the initial crack if the current crack point will produce a centripetal fracture; A selection module, configured to obtain a first connection line between the current crack point and the center of the inner capsule membrane, determine a current centripetal fracture distance corresponding to the current crack point based on the centripetal fracture direction vector, and select an actual crack point on the first connection line; An execution module is used to obtain a line point to be broken, and obtain a second connecting line between the line point to be broken and the center of the circle of the internal capsule membrane, determine a predicted centripetal fracture distance corresponding to the line point to be broken based on the current centripetal fracture distance and the centripetal fracture direction vector, select a predicted crack point on the second connecting line, form a capsulorhexis path through the actual crack point and the predicted crack point, and complete the capsulorhexis simulation.

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