Blood flow velocity calculation method, OCT system, media, products and equipment

Abstract

The present invention belongs to the technical field of optical coherence tomography. A blood flow velocity calculation method, OCT system, medium, product and equipment are provided to perform curvature correction on the collected retinal image based on the axial length of the eye; the curvature-corrected retinal image is three-dimensionally reconstructed to obtain a three-dimensional vascular network, and the vascular coordinates of the three-dimensional vascular network are extracted; each Doppler angle is obtained by combining the scanning beam direction when the scanning beam scans the retina, and the blood flow velocity is calculated using the Doppler angle. The present invention combines retinal curvature information, which can not only improve the accuracy of the three-dimensional model, but also accurately measure the Doppler angle to improve the calculation accuracy of the blood flow velocity, which has important clinical significance for the detection and research of retinal diseases, such as diabetic retinopathy, glaucoma and macular degeneration.

Description

Technical Field

[0001] The present invention relates to the technical field of optical coherence tomography, and in particular to a blood flow velocity calculation method, an OCT system, a medium, a product and a device. Background Art

[0002] The statements in this section merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] Optical Coherence Tomography (OCT) technology, as a high-resolution imaging method, has been widely used in ophthalmic diagnosis. OCT technology can provide micron-level tomographic images of the retina and other tissues of the eyeball through the principle of low-coherence light interference, thereby providing important imaging information for the early detection and treatment of eye diseases. In ophthalmology, OCT technology is not only used to observe the structure of the retina, but also can be applied to the measurement of retinal blood flow velocity. For example, Patent No. CN118351080B provides a method and device for identifying the same capillary without bifurcation, which realizes capillary identification through OCT technology; Patent No. CN118236038B provides a multi-channel OCT system and method for measuring capillary blood flow velocity, which realizes capillary blood flow velocity measurement through OCT technology.

[0004] At present, OCT-based axial length measurement and retinal blood flow velocity analysis mainly rely on two-dimensional imaging or uncorrected three-dimensional retinal models. This method has many shortcomings. First, traditional two-dimensional or simple three-dimensional reconstruction cannot accurately represent the actual curvature of the retina, especially in the posterior area of ​​the eyeball. Since the retinal surface is not a flat structure, but has certain curvatures and undulations, ignoring the curvature will lead to misjudgment of the retinal structure and blood flow direction; second, Doppler OCT technology measures axial blood flow velocity, but to calculate the absolute blood flow velocity, an accurate Doppler angle is required.

[0005] However, existing methods have difficulty in accurately measuring the angle between blood vessels and the scanning beam, especially when the retinal surface is uneven, which directly affects the accuracy of blood flow velocity; moreover, the retinal layer structure is complex and the boundaries between the layers of tissue are not always clearly visible, which further increases the difficulty of measuring blood flow direction and Doppler angle.

[0006] At present, some improvement methods try to improve the measurement accuracy by enhancing the hardware configuration of the OCT system or combining image processing technology. For example, using a higher resolution scanner or complex optical path design to reduce noise and error, however, these methods usually increase the cost of the equipment, and there is still insufficient processing of curvature information in actual use. In addition, although the current three-dimensional reconstruction technology can generate a three-dimensional image of the retina, it ignores the precise curvature information and cannot accurately reflect the spatial orientation of the blood vessels, resulting in inaccurate calculation of the Doppler angle, which in turn affects the accurate measurement of blood flow velocity. Moreover, when the OCT system uses two-dimensional scanning (B-scan) to image a flat object to be measured, as the scanning beam moves in the lateral direction, the optical path (the total propagation distance of light from emission to reception) is not constant. When the scanning beam changes the angle with the measured plane during the scanning process, the optical path at each position has a slight difference, which will cause the final B-scan cross-sectional image to be distorted in the depth direction, and the degree of curvature will also change with the change of the scanning beam angle. Therefore, although the object to be measured is flat, it presents a false arc curvature in the image. Summary of the invention

[0007] In order to address the deficiencies in the prior art, the present invention provides an OCT system, method, medium, product and device for calculating blood flow velocity, which performs curvature correction on the collected retinal image based on the axial length, which can not only improve the accuracy of the three-dimensional model, but also accurately measure the Doppler angle to improve the calculation accuracy of blood flow velocity, which has important clinical significance for the detection and research of retinal diseases, such as diabetic retinopathy, glaucoma and macular degeneration.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for calculating blood flow velocity.

[0010] A blood flow velocity calculation method includes the following process:

[0011] Perform curvature correction based on axial length on the collected retinal images;

[0012] Performing three-dimensional reconstruction on the curvature-corrected retinal image to obtain a three-dimensional vascular network, and extracting the vascular coordinates of the three-dimensional vascular network;

[0013] Each Doppler angle is obtained in combination with the direction of the scanning beam when the scanning beam scans the retina, and the blood flow velocity is calculated using the Doppler angle.

[0014] As a further limitation of the first aspect of the present invention, performing curvature correction based on the axial length on the collected retinal image includes:

[0015] For normal eyes, the axial length of the eye is calculated without any deflection of the scanning beam. , when the scanning beam entering the eye is tilted The axial length of the eye is , then the radius of the ideal sphere is :

[0016] ;

[0017] According to the incident direction of the scanning beam and the radius of the ideal sphere , get the coordinates of each point on the surface of the sphere, all points can be mapped to the same ideal sphere radius On the spherical surface of , the originally distorted retinal image is reconstructed into a point set in a normalized spherical coordinate system to obtain the eyeball model after curvature correction;

[0018] For myopic or hyperopic eyes: use a two-dimensional scanning galvanometer to select multiple lateral positions and scan, and obtain the corresponding axial length at each lateral position by moving the reference arm. Perform curve or surface fitting on the discrete axial length to obtain the curvature-corrected eye model.

[0019] As a further limitation of the first aspect of the present invention, the calculation of the axial length of the eye includes:

[0020] Use a two-dimensional scanning galvanometer to form a line of scanning beam, place the reflector at the fixed point of the scanning beam, perform initial calibration, adjust the imaging parameters, make the imaging signal of the reflector appear at the set frequency position in the preview image, and record the reference arm position. ;

[0021] Keep the corneal vertex of the eye consistent with the position of the previous reflector, move the reference arm so that the image of the retina appears on the preview image, and continue to adjust the reference arm so that the lower edge of the retinal image is aligned with the set frequency position in the preview image, and record the reference arm position ;

[0022] Calculate the total optical path difference: , the axial length of the eye is: .

[0023] As a further limitation of the first aspect of the present invention, performing Doppler angle calculation to obtain the absolute velocity of retinal blood flow includes:

[0024] Performing vascular skeleton extraction on the corrected retinal three-dimensional vascular network to obtain multiple coordinate points of the vascular centerline;

[0025] Fit multiple coordinate points into a spatial blood vessel curve to obtain the blood flow velocity direction of each coordinate point;

[0026] For any coordinate point, the Doppler angle of the coordinate point is determined according to the blood flow velocity direction at the coordinate point and the direction vector of the scanning light beam, and the absolute blood flow velocity at the coordinate point is obtained according to the Doppler angle.

[0027] As a further limitation of the first aspect of the present invention, the direction vector of the scanning beam for: ;

[0028] ;

[0029] ;

[0030] ;

[0031] ;

[0032] ;

[0033] in, for The focal length of the first focusing lens of the system, for The focal length of the system's second focusing lens, and They are respectively the scanning beam passing through the scanning two-dimensional scanning galvanometer. Direction and The deflection angle of the direction, The scanning beam The angle of the direction, For scanning light The eye angle of the direction.

[0034] As a further limitation of the first aspect of the present invention, The direction of blood flow velocity at the coordinate point:

[0035] ;

[0036] in, , and For the The three-axis coordinates of the coordinate points, , and For the The three-axis coordinates of the coordinate points, Respectively Coordinate points along The speed of the three axes.

[0037] As a further limitation of the first aspect of the present invention, The Doppler angle of the coordinate point for: .

[0038] As a further limitation of the first aspect of the present invention, the first The absolute blood flow velocity at the coordinate point: ,in, For the The Doppler shift of the coordinate point is is the refractive index of the medium, is the central wavelength of the light source, For the The Doppler angle of the coordinate point.

[0039] In a second aspect, the present invention provides an OCT system for blood flow velocity calculation.

[0040] An OCT system for blood flow velocity calculation, comprising:

[0041] A light source, a coupler, a spectrometer, a processing terminal, a sample arm and a reference arm, wherein the light source is connected to the coupler via a first collimator and a fiber coupler in sequence, the processing terminal is connected to the spectrometer, the spectrometer is connected to the coupler, the coupler is connected to the sample arm via a polarization controller, and the coupler is connected to the reference arm;

[0042] The sample arm includes a second collimator, a two-dimensional scanning galvanometer, system and an adjustable focus lens, the reference arm comprising a third collimator, a dispersion compensation lens, an adjustable attenuator and a reflector arranged in sequence along the optical path;

[0043] The processing terminal is configured to execute the blood flow velocity calculation method described in the first aspect of the present invention.

[0044] In a third aspect, the present invention provides a computer device, comprising: a processor and a computer-readable storage medium;

[0045] a processor adapted to execute a computer program;

[0046] A computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by the processor, the method for calculating the absolute capillary blood flow velocity as described in the first aspect of the present invention is implemented.

[0047] In a fourth aspect, the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program is suitable for being loaded by a processor and executing the method for calculating capillary absolute blood flow velocity as described in the first aspect of the present invention.

[0048] In a fifth aspect, the present invention provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the method for calculating the absolute capillary blood flow velocity as described in the first aspect of the present invention.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. The present invention can accurately calculate the absolute blood flow velocity of retinal blood vessels through precise mathematical models and optical calculations, which is of great significance for the diagnosis and monitoring of ophthalmic diseases such as diabetic retinopathy, glaucoma and macular degeneration.

[0051] 2. During the image reconstruction process, the present invention obtains and corrects the true curvature of the retina, eliminates the distortion caused by the shape of the eyeball, and improves the accuracy of the calculation of vascular structure and blood flow velocity.

[0052] 3. The present invention combines the incident direction of the scanning light beam and the direction of blood flow to accurately calculate the Doppler angle in a unified coordinate system, thereby improving the accuracy and speed of blood flow velocity measurement.

[0053] 4. Compared with the current flow velocity measurement method, the present invention can measure both the blood flow velocity of large vessels and the blood flow velocity of capillaries.

[0054] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0056] Figure 1 A schematic diagram of a flow chart of a blood flow velocity calculation method provided in Example 1 of the present invention;

[0057] Figure 2 A schematic diagram of an OCT system for calculating blood flow velocity provided in Example 1 of the present invention;

[0058] Figure 3 A scanning schematic diagram of a scanning light beam provided in Embodiment 1 of the present invention;

[0059] Figure 4The radius of the sphere provided in Example 1 of the present invention Calculation diagram;

[0060] Among them, 1. light source; 2. first collimator; 3. fiber coupler; 4. coupler; 5. processing terminal; 6. signal line; 7. polarization controller; 8. sample arm; 9. reference arm; 10. second collimator; 11. two-dimensional scanning galvanometer; 12. first focusing lens; 13. second focusing lens; 14. adjustable focus lens; 15. eye; 16. third collimator; 17. dispersion compensation lens; 18. adjustable attenuator; 19. reflector; 20. spectrometer. DETAILED DESCRIPTION

[0061] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0062] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0063] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0064] Embodiment 1:

[0065] This implementation proposes a blood flow velocity calculation method, such as Figure 1 As shown, the following process is included:

[0066] S1: Perform curvature correction based on the axial length of the collected retinal image;

[0067] S2: Perform three-dimensional reconstruction on the curvature-corrected retinal image to obtain a three-dimensional vascular network, and extract the vascular coordinates of the three-dimensional vascular network;

[0068] S3: Each Doppler angle is obtained in combination with the direction of the scanning beam when the scanning beam scans the retina, and the blood flow velocity is calculated using the Doppler angle.

[0069] The aligned retinal images were subjected to surface fitting and angiography to obtain a three-dimensional vascular network, and Doppler angle calculation was performed to obtain the absolute velocity of retinal vascular blood flow.

[0070] In this implementation, preferably, the blood flow velocity calculation method is as follows: Figure 2 Schematic diagram of an OCT system implementation for blood flow velocity calculation. Figure 2As shown, it includes: a light source 1, a coupler 4 (the splitting ratio is 1:9, that is, 10% of the light is split to the sample arm 8, and 90% of the light is split to the reference arm 9), a spectrometer 20, a processing terminal 5, a sample arm 8 and a reference arm 9, the light source 1 is connected to the coupler 4 through a first collimator 2 and a fiber coupler 3 in sequence, the processing terminal 5 is connected to the spectrometer 20, the spectrometer 20 is connected to the coupler 4, the coupler 4 is connected to the sample arm 8 through a polarization controller 7, and the coupler 4 is connected to the reference arm 9;

[0071] The sample arm 8 includes a second collimator 10, a two-dimensional scanning galvanometer 11 (including an X-axis galvanometer and a Y-axis galvanometer), which are sequentially arranged along the optical path. The system (including a first focusing lens 12 and a second focusing lens 13) and an adjustable focus lens 14, the reference arm 9 includes a third collimator 16, a dispersion compensation lens 17, an adjustable attenuator 18 and a reflector 19 arranged in sequence along the optical path, the processing terminal 5 is connected to the spectrometer 20 through a signal line 6 for sending a scanning control command; the processing terminal 5 is configured to execute the process of S1-S3, which will not be repeated here.

[0072] More specifically, the present implementation reconstructs a three-dimensional model of the retina through OCT and corrects it in combination with the axial length, making the three-dimensional coordinates of the retinal blood vessels more accurate. The corrected three-dimensional model is used in combination with Doppler angle calculation to accurately solve the absolute velocity of retinal blood flow.

[0073] In this implementation, a two-dimensional scanning galvanometer 11 is used to apply a scanning beam (first scan a line), and the reflector 19 is precisely placed on the fixed point of the scanning beam to ensure the initial calibration of the OCT system; by adjusting the imaging parameters of the OCT system, the imaging signal of the reflector 19 appears at the set frequency position in the preview image, and a zero point reference in the depth direction is established, and the optical path L1 of the reference arm 9 at this time is recorded.

[0074] Next, start measuring the eye 15, place the eye 15 in front of the OCT system, move the characteristic point of the cornea to the zero reference position calibrated by the reflector 19, move the reference arm 9 to make the image of the retina appear on the preview image, and continue to adjust the reference arm 9 to move a certain characteristic point or characteristic structure of the retina to the set frequency position. Align with the same set frequency position in the preview image, and at this time, record the optical path L2 of the reference arm 9.

[0075] Calculate the total optical path difference:

[0076] (1);

[0077] The axial length of the eye is: .

[0078] In this implementation, the corneal vertex (fixed point of the light beam) is taken as the origin O, along the optical axis, from the corneal vertex to the inside of the eye (positively pointing to the retina) is the Z axis direction, the horizontal direction perpendicular to the Z axis is the X axis, and the Y axis is perpendicular to the X axis and the Z axis at the same time. The X axis, Y axis and Z axis form a right-handed coordinate system. The B-scan image in this implementation is an XOZ plane image, and the depth of the B-scan image is in the Z direction.

[0079] When scanning the object, the curvature of the reconstructed image will change due to the change in the optical path. Therefore, the false "bend" needs to be corrected. There are two specific cases:

[0080] Case 1 (normal eye 15): After approximation to an ideal sphere, the scanning beam is not deflected, as shown in Figure 3 and Figure 4 As shown, the measured axial length is recorded as , as the scanning beam entering the eye tilts , and the corresponding axial length is , then the curvature of the eye 15 is transformed into the radius of the ideal sphere. , is the deflection angle of the scanning beam after passing through the two-dimensional scanning galvanometer 11, is the focal length of the first focusing lens 12, is the focal length of the second focusing lens 13, The angle value is , , and are the lengths of the three sides of the right triangle, and is the length of the right angle side, is the length of the hypotenuse.

[0081] From trigonometric functions we get:

[0082] (2);

[0083] From the cosine theorem we get:

[0084] (3);

[0085] (4);

[0086] (5);

[0087] (6);

[0088] (7).

[0089] For an ideal sphere, as the incident angle deviates from the central axis, the path of the scanning beam in the sphere shortens. Curvature correction needs to be combined with the obtained axial length of the eye. Once the sphere radius close to the actual one is obtained through measurement, , we can approximate the retina as the inner structure of the sphere. Because ideally, if the eyeball is an ideal sphere, then the retina is part of the sphere.

[0090] When the radius of the sphere is calculated After that, each retinal measurement point (corresponding to a and ) can be theoretically mapped onto a spherical surface: according to the incident direction of the scanning beam and the radius of the sphere , calculate the exact coordinates of the point on the surface of the sphere; since all points can be mapped to the same spherical radius On the spherical surface of the image, the originally distorted image can be reconstructed into a point set in a normalized spherical coordinate system, thereby correcting the "false curvature" caused by changes in the incident angle and depth measurement errors.

[0091] Case 2 (nearsighted or hyperopic eyes 15): A plurality of lateral positions are selected and scanned by the two-dimensional scanning galvanometer 11, and the corresponding axial length data are measured at these selected positions by moving the reference arm 9. Subsequently, these discrete axial length data are fitted with a curve or a surface to construct a more realistic eyeball model.

[0092] Place the eye 15 in front of the OCT system, and ensure that the corneal vertex is consistent with the position of the fixed point of the scanning beam when scanning the flat object before. Adjust the reference arm 9 or system parameters so that a specific layer of the retina (for example, the retinal pigment epithelium) appears in the preview image at the same frequency position as when scanning the flat object, obtain the OCT scanning data of the retina, ensure that the scanning parameters (such as the scanning range and sampling rate of the two-dimensional scanning galvanometer 11) are consistent with those during calibration, and then use the saved correction parameters to obtain the corrected retinal image.

[0093] In order to achieve a more realistic three-dimensional curvature correction, it is necessary to repeat the above measurement steps at multiple lateral positions: by controlling the two-dimensional scanning galvanometer 11, scanning is performed at different positions of the retina, and the corresponding axial length is obtained at each position by moving the reference arm 9. The corrected retinal images scanned at different lateral positions are aligned based on the same axial length, and the aligned retinal images are subjected to surface fitting and angiography to obtain a three-dimensional vascular network.

[0094] The skeleton of the three-dimensional vascular network is extracted, and the coordinates of the vascular centerline are extracted, which are recorded as , represents the coordinates of the centerline of a blood vessel, where , Indicates the number of points.

[0095] Obtain several discrete vascular centerline coordinates in OCT, and fit a spatial vascular curve according to the coordinate values ​​to obtain the first The direction of blood flow velocity at a point for:

[0096] (8);

[0097] in, , and For the The three-axis coordinates of the coordinate points, Respectively Coordinate points along The speed of the three axes.

[0098] The fixed point of the scanning beam needs to be placed at the center of the cornea, and the scanning angle is determined by the voltage of the two-dimensional scanning galvanometer 11 Determine that the scanning beam passes through the two-dimensional scanning galvanometer 11 at an angle Deflection, through The system converts the angle change of the two-dimensional scanning galvanometer 11 into the displacement of the scanning beam in the sample plane. The scanning beam then passes through the cornea and lens and is focused onto the retina:

[0099] (9);

[0100] (10);

[0101] in, and They are respectively the scanning beam passing through the two-dimensional scanning galvanometer 11 and x Direction and y The deflection angle of the direction.

[0102] The direction vector of the scanning beam It can be expressed as: ,in:

[0103] (11);

[0104] (12);

[0105] (13);

[0106] in, The scanning beam The angle of the direction, For scanning light The eye angle of the direction.

[0107] In this implementation, the direction vector of the scanning beam is:

[0108] (14);

[0109] The cosine of the Doppler angle:

[0110] (15);

[0111] According to formula (15), the Doppler angle can be calculated , according to the Doppler angle Get the first The absolute blood flow velocity at the coordinate point:

[0112] (16);

[0113] in, For the The Doppler shift of the coordinate point is is the refractive index of the medium, is the central wavelength of light source 1.

[0114] Embodiment 2:

[0115] This implementation provides a computer device, which includes a processor, a communication interface, and a computer-readable storage medium, wherein the processor, the communication interface, and the computer-readable storage medium may be connected via a bus or other means.

[0116] Among them, the communication interface is used to receive and send data, the computer-readable storage medium can be stored in the memory of the electronic device, the computer-readable storage medium is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer-readable storage medium.

[0117] A processor (or CPU (Central Processing Unit)) is the computing core and control core of an electronic device, which is suitable for implementing one or more instructions, and specifically suitable for loading and executing one or more instructions to implement corresponding method flows or corresponding functions.

[0118] The processor is configured to perform the following process:

[0119] Perform curvature correction based on axial length on the collected retinal images;

[0120] Performing three-dimensional reconstruction on the curvature-corrected retinal image to obtain a three-dimensional vascular network, and extracting the vascular coordinates of the three-dimensional vascular network;

[0121] Each Doppler angle is obtained in combination with the direction of the scanning beam when the scanning beam scans the retina, and the blood flow velocity is calculated using the Doppler angle.

[0122] The specific steps are described in Example 1 and will not be repeated here.

[0123] Embodiment 3:

[0124] This implementation provides a computer-readable storage medium (Memory), which is a memory device in an electronic device for storing programs and data. It is understandable that the computer-readable storage medium here can include both built-in storage media in the electronic device and, of course, extended storage media supported by the electronic device. The computer-readable storage medium provides a storage space that stores the processing system of the electronic device.

[0125] In addition, the storage space also stores one or more instructions suitable for being loaded and executed by the processor, and these instructions may be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here may be a high-speed RAM memory, or a non-volatile memory, such as at least one disk memory; optionally, it may also be at least one computer-readable storage medium located away from the aforementioned processor.

[0126] In one embodiment, the computer-readable storage medium stores one or more instructions; the processor loads and executes the one or more instructions stored in the computer-readable storage medium to implement the following process:

[0127] Perform curvature correction based on axial length on the collected retinal images;

[0128] Performing three-dimensional reconstruction on the curvature-corrected retinal image to obtain a three-dimensional vascular network, and extracting the vascular coordinates of the three-dimensional vascular network;

[0129] Each Doppler angle is obtained in combination with the direction of the scanning beam when the scanning beam scans the retina, and the blood flow velocity is calculated using the Doppler angle.

[0130] The specific steps are described in Example 1 and will not be repeated here.

[0131] Embodiment 4:

[0132] The present implementation provides a computer program product or a computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of an electronic device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the electronic device performs the following process:

[0133] Perform curvature correction based on axial length on the collected retinal images;

[0134] Performing three-dimensional reconstruction on the curvature-corrected retinal image to obtain a three-dimensional vascular network, and extracting the vascular coordinates of the three-dimensional vascular network;

[0135] Each Doppler angle is obtained in combination with the direction of the scanning beam when the scanning beam scans the retina, and the blood flow velocity is calculated using the Doppler angle.

[0136] The specific steps are described in Example 1 and will not be repeated here.

[0137] A person skilled in the art can appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0138] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted through a computer-readable storage medium. The computer instructions can be transmitted from a website site, a computer, a server or a data center to another website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by the computer or a data processing device such as a server, a data center, etc. that includes one or more available media integrated. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)), etc.

[0139] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A blood flow velocity calculation method, characterized in that: The process includes: Perform curvature correction based on axial length on the collected retinal images; Performing three-dimensional reconstruction on the curvature-corrected retinal image to obtain a three-dimensional vascular network, and extracting the vascular coordinates of the three-dimensional vascular network; Each Doppler angle is obtained by combining the scanning beam direction when the scanning beam scans the retina, and the blood flow velocity is calculated using the Doppler angle; The collected retinal images are subjected to curvature correction based on the axial length of the eye, including: For normal eyes, the axial length of the eye is calculated without any deflection of the scanning beam. , when the scanning beam entering the eye is tilted The axial length of the eye is , then the radius of the ideal sphere is : ； According to the incident direction of the scanning beam and the radius of the ideal sphere , get the coordinates of each point on the surface of the sphere, all points can be mapped to the same ideal sphere radius On the spherical surface, the originally distorted retinal image is reconstructed into a point set in a normalized spherical coordinate system to obtain the eyeball model after curvature correction; For myopic or hyperopic eyes: use a two-dimensional scanning galvanometer to select multiple lateral positions and scan, and obtain the corresponding axial length at each lateral position by moving the reference arm. Perform curve or surface fitting on the discrete axial length to obtain the curvature-corrected eye model.

2. The blood flow velocity calculation method according to claim 1, characterized in that: Calculation of axial length of the eye, including: Use a two-dimensional scanning galvanometer to form a line of scanning beam, place the reflector at the fixed point of the scanning beam, perform initial calibration, adjust the imaging parameters, make the imaging signal of the reflector appear at the set frequency position in the preview image, and record the reference arm position. ; Keep the corneal vertex of the eye consistent with the position of the previous reflector, move the reference arm so that the image of the retina appears on the preview image, and continue to adjust the reference arm so that the lower edge of the retinal image is aligned with the set frequency position in the preview image, and record the reference arm position ; Calculate the total optical path difference: , the axial length of the eye is: .

3. The blood flow velocity calculation method according to claim 1, characterized in that: Doppler angle calculation is performed to obtain the absolute velocity of retinal blood flow, including: Performing vascular skeleton extraction on the corrected retinal three-dimensional vascular network to obtain multiple coordinate points of the vascular centerline; Fit multiple coordinate points into a spatial blood vessel curve to obtain the blood flow velocity direction of each coordinate point; For any coordinate point, the Doppler angle of the coordinate point is determined according to the blood flow velocity direction at the coordinate point and the direction vector of the scanning light beam, and the absolute blood flow velocity at the coordinate point is obtained according to the Doppler angle.

4. The blood flow velocity calculation method according to claim 3, characterized in that: The direction vector of the scanning beam for: ; ； ； ； ； ； in, for The focal length of the first focusing lens of the system, for The focal length of the system's second focusing lens, and They are respectively the scanning beam passing through the scanning two-dimensional scanning galvanometer. Direction and The deflection angle of the direction, For scanning beam The angle of the direction, For scanning light The eye angle of the direction.

5. The blood flow velocity calculation method according to claim 1, characterized in that: No. The direction of blood flow velocity at the coordinate point: ； in, , and For the The three-axis coordinates of the coordinate points, , and For the The three-axis coordinates of the coordinate points, Respectively The direction of the coordinate points along the XYZ axes.

6. The blood flow velocity calculation method according to claim 5, characterized in that: No. The Doppler angle of the coordinate point for: .

7. The blood flow velocity calculation method according to claim 6, characterized in that: According to the Doppler angle, the The absolute blood flow velocity at the coordinate point: ,in, For the The Doppler shift of the coordinate point is is the refractive index of the medium, is the central wavelength of the light source, For the The Doppler angle of the coordinate point.

8. An OCT system for blood flow velocity calculation, characterized in that: include: A light source, a coupler, a spectrometer, a processing terminal, a sample arm and a reference arm, wherein the light source is connected to the coupler via a first collimator and a fiber coupler in sequence, the processing terminal is connected to the spectrometer, the spectrometer is connected to the coupler, the coupler is connected to the sample arm via a polarization controller, and the coupler is connected to the reference arm; The sample arm includes a second collimator, a two-dimensional scanning galvanometer, system and an adjustable focus lens, the reference arm comprising a third collimator, a dispersion compensation lens, an adjustable attenuator and a reflector arranged in sequence along the optical path; The processing terminal is configured to execute the blood flow velocity calculation method according to any one of claims 1-7.

9. A computer device, characterized in that: include: a processor and a computer readable storage medium; a processor adapted to execute a computer program; A computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by the processor, the blood flow velocity calculation method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is suitable for being loaded by a processor and executing the blood flow velocity calculation method according to any one of claims 1 to 7.

11. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the blood flow velocity calculation method according to any one of claims 1 to 7 is implemented.

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