Spatial scanning type corneal topographic map detection method and equipment

Abstract

The invention relates to the technical field of corneal topography map detection, in particular to a space scanning type corneal topography map detection method and equipment, and the method comprises the steps: shooting a reflection bright area image of a light transmitting device on a cornea with the radius RC through a camera device, and recording the Y-axis distance wd between the light-transmitting device and the cornea, the radius l1 of the bright area edge of the light-transmitting device and the distance m1 between the bright area edge of the light-transmitting device and the camera device when each reflection bright area image is shot, and completing reconstruction of the cornea surface topography based on the detection data. According to the scheme, the corneal topography can be accurately scanned and captured, so that the corneal topography map with high resolution and high precision is generated.

Description

Technical Field

[0001] The present invention relates to the technical field of corneal topography detection, and in particular to a spatial scanning corneal topography detection method and device. Background Art

[0002] Corneal topography is generally used to measure and map the shape and curvature of the cornea in order to analyze the corneal curvature, surface shape, refractive power distribution and other characteristics.

[0003] Corneal topographers based on Placido disks are widely used in corneal topography detection. They mainly include four parts: Placido disk, lighting system, camera system and image processing system. Placido disk is an optical device composed of multiple concentric circles that alternate between light and dark. The lighting system illuminates the Placido disk and projects the concentric circle pattern onto the corneal surface. After the corneal surface is reflected, the reflected concentric circles containing the corneal surface information will be captured by a high-resolution camera. After the image processing module, a corneal topography displayed in the form of a two-dimensional intuitive image can be generated.

[0004] As mentioned above, the Placido disk is the core optical system of the corneal topographer. The existing Placido disk contains 20-32 rings. Although theoretically, the more rings the Placido disk has, the higher the resolution of the corneal topography and the more detailed the peripheral corneal details are, the Placido disk with multiple rings still has the following problems in design, processing and clinical application:

[0005] ① The non-uniform, high-contrast multi-ring Placido disk will seriously affect the comfort of human visual perception during projection, causing eye discomfort and increasing visual burden.

[0006] ② It is necessary to process light and dark alternating rings with an accuracy of 10μm on the inner surface of the cone cylinder, which has high requirements on materials, processing technology and processing equipment.

[0007] ③Generally, corneal topographers are equipped with a fixed Placido disk, whose circular parameters cannot be adjusted. They can only obtain corneal information of the projection position of the bright ring in the Placido disk, but cannot obtain continuous, high-resolution corneal information. The sampling of the corneal lesion position is insufficient, and there is a risk of misdiagnosis.

[0008] ④ The reflection image captured by the camera system contains multiple light and dark stripes. When the local corneal curvature changes dramatically, the images of different stripes are likely to interfere with each other, increasing the difficulty of the image edge recognition method.

[0009] To solve the above problems, Chinese patent application No. 202210975134.X proposes an alternative solution to the Placido disk and its illumination system: outputting corneal reflection information by projecting annular light onto the cornea. However, this solution still has the following problems:

[0010] ① When the shaping module uses a conical lens to convert parallel light into a hollow conical light beam, dispersion cannot be avoided. The annular image presented on the projection disk is dispersed, and the accuracy of the image on the projection disk cannot be guaranteed, and the imaging quality of the camera system cannot be guaranteed.

[0011] ② The projection disk is just an ordinary frosted plate. The hollow cone light beam is scattered and the brightness is attenuated on the frosted projection disk, and the imaging quality of the ring pattern reflected by the cornea cannot be guaranteed.

[0012] ③ When the first motion mechanism drives the projection disk to move relative to the light source mechanism, the brightness of the annular light beam projected on the flat projection disk will change with the movement distance. Therefore, it is impossible to ensure that the brightness of the projection disk is uniform during the movement, and it is impossible to capture a ring pattern with stable brightness.

[0013] ④ The flat projection disk will limit the projection range of the hollow cone light beam on the cornea. The angle between the incident light and the light reflected by the cornea will not exceed 90°, and the detection ability of the central and marginal parts of the cornea is weak.

[0014] In summary, the above scheme cannot avoid the dispersion, scattering and brightness attenuation problems of the projection device system, nor can it fundamentally solve the problems of low resolution and limited detection range of corneal topographers based on Placido disks.

[0015] To summarize the above analysis, there is still a lack of high-resolution, high-precision, and high-visual-comfort corneal topographers and corresponding corneal topography detection methods. Summary of the invention

[0016] The object of the present invention is to provide a spatial scanning corneal topography detection method and device to solve at least one technical problem existing in the prior art.

[0017] In order to solve the above technical problems, the present invention provides a spatial scanning corneal topography detection method, which is characterized by comprising the steps of:

[0018] S1: Use a camera to photograph the light-transmitting device at a radius of R C The reflected bright area image on the cornea is recorded, and the Y-axis distance wd between the light-transmitting device and the cornea, the edge radius l1 of the bright area of ​​the light-transmitting device, and the distance m1 between the edge of the bright area of ​​the light-transmitting device and the camera device are recorded when each reflected bright area image is captured;

[0019] S2: Extract the image bright area radius r0 of the reflection point P from the reflection bright area image, and C , the relationship between the image bright area radius r0, the Y-axis distance wd, the edge radius l1 of the bright area of ​​the light-transmitting device and the distance m1 between the edge of the bright area of ​​the light-transmitting device and the camera device, draw the distance parameter diagram of the Y-axis calibration curve of the three-dimensional mobile platform, and determine the first distance wd1 and the cut-off distance wd off ; The relationship is:

[0020]

[0021] S3: Preprocess the corneal reflection bright area image by using the corneal reflection bright area image edge extraction method to obtain the image edge feature E and bright area radius r of the corneal reflection bright area image ij , the center coordinates E0 of the first bright area and the radius of the first bright area;

[0022] S4: By the first distance wd1 and the cut-off distance wd off The distance between the edge of the two bright areas and the corneal vertex is not less than wd. i The distance wd between the edge of the bright area and the corneal vertex is obtained by corneal surface topography reconstruction method. i The corresponding bright area reflection point coordinates are used to reconstruct the corneal surface topography;

[0023] S5: Describe the corneal surface morphology at the reflection point coordinates to complete the detection; the description of the corneal surface morphology at the reflection point coordinates includes the corneal curvature radius and refractive power.

[0024] Furthermore, the position of the light-transmitting device on the X-axis and the Z-axis is adjusted by the three-dimensional mobile platform so that the camera device corresponds to the center of the cornea, and an annular or circular bright area is reflected on the cornea, and the center of the cornea coincides with the center of the bright area projected on the cornea by the light-transmitting device;

[0025] Then, the camera device and the light transmission device are driven on the Y axis by the three-dimensional mobile platform, and the bright area image reflected on the cornea by the light of the light transmission device is captured by the camera device;

[0026] When the three-dimensional mobile platform drives the camera device and the light transmission device on the Y axis, the distance from the light transmission device to the cornea is continuously changed, so that the radius of the bright area projected on the corneal reflection bright area image changes evenly as it moves along the Y axis;

[0027] The minimum arc length projected on the corneal surface is between 3-4 mm, and the minimum projection radius is between 1.5-2 mm. At this time, the bright area is defined as the first bright area, and the Y-axis scale is defined as the first distance wd1.

[0028] Furthermore, the distance parameter diagram of the Y-axis calibration curve of the three-dimensional mobile platform includes the following parameters: the first distance wd1 is the Y-axis distance corresponding to when r is equal to the radius of the first bright area; the cut-off distance wd off is the Y-axis distance when the bright area radius is the largest, and the maximum bright area radius is r off ; Maximum detection angle θ max is the maximum detection angle of the spatial scanning corneal topography detection system, calculated as

[0029] θ max =2sin -1 (r off / R c ).

[0030] Furthermore, the method for extracting the edge of the corneal reflection bright area image includes: filtering and denoising the corneal reflection bright area image and performing image binarization filtering, then performing image edge segmentation, and calculating the corneal center after the image edge segmentation.

[0031] Furthermore, the filtering and noise reduction is used to process the image to remove the uneven background of the image, enhance the local features of the bright area, filter the image noise, and improve the image segmentation and binarization effects.

[0032] Furthermore, the image edge segmentation is used to process the first bright area image and the non-first bright area image; when processing the first bright area image, the image edge feature E is extracted, and the coordinates of the center of the first bright area E0 and the radius of the first bright area are identified; when processing the non-first bright area image, the image edge feature E is extracted, and the image edge feature E is sampled according to different corneal meridian directions to obtain different bright area radii r ij ;

[0033] The image edge feature E is represented as follows: for a circular ring light-transmitting device, the image edge feature E is represented by a bright ring of the bright area image reflected by the cornea; for a disk light-transmitting device, the image edge feature E is represented by the edges of the circular bright area and dark area of ​​the bright area image reflected by the cornea.

[0034] Furthermore, the corneal surface topography reconstruction method is specifically as follows: when the distance between the edge of the bright area and the corneal vertex is wd i When the reflection point coordinates (r i ,y i )、(r i-1 ,y i-1 ), tangent slope t i ,t i-1 Satisfying relationship between:

[0035]

[0036] According to the coordinates of the first bright area reflection point (r0, y0) and the tangent slope t0=0, the coordinates of the remaining bright area reflection points are iteratively calculated, where i>1.

[0037] Furthermore, the first bright area coordinate y0 is approximated as the curvature radius at the center of the cornea: According to the formula

[0038]

[0039] Calculate the center radius of the bright area of ​​the corneal reflection bright area image, and solve the first bright area coordinate y0 as the curvature radius of the corneal center. The solution method of y0 is:

[0040]

[0041] Furthermore, the geometric relationship of the light paths in the remaining bright areas is calculated:

[0042]

[0043]

[0044] According to the coordinates of the first bright area reflection point (r0, y0) and the tangent slope t0 = 0, wd is iteratively calculated. i The corneal surface coordinates are located to complete the reconstruction of the corneal surface topography;

[0045] Calculate the reflection point P based on the reconstructed data of the corneal surface topography ij (r ij ,y ij ) Corneal curvature radius ρ ij :

[0046]

[0047] Where γ(y) represents the polynomial curve expression of the cornea fitting along the meridian;

[0048] P is calculated based on the reconstructed data of corneal surface topography. ij Corneal diopter at the reflection point K ij for:

[0049]

[0050] Where n*=337.5, represents the corneal refractive index.

[0051] On the other hand, the present application also discloses a spatial scanning corneal topography detection device, including a light transmission device, a camera device, a three-dimensional mobile platform, a corneal topography reconstruction module and a display module;

[0052] The camera device is arranged on the light-transmitting device;

[0053] The light transmission device is arranged on the three-dimensional moving platform;

[0054] The three-dimensional mobile platform controls the light-transmitting device to move in the X, Y and Z directions;

[0055] The camera device is electrically connected to the corneal topography reconstruction module, and the corneal topography reconstruction module reconstructs the corneal topography according to the information transmitted by the camera device;

[0056] The corneal topography reconstruction module is conductively connected to the display module, and the corneal topography reconstruction result is displayed through the display module.

[0057] Furthermore, the light-transmitting device includes an annular light-transmitting area or a circular light-transmitting area, and except for the annular light-transmitting area or the circular light-transmitting area, other areas are not light-transmitting.

[0058] Furthermore, the light-transmitting device also includes a lighting system, which is arranged behind the annular light-transmitting area or the circular light-transmitting area to provide lighting to form a backlight so that the transmitted light is projected onto the corneal surface.

[0059] Furthermore, the three-dimensional mobile platform first adjusts the position of the light-transmitting device on the X-axis and the Z-axis to make the camera device correspond to the center position of the cornea, and a ring or a circular bright area is reflected on the cornea. The center of the cornea coincides with the center of the bright area projected on the cornea by the light-transmitting device. Then, the Y-axis movement range is planned according to the calibration curve, and the distance from the light-transmitting device to the cornea is continuously changed, and the radius of the bright area projected on the cornea will also change accordingly.

[0060] Furthermore, when the light transmitting device moves along the Y axis, the radius of the bright area projected on the corneal reflected bright area image changes uniformly as it moves along the Y axis.

[0061] Furthermore, the trajectory of the light transmission device moving along the Y axis adopts the method of moving from far to near. According to the calibration curve, the Y axis distance moves from the first distance wd1 to the cut-off distance wd off , that is, the radius of the bright area projected on the corneal surface of the eye being tested gradually increases.

[0062] Furthermore, the trajectory of the light transmission device moving along the Y axis adopts the method of moving from near to far. According to the calibration curve, the Y axis distance is determined by the cut-off distance wd off When the distance moves to the first distance wd1, the radius of the bright area projected on the corneal surface of the eyeball being measured gradually decreases.

[0063] Furthermore, the minimum arc length projected on the corneal surface is between 3-4 mm, and the minimum projection radius is between 1.5-2 mm. At this time, the bright area is the first bright area, and the Y-axis scale is the first distance.

[0064] Furthermore, the camera device is arranged at the center of the light transmission device, and is used to capture the light reflected from the corneal surface, so as to obtain a corneal reflection bright area image including bright areas and dark areas;

[0065] When the light-transmitting device moves along the Y-axis direction, the camera device captures corneal reflection bright area images corresponding to different bright area radii at different Y-axis coordinates and transmits the images to the corneal topography reconstruction module;

[0066] The corneal topography reconstruction module reconstructs the corneal topography by a corneal reconstruction method, thereby generating a high-resolution and high-precision corneal topography map which is displayed by the display module.

[0067] Furthermore, the light-transmitting device includes an annular light-transmitting area, and the corneal topography reconstruction module performs edge detection and feature extraction on the entire annular reflective area, and finally obtains corneal topography information of the annular reflective area.

[0068] Furthermore, the light-transmitting device includes a circular light-transmitting area, and the corneal topography reconstruction module detects and extracts features from the edges of the reflected bright and dark areas, and finally obtains corneal topography information at the edges.

[0069] Furthermore, the lighting system has a light source array designed according to the photopic spectral luminous efficiency of human eyes, the spectral response curve of the photoelectric conversion element, and the instrument's requirements for the illumination and luminous uniformity of the surface light source.

[0070] Furthermore, the camera system includes a lens group and a camera, and the camera is a CCD camera or a CMOS camera.

[0071] Furthermore, the three-dimensional mobile platform is an XYZ three-axis precision platform driven by a stepper motor.

[0072] By adopting the above technical solution, the present invention has the following beneficial effects:

[0073] (1) By combining a high-precision three-dimensional mobile platform with an advanced camera device, it is possible to accurately scan and capture the corneal topography, thereby generating a high-resolution, high-precision corneal topography map.

[0074] (2) The device is reasonably designed and easy to operate. A comprehensive scan of the cornea can be achieved by simply adjusting the position of the light-transmitting device, which greatly simplifies the detection process and improves work efficiency.

[0075] (3) The light-transmitting device can select an annular or circular light-transmitting area according to actual needs, which can flexibly meet the detection needs of different corneal morphologies and enhance the versatility and practicality of the device.

[0076] (4) The lighting system is carefully designed based on the visual characteristics of the human eye and the requirements of the instrument, ensuring the uniformity and stability of the light, further improving the accuracy and reliability of the test results.

[0077] (5) The three-dimensional mobile platform can adjust the position and angle of the light-transmitting device according to the detection requirements, cooperate with the real-time capture of the camera device and the rapid processing of the corneal topography reconstruction module, and realize the automation and intelligence of the detection process.

[0078] (6) The corneal topography reconstruction module uses advanced methods to process and analyze the captured images and can accurately extract corneal topography information.

[0079] (7) The image preprocessing step of this scheme effectively improves the segmentation effect of the corneal reflection bright area image and the extraction accuracy of edge features, providing a reliable basis for the subsequent corneal surface morphology reconstruction.

[0080] (8) By combining the corneal surface topography reconstruction method with the corneal surface topography description, the coordinates of the corneal surface feature points can be quickly calculated and the corneal topography can be described, which greatly shortens the detection time and improves work efficiency.

[0081] (9) The entire detection process is highly automated, from adjusting the position of the light-transmitting device, capturing the corneal reflection bright area image, to image preprocessing, feature extraction and corneal morphology reconstruction. No human intervention is required, which reduces the difficulty of operation and human error.

[0082] (10) This scheme provides a new method for low-cost, high-precision corneal topography detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0084] Figure 1 It is a schematic diagram of the three-dimensional structure of a spatial scanning corneal topography detection device;

[0085] Figure 2 It is a schematic diagram of the three-dimensional structure of the light transmission device;

[0086] Figure 3 This is a schematic diagram for solving the Y-axis calibration curve of the three-dimensional displacement platform;

[0087] Figure 4 It is the distance parameter diagram of the Y-axis calibration curve of the three-dimensional mobile platform;

[0088] Figure 5 This is a flow chart of the edge extraction method of the corneal reflection bright area image;

[0089] Figure 6 defined for the edge E of the ring and disk images;

[0090] Figure 7 Schematic diagram for solving the central curvature radius of the cornea;

[0091] Figure 8 wd is the distance between the edge of the bright area and the corneal vertex i Corneal height y i Solution diagram;

[0092] Fig. 9 is the corneal curvature radius ρ ij Solution diagram;

[0093] Fig.10 It is a system calibration curve diagram drawn according to the actual system parameters;

[0094] Fig.11 The figure is a detailed flow chart of the spatial scanning corneal topography detection method.

[0095] Reference numerals:

[0096] 1-light transmission device; 2-illumination system; 3-camera device; 4-three-dimensional mobile platform; 5-tested eyeball; 6-corneal topography reconstruction module; 7-display module. DETAILED DESCRIPTION

[0097] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0098] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0099] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0100] It should also be noted that the following specific embodiments or specific implementations are a series of optimized settings listed in the present invention to further explain the specific content of the invention, and these settings can be used in combination or in association with each other.

[0101] The present invention is further explained below in conjunction with specific implementation modes.

[0102] Example 1

[0103] like Figure 1-2 As shown, a spatial scanning corneal topography detection device provided in this embodiment includes a light transmission device 1, a camera device 3, a three-dimensional mobile platform 4, a corneal topography reconstruction module 6 and a display module 7.

[0104] The camera device 3 is arranged on the light-transmitting device 1;

[0105] The light transmission device 1 is arranged on the three-dimensional mobile platform 4;

[0106] The three-dimensional mobile platform 4 controls the light-transmitting device 1 to move in the X, Y and Z directions;

[0107] The camera device 3 is electrically connected to the corneal topography reconstruction module 6, and the corneal topography reconstruction module 6 reconstructs the corneal topography of the eyeball 5 to be measured through the information transmitted by the camera device 3;

[0108] The corneal topography reconstruction module 6 is electrically connected to the display module 7 , and displays the corneal topography reconstruction result of the measured eyeball 5 through the display module 7 .

[0109] As a further implementation of this embodiment, the light-transmitting device 1 includes an annular light-transmitting area or a circular light-transmitting area, and except for the annular light-transmitting area or the circular light-transmitting area, other areas are not light-transmitting.

[0110] As a further implementation of this embodiment, the light-transmitting device 1 also includes an illumination system 2, which is arranged behind the annular light-transmitting area or the circular light-transmitting area to provide illumination to form a backlight so that the transmitted light is projected onto the corneal surface of the eyeball 5 to be tested.

[0111] As a further implementation of this embodiment, the three-dimensional mobile platform 4 first adjusts the position of the light-transmitting device 1 on the X-axis and the Z-axis to make the camera device 3 correspond to the center position of the cornea of ​​the eyeball 5 to be tested. At this time, a ring or a circular bright area is reflected on the cornea of ​​the eyeball 5 to be tested, and the center of the cornea of ​​the eyeball 5 to be tested coincides with the center of the bright area projected on the cornea of ​​the eyeball 5 by the light-transmitting device 1. Then, the farthest distance between the light-transmitting device 1 and the eyeball 5 to be tested is calculated according to the calibration curve, which is called the first distance wd1, and the shortest distance between the light-transmitting device 1 and the eyeball 5 to be tested is calculated, which is called the cut-off distance wd off According to the first distance wd1 and the cut-off distance wd off The Y-axis moving range is planned to continuously change the distance from the light-transmitting device 1 to the cornea of ​​the eyeball 5 to be tested, and the radius of the bright area projected on the cornea of ​​the eyeball 5 to be tested will also change accordingly.

[0112] As a further implementation of this embodiment, when the light transmitting device 1 moves along the Y axis, the radius of the bright area in the corneal reflection bright area image projected on the eyeball 5 to be tested changes uniformly as it moves along the Y axis.

[0113] As a further implementation of this embodiment, the trajectory of the light transmission device 1 moving along the Y axis adopts the method of moving from far to near. According to the calibration curve, the Y axis distance moves from the first distance wd1 to the cut-off distance wd off , that is, the radius of the bright area projected on the corneal surface of the eyeball 5 being tested gradually increases.

[0114] As a further implementation of this embodiment, the trajectory of the light transmission device 1 moving along the Y axis adopts the method of moving from near to far. According to the calibration curve, the Y axis distance is determined by the cut-off distance wd off When the distance moves to the first distance wd1, the radius of the bright area projected on the corneal surface of the eyeball 5 to be measured gradually decreases.

[0115] As a further implementation of this embodiment, the minimum arc length projected on the corneal surface of the eyeball 5 to be tested is between 3-4 mm, and the minimum projection radius is between 1.5-2 mm. At this time, the bright area is the first bright area, and the Y-axis scale is the first distance.

[0116] As a further implementation of this embodiment, the camera device 3 is arranged at the center of the light transmission device 1, and is used to capture the light reflected from the corneal surface of the eyeball 5 to be tested, so as to obtain a corneal reflection bright area image of the eyeball 5 to be tested, which includes bright areas and dark areas;

[0117] When the light transmission device 1 moves along the Y-axis direction, the camera device 3 captures corneal reflection bright area images corresponding to different bright area radii at different Y-axis coordinates and transmits the images to the corneal topography reconstruction module 6;

[0118] The corneal topography reconstruction module 6 reconstructs the corneal topography of the eyeball 5 to be measured by a corneal reconstruction method, thereby generating a high-resolution and high-precision corneal topography map which is displayed by the display module 7 .

[0119] As a further implementation of this embodiment, the light-transmitting device 1 includes an annular light-transmitting area, and the corneal topography reconstruction module 6 performs edge detection and feature extraction on the entire annular reflective area, and finally obtains the corneal morphology information of the measured eyeball 5 in the annular reflective area.

[0120] As a further implementation of this embodiment, the light-transmitting device 1 includes a circular light-transmitting area, and the corneal topography reconstruction module 6 detects and extracts features from the edges of the reflected bright and dark areas, and finally obtains corneal topography information at the edges.

[0121] As a further implementation of this embodiment, the lighting system 2 is a light source array designed based on the photopic spectral luminous efficiency of the human eye, the spectral response curve of the photoelectric conversion element, and the instrument's requirements for the illumination and luminous uniformity of the surface light source.

[0122] As a further implementation of this embodiment, the camera system includes a lens group and a camera, and the camera is a CCD camera or a CMOS camera.

[0123] As a further implementation of this embodiment, the three-dimensional mobile platform 4 is an XYZ three-axis precision platform driven by a stepper motor.

[0124] By adopting the above technical solution, the present invention has the following beneficial effects:

[0125] (1) Through the precise control of the three-dimensional mobile platform 4, combined with the camera device 3 and the corneal topography reconstruction module 6, high-resolution and high-precision reconstruction of the corneal topography of the eyeball 5 can be achieved, which significantly improves the accuracy of detection compared with traditional methods.

[0126] (2) The light-transmitting device 1 is simple in design and only includes a bright ring or a bright disk, which reduces visual interference, makes the detection process more comfortable, and simplifies the operation process.

[0127] (3) The light-transmitting device 1 has a built-in lighting system 2, which provides a stable backlight effect, ensuring that a clear corneal reflection bright area image can be obtained under different lighting conditions, thereby enhancing the applicability and stability of the device.

[0128] (4) The three-dimensional mobile platform 4 can automatically adjust the position of the light-transmitting device 1 according to a preset trajectory, quickly capture the corneal reflection bright area image under different Y-axis coordinates, and combine with an efficient corneal reconstruction method to significantly shorten the detection time.

[0129] (5) The light-transmitting device 1 can select an annular or circular light-transmitting area according to needs, and the corneal topography reconstruction module 6 can perform edge detection and feature extraction for reflective areas of different shapes, thereby adapting to the detection needs of different corneal morphologies.

[0130] (6) The lighting system 2 is designed according to the visual characteristics of the human eye and the response curve of the photoelectric conversion element, ensuring the uniformity and illumination of the light source and further improving the accuracy of the detection results.

[0131] Example 2

[0132] like Figure 1-11 As shown, this embodiment provides a spatial scanning corneal topography detection method, which is completed using the device in Example 1.

[0133] Referring to Example 1, the position of the light-transmitting device on the X-axis and Z-axis is adjusted by the three-dimensional mobile platform so that the camera device corresponds to the center of the cornea, a ring or circular bright area is reflected on the cornea, and the center of the cornea coincides with the center of the bright area projected on the cornea by the light-transmitting device. The distance from the light-transmitting device to the cornea is continuously changed so that the radius of the bright area projected on the cornea reflected bright area image changes uniformly along the Y-axis, so that the minimum arc length projected on the corneal surface is between 3-4 mm, and the minimum projection radius is between 1.5-2 mm. At this time, the bright area is defined as the first bright area, and the Y-axis scale is defined as the first distance. In the above process, the camera device captures corneal reflected bright area images corresponding to different bright area radii at different Y-axis coordinates and transmits the images to the corneal topography reconstruction module.

[0134] Figure 3 The schematic diagram of solving the Y-axis calibration curve of the three-dimensional displacement platform during the above operation, S R The light at the cornea is reflected by the CCD camera and then captured to obtain the cornea reflection bright area image. Before corneal topography reconstruction, the light source S needs to be calculated using the model eye data. R The relationship between the Y-axis component of the corneal vertex (ie, the Y-axis distance wd) and the reflection point P is used to calibrate the parameters of the spatial scanning corneal topography detection system.

[0135] The corneal topography reconstruction module abstracts the cornea into a C According to the light reflection theorem, the following geometric relationship exists on the spherical surface:

[0136]

[0137] Among them, r0 is the coordinate of the reflection point P in the r-axis direction, that is, the radius of the bright area of ​​the image, l1 is the radius of the edge of the bright area of ​​the light-transmitting device, and m1 is the distance between the edge of the bright area of ​​the light-transmitting device and the camera CCD. Combining the above formula, the relationship equation between the image bright area radius r and the Y-axis distance wd is obtained:

[0138]

[0139] The numerical solution of wd-r is calculated and plotted as follows Figure 4 The Y-axis calibration curve distance parameter diagram of the three-dimensional mobile platform shown in the figure, wherein the first distance wd1 refers to the Y-axis distance corresponding to when r is equal to the radius of the first bright area; the cut-off distance wd off is the Y-axis distance when the bright area radius is the largest. The maximum bright area radius (i.e., the cutoff radius) is r off ; Maximum detection angle θ max is the maximum detection angle of the spatial scanning corneal topography detection system, equal to

[0140] θ max =2sin -1 (r off / R C ) (6).

[0141] As a further implementation of this embodiment, the parameter R of the model eye C =7.8mm, system parameters m1 = 40mm, l1 = 100mm, the calculated system calibration curve is as follows Fig.10 In this example, the system first distance wd1 = 237.66 mm, the cut-off distance wd off =-1.33mm, cut-off radius (i.e., maximum bright area radius) r off =5.14mm, maximum detection angle θ max =88.34°. Since the distance between the upper and lower eyelids of humans is generally between 9-10mm, the transverse diameter of the cornea is about 11.5-12mm, and the vertical diameter is about 10.5-11mm, and the maximum diameter that can be detected by this application is 10.28mm, which can basically cover the entire cornea, and thus can meet the requirements of full corneal surface morphology detection.

[0142] During the corneal reconstruction process, the corneal reflection image is preprocessed, the coordinates of the corneal surface feature points are calculated, and the corneal morphology is described through the corneal reflection bright area image edge extraction method, corneal surface morphology reconstruction method, and corneal surface morphology description.

[0143] The method for extracting the edge of the corneal reflection bright area image comprises: filtering and denoising the corneal reflection bright area image and performing image binarization filtering, then performing image edge segmentation, and calculating the corneal center after the image edge segmentation.

[0144] Preferably, the filtering and noise reduction processes the image to remove the uneven background of the image, enhance the local features of the bright area, filter the image noise, and improve the image segmentation and binarization effects.

[0145] Furthermore, the image binarization filtering uses Otsu binarization to convert the grayscale image obtained through filtering and noise reduction processing into a binary image, so as to facilitate image segmentation.

[0146] Preferably, the image edge segmentation is used to process the first bright area image and the non-first bright area image after the image binarization filtering process. When processing the first bright area image, the image edge feature E is extracted, and the coordinates of the center of the first bright area E0 and the radius of the first bright area are identified; when processing the non-first bright area image, the image edge feature E is extracted, and the image edge feature E is sampled according to different corneal meridian directions to obtain different bright area radii r ij Among them, light transmission devices of different shapes have different definitions for the image edge feature E. For the ring light transmission device, the bright ring of the bright area image reflected by the cornea is used to represent the image edge feature E, and for the disk light transmission device, the edges of the circular bright area and dark area of ​​the bright area image reflected by the cornea are used to represent the image edge feature E.

[0147] like Figure 7 As shown, S R The light is reflected by the cornea P and captured by the CCD camera to obtain an image of the first bright area radius. At this time, the bright area radius is the minimum bright area radius.

[0148] When the corneal surface topography is reconstructed, when the distance between the edge of the bright area and the corneal vertex is wd i (i>1 and is an integer), the reflection point coordinates (r i ,y i )、(r i-1 ,y i-1 ), tangent slope t i ,t i-1 Satisfying relationship between:

[0149]

[0150] Therefore, the coordinates of the remaining bright area reflection points can be iteratively calculated based on the coordinates of the first bright area reflection point (r0, y0) and the tangent slope t0=0.

[0151] Specifically, the distance wd between the edge of the bright area and the corneal vertex is i The value range is between the first distance wd1 and the cut-off distance wd off In actual operation, wd i The number of values ​​can be increased or decreased according to actual conditions, but should not be less than 2.

[0152] Specifically, Figure 7 , the coordinate y0 of the first bright area is approximately the radius of curvature at the center of the cornea, according to the formula

[0153]

[0154] The center radius of the bright area of ​​the corneal reflection bright area image is calculated, and the geometric relationship of light reflection is obtained:

[0155]

[0156] θ=φ-α (12)

[0157] Combining the above formulas, we can solve the first bright area coordinate y0, which is the radius of curvature of the corneal center:

[0158]

[0159] Specifically, Figure 8 , calculate the geometric relationship of the light path of the remaining bright areas:

[0160]

[0161] According to the coordinates of the first bright area reflection point (r0, y0), the tangent slope t0 = 0, combined with formula (7), wd is calculated iteratively i The corneal surface coordinates are located at the corneal surface to complete the reconstruction of the corneal surface morphology.

[0162] The corneal surface morphology is Fig. 9 As shown, the corneal curvature radius and refractive power are calculated based on the reconstructed data of the corneal surface topography.

[0163] Calculate the reflection point P ij (r ij ,y ij ) Corneal curvature radius ρ ij :

[0164]

[0165] Where γ(y) represents the polynomial curve expression of the cornea fitting along the meridian. ij The corneal diopter at the reflection point is:

[0166]

[0167] Where n*=337.5 represents the corneal refractive index (1 / m).

[0168] By adopting the above technical solution, the present invention has the following beneficial effects:

[0169] (1) The position of the light-transmitting device is precisely adjusted by a three-dimensional mobile platform, combined with advanced camera devices and corneal topography reconstruction modules, to achieve high-precision detection of corneal topography. Using the model eye features and light reflection theorem, an accurate geometric relationship model is constructed, further improving the accuracy of the detection results.

[0170] (2) The entire detection process is highly automated. From adjusting the position of the light-transmitting device, capturing the corneal reflection bright area image, to image preprocessing, feature extraction and corneal morphology reconstruction, no human intervention is required, which greatly reduces the difficulty of operation and human error.

[0171] (3) The use of advanced filtering noise reduction, image binarization filtering and image edge segmentation effectively improves the quality of corneal reflection bright area images and provides a reliable basis for subsequent corneal surface morphology reconstruction.

[0172] (4) The corneal surface topography reconstruction method obtains the corneal surface coordinates through iterative calculation, achieving accurate reconstruction of the corneal topography. At the same time, based on the reconstructed data of the corneal surface topography, the corneal curvature radius and refractive power are described, providing more intuitive corneal topography information.

[0173] (5) This method can adapt to light-transmitting devices of different shapes. Whether it is a ring or a disk, it can be processed by the corresponding image edge feature extraction method, which enhances the versatility and flexibility of detection.

[0174] (6) The generated corneal topography can clearly show the subtle changes on the corneal surface, which helps to accurately judge the corneal condition.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A spatial scanning corneal topography detection method, characterized in that: Includes steps: S1: Use a camera to photograph the light-transmitting device at a radius of R C The reflected bright area image on the cornea is recorded, and the Y-axis distance wd between the light-transmitting device and the cornea, the edge radius l1 of the bright area of ​​the light-transmitting device, and the distance m1 between the edge of the bright area of ​​the light-transmitting device and the camera device are recorded when each reflected bright area image is captured; S2: Extract the image bright area radius r0 of the reflection point P from the reflection bright area image, and C , the relationship between the image bright area radius r0, the Y-axis distance wd, the edge radius l1 of the bright area of ​​the light-transmitting device and the distance m1 between the edge of the bright area of ​​the light-transmitting device and the camera device, draw the distance parameter diagram of the Y-axis calibration curve of the three-dimensional mobile platform, and determine the first distance wd1 and the cut-off distance wd off ; The relationship is: S3: Preprocess the corneal reflection bright area image by using the corneal reflection bright area image edge extraction method to obtain the image edge feature E and bright area radius r of the corneal reflection bright area image. ij , the center coordinates E0 of the first bright area and the radius of the first bright area; S4: By the first distance wd1 and the cut-off distance wd off The distance between the edge of the two bright areas and the corneal vertex is not less than wd. i The distance wd between the edge of the bright area and the corneal vertex is obtained by corneal surface topography reconstruction method. i The corresponding bright area reflection point coordinates are used to reconstruct the corneal surface topography; S5: Describe the corneal surface morphology at the reflection point coordinates to complete the detection; the description of the corneal surface morphology at the reflection point coordinates includes the corneal curvature radius and refractive power.

2. The spatial scanning corneal topography detection method according to claim 1, characterized in that: The position of the light-transmitting device on the X-axis and the Z-axis is adjusted by a three-dimensional mobile platform so that the camera device corresponds to the center of the cornea, and an annular or circular bright area is reflected on the cornea, and the center of the cornea coincides with the center of the bright area projected on the cornea by the light-transmitting device; Then, the camera device and the light transmission device are driven on the Y axis by the three-dimensional mobile platform, and the bright area image reflected on the cornea by the light of the light transmission device is captured by the camera device; When the three-dimensional mobile platform drives the camera device and the light transmission device on the Y axis, the distance from the light transmission device to the cornea is continuously changed, so that the radius of the bright area projected on the corneal reflection bright area image changes evenly as it moves along the Y axis; The minimum arc length projected on the corneal surface is between 3-4 mm, and the minimum projection radius is between 1.5-2 mm. At this time, the bright area is defined as the first bright area, and the Y-axis scale is defined as the first distance wd1.

3. The spatial scanning corneal topography detection method according to claim 1, characterized in that: The distance parameter diagram for drawing the Y-axis calibration curve of the three-dimensional mobile platform includes the following parameters: the first distance wd1 is the Y-axis distance corresponding to when r is equal to the radius of the first bright area; the cutoff distance wd off is the Y-axis distance when the bright area radius is the largest, and the maximum bright area radius is r off ; Maximum detection angle θ max is the maximum detection angle of the spatial scanning corneal topography detection system, calculated as i max =2sin -1 (r off / R c )。 4. The spatial scanning corneal topography detection method according to claim 1, characterized in that: The method for extracting the edge of a corneal reflection bright area image comprises: filtering and denoising the corneal reflection bright area image and performing image binarization filtering, then performing image edge segmentation, and calculating the corneal center after the image edge segmentation.

5. The spatial scanning corneal topography detection method according to claim 4, characterized in that: The filtering and noise reduction is used to process the image to remove the uneven background of the image, enhance the local features of the bright area, filter the image noise, and improve the image segmentation and binarization effects.

6. The spatial scanning corneal topography detection method according to claim 4, characterized in that: The image edge segmentation is used to process the first bright area image and the non-first bright area image; when processing the first bright area image, the image edge feature E is extracted, and the coordinates of the center of the first bright area circle E0 and the radius of the first bright area are identified; when processing the non-first bright area image, the image edge feature E is extracted, and the image edge feature E is sampled according to different corneal meridian directions to obtain different bright area radii r ij ; The image edge feature E is represented as follows: for a circular ring light-transmitting device, the image edge feature E is represented by a bright ring of the bright area image reflected by the cornea; for a disk light-transmitting device, the image edge feature E is represented by the edges of the circular bright area and dark area of ​​the bright area image reflected by the cornea.

7. The spatial scanning corneal topography detection method according to claim 6, characterized in that: The corneal surface topography reconstruction method is specifically as follows: when the distance between the edge of the bright area and the corneal vertex is wd i When the reflection point coordinates (r i ,y i )、(r i-1 ,y i-1 ), tangent slope t i ,t i-1 Satisfying relationship between: According to the coordinates of the first bright area reflection point (r0, y0) and the tangent slope t0=0, the coordinates of the remaining bright area reflection points are iteratively calculated, where i>1.

8. The spatial scanning corneal topography detection method according to claim 7, characterized in that: The first bright area coordinate y0 is approximated as the radius of curvature at the center of the cornea: According to the formula Calculate the center radius of the bright area of ​​the corneal reflection bright area image, and solve the first bright area coordinate y0 as the curvature radius of the corneal center. The solution method of y0 is:

9. The spatial scanning corneal topography detection method according to claim 8, characterized in that: Calculate the geometric relationship of the light paths in the remaining bright areas: According to the coordinates of the first bright area reflection point (r0, y0) and the tangent slope t0 = 0, wd is iteratively calculated. i The corneal surface coordinates are located to complete the reconstruction of the corneal surface topography; Calculate the reflection point P based on the reconstructed data of the corneal surface topography ij (r ij ,y ij ) Corneal curvature radius ρ ij : Where γ(y) represents the polynomial curve expression of the cornea fitting along the meridian; P is calculated based on the reconstructed data of corneal surface topography. ij Corneal diopter at the reflection point K ij for: Where n*=337.5, represents the corneal refractive index.

10. A spatial scanning corneal topography detection device, characterized in that: It includes a light transmission device, a camera device, a three-dimensional mobile platform, a corneal topography reconstruction module and a display module; The camera device is arranged on the light-transmitting device; The light transmission device is arranged on the three-dimensional moving platform; The three-dimensional mobile platform controls the light-transmitting device to move in the X, Y and Z directions; The camera device is electrically connected to the corneal topography reconstruction module, and the corneal topography reconstruction module reconstructs the corneal topography based on the data transmitted by the camera device and through the spatial scanning corneal topography detection method according to any one of claims 1 to 9; The corneal topography reconstruction module is conductively connected to the display module, and the corneal topography reconstruction result is displayed through the display module; the light-transmitting device includes an annular light-transmitting area or a circular light-transmitting area, and other areas except the annular light-transmitting area or the circular light-transmitting area are not light-transmitting; The light-transmitting device also includes a lighting system, which is arranged behind the annular light-transmitting area or the circular light-transmitting area to provide lighting to form a backlight so that the transmitted light is projected onto the corneal surface.

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