Corneal curvature monitoring device

Abstract

The invention relates to a corneal curvature monitoring device, which comprises a first corneal contact lens, a second corneal contact lens and a third corneal contact lens, the photogrammetric glasses are used for taking an image of the measurement target on the first corneal contact lens; and the terminal equipment is used for acquiring an image captured by the photogrammetry glasses and determining the position of the measurement target according to the image. According to the invention, continuous and dynamic monitoring of the corneal curvature can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of corneal curvature monitoring, and in particular to a corneal curvature monitoring device. Background Art

[0002] The cornea and sclera together form the outermost fibrous membrane of the eyeball. The cornea is also an important refractive matrix and is the only way for external light to enter the eye and form an image on the retina. The surface of the cornea is not a standard sphere. The central 1 / 3 of the front surface is close to a sphere, and the peripheral area is relatively flat. The average radius of curvature of the central cornea is 7.8mm (6.7-9.4mm). Corneal disease is one of the main causes of blindness in my country, and its incidence cannot be ignored.

[0003] Corneal curvature is important for understanding eye morphology changes, monitoring eye refractive errors, and inferring changes in intraocular pressure. Traditional corneal curvature monitoring is generally instantaneous static monitoring, lacking long-term dynamic continuous monitoring devices. Corneal curvature monitoring must be performed in the hospital, which is not only time-consuming and laborious for doctors and patients, but also unable to capture small changes in curvature in time. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a corneal curvature monitoring device which can realize continuous and dynamic monitoring of corneal curvature.

[0005] The technical solution adopted by the present invention to solve the technical problem is: to provide a corneal curvature monitoring device, comprising:

[0006] a first corneal contact lens, wherein a measurement target is disposed on the first corneal contact lens;

[0007] Photogrammetry glasses for capturing images of measurement targets on the first contact lens;

[0008] The terminal device is used to obtain the image captured by the photogrammetry glasses and determine the position of the measurement target according to the image.

[0009] There are four measurement targets, which are evenly distributed in the circumferential direction of the first corneal contact lens.

[0010] The measurement target is in the form of a circular mark, a diagonal mark and a coded mark.

[0011] The first corneal contact lens is made of flexible polydimethylsiloxane material.

[0012] The photogrammetry glasses include a glasses frame, a camera is arranged on the lens frame of the glasses frame, and the shooting direction of the camera is toward the user to be monitored; a controller and a memory are integrated in the temples of the glasses frame, and the controller is connected to the camera and is used to control the camera to shoot; the memory is used to store images taken by the camera; and a transmission line connected to the controller is provided at the end of the temple of the glasses frame, and the transmission line is used to be connected to the terminal device.

[0013] The corneal curvature monitoring device further comprises: a second corneal contact lens, on which a calibration plate is arranged.

[0014] The calibration plate is in the form of a checkerboard.

[0015] The controller is provided with a blink detection model, and the blink detection model determines whether the monitored user blinks according to the image information acquired by the camera. When the monitored user blinks, the controller controls the camera to take pictures.

[0016] The terminal device comprises:

[0017] A storage unit, used for storing an initial position of the measurement target on the first corneal contact lens;

[0018] A conversion unit, used for obtaining the position of the measurement target according to the mathematical correspondence between the points on the image and the spatial target points;

[0019] A calculation unit, used to calculate the curvature radius of the initial position and the curvature radius of the position of the measurement target, to obtain an initial curvature radius and a final curvature radius;

[0020] A comparison unit, used for comparing the initial curvature radius and the final curvature radius;

[0021] The determination unit is used to determine that the corneal curvature has changed when the difference between the initial curvature radius and the final curvature radius exceeds a threshold value.

[0022] Beneficial Effects

[0023] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: the present invention applies photogrammetry to corneal curvature measurement, and solves the problem that the traditional monitoring method cannot continuously monitor by making the corneal curvature monitoring equipment portable and using it in the form of disposable corneal contact lenses in conjunction with photogrammetry glasses, thereby achieving continuous and dynamic monitoring of corneal curvature. The present invention adopts video measurement technology, combines computer vision with traditional photogrammetry, and utilizes the advantages of high precision, non-contact, rich information, and continuous operation to improve the accuracy and efficiency of measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the structure of the photogrammetry glasses in an embodiment of the present invention;

[0025] Figure 2 is a schematic structural diagram of the temples of the photogrammetry glasses in an embodiment of the present invention;

[0026] Figure 3 is a schematic structural diagram of a second corneal contact lens in an embodiment of the present invention;

[0027] Figure 4 is a schematic structural diagram of a first corneal contact lens in an embodiment of the present invention;

[0028] Figure 5 is a schematic diagram of a measurement target on a first corneal contact lens in an embodiment of the present invention;

[0029] Figure 6 It is a schematic diagram of the relationship between a spatial target point and its camera image point. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0031] An embodiment of the present invention relates to a corneal curvature monitoring device, comprising: a first corneal contact lens, on which a measurement target is provided; photogrammetric glasses, used to capture an image of the measurement target on the first corneal contact lens; and a terminal device, used to obtain the image captured by the photogrammetric glasses and determine the position of the measurement target based on the image.

[0032] like Figure 1 and Figure 2 As shown, the photogrammetry glasses in this embodiment include a glasses frame 1, a camera 2 is arranged on the lens frame of the glasses frame 1, and the shooting direction of the camera 2 is toward the user to be monitored; a controller and a memory are integrated in the temples of the glasses frame 1, and the controller is connected to the camera 2 for controlling the camera 2 to shoot; the memory is used to store the image shot by the camera 2; and a transmission line 3 connected to the controller is arranged at the end of the temple of the glasses frame 1, and the transmission line 3 is used to connect to the terminal device. When in use, the photogrammetry glasses are worn in front of the eyes of the monitored user.

[0033] Figure 2A button 4 is also provided at the bottom of the temple of the eyeglass frame 1. The button 4 is connected to the controller. When the button 4 is pressed, the controller sends a shooting instruction to the camera 2. The camera 2 can shoot after receiving the shooting instruction. A contact sensor 5 is also provided at the bottom of the temple of the eyeglass frame 1. The contact sensor 5 can be used to determine whether the photogrammetry glasses are in a wearing state. The contact sensor 5 can be a pressure sensor.

[0034] It is worth mentioning that a blink detection model is also provided in the controller of the present embodiment, which can extract four key points of the human eye (respectively, the left eye corner point, the right eye corner point, the upper eyelid center and the lower eyelid center), and then calculate the horizontal distance of the eyes according to the left eye corner point and the right eye corner point, and calculate the vertical distance of the eyes according to the upper eyelid center and the lower eyelid center, and then determine whether the user is blinking according to the ratio of the vertical distance to the horizontal distance. When the user is detected to blink, the controller controls the camera 2 to take pictures.

[0035] This embodiment determines to start an image acquisition measurement after each blink, and uses the physiological characteristics that the eyeball position is relatively fixed and the tear film is stable after blinking, thereby reducing the measurement error caused by eyeball movement and improving the accuracy of the measurement.

[0036] like Figure 4 As shown, there are four measurement targets on the first corneal contact lens in this embodiment, and the four measurement targets are evenly distributed in the circumferential direction of the first corneal contact lens. The first corneal contact lens can be made of a flexible polydimethylsiloxane material, which can be deformed in coordination with the deformation of the eyeball. When in use, the first corneal contact lens fits the cornea of ​​the monitored user. Figure 5 As shown, in this embodiment, the measurement target can be in any of the following forms: a circular mark, a diagonal mark, and a coded mark.

[0037] The terminal device in this embodiment can be connected to the photogrammetry glasses through the transmission line 3, so that the image in the memory of the photogrammetry glasses can be received. Then, according to the mathematical correspondence between the camera image point and a certain point of the space target (see Figure 6 ), the position of the measurement target in the obtained image in space can be obtained, and the position can be compared with the pre-stored initial position to determine whether the measurement target has been displaced. When the measurement target has been displaced significantly, it can be determined whether the corneal curvature has changed.

[0038] The mathematical correspondence between the camera image point and a point of the space target can be obtained by calibrating the camera through the second corneal contact lens. Figure 3As shown, a calibration plate is provided on the second corneal contact lens in the present embodiment. The calibration plate is in the form of a chessboard. The calibration process is to estimate the parameters of the camera mathematical model, and the parameters mainly include two parts of data: the internal parameters of the camera and the external parameters reflecting the chessboard orientation information. The internal parameters of the camera are the inherent parameters of the camera and have nothing to do with the scene being photographed. By adjusting the orientation of the chessboard in the second corneal contact lens and based on the RANSAC algorithm (Fisher, 1981), the camera calibration can be achieved to obtain the mathematical correspondence between the camera image point and a certain point of the spatial target.

[0039] In order to more accurately determine whether the corneal curvature has changed, the terminal device in this embodiment also includes: a storage unit, used to store the initial position of the measurement target on the first corneal contact lens; a conversion unit, used to obtain the position of the measurement target according to the mathematical correspondence between the point on the image and the spatial target point; a calculation unit, used to calculate the curvature radius of the initial position and the curvature radius of the position of the measurement target to obtain the initial curvature radius and the final curvature radius; a comparison unit, used to compare the initial curvature radius and the final curvature radius; a determination unit, used to determine that the corneal curvature has changed when the difference between the initial curvature radius and the final curvature radius exceeds a threshold.

[0040] In the implementation, the initial position images of the measurement targets in the four centrally symmetrical quadrants on the first corneal contact lens are first acquired through the camera, and the initial image coordinates are (ax0, ay0, az0), (bx0, by0, bz0), (cx0, cy0, cz0), (dx0, dy0, dz0), where the direction of x is the circumferential direction of the corneal hemisphere, y is the normal direction of x, and z is the distance between each monitoring point and the fixed observation point. Then, according to the mathematical correspondence between the camera image point and a certain point of the spatial target, the initial position P of each measurement target can be obtained. i0 =(x 0i ,y 0i ,z 0i ), and store the initial position in a storage unit of the terminal device.

[0041] After a period of time, the images of the four measurement targets on the first corneal contact lens are acquired again through the camera, and the coordinates of the final images are (ax1, ay1, az1), (bx1, by1, bz1), (cx1, cy1, cz1), and (dx1, dy1, dz1). Similarly, the final positions P of the four measurement targets are obtained through the mathematical correspondence between the camera image points and a certain point of the spatial target. i1 =(x 1i ,y 1i ,z 1i ).

[0042] Afterwards, the radius of curvature of each measurement target is calculated: For the point (x i ,y i ,z i ), the radius of curvature R can be given by the following formula: Among them, r is the point (x i ,y i ,z i ) to the center of the first corneal contact lens hemisphere; through the above calculation, the initial curvature radius and final curvature radius of each measurement target can be obtained.

[0043] Finally, the initial curvature radius and the final curvature radius of each measurement target are compared. If the difference between the initial curvature radius and the final curvature radius is small, it means that the curvature radius has not changed much, and the corneal curvature has changed very little. If the difference between the initial curvature radius and the final curvature radius exceeds the threshold, it means that the curvature radius has changed significantly, indicating that the corneal curvature has changed.

[0044] It is not difficult to find that the present invention applies photogrammetry to corneal curvature measurement. By making the corneal curvature monitoring device portable and using it in the form of disposable corneal contact lenses in conjunction with photogrammetry glasses, the problem of the inability of traditional monitoring methods to continuously monitor is solved, and continuous and dynamic monitoring of corneal curvature is achieved. The present invention adopts video measurement technology, combines computer vision with traditional photogrammetry, and utilizes the advantages of high precision, non-contact, rich information, and continuous operation to improve the accuracy and efficiency of measurement.

Claims

1. A corneal curvature monitoring device, characterized in that: include: a first corneal contact lens, wherein a measurement target is disposed on the first corneal contact lens; Photogrammetry glasses for capturing images of measurement targets on the first contact lens; The terminal device is used to obtain the image captured by the photogrammetry glasses and determine the position of the measurement target according to the image.

2. The corneal curvature monitoring device according to claim 1, characterized in that: There are four measurement targets, which are evenly distributed in the circumferential direction of the first corneal contact lens.

3. The corneal curvature monitoring device according to claim 1, characterized in that: The measurement target is in the form of a circular mark, a diagonal mark and a coded mark.

4. The corneal curvature monitoring device according to claim 1, characterized in that: The first corneal contact lens is made of flexible polydimethylsiloxane material.

5. The corneal curvature monitoring device according to claim 1, characterized in that: The photogrammetry glasses include a glasses frame, a camera is arranged on the lens frame of the glasses frame, and the shooting direction of the camera is toward the user to be monitored; a controller and a memory are integrated in the temples of the glasses frame, and the controller is connected to the camera and is used to control the camera to shoot; the memory is used to store images taken by the camera; and a transmission line connected to the controller is provided at the end of the temple of the glasses frame, and the transmission line is used to be connected to the terminal device.

6. The corneal curvature monitoring device according to claim 1, characterized in that: Also includes: A second corneal contact lens, wherein a calibration plate is arranged on the second corneal contact lens.

7. The corneal curvature monitoring device according to claim 6, characterized in that: The calibration plate is in the form of a checkerboard.

8. The corneal curvature monitoring device according to claim 5, characterized in that: The controller is provided with a blink detection model, and the blink detection model determines whether the monitored user blinks according to the image information acquired by the camera. When the monitored user blinks, the controller controls the camera to take pictures.

9. The corneal curvature monitoring device according to claim 1, characterized in that: The terminal device comprises: A storage unit, used for storing an initial position of the measurement target on the first corneal contact lens; A conversion unit, used for obtaining the position of the measurement target according to the mathematical correspondence between the points on the image and the space target points; A calculation unit, used for calculating the curvature radius of the initial position and the curvature radius of the position of the measurement target, to obtain an initial curvature radius and a final curvature radius; A comparison unit, used for comparing the initial curvature radius and the final curvature radius; The determination unit is used to determine that the corneal curvature has changed when the difference between the initial curvature radius and the final curvature radius exceeds a threshold value.

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