Refractive processing center positioning method and system

Abstract

Disclosed in the present invention are a refractive processing center positioning method and system. The method comprises the following steps: acquiring image information of a tear film mark contour, and calculating the center point of the tear film mark contour, the tear film mark contour being a contour formed by a contact lens coming into contact with a cornea; and enabling the center point of the tear film mark contour to coincide with the center point of a processing lens. According to the present invention, the change of a tear film mark in the process of a cornea coming into contact with a contact lens is collected in real time, a tear film mark contour is extracted, and coordinates of the center of the contour are calculated, such that dynamic visualization of the coordinates of the center of the contour is implemented, and by incorporating a movable patient bed, the spatial position and body posture of a patient are finely adjusted, thereby guiding a doctor to achieve accurate and automatic alignment of the processing center and an optimal refractive center, and effectively improving the precision.

Description

A refractive processing center positioning method and system Technical Field

[0001] The present invention relates to the field of laser refractive technology, and in particular to a refractive processing center positioning method and system. Background Art

[0002] In laser corneal refractive surgery, the visual axis and corneal focal point serve as the optimal refractive center. Existing commercial laser refractive equipment uses the pupil center as the processing center to guide the doctor's alignment. For example, patent CN113940812A proposes a solution using the pupil center as the refractive processing center. This solution identifies the pupil contour, calculates the pupil center position, and uses this position as the refractive processing center. However, this solution introduces significant surgical coma for patients with a large kappa angle (the angle between the visual axis and the pupil axis, as shown in Figure 1), significantly affecting the patient's postoperative visual quality. Patent CN113520717A proposes a solution using Purkinje images to locate the optimal refractive center. This solution effectively locates the optimal refractive center by observing the position of the fixation light reflection point on the anterior corneal surface. However, this method can only be used to locate the optimal refractive center before the cornea and contact lens make contact. Once the cornea and contact lens make contact, the first-order Purkinje image becomes unobservable. During the continued alignment process between the cornea and contact lens, there may be offset, resulting in inaccurate alignment of the processing center.

[0003] Summary of the Invention

[0004] The present invention provides a refractive processing center positioning method and system. By extracting the watermark contour and calculating the contour center coordinates, the contour center coordinates can be dynamically visualized. The system also cooperates with the adjustment platform to fine-tune the spatial position and posture of the object to be detected, guiding the doctor to achieve precise and automatic docking between the machining center and the optimal refractive center, thereby solving at least one of the problems pointed out in the background technology.

[0005] A method for positioning a refractive processing center comprises the following steps:

[0006] Acquiring watermark profile image information and calculating the center point of the watermark profile, wherein the watermark profile is the profile formed by the contact lens and the cornea;

[0007] Make the center point of the watermark outline coincide with the center point of the processed lens.

[0008] The method for obtaining watermark outline image information is as follows:

[0009] The light reflected by the outline formed by the contact lens and cornea is obtained and converted into an image.

[0010] The center point of the watermark outline is calculated as follows:

[0011] The obtained watermark contour image information is denoised and calculated to obtain the center point of the watermark contour.

[0012] The method for denoising the watermark contour image information is as follows:

[0013] intercepting the central field of view image to obtain a intercepted central field of view denoised image;

[0014] Binarization is performed on the intercepted central field of view denoised image to obtain a binary image;

[0015] Perform Gaussian filtering and noise reduction on the binarized image;

[0016] Extract the edge of the image after noise reduction, set double thresholds to extract the center watermark edge, and obtain the watermark contour boundary image;

[0017] Perform ellipse fitting on the obtained watermark contour boundary image, obtain the center visualization image after ellipse fitting, calculate the center point of the ellipse, and obtain the center point of the watermark contour.

[0018] A refractive processing center positioning system, comprising:

[0019] A watermark contour image acquisition unit acquires the contour image formed by the contact lens and the cornea in real time and sends it to the image calculation unit;

[0020] The image calculation unit receives the acquired contour image and calculates the center point of the contour image.

[0021] It also includes an adjustment platform, which is used to adjust the position of the object to be detected, allowing the object to be detected to move along the X-axis, Y-axis or Z-axis so that the cornea fits the contact lens and the center point of the watermark outline coincides with the center point of the processed lens.

[0022] The movement accuracy of the X-axis and Y-axis of the adjustment platform is 10μm, and the movement accuracy of the Z-axis is 1μm.

[0023] It also includes a wide-angle camera, which is communicatively connected to the adjustment platform. The wide-angle camera is used to roughly locate the position coordinates of the object to be detected and feed the position coordinates back to the adjustment platform. The adjustment platform places the object to be detected at the position to be treated based on the position coordinates.

[0024] Compared with the existing technology, the beneficial effects of the present invention are: the present invention realizes dynamic visualization of the contour center coordinates by real-time acquisition of the changes in the watermark during the contact process between the cornea and the contact lens, extracts the watermark contour and calculates the contour center coordinates, and cooperates with the adjustment platform to fine-tune the spatial position and posture of the object to be detected, guiding the doctor to achieve precise and automatic docking between the processing center and the optimal refractive center, thereby effectively improving the accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of the eyeball κ angle;

[0026] FIG2 is a schematic structural diagram of a refractive processing system according to the present invention;

[0027] FIG3 is a schematic diagram of initial contact between the patient's cornea and the patient's contact lens;

[0028] FIG4 is a schematic diagram showing the complete fit between the patient's cornea and the patient's contact lens;

[0029] FIG5 shows images captured and processed by a camera of a patient's cornea and a patient's contact lens during initial contact, contact, and complete contact;

[0030] FIG6 is a schematic diagram of the structure of the adjustment platform to achieve automatic focusing of the patient;

[0031] FIG7 is a flow chart of the watermark contour center extraction algorithm.

[0032] Explanation of the accompanying symbols: 1-camera, 2-tube lens, 3-first beam splitter, 4-second beam splitter, 5-processing lens, 6-patient interface, 61-contact lens, 7-cornea, 8-fixation light source, 81-fixation light, 9-scanning optical system, 91-processing laser, 10-adjustment platform, 11-watermark reflected light, 12-image calculation unit, 111-watermark contour, 112-processing lens center, 113-refractive positioning center, 201-original image, 202-cropped central field of view denoised image, 203-binarized image, 204-watermark contour boundary image, 205-central visualization image after ellipse fitting, 21-wide-angle camera. DETAILED DESCRIPTION

[0033] A specific embodiment of the present invention is described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiment.

[0034] Most existing all-femtosecond refractive devices use the pupil as the refractive center; however, research has shown that the theoretical optimal refractive processing center is the focal point of the visual axis and the cornea, as shown in Figure 1; the axis passing through the pupil center is the pupil axis, the line connecting the gaze point and the fovea is the visual axis, and the angle between the pupil axis and the visual axis is the κ angle; existing commercial all-femtosecond refractive surgeries mostly rely on the doctor's experience to find the pupil center to determine the refractive processing center. This center deviates far from the optimal refractive center, resulting in patients' postoperative visual quality not achieving optimal results; in actual surgery, the intersection of the visual axis and the cornea is difficult to accurately determine. Clinical trials have shown that when the subject to be tested (hereinafter referred to as the patient, not specifically the patient) looks forward, the corneal vertex is very close to the intersection of the visual axis and the anterior corneal surface; when the patient looks forward, the center point of the watermark outline formed by the patient's cornea and the patient's contact lens is very close to the corneal vertex;

[0035] Example 1

[0036] As shown in Figures 2 to 3, a refractive processing center positioning system provided by an embodiment of the present invention includes a watermark contour image acquisition unit and an image calculation unit 12. The watermark contour image acquisition unit acquires a contour image formed by the contact lens and the cornea in real time and sends it to the image calculation unit 12; the image calculation unit 12 receives the acquired contour image and calculates the center point of the contour image;

[0037] The refractive processing center positioning system proposed in this embodiment is a part of the refractive processing system, which also includes a processing lens 5, a patient interface 6, a contact lens 61, a scanning optical system 9, a first beam splitter 3, a second beam splitter 4, and an injection light source 8;

[0038] The injection light source 8 is used to emit injection light 81. The observation light 81 is reflected by the first beam splitter 3 and transmitted through the second beam splitter 4 to enter the processing lens 5. The observation light 81 propagates along the optical axis of the processing lens 5 and is emitted through the center of the processing lens 5.

[0039] The scanning optical system 9 is used to emit a processing laser 91, which is reflected by the second beam splitter 4 into the processing lens 5;

[0040] The contact lens 61 contacts the patient's cornea 7. Since the cornea 7 is moist, a watermark is formed on the edge of the contact surface when in contact with the contact lens 61. The watermark reflected light 11 is received by the processing lens 5. The watermark reflected light 11 passes through the first beam splitter 4 and the second beam splitter 3 respectively, and is converged by the tube lens 2 onto the target surface of the camera 1 (watermark contour image acquisition unit), thereby capturing the morphological changes of the watermark in real time.

[0041] The image calculation unit 12 is in communication with the camera 1, receives the contour image, calculates the center point of the contour image, and changes the position of the patient according to the center point of the contour image so that the center point of the contour image coincides with the center point of the processing lens 5. The patient's position is changed by adjusting the platform 10;

[0042] The adjustment platform 10 can correct the patient's three-dimensional spatial position and body position based on the distance deviation instruction between the refractive positioning center 113 (the center point of the contour image) and the processing lens center 112 determined by the signal processing controller of the image calculation unit 12 to ensure that the refractive positioning center 113 and the processing lens center 112 remain coincident. The patient can be moved along the X-axis, Y-axis, or Z-axis (the adjustment method can be conventional methods such as cylinders and screws, which will not be described here) to ensure that the cornea and contact lens are aligned and the center point of the watermark contour coincides with the center point of the processing lens. The movement accuracy of the adjustment platform on the X-axis and Y-axis is 10μm, and the movement accuracy on the Z-axis is 1μm.

[0043] FIG3 is a schematic diagram of the initial contact between the patient's cornea 7 and the contact lens 61. The left side of FIG5 is the contour image captured by the camera 1 at this time, wherein the cross mark 112 is the center of the processed lens and the circular mark 113 is the center of the watermark contour identified by the algorithm;

[0044] FIG4 is a schematic diagram of the patient's cornea 7 and the contact lens 61 being completely fitted together, and the right side of FIG5 is a contour image captured by the camera 1 at this time;

[0045] The middle image in FIG5 is a contour image captured by the camera when the patient's cornea 7 and the contact lens 61 are in a state from initial contact to complete contact;

[0046] In addition, as shown in FIG6 , to achieve full autofocus of the patient, this embodiment also includes a wide-angle camera 21. This camera is used to capture the patient's lying position on the bed, roughly locate their position coordinates, and feed these coordinates back to the adjustment platform 10, causing the adjustment platform 10 to move into the field of view of the processing objective lens 81. At this point, the camera 1 begins operating, capturing the patient's corneal image information. When the patient's cornea 7 contacts the contact lens 61, forming a watermark, the algorithm is activated to identify the watermark center in real time, guiding the adjustment platform 10 to fine focus, ultimately achieving precise focus between the processing lens center 112 and the corneal refractive positioning center 113.

[0047] Example 2

[0048] This embodiment proposes a refractive processing center positioning method based on the first embodiment, including the following steps:

[0049] Acquire watermark profile image information and calculate the center point of the watermark profile 111, where the watermark profile is the profile formed by the contact lens and the cornea;

[0050] The watermark is formed when the patient's cornea 7 contacts the contact lens 61. The surface of the cornea 7 is moist. When it contacts the glass contact surface, the reflection of the edge watermark outline is enhanced, and a uniform bright ring is observed in the imaging light path, which is the watermark outline.

[0051] The light reflected by the watermark is collected by the processing lens, and the reflected light is reflected into the tube lens through the beam splitter, and then imaged by the tube lens to the camera, thereby collecting the watermark pattern.

[0052] Make the center point of the watermark outline coincide with the center point of the processed lens;

[0053] The method for obtaining the above watermark outline image information is as follows:

[0054] Camera 1 captures the light reflected by the outline formed by the contact lens and cornea and converts it into an image.

[0055] The center point of the watermark outline 111 is calculated as follows:

[0056] The acquired watermark contour image information is denoised and calculated to obtain the center point of the watermark contour 111.

[0057] The above method for denoising the watermark contour image information is as follows:

[0058] Intercept the central field of view image;

[0059] Binarization processing is performed on the intercepted central field of view image;

[0060] Perform Gaussian filtering and noise reduction on the binarized image;

[0061] Extract the edge of the image after noise reduction, set double thresholds to extract the center watermark edge, and obtain the watermark contour boundary;

[0062] Performing ellipse fitting on the obtained watermark contour boundary to obtain a fitted ellipse, calculating the center point of the ellipse, and obtaining the center point of the watermark contour 111;

[0063] That is, as shown in FIG7 , a flow chart of the watermark contour center extraction algorithm; after the camera 1 captures the original image 201 (the camera 1 converts light into an image according to the existing technology, so it will not be described in detail here), the captured original image 201 is first pre-processed to remove edge noise information, and the center field of view cropping scheme is first used to obtain the region of interest, and the intercepted center field of view denoised image 202 is obtained; secondly, the intercepted center field of view denoised image 202 is binarized to improve the image processing speed, and the binarized image is subjected to Gaussian filtering denoising to obtain the denoised binarized image 203; the next step is to use the denoised binarized image 203 to perform the denoised binarization. The Canny operator is used to extract edges, and an appropriate dual threshold is set to extract the center watermark edge, obtaining a watermark contour boundary image 204. Finally, an ellipse is fitted to the extracted boundary to obtain the fitted ellipse. The center coordinate threshold, ellipse size threshold, and ellipse aspect ratio threshold are set to filter out abnormal watermarks, and the ellipse center point is found. The watermark contour center point 113 and the processing lens center 112 are displayed in real time on the final ellipse-fitted center visualization image 205. The visualization is performed by dynamically marking the watermark contour center, the processing lens center, and the distance line between the two on the display screen in real time, thereby guiding the doctor to achieve accurate alignment between the processing center and the optimal refractive center.

[0064] In this embodiment, the roughness of the patient's corneal surface does not affect the positioning accuracy of this patented method. When the patient's cornea is damaged, resulting in uneven corneal surface, physiological fluid will be used to moisten the corneal surface before negative pressure docking to fill in the smaller uneven areas. If the patient's corneal damage is more serious, with larger pits, the watermark outline generated during the negative pressure docking process will be incomplete. In this case, the image recognition algorithm of this patent will compensate and optimize the outline boundary, and can still complete the extraction of the boundary outline and the positioning of the outline center.

[0065] The method for accurately locating the refractive processing center based on the present invention can more accurately locate the refractive processing center in laser refractive surgery applications, reduce the difficulty of operation for doctors, improve surgical consistency, and enhance the patient's postoperative visual quality.

[0066] The specific process of this implementation is as follows: the patient looks forward and stares at the fixation illumination light emitted from the center of the processing lens; the platform is adjusted to move, driving the patient's cornea to rise and slowly contact the patient's contact lens; after the patient's cornea contacts the contact lens, the watermark outline of the contact between the two can be observed through the imaging optical path; the watermark image is collected in real time and the center coordinates of the watermark outline are extracted and calculated; the spatial distance between the watermark center coordinates and the processing lens center coordinates is calculated and visualized, guiding the multi-dimensional movement of the patient bed, and real-time correction is made to ensure that the watermark center coincides with the processing lens center; the cornea is completely attached to the patient's contact lens, and the deviation between the watermark center and the processing lens center is less than 100μm, the patient interface negative pressure adsorption is turned on, the cornea is adsorbed on the contact lens, and the positioning work is completed.

[0067] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit and essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0068] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for positioning a refractive processing center, characterized in that: The steps include: Acquire watermark contour image information and calculate the center point of the watermark contour, wherein the watermark contour is the contour formed by the contact lens and the cornea; Make the center point of the watermark outline coincide with the center point of the processed lens.

2. The method for positioning a refractive processing center according to claim 1, characterized in that: The method for obtaining the watermark profile image information is as follows: The light reflected by the outline formed by the contact lens and the cornea is obtained and converted into an image.

3. The method for positioning a refractive processing center according to claim 1, characterized in that: The calculation method of the center point of the watermark outline is as follows: The watermark contour image information is denoised and calculated to obtain the center point of the watermark contour.

4. The method for positioning a refractive processing center according to claim 3, characterized in that: The method for denoising the acquired watermark contour image information is as follows: intercepting the central field of view image to obtain an intercepted central field of view denoised image; Binarization is performed on the intercepted central field of view denoised image to obtain a binary image; Perform Gaussian filtering and noise reduction on the binarized image; Extract the edge of the image after noise reduction, set double thresholds to extract the center watermark edge, and obtain the watermark contour boundary image; Perform ellipse fitting on the obtained watermark contour boundary image, obtain the center visualization image after ellipse fitting, calculate the center point of the ellipse, and obtain the center point of the watermark contour.

5. A refractive processing center positioning system, characterized in that: include: A watermark contour image acquisition unit acquires a contour image formed by the contact lens and the cornea in real time and sends it to the image calculation unit; The image calculation unit receives the acquired contour image and calculates the center point of the contour image.

6. The refractive processing center positioning system according to claim 5, characterized in that: It also includes an adjustment platform, which is used to adjust the position of the object to be detected so that the object to be detected can move along the X-axis, Y-axis or Z-axis, so that the cornea of ​​the object to be detected fits with the contact lens and the center point of the watermark contour coincides with the center point of the processed lens.

7. The refractive processing center positioning system according to claim 6, characterized in that: The movement accuracy of the adjustment platform on the X-axis and Y-axis is 10 μm, and the movement accuracy of the Z-axis is 1 μm.

8. The refractive processing center positioning system according to claim 6, characterized in that: It also includes a wide-angle camera, which is communicatively connected to the adjustment platform. The wide-angle camera is used to roughly locate the position coordinates of the object to be detected and feed the position coordinates back to the adjustment platform. The adjustment platform locates the object to be detected at the position to be treated based on the position coordinates.

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