A fixation property quantitative detection method based on light brush positioning

Abstract

The application provides a fixation property quantitative detection method based on light brush positioning. With the help of a fixation property detection system, a central fovea mark target is moved to coincide with a light brush image, and fixation property data of an eye to be detected are obtained. Compared with a traditional direct ophthalmoscope method, a Kappa angle method and a microperimeter method, the method is simple, high in accuracy and good in repeatability.

Description

Technical Field

[0001] This invention relates to the field of ophthalmic testing technology, specifically to a quantitative detection method for gaze characteristics based on light brush positioning, used to determine the gaze characteristics of the examined eye. Background Technology

[0002] Fixation type refers to the location on the retina used by the eye to fixate on a target. A normal eye uses the fovea to fixate on a target; in pathological conditions, the affected eye uses a location on the retina outside the fovea as the fixation point (eccentric fixation point). In this case, the fixation ability of the fovea is weaker than that of the eccentric fixation point. The book *Practical Ophthalmology* (published by People's Medical Publishing House in August 2010, edited by Liu Jiaqi) classifies fixation type into central fixation, parafoveal fixation, macular fixation, and peripheral fixation, with the latter three collectively referred to as eccentric fixation in ophthalmology. The location on the retina used by an eccentrically fixating eye to fixate on a target is called the eccentric fixation point. Eccentric fixation is a rare and difficult type of fixation in ophthalmology. Clinically, the two most common methods for detecting fixation type are direct ophthalmoscopy and the Kappa angle method. In recent years, some hospitals have also used microperimeters to assist in determining fixation type. Microperimeters are expensive to purchase and are currently difficult to widely adopt; direct ophthalmoscopy requires solid ophthalmological skills, and examination with small pupils is very difficult; the Kappa angle method is affected by factors such as macular ectopia, making its accuracy questionable; regardless of the method used to detect fixation, full cooperation from the subject is essential. The difficulty increases further if the subject is a child.

[0003] The brush effect is an endoscopic phenomenon. When the human eye observes a rotating polarized light plate against a solid-color background, a symmetrical funnel-shaped shadow is perceived at the corresponding spatial location of the fovea in the visual field. Ophthalmologists call this the brush effect. The brush effect changes position depending on the eye's gaze orientation, but it always corresponds to the fovea in the visual field of that eye. The book *Amblyopia* (published by Science Press in August 2007, edited by Yan Hong) describes the brush effect as follows: "The brush effect only appears on the fovea of ​​the retina. When people can observe this 'brush' through instruments, it means that the 'brush' is projected onto the fovea." The patent "Afterimage Amblyopia Treatment Instrument Guided by Light Brush" (CN1282448C) uses the technical solution of "generating foveal fixation by Haidinger brush and transferring the Haidinger brush image to the center of the light brush plate". It utilizes the principle of Haidinger light brush marking the spatial position of the fovea. However, the technical solution disclosed in this patent is not used for fixation property detection. Instead, it uses the line of sight to transfer the position of the Haidinger light brush to the center of the light brush plate for afterimage lamp illumination. Summary of the Invention

[0004] The purpose of this invention is to provide a quantitative detection method for gaze characteristics based on optical brush positioning. This method can easily and accurately detect gaze characteristics, and it is also inexpensive to implement.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This solution utilizes a gaze property detection system composed of a Haidinger light brush and a gaze property detection interface, wherein the gaze property detection interface is provided with a gaze point target and a foveal marker target, and the position of the foveal marker target is adjustable; when the system is running, the polarizer in the Haidinger light brush rotates, so that the eye being examined observes the light brush image projected on the gaze property detection interface through the polarizer area, while the eye being examined gazes at the gaze point target; the foveal marker target is moved so that its position coincides with the position of the light brush image, and the gaze property data of the eye being examined is obtained according to the positional relationship between the gaze point target and the foveal marker target.

[0006] An eccentric fixating eye preferentially uses the eccentric fixation point near the fovea to fixate on a target. When using a light brush, the target fixation point of the eccentric fixating eye is not at the same location as the light brush. This invention is designed based on this ophthalmological cognitive foundation.

[0007] When an eye with eccentric fixation is tested using this system for fixation property detection, the eccentric fixation point in the fundus will fixate on the aforementioned fixation target, and the position of the brush image perceived by the tested eye corresponds to the spatial position of the fovea. In ophthalmology, the spatial relationship between the eccentric fixation point and the fovea corresponds to the various fixation properties mentioned above. Traditional fixation property detection only qualitatively determines fixation property by observing the position of the eccentric fixation point within concentric rings with 1°, 2°, 3°, 4°, and 5° angles centered on the fovea (i.e., eccentric fixation angle). For example, if the fixation point is within the 1° ring, it is central fixation; if the fixation point is between the 1° and 3° rings, it is eccentric fixation; if the fixation point is between the 3° and 5° rings, it is macular fixation; and if the fixation point is outside the 5° ring, it is peripheral fixation. In this invention, the physical distance between the recorded fixation target position and the foveal target position, as well as the detection distance, can be used to calculate the eccentric fixation angle with an accuracy of 0.1° or even higher using trigonometric functions. The angle between the line connecting the fixation point target and the fovea marker target, and the horizontal meridian passing through the fovea marker target, can be used to obtain the precise eccentric fixation point along the meridian direction of the horizontal line where the fovea is located by reversing the orientations.

[0008] By recording these precise changes in the eccentric gaze angle during treatment, it is possible to quantitatively assess whether the treatment has improved (a progressive decrease in the eccentric gaze angle value indicates that the treatment is effective).

[0009] In the above technical solution, the background color and brightness of the gaze detection interface are adjustable. The advantage of this design is that it allows for the acquisition of clearer brush images.

[0010] In the above technical solution, the shape, color, and size of the fixation point target and the foveal marker target are adjustable. The advantage of this design is that it provides the examinee with a wider selection of recognizable target graphic styles and can also be used for cross-validation of test results.

[0011] In the above technical solution, the fixation point target and the foveal mark target have coordinate values. The advantage of this design is that it can obtain both physical distance information and orientation information.

[0012] In the above technical solution, the rotation speed of the polarizer within the Haidinger brush is adjustable. The advantage of this design is that it allows the examined eye to more easily observe the different brush images taken at varying rotation speeds.

[0013] In the above technical solution, the rotation direction of the polarizer within the Haidinger brush is adjustable. The advantage of this design is that it allows the examined eye to more easily observe clockwise or counterclockwise rotating brush images, and it can also be used for cross-validation of test results.

[0014] In the above technical solution, the Haidinger optical brush is equipped with polarizing filters of various transmittances. The advantage of this design is that it can adapt to different visual conditions of the examined eye by using polarizing filters with different transmittances, thereby improving the clarity of the optical image and the accuracy of the detection.

[0015] In the above technical solutions, the foveal marker can be moved using one or more of the following methods: physical buttons, virtual on-screen buttons, gyroscope sensing, touchscreen sensing, motion capture, wearable device operation, voice control technology, and eye-tracking technology. The advantage of this design is that it allows different subjects to operate the foveal marker in more ways and with greater familiarity.

[0016] In the above technical solution, during the initialization of the gaze detection interface, the size and positional relationship of the graphics on the gaze detection interface are verified by measuring the physical size of a preset graphic. This is to accommodate display devices with different screen sizes when the invention is applied to home use scenarios, and to calculate more accurate physical size and orientation information by combining the obtained physical size of the preset graphic with the aforementioned target coordinate values.

[0017] The beneficial effects of this invention are: by using a gaze property detection system, the gaze property data of the examined eye can be obtained by moving a foveal marker to coincide with a light brush image. This method is simple, accurate, repeatable, easy to operate, and widely applicable. Attached Figure Description

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention as described above or otherwise will become clearer.

[0019] Figure 1 This is a schematic diagram of the overall appearance of an embodiment of the present invention.

[0020] Figure 2 This is a diagram showing the separation state of the Haidinger light brush and the gaze property detection interface in an embodiment of the present invention.

[0021] Figure 3 This is a top view of the initial state of the gaze property detection interface during operation of an embodiment of the present invention.

[0022] Figure 4 This is a top view of the state when the central concave mark is moved to coincide with the light brush image during operation, according to an embodiment of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be understood that the terms "center", "central", "vertical", "horizontal", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can be a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Figure 1 This is a schematic diagram of the overall appearance of an embodiment of the present invention. The gaze property detection system consists of a Haidinger light brush 1 and a mobile phone 2. A motor 3 on the Haidinger light brush 1 drives a rotating ring 5 to rotate. A polarizing filter 4, a linear polarizer, is fixed to the rotating ring 5 and rotates with it. Against a solid-color background, the human eye can observe the light brush image through the rotating polarizing filter. A speed knob 6 adjusts the rotational speed of the rotating ring 5; a direction knob 7 controls the rotation of the rotating ring 5 between clockwise and counterclockwise rotation. The screen 8 on the mobile phone 2 displays the gaze property detection interface, and a virtual control button 9 on the screen 8 controls the position movement of the concave marker target in the gaze property detection interface.

[0028] Figure 2 This is a diagram showing the separation state of the Haidinger light brush and the gaze property detection interface according to an embodiment of the present invention. The Haidinger light brush 1 is clamped onto the mobile phone 2 by a support stand 10. After the clamping is stable, the distance between the polarizing film 4 and the screen 8 remains fixed. The polarizing film 4 is semi-transparent, and the image displayed on the screen 8 can be seen through the polarizing film 4.

[0029] Figure 3 This is a top view of the initial state of the gaze property detection interface during operation in this embodiment of the invention. Connecting wire 11 is the power supply wire for the Haidinger light brush 1. In this embodiment, the overall background color of the gaze property detection interface on screen 8 is pure blue (RGB color code: R0G0B255). The gaze point target 12 and the foveal marker target 13 are icons with black borders, and the color displayed within the borders of these two icons is pure blue, consistent with the overall background color. The subject can control the position of the foveal marker target 13 on the interface by touching the virtual control button 9 with their finger.

[0030] To clearly explain this embodiment, the subject's left eye is used for demonstration, exhibiting eccentric fixation. The subject's left eye will be referred to as the "examined eye" below. The subject wears their own refractive glasses, with a monocular eye patch covering the right eye and the examined eye remaining open. The examined eye is perpendicular to the plane of screen 8, and the viewing distance between the examined eye and the plane of screen 8 is maintained at 30 cm. The examined eye fixates perpendicularly on the fixation target 12 through the polarizing filter 4 area. After power is applied and turned on, motor 3 rotates, thereby driving the polarizing filter 4 to rotate. At this time, a brush image 14 appears in the field of view of the examined eye within the polarizing filter 4 area. According to the Haidinger brush principle, the direction of the line connecting the center of the brush image 14 and the fovea centralis of the examined eye's fundus is the spatial projection direction of the fovea centralis at this time.

[0031] Figure 4 This is a top view of the state when the foveal marker is moved to coincide with the light brush image during operation of this embodiment of the invention. While maintaining focus on the fixation point marker 12, the subject uses their finger to push the virtual control button 9 on the touchscreen to move the position of the foveal marker 13 to coincide with the light brush image 14. Here, "coincidence" refers to the center position of the foveal marker 13 coinciding with the center position of the light brush image 14. After confirming the coincidence, the system determines the distance between the center positions of the fixation point marker 12 and the foveal marker 13 based on their coordinates. Using this distance as the base length of a right triangle, the viewing distance plus the distance between the optical node of a normal human eye and the anterior central vertex of the cornea is used as the height of the right triangle. The vertex angle of this right triangle, with the optical node of the examined eye as its vertex, is calculated using trigonometric functions; this is the eccentric fixation angle of the examined eye. The eccentric fixation angle can be used to describe the fixation characteristics of the examined eye.

[0032] If the examined eye does not detect the brush image in the visual field of polarizer 4, try adjusting the rotation speed of polarizer 4 using the rotation knob 6, switching the rotation direction of polarizer 4 using the direction knob 7, adjusting the background color and brightness, or replacing the polarizer with one of different optical properties to encourage the examined eye to detect the brush image. If, after these adjustments, the examined eye still cannot detect the brush image, it suggests that the visual acuity of the examined eye is too low, or that the eccentric fixation point of the examined eye is too far from the fovea center, requiring the use of other fixation characteristic testing tools to clarify the fixation characteristic of the eye.

[0033] To accommodate monitors of different sizes and facilitate direct calculation of detection results by the system, a preset line segment is displayed during the initialization of the gaze property detection interface. By measuring and recording the physical dimensions of this line segment, the physical distance between coordinates on monitors of different sizes and display attributes can be verified.

[0034] To better stabilize the subject's head position, the eye's gaze angle, and the viewing distance during gaze property testing, other embodiments of the invention include a head support with a chin rest and a forehead rest. The horizontal relative position of the Haidinger light brush and the gaze property testing interface can also be shifted via a mechanical sliding structure to facilitate testing of both eyes. These are standard configurations for visual testing equipment and will not be elaborated upon in this specification.

[0035] In this embodiment, the gaze detection interface is displayed on a mobile phone screen. In other embodiments of the present invention, the gaze detection interface may be displayed on a separate display unit, a computer monitor, a tablet computer monitor, a VR headset, an AR headset, a smart glasses display interface, or a projected image.

Claims

1. A method for quantitative detection of gaze characteristics based on optical brush positioning, characterized in that, This method utilizes a gaze property detection system consisting of a Haidinger light brush and a gaze property detection interface. The gaze property detection interface includes a gaze point target and a foveal marker target, the position of which is adjustable. During system operation, a polarizer within the Haidinger light brush rotates, allowing the examined eye to observe the light brush image projected onto the gaze property detection interface through the polarizer area, while the examined eye gazes at the gaze point target. The foveal marker target is then moved to align with the position of the light brush image, and the gaze property is determined based on the gaze point target and the foveal marker target. The positional relationship of the optotypes is used to obtain the fixation characteristics data of the examined eye. After confirming the overlap, the distance between the two center positions is determined based on the coordinates of the center position of the fixation point optotype and the center position of the fovea mark optotype. This distance is used as the base length of a right triangle. The height of the right triangle is the visual distance plus the distance between the optical node of a normal human eye and the anterior central vertex of the cornea. The vertex angle of the right triangle with the optical node of the examined eye as the vertex is calculated according to trigonometric functions. This vertex angle is the eccentric fixation angle of the examined eye, which is used to describe the fixation characteristics of the examined eye.

2. The method for quantitative detection of gaze characteristics based on optical brush positioning according to claim 1, characterized in that, The background color and brightness of the gaze property detection interface are adjustable.

3. The method for quantitative detection of gaze characteristics based on optical brush positioning according to claim 1 or 2, characterized in that, The shape, color, and size of the fixation point target and the foveal mark target are adjustable.

4. The method for quantitative detection of gaze characteristics based on optical brush positioning according to claim 1 or 2, characterized in that, The fixation point target and the fovea mark target have coordinate values.

5. The method for quantitative detection of gaze characteristics based on optical brush positioning according to claim 1 or 2, characterized in that, The rotational speed of the polarizer in the Haidinger brush is adjustable.

6. The method for quantitative detection of gaze characteristics based on optical brush positioning according to claim 1 or 2, characterized in that, The polarizer inside the Haidinger brush has an adjustable rotation direction.

7. The method for quantitative detection of gaze characteristics based on optical brush positioning according to claim 1 or 2, characterized in that, The Haidinger light brush is equipped with polarizing filters of various transmittance.

8. The method for quantitative detection of gaze characteristics based on optical brush positioning according to claim 1 or 2, characterized in that, The central concave marker can be moved using one or more of the following methods: physical buttons, on-screen virtual buttons, gyroscope sensing, touchscreen sensing, motion capture, wearable device operation, voice control technology, and eye-tracking technology.

9. The method for quantitative detection of gaze characteristics based on optical brush positioning according to claim 1 or 2, characterized in that, When the gaze property detection interface is initialized, the physical dimensions of the preset graphics are measured to verify the graphics, spacing, and positional relationships on the gaze property detection interface.

Images