Vision change condition monitoring device
By combining the principle of laser speckle refraction with a cam zoom system, efficient and accurate detection of myopia, hyperopia and astigmatism in the home is achieved, solving the problems of complexity and high cost of existing equipment and meeting the needs of home vision monitoring.
Patent Information
- Application Number
- CN202411354516.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2025-11-14
AI Technical Summary
Existing vision testing equipment is complex, expensive, and cannot conveniently and accurately monitor changes in refractive error at home, especially for refractive errors such as myopia and astigmatism. This results in poor timeliness and fails to meet the needs of teenagers and the elderly.
It adopts the principle of laser speckle refraction, combining a laser speckle generation system and a cam zoom system. By adjusting the focal length of the zoom system, the imaging pattern of laser speckle on the human eye's retina is changed, enabling the detection of myopia, hyperopia, and astigmatism. It is easy to use and does not require the patient to distinguish the clarity of the image.
This invention provides a simple and reliable vision change monitoring device that can detect refractive error changes in real time and accurately at home. It is suitable for teenagers and middle-aged and elderly people, improving the timeliness and accessibility of vision testing.
Smart Images
Figure CN120938332A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of vision testing technology, and specifically relates to a device for monitoring changes in vision. Background Technology
[0002] In recent years, with the rapid development of electronic products such as smartphones and personal computers, people's outdoor activity time has significantly decreased while their intensive close-range screen time has increased markedly. Compared to adults, teenagers, whose eyeballs are not yet fully developed, have stronger eye muscle activity. When these eye muscles are under prolonged and continuous tension, it eventually leads to myopia. Therefore, teenagers, due to heavy academic pressure, long screen time, and staying up late using electronic products in low-light conditions, have become a major group suffering from myopia. In addition to myopia, prolonged close-range use of smartphones can also lead to other refractive errors such as astigmatism (unequal refractive power of the eye along different meridians). Furthermore, for middle-aged and elderly people, due to the continuous aging of the body, the lens's accommodative ability gradually declines, often resulting in physiological presbyopia, which also significantly impacts their quality of life. Therefore, refractive errors, mainly myopia, astigmatism, hyperopia, and presbyopia, will pose a serious challenge to future medical resources and population health.
[0003] The most common method for detecting refractive error is refraction. If patients can regularly test their refractive error themselves to understand recent changes, they can adjust their eye habits in a timely manner and seek targeted help from professionals, which is very beneficial for alleviating and correcting refractive errors. However, due to the complexity and specialization of current optometric equipment, refraction cannot be performed at home and must be conducted using a professional refractometer, requiring the involvement of an optometrist. This presents difficulties for vision assessment. Of course, smart refraction devices exist on the market, such as the Hipee smart refractometer, but they are still relatively expensive and have some usability issues, resulting in low public adoption. Overall, existing testing methods and equipment have certain limitations: hospital refraction is accurate but lacks timeliness; home vision charts are convenient but cannot provide specific refractive error values; mobile phone refraction apps use the far-point method to measure diopter, which is smart and convenient, but lacks accuracy.
[0004] Some optometry equipment can only monitor myopia and hyperopia, but cannot measure astigmatism. If a patient has both myopia and astigmatism, multiple devices need to be used for monitoring, or the patient may ultimately need to go to a hospital or optician for comprehensive vision monitoring, which is complicated and not timely.
[0005] Adolescents' eyes are in a crucial period of growth and development. Therefore, being able to perform real-time, efficient refractive error testing at home not only facilitates timely and targeted treatment and correction, and the replacement of glasses with more suitable ones, but also provides guidance for rationally managing screen time and habits, thus protecting our eyes. Therefore, there is an urgent need for a convenient and timely device for monitoring refractive error changes. Summary of the Invention
[0006] This invention addresses the problems existing in the prior art by providing a vision change monitoring device. The vision change monitoring device is simple, reliable, and easy to use, and can complete vision monitoring without requiring the patient to distinguish the clarity of the image.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0008] A vision change monitoring device includes a laser speckle generation system and a cam zoom system. The laser speckle generation system includes a laser source, a diffuse reflection disk that rotates around its central axis, a slit, a field-of-view segmentation and reversal system, and a radially rotating third prism that rotates the incident light beam. The laser source emits laser light, which forms laser speckle after passing through the rotating diffuse reflection disk. The laser speckle then forms diffraction fringes after passing through the slit. These diffraction fringes then pass through the field-of-view segmentation and reversal system and become two sets of fringes with opposite directions of motion. The two sets of fringes then pass through the radially rotating third prism and reach the cam zoom system, finally reaching the retina.
[0009] Furthermore, the laser source is a helium-neon laser, which emits 0.5-1mW of laser light.
[0010] Furthermore, the rotating diffuse reflection disk is a frosted glass rotating disk, which includes a motor and a frosted glass disk, and the frosted glass disk is driven by the motor.
[0011] Furthermore, the thickness of the frosted glass disk is 1mm-5mm.
[0012] Furthermore, the field-of-view segmentation and reversal system is formed by coupling a first prism and a second prism, wherein the first prism and the second prism have different refractive indices.
[0013] Furthermore, a right-angle prism is provided between the laser source and the frosted glass rotating disk, and / or a right-angle prism is provided between the third prism and the cam zoom system, so as to change the direction of the light path by reflecting through the right-angle prism.
[0014] Furthermore, the cam zoom system includes a front fixed group, a zoom group, a compensation group, and a rear fixed group. The zoom group and the compensation group move relative to each other, and the movement of the zoom group and the compensation group makes the sum of the changes in the conjugate distance of the image equal to zero.
[0015] Furthermore, the focal length range of the cam zoom system is 50mm-400mm.
[0016] Furthermore, the horizontal movement of the zoom group and the compensation group is controlled by rotating the cam cylinder, and the motion trajectory fitting function of the zoom group and the compensation group is:
[0017] y1=q1
[0018] y2 = -0.006q1 4 +0.4032q1 3 -0.80311q1 2 +76.47q1-270.32,
[0019] In the formula, q1 is the rotation angle of the cam cylinder, y1 is the moving distance of the variable magnification group, and y2 is the moving distance of the compensation group.
[0020] Furthermore, the cam cylinder is provided with a curved groove, the rise angle of which is 15°-30°.
[0021] Compared to existing technologies, this invention offers the following advantages: The vision change monitoring device provided by this invention is based on the principle of laser speckle refraction. By adjusting the focal length of the zoom system, it changes the imaging pattern of laser speckle on the human retina, thereby helping subjects determine their visual acuity. It is simple, reliable, and eliminates the need for patients to distinguish the clarity of the image. Furthermore, by using a radially rotating third prism, this invention can measure not only myopia and hyperopia but also astigmatism, making it convenient to use. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the vision change monitoring device provided in the embodiments of the present invention;
[0023] Figure 2 This is an optical path diagram provided in the embodiments of the present invention;
[0024] Figure 3 for Figure 1 The diagram shows the structure of the cam cylinder in the vision change monitoring device.
[0025] In the diagram, 1 is the laser source; 2 is the frosted glass disk; 3 is the motor; 4 is the slit; 5 is the field-of-view segmentation and reversal system; 6 is the third prism; 7 is the right-angle prism; 8 is the front fixed group; 9 is the zoom group; 10 is the compensation group; 11 is the rear fixed group; 12 is the cam cylinder; and 13 is the curved groove. Detailed Implementation
[0026] Laser light is a near-coherent light. When a laser beam is projected onto a rough surface or a surface with an uneven refractive index, the human eye can see a speckle pattern. Laser speckle refers to this type of speckle pattern, and this speckle carries relevant information about the rough surface.
[0027] By utilizing the phenomenon of laser speckle refraction and in conjunction with a relevant zoom system, the refractive power of the human eye can be detected. If a coherent source is observed within a circular area at the edge of a slowly rotating diffuse disc, a moving speckle pattern will be generated on the patient's retina. The speed of movement of the speckles in the speckle pattern is determined by the distance between the plane of the diffuse disc and the focal plane of the eye. In myopia, the direction of movement of the speckle pattern is the same as the direction of rotation of the ground glass disc; in hyperopia, the opposite movement can be observed. If the point light source is axially adjusted until it is conjugate to the retinal plane, the speckle will not move in any direction regardless of the speed or axial position of the diffuse disc. This is the basic principle of laser speckle refraction. Specifically, when the ciliary muscle is in a non-tense state and the diffuse disc is stationary, laser speckle can be seen by emmetropia, hyperopia, or myopia, but the size of the speckle particles differs significantly; when the diffuse disc is in motion, the direction of movement of the speckle pattern seen by emmetropia, hyperopia, or myopia will differ. Using laser speckle to measure the refractive power of the human eye is a relatively accurate method of optometry.
[0028] The vision change monitoring device provided by this invention consists of two main parts: a laser speckle generation system and a cam zoom system. For example... Figure 1 As shown, the laser speckle generation system includes a laser source 1, a diffuse reflection disk that rotates around its central axis, a slit 4, a field-of-view segmentation and inversion system 5, and a radially rotating third prism 6. The diffuse reflection disk is an object with a rough and uneven surface, such as a frosted glass rotating disk. The frosted glass rotating disk includes a motor 3 and a frosted glass disk 2, which is driven by the motor 3.
[0029] For laser source 1, considering that high-power lasers can damage the human eye, only a low-power laser source 1 can be used. Specifically, a helium-neon laser can be used, which emits 0.5-1mW of laser light. At this power, the laser speckle produced by the helium-neon laser is a surface light source, and the power entering the eye is classified as Class I laser, which will not cause harm to the eyes. Even considering unforeseen circumstances such as damage to the helium-neon laser that may prevent the laser from producing speckle, the laser emitted by the helium-neon laser still belongs to Class II laser after passing through optical devices such as right-angle prisms before entering the eye. Short-term direct viewing will not cause damage to the eyes, and people will instinctively avoid it, ensuring absolute safety for the eyes.
[0030] To prevent significant laser loss from the frosted glass disk 2 during laser transmission, and also to maintain the structural rigidity of the frosted glass disk 2, its thickness must be limited to a reasonable range, such as 1mm-5mm. Since a low-power laser source 1 is used, to reduce the power loss of the laser from the frosted glass disk 2 while effectively generating distinct laser speckle fringes, a 2mm thick frosted glass disk 2 is preferred.
[0031] Furthermore, the field-of-view splitting and reversing system 5 is formed by coupling a first prism and a second prism. It can be a square prism and a trapezoidal prism. The first prism and the second prism have different refractive indices. When the light path enters from one end, it will be reflected multiple times inside the coupling prism, and the emitted light is split into upper and lower parts.
[0032] To rotate the incident beam, the third prism 6 can be a radially rotating Dove prism or a pair of radially rotating triangular prisms; a Dove prism is preferred due to its simple structure. The Dove prism has the following optical characteristics: when it rotates by an angle α around its optical axis, the reflected image rotates by 2α in the same direction. Therefore, when the Dove prism rotates by 45°, the reflected image rotates by 90°, thus enabling the detection of astigmatism along various meridians.
[0033] To facilitate the reflection of the light path to a designated position, a right-angle prism is provided between the laser source and the frosted glass rotating disk, and / or a right-angle prism is provided between the third prism 6 and the cam zoom system, so as to change the direction of the light path by reflecting through the right-angle prism 7.
[0034] Another key design element of this device is the cam zoom system, which directly affects the accuracy and repeatability of visual acuity measurement. The zoom system achieves image sharpness and stability by changing the positions of several components. The cam zoom system comprises four main parts: a front fixed group 8, a zoom group 9, a compensation group 10, and a rear fixed group 11. As the names suggest, the front fixed group 8 and the rear fixed group 11 remain stationary within the system. The zoom group 9 is the key component for changing the focal length, and the compensation group 10 is designed to maintain the image plane position.
[0035] According to the type of system compensation, zoom systems can be divided into four main types: mechanical compensation zoom systems, dual-group linkage zoom systems, optical compensation zoom systems, and all-motion zoom systems. This vision monitoring device is designed based on a mechanical compensation zoom system. The mechanical compensation zoom system only uses mechanical means to realize the relative movement of the zoom group and the compensation group. Its movement requirement is that the sum of the changes in the conjugate distance of the object and the image is equal to zero in order to maintain the continuous stability of the object and the image. In order to achieve this, the movement of the zoom group is defined as a near-linear translation, while the movement of the compensation group is predicted as a non-linear translation.
[0036] The degree of myopia in the human eye can be roughly divided into low myopia (less than 300 degrees), moderate myopia (between 300 and 600 degrees), high myopia (between 600 and 900 degrees), and extreme myopia (more than 900 degrees).
[0037] Similar to how eyeglasses correct nearsightedness, this vision change monitoring device also corrects vision using a zoom lens group until the patient sees a no longer moving laser speckle. The focal length value at this point is then converted to obtain the eye's refractive power. The conversion formula is as follows:
[0038]
[0039] Where D represents diopter and f represents the real-time focal length of the lens.
[0040] In summary, the parameters of the cam zoom system are set as shown in Table 1:
[0041] Table 1 Parameters of Cam Variable Zoom System
[0042]
[0043] When the focal length f is 50mm, D = 1 / d = 1 / 0.05 = 20D = 2000 degrees; when the focal length f is 400mm, it is equivalent to parallel light entering the human eye, which can be approximated as 0 degrees. The motion trajectory of compensation group 10 is accurately calculated using formula (1-1), and a MATLAB mathematical model is further established to obtain the motion trajectory fitting function between zoom group 9 and compensation group 10:
[0044]
[0045] In the formula, q1 is the rotation angle of cam cylinder 12, y1 is the moving distance of the variable magnification group, and y2 is the moving distance of the compensation group.
[0046] The horizontal movement of the zoom group 9 and the compensation group 10 is controlled by the rotation of the cam cylinder 12, such as... Figure 3 As shown in the figure, this is a schematic diagram of the cam cylinder 12, which has a curved groove 13. The helix angle refers to the angle between the side of the curved groove 13 and the vertical line. The range of the helix angle is affected by the torque of the motor 3 and the friction coefficient of the contact surface. The larger the friction coefficient, the smaller the range. A larger helix angle has the negative effect of greatly increasing the load on the motor 3 and increasing the friction between the guide pin and the curved groove 13. Increasing the width of the curved groove 13 (i.e., extending the curve as much as possible in length) can reduce the helix angle or pressure angle, but this will greatly reduce the rigidity of the cam structure, which is not conducive to ensuring design accuracy. Too small a width will result in an excessively large helix angle, which is also unfavorable. Therefore, considering various factors, the helix angle is selected to be between 15° and 30°.
[0047] like Figure 1 , Figure 2 As shown, the working principle of the vision change monitoring device is as follows:
[0048] A 0.5-1mW laser emitted from a helium-neon laser is reflected by a right-angle prism 7 and then strikes a ground glass disk 2. After diffuse reflection by the ground glass disk 2, the laser forms a speckle pattern moving in one direction. When this moving speckle passes through a slit 4, it forms diffraction fringes that move in a specific direction. These fringes then pass through a field-splitting and reversing system 5 composed of two prisms, transforming them into two sets of fringes moving in opposite directions: upper and lower. Subsequently, these two sets of fringes pass through a radially rotatable third prism 6 and reach the cam-based zoom system, finally reaching the retina. For myopia and hyperopia, when the laser focus is on the retina, the eye sees two stationary sets of upper and lower fringes. If the focus is not on the retina, the patient sees two sets of fringes moving in opposite directions. In this case, the cam-based zoom device can be adjusted until the patient can see the stationary upper and lower fringes. For astigmatism measurement, the third prism 6 needs to be activated. The third prism 6 can change the meridian angle between 0 and 180° to calculate the two extreme values of the astigmatic refractive power on the corneal meridian, and the difference is the astigmatic power.
[0049] The vision change monitoring device provided by this invention is based on the principle of laser speckle refraction. By adjusting the focal length of the zoom system, it changes the imaging pattern of laser speckle on the human retina, thereby helping subjects determine their visual acuity. It is simple, reliable, and requires no patient intervention to determine the clarity of the image. In addition to measuring myopia and hyperopia, it can also measure astigmatism, making it convenient to use.
[0050] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.
Claims
1. A device for monitoring changes in visual acuity, characterized in that: The system includes a laser speckle generation system and a cam zoom system. The laser speckle generation system includes a laser source, a diffuse reflection disk that rotates around its central axis, a slit, a field-of-view splitting and reversing system, and a radially rotating third prism that rotates the incident beam. The laser source emits laser light, which forms laser speckle after passing through the rotating diffuse reflection disk. The laser speckle then forms diffraction fringes after passing through the slit. These diffraction fringes then pass through the field-of-view splitting and reversing system and become two sets of fringes with opposite directions of motion. The two sets of fringes then pass through the radially rotating third prism and reach the cam zoom system, finally reaching the retina.
2. The vision change monitoring device according to claim 1, characterized in that: The laser source is a helium-neon laser, which emits 0.5-1mW of laser light.
3. The vision change monitoring device according to claim 1, characterized in that: The rotating diffuse reflection disk is a frosted glass rotating disk, which includes a motor and a frosted glass disk, and the frosted glass disk is driven by the motor.
4. The vision change monitoring device according to claim 3, characterized in that: The thickness of the frosted glass disk is 1mm-5mm.
5. The vision change monitoring device according to claim 1, characterized in that: The field-of-view splitting and reversing system is formed by coupling a first prism and a second prism, with the first prism and the second prism having different refractive indices.
6. The vision change monitoring device according to claim 1, characterized in that: A right-angle prism is provided between the laser source and the frosted glass rotating disk, and / or a right-angle prism is provided between the third prism and the cam zoom system, so as to change the direction of the light path by reflecting through the right-angle prism.
7. The vision change monitoring device according to claim 1, characterized in that: The cam zoom system includes a front fixed group, a zoom group, a compensation group, and a rear fixed group. The zoom group and the compensation group move relative to each other, and the movement of the zoom group and the compensation group makes the sum of the changes in the conjugate distance of the image equal to zero.
8. The vision change monitoring device according to claim 7, characterized in that: The focal length range of the cam zoom system is 50mm-400mm.
9. The vision change monitoring device according to claim 8, characterized in that: The horizontal movement of the zoom group and the compensation group is controlled by rotating the cam cylinder. The motion trajectory fitting function of the zoom group and the compensation group is: y1=q1 y2=-0.006q1 4 +0.4032q1 3 -0.80311q1 2 +76.47q1-270.32; In the formula, q1 is the rotation angle of the cam cylinder, y1 is the moving distance of the variable magnification group, and y2 is the moving distance of the compensation group.
10. The vision change monitoring device according to claim 9, characterized in that: The cam cylinder is provided with a curved groove, and the rise angle of the curved groove is 15°-30°.