Children vision screening system

Abstract

The utility model discloses a vision screening system for children. Comprising an anterior eye aligning and focusing subsystem, a fundus diopter and defocusing amount measuring subsystem, an anterior eye aligning and focusing subsystem and a fundus diopter and defocusing amount measuring subsystem, wherein the anterior eye aligning and focusing subsystem is used for centering and focusing anterior eyes; the eye axis measuring subsystem is used for measuring the eye axis length of the human eyes; the automatic visual chart checking subsystem is used for providing a visual chart to check the vision of the human eyes; the diopter and defocusing amount measurement subsystem comprises a light source module, a light projection module and an imaging detection module; the light projection module comprises a galvanometer, a relay lens and an eyepiece which are sequentially arranged along a projection light path; the mirror surface of the galvanometer is conjugated with the pupil of the detected eye; the relay lens can move back and forth between the galvanometer and the eyepiece along the light path for diopter compensation.

Description

Technical Field

[0001] The utility model relates to a field, and in particular to a vision screening system for children and adolescents. Background Art

[0002] Currently, platforms for children's vision health records are being established in various places, but only a few children have actually established vision health records. There are two main reasons for this: one is that the medical and patient information of each hospital is kept independently, and the results of parents taking their children to various hospitals for examinations cannot be interconnected and shared; the other reason is that a lot of equipment is required to complete these tests, including eye charts, computer ophthalmometers, biometers, and multispectral imaging meters for peripheral defocus measurements. These devices are all independent and integrated, and each device requires trained professionals to use correctly. Therefore, each vision screening organized by the National Health Commission or the Education Commission requires multiple optometrists or technicians to screen a large number of kindergartens, primary and secondary schools one by one, which is a huge workload and difficult for medical and health institutions to complete independently. Utility Model Content

[0003] The utility model aims to provide a vision screening system for children and adolescents, so as to solve the problem that the current vision screening equipment is independent of each other and has a single function, which leads to a large workload of vision screening.

[0004] In order to solve the above technical problems, the present invention provides a vision screening system for children and adolescents, comprising an anterior eye alignment and focusing subsystem for centering and focusing the anterior eye, a fundus refractive power and defocus measurement subsystem for measuring the diopter and peripheral defocus of a human eye, an axial length measurement subsystem for measuring the axial length of a human eye, and an automatic eye chart inspection subsystem for providing an eye chart to inspect the vision of a human eye; the refractive power and defocus measurement subsystem comprises a light source module for providing a measuring light source, a light projection module for projecting the measuring light source onto the fundus of a tested eye and projecting the fundus image of the tested eye onto an imaging detection module, and an imaging detection module for detecting fundus image information of the tested eye; the light projection module comprises a galvanometer, a relay lens, and an eyepiece sequentially arranged along a projection light path; the mirror surface of the galvanometer is conjugate with the pupil of the tested eye; the relay lens can move back and forth along the light path between the galvanometer and the eyepiece to perform diopter compensation.

[0005] Furthermore, the light source module includes a first laser light source, a first collimator, a splitter consisting of a slit and a double wedge, and a second collimator, which are arranged in sequence; the first laser light source is collimated by the first collimator and then passes through a slit to form a slit light source, and the slit light source is then evenly irradiated to the splitter, and then the first laser light source is divided into two identical parallel light beams by the splitter and the second collimator and emitted as a splitting light source.

[0006] Furthermore, the light projection module also includes a first beam splitter, and the split light source emitted by the light source module is transmitted to the galvanometer through the first beam splitter, and then passes through the relay lens and the eyepiece in sequence, irradiates the pupil, and is projected to the fundus of the eye to be tested through the eye imaging system; the fundus splitting imaging image of the eye to be tested then passes through the eyepiece and the relay lens in sequence and returns to the galvanometer, and is finally reflected to the imaging detection module through the first beam splitter.

[0007] Furthermore, the imaging detection module includes a first image detector and a first imaging lens arranged on the incident light path of the first image detector. The fundus splitting imaging image of the eye being tested passes through the eye refractive system and then sequentially passes through the eyepiece, relay mirror, galvanometer and first imaging lens to be imaged onto the first image detector.

[0008] Furthermore, the light source module includes a third collimator and a second laser light source; the second laser light source is collimated by the third collimator and then sequentially passes through the galvanometer, relay lens and eyepiece to be projected onto the fundus of the eye to be tested; the imaging detection module also includes a second imaging lens and a second image detector for acquiring the fundus image of the eye to be tested, and the fundus image of the eye to be tested passes through the eye refractive system and then sequentially passes through the eyepiece, relay lens, galvanometer and second imaging lens to be imaged onto the second image detector.

[0009] Furthermore, the light projection module also includes a second beam splitter and a first dichroic mirror; the spot imaging light source emitted by the light source module is transmitted to the first dichroic mirror through the second beam splitter, and then reflected to the galvanometer through the first dichroic mirror; the spot imaging image of the fundus of the eye being tested is reflected to the second beam splitter through the first dichroic mirror after passing through the galvanometer, and then reflected to the second imaging lens through the second beam splitter.

[0010] Furthermore, an eye alignment and focusing subsystem is provided, which includes a stereo camera module composed of dual imaging modules; after collecting the human eye image through the dual cameras, the coordinates of the pupil center in the image are extracted through image processing, the coordinates of the human eye center and the coordinates of the object to be aligned are calculated, and then the position of the human eye is adjusted so that the coordinates of the human eye center and the coordinates of the object to be aligned coincide, thereby achieving alignment.

[0011] Furthermore, an axial length measurement subsystem is provided; the axial length measurement subsystem comprises a third laser light source, an optical fiber coupler, a measuring branch optical path and a Michelson interferometer; the third laser light source is divided into a first light beam and a second light beam via the optical fiber coupler; the first light beam enters the measuring branch optical path, is irradiated to the cornea via the measuring branch optical path, the relay lens and the eyepiece, and is irradiated to the macular part of the fundus via the pupil; the light reflected from the macular part of the fundus returns along the original path; the second light beam enters the Michelson interferometer and returns; the light returned via the measuring branch optical path and the light returned via the Michelson interferometer form coherent light that is incident on the spectrometer, and the power spectrum received by the third image detector is transformed through Fourier transform to obtain the intervals between the various reflection parts of the eye, thereby obtaining the length of the axial length.

[0012] Furthermore, the automatic eye chart checking subsystem includes a display screen for displaying the eye chart, a virtual indicator stick arranged on the display screen for indicating a virtual indication of an icon on the eye chart, and a transponder for feeding back the indication direction input by the tester; the display range of the eye chart on the display screen is adjustable.

[0013] The beneficial effects of the utility model are:

[0014] 1. By integrating the front of the eye focusing subsystem, fundus refractive power and defocus measurement subsystem, axial length measurement subsystem and automatic eye chart inspection subsystem, one set of equipment can simultaneously complete the measurement of visual acuity, refractive power, axial length and peripheral defocus, which simplifies the operation, improves the efficiency of vision screening, and realizes early monitoring, early detection, early warning and early intervention of myopia, contributing to reducing the myopia rate in my country and the number of people with high myopia.

[0015] 2. By moving the relay mirror back and forth to perform diopter compensation, clear imaging of the light spot can be achieved, so that the human diopter can be calculated based on the light spot later; by setting a galvanometer in the optical path and making the galvanometer perform XY optical scanning, the defocus amount of areas other than the macular area of ​​the fundus can be measured, thereby realizing the measurement of the defocus amount of the entire retinal area. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The same reference numerals are used in these drawings to represent the same or similar parts. The exemplary embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0017] Figure 1 A schematic diagram of light path distribution according to an embodiment of the present invention;

[0018] Figure 2 A schematic diagram of a split imaging measurement principle according to an embodiment of the present invention;

[0019] Figure 3(a) is the optical path diagram under the condition of hyperopia + relay lens compensation;

[0020] Figure 3(b) is the optical path diagram under the condition of myopia + relay lens compensation;

[0021] Figure 3(c) is a diagram of the myopic defocus optical path when the relay lens is not compensated;

[0022] Figure 4 This is a schematic diagram of the alignment and focusing principle of a stereo camera module according to an embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of the eye axis measurement principle according to an embodiment of the present invention.

[0024] Among them, 101, first optical fiber; 102, first collimator; 103, spectrum splitter; 104, second collimator; 105, first beam splitter; 106, first imaging lens; 107, first image detector; 201, second optical fiber; 202, third collimator; 203, second beam splitter; 204, first dichroic mirror; 205, second imaging lens; 206, second image detector; 301, galvanometer; 302, relay mirror; 303, eyepiece; 401, first stereo camera; 402 , third imaging lens; 403, second stereo camera; 404, fourth imaging lens; 501, third optical fiber; 502, fourth collimator; 503, second dichroic mirror; 504, third dichroic mirror; 505, fifth imaging lens; 506, first reflector; 507, fixation mark; 508, fourth optical fiber; 509, fifth collimator; 511, shading plate; 512, rotating shaft; 513, sixth imaging lens; 514, second reflector; 515, seventh imaging lens; 516, third reflector. DETAILED DESCRIPTION

[0025] like Figure 1 The vision screening system for children and adolescents shown in the figure includes an anterior eye alignment and focusing subsystem for centering and focusing the anterior eye, a fundus refractive power and defocus measurement subsystem for measuring the refractive power and peripheral defocus of the human eye, an axial length measurement subsystem for measuring the axial length of the human eye, and an automatic vision chart inspection subsystem for providing a vision chart to inspect the vision of the human eye. The system integrates the anterior eye alignment and focusing subsystem, the fundus refractive power and defocus measurement subsystem, the axial length measurement subsystem, and the automatic vision chart inspection subsystem. A set of equipment can simultaneously complete the measurement of vision, refractive power, axial length, and peripheral defocus, which simplifies the operation, improves the efficiency of vision screening, and realizes early monitoring, early detection, early warning, and early intervention of myopia, contributing to reducing the myopia rate in my country and the number of people with high myopia.

[0026] The fundus refractive power and defocus measurement subsystem includes a light source module, a light projection module and an imaging detection module. The light source module is used to provide a measuring light source; the light projection module is used to project the measuring light source to the fundus of the eye to be measured and to project the fundus image of the eye to be measured to the imaging detection module; the light projection module includes a galvanometer 301, a relay lens 302 and an eyepiece 303 arranged in sequence along the projection light path; the mirror surface of the galvanometer 301 is conjugate with the pupil to ensure that the light spot can completely pass through the pupil to irradiate the fundus; the relay lens 302 can move forward and backward along the light path between the galvanometer 301 and the eyepiece 303 to perform diopter compensation; the imaging detection module is used to detect the fundus image information of the eye to be measured. By moving the relay lens 302 forward and backward to achieve diopter compensation, clear imaging of the light spot can be achieved; by setting the galvanometer 301 in the light path and making the galvanometer 301 perform XY optical scanning, the defocus amount of the area outside the macular area of ​​the fundus can be measured, thereby measuring the defocus amount of the entire retinal area.

[0027] According to an embodiment of the present application, the light source module includes a first laser light source, a first collimator 102, a splitter 103, and a second collimator 104 arranged in sequence; the first laser light source is collimated by the first collimator 102 and then passes through a slit to form a slit light source, and the slit light source is then evenly irradiated to the splitter 103, and then the first laser light source is split into two identical parallel lights by the splitter 103 and the second collimator 104 and emitted as a splitting light source. The splitting light source emitted by the light source module passes through the galvanometer 301 and forms a primary image of the slit on the focal plane of the relay lens 302; the image of the slit is irradiated to the fundus through the eyepiece 303. When the eye refractive system does not have hyperopia or myopia, the slit is secondary imaged to the fundus to form a bright slit image, but if the eye has refractive errors, the slit forms two separate light spots on the fundus.

[0028] According to an embodiment of the present application, the light projection module further includes a first beam splitter 105, and the split light source emitted by the light source module is transmitted to the galvanometer 301 through the first beam splitter, and then sequentially passes through the relay lens 302 and the eyepiece 303, irradiates the pupil, and is projected to the fundus of the eye under test through the eye imaging system; the fundus split imaging image of the eye under test then sequentially passes through the eyepiece 303 and the relay lens 302 to return to the galvanometer 301, and finally is reflected to the imaging detection module through the first beam splitter 105. The first beam splitter 105 can facilitate the coupling of the split light source and the detection light path.

[0029] The imaging detection module includes a first image detector 107 and a first imaging lens 106 arranged on the incident light path of the first image detector 107. The fundus splitting imaging image of the eye under test passes through the eye refractive system, and then passes through the eyepiece 303, the relay lens 302, the galvanometer 301 and the first imaging lens 106 in sequence to be imaged on the first image detector 107. Due to the refractive error of the eye, the image detected on the image detector is not a perfect image, which affects the determination of the boundary and center position of the spot image by the image processing, resulting in a limited measurement range of the splitting imaging; in this system, the relay lens 302 and the eyepiece 303 are confocal, and the relay lens 302 can move forward and backward to achieve diopter compensation.

[0030] According to one embodiment of the present application, the light source module includes a third collimator 202 and a second laser light source; after the second laser light source is collimated by the third collimator, it passes through the galvanometer 301, the relay lens 302 and the eyepiece 303 in sequence and is projected onto the fundus of the eye to be tested; the imaging detection module also includes a second imaging lens 205 and a second image detector 206 for acquiring the fundus image of the eye to be tested, and the fundus image of the eye to be tested passes through the eye refractive system and then passes through the eyepiece 303, the relay lens 302, the galvanometer 301 and the second imaging lens 205 in sequence and is imaged onto the second image detector 206.

[0031] According to one embodiment of the present application, the light projection module also includes a second beam splitter 203 and a first dichroic mirror 204; the spot imaging light source emitted by the light source module is transmitted to the first dichroic mirror 204 through the second beam splitter 203, and then reflected to the galvanometer 301 through the first dichroic mirror 204; the spot imaging image of the fundus of the eye being tested is reflected to the second beam splitter 203 through the first dichroic mirror 204 after passing through the galvanometer 301, and then reflected to the second imaging lens 205 through the second beam splitter 203.

[0032] like Figure 1 As shown, the second laser light source from the second optical fiber 201 is collimated by the third collimator and coupled into the split imaging optical path by the first dichroic mirror 204. The optical path returned from the fundus is separated by the first dichroic mirror 204, and is imaged to the second imaging lens 205 after being reflected by the second beam splitter 203. The circular light spot is not so sensitive to the boundary mode caused by the refractive error of the human eye. Combined with the refractive compensation of the relay lens 302, the refractive power within the range of ±15D can be measured. The spot ellipticity analysis of the circular light spot can realize the astigmatism of the eye refractive system, that is, the cylindrical power.

[0033] According to one embodiment of the present application, Figure 2As shown, the pattern of the split or light spot in myopia that hits the fundus is the object of the entire imaging system, and the object is imaged to the far point by the eye imaging system, and the reciprocal of the distance from this position point to the eye (in meters) is the diopter. The image of the far point is imaged by the eyepiece 303 as the object of the eyepiece 303 to a certain position in front of the relay lens 302, and the distance from this position to the focus of the relay lens 302 is the refractive compensation movement distance of the relay lens 302. The relay lens 302 and the imaging lens will image the image formed by the eyepiece 303 onto the image detector again. However, at this time, the image detector is not in the ideal image plane position, so it is a relatively blurred image spot. Through image processing, the center separation distance of the two separated image spots obtained by the first image detector 107 (or the spot size obtained by the second image detector 206) can be obtained. Then, the refractive compensation distance of the relay lens 302 and the refractive power of the human eye can be calculated based on the center separation distance of the two separated image spots obtained by the first image detector 107 (or the spot size obtained by the second image detector 206).

[0034] When the first laser light source is used for measurement, the first image detector 107 obtains two separated image spots. This measurement method is called split imaging measurement. The principle is as follows: Figure 2 As shown, at this time, the calculation formula of the diopter compensation distance of the first relay lens 302 is:

[0035]

[0036] The formula for calculating the refractive power of the human eye is:

[0037]

[0038] Among them, a, b, and c are

[0039] a=f 2 f 3 +f 3 f 4 -f 2 f 4 -f 2 d 3 -f 3 d 2 +f 4 d 2 +f 3 d 3 +d 2 d 3

[0040] b=f 2 f 3 2 -f 2 2 f 3 +f 22 f 4 -f 2 f 3 f 4 +f 2 f 3 d 1 +f 2 f 3 d 2 +f 2 2 d 3 -f 3 2 d 1 -f 2 f 3 d 3 -f 2 f 4 d 1 -f 2 f 4 d 2 +f 3 f 4 d 1 -f 2 d 2 d 3 -f 3 d 1 d 2 +f 3 d 1 d 3 +d 1 d 2 d 3 +d 1 d 2 d 4

[0041] c=b+a*(d 1 -f 2 ')

[0042] f 2 、f 3 、f 4 are the object focal lengths of the eyepiece 303, the relay lens 302 and the imaging lens, respectively, and f′ 2 , f′ 3 , f′ 4 are the image-side focal lengths of the eyepiece 303, the relay lens 302 and the imaging lens; d 1 d 2 d 3 They are respectively the distance from the image principal point of the human eye to the object principal point of the eyepiece 303, the distance from the image principal point of the eyepiece 303 to the object principal point of the relay lens 302, and the distance from the image principal point of the relay lens 302 to the object principal point of the imaging lens.

[0043] When the second laser light source is used for measurement, the second image detector 206 obtains a circular light spot. This measurement method is light spot imaging measurement. The principle is as follows: Figure 3(a) , 3(b) As shown in Figure 3(c), the diopter compensation distance d of the relay lens is lx The calculation formula is:

[0044]

[0045] When the relay lens is far away from the eyepiece, it is positive, otherwise it is negative.

[0046] a=s d [f′ 2 (f′ 3 -d 3 )] 2 -π(h 1 f′ 4 f 3 ) 2

[0047] b=2s d (f′ 2 f′ 3 2 )f′ 2 (f′ 3 -d 3 )

[0048] c=s d (f′ 2 f′ 3 2 ) 2

[0049] The calculation formula of human eye's diopter D is:

[0050]

[0051] The value units of each symbol in the formula are mm; s d is the size of the image collected by the second image detector; l r For a longer distance.

[0052] According to one embodiment of the present application, the front of the eye alignment and focusing subsystem includes a stereo camera module composed of dual imaging modules; after the dual cameras collect the human eye image, the coordinates of the pupil center in the image are extracted through image processing, the coordinates of the human eye center and the coordinates of the object to be aligned are calculated, and then the human eye position is adjusted so that the coordinates of the human eye center and the coordinates of the object to be aligned coincide, so as to achieve alignment. The front of the eye alignment and focusing subsystem can quickly realize the centering and focusing of the front of the eye, and its implementation principle is as follows:

[0053] Establish as Figure 4 The coordinate system shown is the three-dimensional coordinate system (x 1 ,y 1 ,z 1 ), the three-dimensional coordinate system (x 2 ,y 2 ,z 2 ), the three-dimensional coordinate system of the space where the eye to be detected is located (x 0 ,y 0 ,z 0 ). The two cameras are placed symmetrically, OO 1 'O 1 ″ is the optical axis of the first stereo camera 401, OO 2 'O 2 ″ is the optical axis of the second stereo camera 403. The optical axes of the two imaging systems intersect at point O, which is the object point of the ideal imaging. When the pupil center is located at this point, it will be imaged to the center of the two cameras, O. 1 ″、O 2 ″, the center is the center of the convex mirror of the first stereo camera 401 or the second stereo camera 403, and the system is in an aligned state. The straight line where OM is located is the symmetry axis of the two cameras, that is, the imaging optical path axis of the imaging unit. 1 ″O 2 The distance between ″ is 2a, O 1 'O 1 =O 2 'O 2 = b, establish the coordinate system as shown above, CCD1 is located at X 1 , Z 1 In the coordinate plane, the origin of the coordinate is located at the center O of CCD1 1 ″;CCD2 is located at X 2 , Z 2 In the coordinate plane, the origin of the coordinate is located at the center O of CCD2 2 ″; The object is located at X 0 , Y 0 , Z 0 In the coordinate system, the origin is point O. The X and Y planes of the three coordinate systems are coplanar.

[0054] After the dual cameras capture the eye image, the image processing extracts the coordinates of the pupil center in the image. Using formula (5), it can be obtained that the center of the human eye is at (X 0 ,Y 0 )The distance that the plane deviates from the ideal object point.

[0055]

[0056] Among them, x o Indicates the deviation of the point A to be aligned in the X direction, yo Indicates the deviation of the point A to be aligned in the Y direction, x 1 represents the X-axis coordinate of the image point A1, a represents half of the distance between the center of the first stereo camera 401 and the center of the second stereo camera 403, b represents the distance from the intersection of the optical axis of the first stereo camera 401 and the optical axis of the second stereo camera 403 to the first stereo camera 401 or the second stereo camera 403, and α represents the angle between the optical axis of the first stereo camera 401 and the axis of symmetry of the first stereo camera 401 and the second stereo camera 403.

[0057] In the vertical direction (Z-axis direction), the deviation of the eye center from the ideal position can be calculated by the deviation of the pupil center from the ideal image point position on the image: Among them, Z 0 represents the deviation of the intersection point A on the Z axis, Z1 represents the Z axis coordinate of the image point A1 of the intersection point A on the first stereo camera 401, and m represents the magnification of the stereo camera imaging system.

[0058] Calculate the position of the object A to be aligned at X 0 , Y 0 , Z 0 After the coordinates of the coordinate system, the system where the two stereo cameras are located is along the X 0 , Y 0 , Z 0 The coordinate axis moves the coordinate value of point A so that point A coincides with point O to achieve alignment.

[0059] According to one embodiment of the present application, Figure 5 As shown, the axial length measurement subsystem includes a third laser light source, a fiber optic coupler, a measuring branch optical path and a Michelson interferometer; the third laser light source is divided into a first light beam and a second light beam through the fiber optic coupler; the first light beam enters the measuring branch optical path, irradiates the cornea through the measuring branch optical path, the relay lens 302 and the eyepiece 303, and irradiates the macular part of the fundus through the pupil; the light reflected from the macular part of the fundus returns along the original path; the second light beam enters the Michelson interferometer and returns; the light returned through the measuring branch optical path and the light returned through the Michelson interferometer form coherent light that is incident on the spectrometer, and the power spectrum received by the third image detector is transformed by Fourier transform to obtain the intervals between the various reflection parts of the eye, and the length of the axial length is obtained. The measuring branch includes a third laser light source, a fourth collimator 502, a second dichroic mirror 503 and a third dichroic mirror 504. The third laser light source is irradiated to the cornea via the fourth collimator 502, the second dichroic mirror 503, the third dichroic mirror 504, the relay lens 302 and the eyepiece 303, and is irradiated to the macular part of the fundus via the pupil; the light reflected from the macular part of the fundus is returned to the fiber coupler along the eyepiece 303, the relay lens 302, the third dichroic mirror 504, the second dichroic mirror 503 and the fourth collimator 502.

[0060] Due to the limited measurement range of the system, the axial length measurement needs to be completed by secondary measurement. First, the distance between the cornea and the lens in the front of the eye and the zero-path difference distance with reference branch 1 are measured; then the distance between the return light beam from the fundus and the zero-path difference of reference branch 2 is measured. These distances plus the distance between reference branch 1 and reference branch 2 are the distances from the fundus to the cornea.

[0061] According to one embodiment of the present application, the automatic eye chart examination subsystem includes a display screen for displaying an eye chart, a virtual indicator stick provided on the display screen for indicating a virtual indication of an icon on the eye chart, and a transponder for feeding back the indication direction input by the tester; the display range of the eye chart on the display screen is adjustable. The eye chart is prepared in accordance with the national new version of the eye chart standard (GB11533-2011), and the illumination is 80-320cd / m2 (candela / square meter). The display uses a liquid crystal or LED display screen, and the display size of the eye chart icon can be adjusted based on the size of the venue, so that when the logarithmic eye chart is 5.0 or the international eye chart is 1.0, the angle between the adjacent horizontal or vertical lines of the icon and the eye node (about 7mm behind the corneal vertex) is 1 arc minute.

[0062] During measurement, the virtual indicator stick on the display screen is located at the lower right of the icon. Starting from the largest icon, the test participant determines the direction in which the opening of the icon indicated by the virtual indicator stick is facing, and points out the direction through the handle of the transponder. There is a cross-shaped slot at the base of the handle. When the handle is pushed in a certain direction, the handle is connected to the electrode sheet in that direction, and the electrode in that direction changes from a low level to a high level. The high-level signal is transmitted to the data acquisition card (DAQ) and compared with the direction of the icon indicated by the virtual indicator stick to obtain the result of judging right or wrong. During the measurement process, starting from the large icon, in the 0.1 to 0.4 lines of the international visual acuity chart, each line only needs to judge one icon correctly to jump to the next line. For lines 0.5 and later, two consecutive icons need to be correct to jump to the next line, otherwise, it is considered that there is a problem with the vision in this line, and the vision value can only reach the previous line.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A vision screening system for children and adolescents, characterized in that: The invention comprises an anterior eye alignment and focusing subsystem for centering and focusing the anterior eye, a fundus refractive power and defocus measurement subsystem for measuring the diopter and peripheral defocus of a human eye, an axial length measurement subsystem for measuring the axial length of a human eye, and an automatic vision chart checking subsystem for providing a vision chart to check the vision of a human eye; the refractive power and defocus measurement subsystem comprises a light source module for providing a measurement light source, a light projection module for projecting the measurement light source onto the fundus of a measured eye and projecting the fundus image of the measured eye onto an imaging detection module, and an imaging detection module for detecting fundus image information of the measured eye; the light projection module comprises a galvanometer, a relay lens and an eyepiece arranged in sequence along a projection light path; the mirror surface of the galvanometer is conjugate with the pupil of the measured eye; the relay lens can move back and forth along the light path between the galvanometer and the eyepiece to perform diopter compensation.

2. The vision screening system for children and adolescents according to claim 1, characterized in that: The light source module comprises a first laser light source, a first collimator, a splitter consisting of a slit and a double wedge, and a second collimator, which are arranged in sequence; the first laser light source is collimated by the first collimator and then passes through a slit to form a slit light source, the slit light source is then evenly irradiated to the splitter, and then the first laser light source is divided into two identical parallel lights by the splitter and the second collimator to be emitted as a splitting light source.

3. The vision screening system for children and adolescents according to claim 2, characterized in that: The light projection module also includes a first beam splitter. The split light source emitted by the light source module is transmitted to the galvanometer through the first beam splitter, and then passes through the relay lens and the eyepiece in sequence to illuminate the pupil, and then is projected to the fundus of the eye to be tested through the eye imaging system; the fundus splitting imaging image of the eye to be tested then passes through the eyepiece and the relay lens in sequence and returns to the galvanometer, and finally is reflected to the imaging detection module through the first beam splitter.

4. The vision screening system for children and adolescents according to claim 3, characterized in that: The imaging detection module includes a first image detector and a first imaging lens arranged on the incident light path of the first image detector. The fundus splitting imaging image of the eye being tested passes through the eye refractive system and then sequentially passes through the eyepiece, relay mirror, galvanometer and first imaging lens to be imaged onto the first image detector.

5. The vision screening system for children and adolescents according to claim 1, characterized in that: The light source module includes a third collimator and a second laser light source; the second laser light source is collimated by the third collimator and then sequentially passes through the galvanometer, relay lens and eyepiece to be projected onto the fundus of the eye to be tested; the imaging detection module also includes a second imaging lens and a second image detector for acquiring the fundus image of the eye to be tested, and the fundus image of the eye to be tested passes through the eye refractive system and then sequentially passes through the eyepiece, relay lens, galvanometer and second imaging lens to be imaged onto the second image detector.

6. The vision screening system for children and adolescents according to claim 5, characterized in that: The light projection module also includes a second beam splitter and a first dichroic mirror; the spot imaging light source emitted by the light source module is transmitted to the first dichroic mirror through the second beam splitter, and then reflected to the galvanometer through the first dichroic mirror; the spot imaging image of the fundus of the eye being tested is reflected to the second beam splitter through the first dichroic mirror after passing through the galvanometer, and then reflected to the second imaging lens through the second beam splitter.

7. The vision screening system for children and adolescents according to claim 1, characterized in that: The front of the eye focusing subsystem comprises a stereo camera module composed of dual imaging modules.

8. The vision screening system for children and adolescents according to claim 1, characterized in that: The eye axis measurement subsystem; the eye axis measurement subsystem includes a third laser light source, a fiber optic coupler, a measurement branch optical path and a Michelson interferometer; the third laser light source is divided into a first light beam and a second light beam through the fiber optic coupler; the first light beam enters the measurement branch optical path, irradiates the cornea through the measurement branch optical path, the relay lens and the eyepiece, and irradiates the macular part of the fundus through the pupil; the light reflected from the macular part of the fundus returns along the original path; the second light beam enters the Michelson interferometer and returns; the light returned through the measurement branch optical path and the light returned through the Michelson interferometer form coherent light that is incident on the spectrometer, and the power spectrum received by the third image detector is transformed by Fourier transform to obtain the intervals between various reflection parts of the eye, and the length of the eye axis is obtained.

9. The vision screening system for children and adolescents according to claim 1, characterized in that: The automatic eye chart checking subsystem includes a display screen for displaying the eye chart, a virtual indicator stick arranged on the display screen for indicating the virtual indication of the icon on the eye chart, and a transponder for feeding back the indication direction input by the tester; the display range of the eye chart on the display screen is adjustable.

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