Device and method for automatically measuring eyeball deflection and / or vertical and horizontal visual angles

Abstract

An apparatus for automatically measuring eyeball deflection and / or vertical and horizontal viewing angles, comprising an optical-mechanical system cooperating with an image recording and display device, having a screen (1) placed in an integrated housing (15), in front of which two symmetrically embedded optical-mechanical modules are mounted on a side arm (12), the side arms (12) are movably embedded in horizontal guide rails (16) which are vertically arranged relative to the side arms and are arranged side by side, and are driven along the guide rails by a servo driver (9) and a driving element (10). Each ray-machine module has a camera (2) operating in the invisible spectrum, an optical lens barrel (5) for fixing a lens system (8), a line-of-sight closing system (6) and a pupil illuminator (11) operating in the invisible spectrum, the screen (1) being placed perpendicularly to the axis of the lens system (8), according to the invention, the lens system (8) is arranged between the camera (2) and the screen (1) and is located at a position which allows the screen (1) to be observed sensitively and which covers as large as possible the eye field of view, and furthermore, the selection element (7) is arranged between the lens system (8) and the screen (1) such that both pupil images in the invisible spectral field of view can be reflected to the camera (2) and at the same time the screen (1) can be observed continuously, the pupil illuminator (11) is fixedly mounted on the side arm (12) in such a way as to illuminate the entire pupil of the eye while also preventing light reflections on the lens surface (8) from being displayed on the image of the camera (2), in addition, the screen (1), the camera (2), the line-of-sight closing system (6), the servo driver (9) and the drive element (10) are connected to and controlled by the computer (4).

Description

Technical Field

[0001] The object of the present invention is to provide a method and device for automatically measuring eye deviation and / or vertical and horizontal visual angles, which consists of a screen, a movable camera, a reflector, and a correction lens that can be automatically adjusted to the distance of an individual's eyes. By using the technology of alternately and cyclically projecting graphic patterns on the screen and synchronously covering the eyes, analyzing and recording the eye movement adjustments caused by the movement of these patterns, dynamically determining the new position of the patterns according to the direction of the recorded naked-eye adjustment movement, and finally calculating the vertical and horizontal strabismus angles based on the position of the finally recorded graphic pattern on the screen after the eye movement adjustment stops, as well as relevant information such as the patient's individual pupil distance and the field distortion caused by the patient's refractive lens. Background Art

[0002] In the consulting rooms of ophthalmologists and vision correction doctors, a prism bar is usually used for time-consuming unilateral alternating "cover test" to evaluate the actual value of the strabismus angle. This examination method may not be reliable and may produce errors due to the subjective and visual evaluation of eye movement by the examiner, depending on the skills and experience of the examiner. In addition, this examination takes a long time and requires the patient's good cooperation. In the case of complex strabismus and / or difficulties in the cooperation between the patient and the doctor and / or optometrist, the help of other personnel is also required.

[0003] The commonly used device for measuring the strabismus angle is an opto-mechanical synoptophore. In its basic form, it consists of two rotating optical modules placed close to the patient's eyes for projecting and observing static images. The structure of the images allows them to be combined into one image because the patient can properly position the optical modules and the synoptophore arm to combine them into one image. As the optical modules gradually rotate, the images alternately disappear, forcing the patient's eyes to make adjustment movements. The optometrist evaluates the strabismus angle based on the visual evaluation of the adjustment movement and the current rotation angle of the optical module read from a scale or digital encoder. The synoptophore is a complex device that requires the examiner / optometrist to have rich experience, and the detection result depends on the subjective visual impression of the patient.

[0004] Chinese Patent Document CN101433456A discloses an intelligent synoptophore for diagnosing the type and degree of strabismus, equipped with a camera, a liquid crystal display screen, and eye movement detection software to assist the optometrist. In this synoptophore, the position of the image is mechanically adjusted by an electric motor. This solution cannot properly calibrate the optical system of the camera, that is, it cannot convert the intensity of eye movement into the angle of the driving position, which is a stepper motor for properly positioning the optical module in this case.

[0005] Chinese Patent Document CN105942966A discloses a strabismus automatic detection system based on a digital synoptophore, which improves the autonomy of the device operation and its efficiency in detecting and diagnosing strabismus. Similar to the solution of CN101433456A, since the optical system of the camera cannot be calibrated, the measurement results are inaccurate. In addition, this device is not used for measuring the strabismus angle, but only for detecting strabismus, resulting in a lack of accurate diagnostic results.

[0006] A common method for evaluating the strabismus angle is to observe the position of the reflected light point on the pupil surface. Some automatic devices also use this method. There are also many descriptions in scientific and technical literature about the techniques for measuring the eye position and movement based on the analysis of the position and shape of the pupil in the camera image.

[0007] International Patent Document WO2011021936A1 discloses a device and method for automatically determining the strabismus angle through a reflection test. The device irradiates at least one beam of visible light onto the patient's eyes and requires the patient's eyes to focus on the beam, and then uses at least one imaging device to analyze the reflected light to detect the fixating eye, and conducts a reflection test on both eyes to estimate the strabismus angle. This reflection test includes using at least two light sources at known alternating positions and measuring their reflection positions on the corneas of both eyes. The recorded reflections are used to obtain the coordinates of the centers of the corneas of both eyes and estimate the coordinates of the pupil centers, and are further used to estimate the strabismus angle. For the fixating eye, the angle between the optical axis of the eye passing through the center of the cornea and the pupil center and the visual axis passing through the center of the cornea and the center of the eye's visual field is calculated, and then this angle is converted into the strabismus angle.

[0008] Russian Patent Document RU2669734C1 discloses a system for calculating the strabismus angle of a patient, which has a relatively low error, where Δα = 0.4°. The measurement process described in this solution is non-autonomous and requires a lot of participation from the operator. In order to match the number of pixels in the image with the actual distance, a measurement line needs to be applied to the face of each patient for a calibration procedure. During the measurement process, a camera and a light source are required for the patient to fixate on, and the patient's head is fixed on the forehead-chin bracket. On the recorded image, the distance between the vertical lines passing through the outer and inner corners of the fixating eye and the distance between the pupil center and the glare of the light source on the strabismic eye are measured, and then the radius of curvature of the sclera and the strabismus angle are calculated using the mathematical formula in this solution.

[0009] In the prior art, according to the disclosure of Chinese Patent Document CN110575132A, a method for calculating the degree of strabismus based on eye imaging and using artificial intelligence algorithms, namely deep learning in neural networks, is also known. In this solution, the pupil image and the reflection point of the corneal light in the pupil image are analyzed, and whether strabismus exists is determined based on their positions. If it exists, the degree of strabismus is determined. According to the ratio of the offset distance between the corneal light reflection point and the pupil center to the pupil radius, the strabismus degree can be calculated. This solution only discloses a measurement method and does not introduce the device structure for performing recording and image analysis, and the measurement is based on subjective optometry.

[0010] In another disclosed US Patent Document US2014268051A1, a method and device for detecting strabismus in an eye image recorded by a camera using the reflection of a light source on the eye are described. The subject is asked to fixate on a target, which can move within a range of 5 - 10 cm from the light source at a known distance. The moving target provides a fixation point for the subject, which can guide the subject to fixate on the target and capture an image (and / or fixate on the target reflexively). By knowing the relative positions of the subject, the light source, and the target, reference data can be determined, and these data can be compared with the data determined from the captured image to measure strabismus. The reference data represents the expected reflection shift distance in the non-strabismic eye. The eye image recording device can be a camera, a smartphone, a laptop computer, a corneal curvature meter, and / or any other device capable of capturing images and having computing power (processor). This solution does not describe how to determine the strabismus angle, nor does it describe the method of calibrating the device and obtaining the reference data, and determining the threshold that defines the boundary between healthy people and strabismus patients based on the reference data.

[0011] The position where the observation point light is reflected on the pupil surface can also be used for training to reduce the strabismus angle. From the description of Chinese Patent Document CN112807200A, there is a device for treating strabismus. By performing visual training, the degree of strabismus can be gradually reduced. The device has at least one camera, two LED light sources working together in the near-infrared band, two polarizers for the left and right eyes respectively, and a display. The camera is used to detect the position of the eyes in the image. The near-infrared light source provides illumination and is captured by the near-infrared camera, and a corneal reflection point is generated through the reflection on the outer surface of the cornea, serving as a reference point for eye movement calculation. This device cannot determine the strabismus angle and cannot be automatically adjusted according to the individual physical characteristics of the patient.

[0012] Another Chinese patent document CN112336301A proposes a device for measuring the strabismus angle by alternately covering the two eyes with a filter, wherein the spatial position of the eye axis is determined by a stereoscopic vision system based on the positions of the pupil and corneal reflections. These data are used to initially calibrate the relationship between the coordinates of the fixation point of the eye on the screen and the coordinates of the pupil movement in the image of the fixation target across the entire display plane. Several points with known positions on the screen are used for the first calibration. In the next stage of single-point calibration, the Kappa angle of each patient can be determined, which determines the deviation between the geometric axis of the eye and the true visual axis. Then, a calibration model is determined for the fixation target at any position. The device provided by this disclosure can be used to reveal the type of strabismus and its direction trend. In this disclosure, except for analyzing the rotation of the eye iris and / or calculating the angle between the visual axes of the naked eye and the covered eye, no detailed information about how to determine the strabismus angle method is disclosed, which would be equivalent to using a prism with an appropriate optical power. In the absence of strabismus, the axes should coincide. There is no explanation about whether the method for determining the position of the fixation target during the examination is manual or automatic and on what basis it is performed. This disclosure indicates the possibility of automating the device and obtaining similar results. However, whether the device takes into account the significant influence of individual refractive errors on the test results and how to effectively decompose the image fusion of the patient have not been disclosed yet.

[0013] The methods based on analyzing the reflections on the pupil plane, the reflections from the cornea and deeper layers, or based on analyzing the shape of the pupil on the image are unreliable because they do not take into account the true light path from the observed object to the macula of the retina and do not consider the various anatomical structures of the eye, even if the angle between the visual axis and the corneal central axis has been estimated. Both methods can only be used as a preliminary estimated diagnosis of the presence and type of strabismus.

[0014] It can be seen from the description of the European patent document EP2403260A2 that the device in the solution is the so-called 3D glasses, whose principle is to alternately cover the two eyes with an electronically controlled liquid crystal panel and synchronously display different images for the left and right eyes on the screen to obtain a spatial visual impression. Additionally, polarized glasses can also be used, and the images on the screen must also be appropriately polarized for the left and right eyes. Similar glasses are also used for fusion exercises for strabismus patients.

[0015] Chinese patent document CN104799998A proposes an optical strabismus corrector based on 3D glasses imaging. The patient can change the image display position by pressing a button by himself to experience stereoscopic vision. This device is not used for measuring the strabismus angle and precise diagnosis.

[0016] As can be seen from U.S. Patent Documents US2016143527A1 and US9572488B2, the goggles integrate an infrared camera for observing pupil movement and an LCD screen for alternately covering the eyes. These devices can perform an automatic Hess test, that is, only evaluate the motility of the eyeballs. The described device and measurement method can objectively and repeatedly measure eye movements.

[0017] VR (Virtual Reality) goggles integrated with an eye tracking system have been widely popularized. These solutions are used to control virtual interfaces, or virtual and augmented reality technologies, for visualization, multimedia, or entertainment purposes.

[0018] According to the description of Chinese Patent Document CN112107416A, this solution proposes a strabismus correction visual imaging device based on VR technology. A front acquisition module is installed at the front of the body part, and two image display modules and an image data processing module are installed inside the goggles. Processing the real-time video information of the external environment can enable the vision of strabismus patients to be undisturbed, facilitating the patients to normally observe and obtain the surrounding environment. The image conversion is based on the recorded eye movement trajectories and the results of individual medical examinations. This solution does not disclose the details of system calibration and the method of converting images into the strabismus angle of patients, nor is it a diagnostic device.

[0019] On the other hand, the descriptions of Chinese Patent Document CN111820860A and International Patent Document WO2020184775A1 propose similar solutions for measuring the strabismus angle. This solution is based on the display of stereoscopic images, such as using a system for recording eye position and / or movement in VR goggles. The computer controls the position of the indicator displayed on the screen for visual tracking when the left and right images of the VR glasses are alternately closed and / or blocked. The camera is used to take pictures of the pupils when one of the frame images is closed, and the computer is used to simultaneously evaluate the movements of both pupils and determine a new pointer shift based on the analysis of the strabismus eye movement. The pointer shifts until the pupils stop moving, and the last position of the pointer is used to determine the strabismus angle. The publications show that these devices rely on the subjectivity of the examinee and the measurement results are accurate. However, both of these solutions ignore the aspects of field of view calibration related to individual anatomical features, especially the distance between the pupils and the distance between the eyes and the screen, which will greatly affect the measurement results in the case of relatively small changes and a relatively small distance between the eyes and the screen. These publications also do not disclose whether the possible calibration allows taking into account the refractive error of the patient and the distortion of the patient's field of view caused by the lens, which has a significant impact on the convergence degree and the final result of the angle measurement.

[0020] Chinese Patent Document CN109288493A discloses a strabismus diagnosis device and method, including a graphic pattern on a screen, an infrared camera and / or a visible light camera, an automatic eye covering module, and a head support equipped with a prism rod. This device uses two independent display screens to display and measure images at a long distance of 6 meters and a short distance of 33 centimeters respectively. This solution does not disclose the degree of automation of such measurement. According to the description, the device first conducts a strabismus presence test and evaluates its direction, and then places a prism with a pre-estimated degree obtained in the qualitative test on a prism holder directly in front of the patient's eyes. The device will automatically cover the eyes and record the movement of the pupil center in the image. This device omits the technologies for measuring the strabismus angle and calibrating the position and field of view.

[0021] International Patent Document WO2017123086A1 discloses a method and a computer system for determining the strabismus angle. The method includes placing a patient in front of an eye movement tracking device and any image display device, conducting near and far vision tests at different distances from 0.3 to 5 meters, displaying a small graphic element in one and / or nine main viewing directions on the screen, measuring the line of sight direction of the human eye with the eye movement tracking device by a computer, and calculating the strabismus angle between the eyes by calculating the difference between the horizontal line of sight direction and the vertical line of sight direction. However, the method for selecting the line of sight direction is not described in detail. In this device, an infrared filter can be used to observe latent strabismus, and two infrared cameras with illuminators can also be used, and each infrared camera can observe both eyes in real time. This publication also points out that corneal reflection and an eyeball model can be used to evaluate the shape of the eyeball and the position of the eye axis in space. The advantage of this solution is that it can independently observe eye movement and head movement, which provides convenience for the examination of pediatric patients. This solution also omits the device calibration technology that does not require patient participation and ensures the possibility of adjusting the measurement to the distance between the pupils and correcting refractive errors, which is very important during the examination process.

[0022] Another solution, as can be seen from the disclosure of Korean Patent Document KR101825830B1, proposes a system and method for measuring strabismus angles, using occlusion tests and eye movement analysis to observe graphic patterns displayed on a screen (such as a mobile phone, tablet, LCD screen, etc.). This test can be carried out at a fixed distance of 30 cm to 1 m and is also applicable to visually impaired persons, but this solution does not explain the impact of this defect on the measurement method and effect. The occlusion is manually moved by the patient and / or can be glasses with an occluder worn on the head, and it can also have a module for identifying the pupil position and distance. The determined pupil distance is related to the position of the pattern displayed on the screen. The device identifies the stop moment of the adjustment movement based on continuously captured binocular photos and calculates the strabismus angle. During the examination, the eyes follow the moving template on the screen, but the algorithm for its planned positions (points P2, P3) and whether it is an automatic or manual process are not described. The shown device is not an integrated structure, and there is no known calibration procedure for any viewing direction and any visual impairment. The determined eye deviation angle (theta angle) depends on the position of the template on the screen when the eyes do not make adjustments, but this solution does not consider other important factors for calculating prism diopters, such as corrective lenses.

[0023] U.S. Patent Document US2015265146A1 also discloses a device for diagnosing and quantifying strabismus. The device includes a crossbar, a camera, a light source for generating Purkinje reflections, and a computer. The patient fixates on a target at a known angle (such as -30°, 0°, +30°), and at the same time the camera records the patient's eyes, and then the images are sent to the computer, which analyzes each frame of the image to identify the pupils and Purkinje reflections. This method is very effective, but requires a well-trained and experienced operator. The position of the patient's head relative to the camera is not fixed, and the patient still has to keep the head still without using any external device. Therefore, in the case of measuring strabismus in children, this device is not suitable and / or difficult to operate. The device can be used both for strabismus screening and as a quantitative tool for surgical planning to reduce the number of surgeries. This method calculates the strabismus angle by means of linear regression using the Hirschberg ratio, which means that this method is not accurate.

[0024] According to the disclosure of Chinese patent document CN107898429A, there is currently a known solution that can quickly perform a strabismus screening test to determine whether the subject has strabismus, clarify the nature of the strabismus, and determine whether it is latent strabismus and / or manifest strabismus, horizontal strabismus and / or vertical strabismus. The subject gazes at the visual target placed at a distance of 33 cm and / or 5 m, and the thermal imaging camera records the image. This is a test based on the principle of covering the eyes. The video recorded when covering the eyes will be transmitted to the computer for analysis and storage. In order to obtain appropriate screening test results, the table included in the patent specification is used. This solution cannot perform accurate diagnosis, nor does it reveal the possibility and principle of optical system calibration. Summary of the Invention

[0025] As far as the inventor knows, there is no device and method in the prior art that can accurately and fully automatically measure the eye deviation and / or vertical and horizontal visual angles, and significantly correct the individual pupil distance and the distortion introduced by the additional lenses suitable for the patient's personal refractive error during the measurement. The device and method operate in the following manner. During the alternating cycle of closing the line of sight of one and / or the other eye, the patient observes the patterns displayed on the screen, and the positions of these patterns are dynamically determined according to the deviation of the current pupil relative to the fixation position recorded in the camera image.

[0026] The term "patient" includes persons diagnosed for medical purposes and all persons who need to measure the individual characteristics of their visual systems in order to match the best stereoscopic imaging devices, such as virtual and augmented reality interfaces, to ensure more comfortable use or work on these devices.

[0027] The terms "opening the line of sight" and "closing the line of sight" should be understood as using any technical means to partially and / or completely prevent light from entering the eyes, so that there are no objects to fixate on in the visual field of the eyes. These terms do not apply to, for example, vision suppression caused by long-term diseases and the dominance of one eye over the other.

[0028] The object of the present invention is to propose a solution based on the true trajectory of light radiating to the eye point on the visual axis, and it will eliminate the need to calculate the position of this visual axis relative to the geometric axis of the eye, as is the case in many of the above-mentioned solutions.

[0029] In daily life, without using appropriate prism correction, strabismus patients will switch vision between the two eyes and / or select a dominant eye, which will cause alternating adjustment of eye movements when trying to focus on an indicator. After using traditional prism correction, when observing the indicator alternately, it will no longer cause the patient's eye adjustment movements. Similarly, in the synoptophore examination, due to the proper positioning of the optomechanical module and the images it displays, and / or using traditional prism bars to select appropriate prisms during the examination, the adjustment movements will also disappear.

[0030] The mechanical synoptophore and / or prism bar can be replaced by images that move dynamically on a screen, based on the analysis of the eye's adjustment movements and the synchronous occlusion and / or alternating covering of each eye separately, so that the patient regains the impression of spatial binocular vision and the adjustment movements stop. The occluded line of sight can be achieved by using mechanical and / or electronic covers, or by using separate visual areas with occlusion possibilities on the screen. In addition, if the image movement is related to the lens correction of the patient's own refractive error and the patient's individual interpupillary distance, the angle between the binocular axes can be accurately determined.

[0031] Therefore, the solution of the present invention largely mimics the traditional cover test using a prism bar, but it can be fully automated, without the disadvantages of this method and other previously proposed methods, and it is not based on unreliable methods such as the analysis of light reflection in the anterior eye structure or the analysis of the eye structure shape.

[0032] There is provided an apparatus for automatically measuring eye deviation and / or vertical and horizontal visual angles, including an optomechanical system cooperating with an image recording and display device, wherein the optomechanical system has a screen placed in an integrated housing. In front of the screen, two symmetrically embedded optomechanical modules are mounted on side arms, constituting an optomechanical system. The above modules are mounted on the side arms, and the side arms are movably embedded in horizontal guide rails arranged side by side and vertically disposed relative to the side arms, and are driven along these guide rails by a servo drive and a drive element (such as a toothed belt or a lead screw). Each optomechanical module has a camera operating in the invisible light spectrum (such as near infrared), a system for closing the line of sight (such as a mechanical cover), an optical barrel for fixing the lens system, and an eye pupil illuminator operating in a spectrum invisible to the human eye. The screen is placed perpendicular to the axis of the lens system and is located at a position that allows the screen to be clearly observed and covers as large an eye field of view as possible. In addition, a selection element, such as glass coated with a selective filter element or a beam splitter, is provided between the optical barrel and the screen, so that two pupil images in the invisible spectrum can be reflected to the camera, but at the same time the screen can be continuously observed. The illuminator is installed in such a way as to illuminate the entire pupil of the eye while avoiding the display of light reflection on the lens surface in the camera image. Importantly, the screen, the camera, the line-of-sight closing system, the servo drive, and the drive element are all connected to and controlled by a computer.

[0033] Particularly preferably, the integrated housing is equipped with a fixedly mounted head stabilizer, such as in the form of a stabilizing frame and / or a suitable shape of the housing, so as to be able to closely adhere to the face of the subject while minimizing the amount of external scattered light falling on the retina.

[0034] The possibility of changing the parameters of the lens system is also advantageous, for example by changing the focal length of the lens system, the axial movement of the lens, the movement of the screen, and / or the movement of these two elements relative to the eye, and / or by mounting additional trial lenses to correct the refractive error of the patient, since the refractive error has a significant impact on the correct assessment of the position of the test pattern and thus on the measurement results of the eye deviation and / or the vertical and horizontal visual angles (including the oblique visual angle).

[0035] In another preferred embodiment, each side arm of the opto-mechanical module has at least one vertical guide rail, perpendicular to the horizontal guide rail and embedded in an integrated housing. The horizontal and vertical guide rails cooperate together to enable the module to move independently in the horizontal and vertical directions towards the left and right eyes respectively.

[0036] In another preferred variant, each opto-mechanical module can have its own integrated screen, which allows for better control of the cyclic display of the test pattern and enables complete separation of the visual fields of the left and right eyes, and moreover without the need for an additional cover.

[0037] The essence of the present invention is still a method for automatically measuring the angle of strabismus using this device. This method utilizes the measurement of the interpupillary distance of the observer and the model of the geometric distortion of the visual field. In this method, first, it is necessary to determine the magnitudes of the vertical and horizontal distortions generated by the lens system (including additional correction lenses, i.e., spherical and / or cylindrical lenses) used in front of the observer's eyes, so as to be able to observe the screen at an infinite distance; then, adapt the lens system to the individual refractive error of the patient, for example by placing trial lenses suitable for their individual refractive error in front of the patient's eyes; next, drive by a servo driver and use the alternating occlusion system to center the main axis of the opto-mechanical module relative to the positions of the left and right eye pupils, thereby obtaining information on the actual horizontal pupil distance of the observer, determining that the position of the fixation point on the screen is in front of each eye, preferably with the mutual distance on the screen corresponding to the distance between the pupils. Then, during the alternating and periodic occlusion of the vision of one of the eyes, an image pattern is displayed at a fixed position directly in front of one eye on the screen, and an image pattern is displayed at a variable position relative to the fixation point directly in front for the other eye. According to the intensity and direction of the pupil adjustment movement recorded by the camera when the line of sight is opened, the variable position is determined in each cycle. After the pupil stops moving, after the pupil movement stops, the graphic pattern is set on the natural visual axes of the patient's both eyes, and using the model of the geometric distortion of the visual field, the final changed position of the pattern is corrected by the vertical and horizontal distortion values introduced by the lens system. Finally, based on the knowledge of the corrected position and the distance from the screen, the vertical and horizontal visual angles of the graphic pattern are determined.

[0038] Particularly preferably, the integrated housing has a fixedly mounted head stabilizer, such as a stabilizing bracket, and / or has a suitable housing shape that allows the face of the person to be examined to be placed closely and can reduce scattered external light from falling on the retina.

[0039] It is also advantageous to be able to change the parameters of the lens system, for example by changing the focal length of the lens system, the axial movement of the lens, the movement of the screen, and / or the movement of these two elements relative to the eye, and / or by mounting additional trial lenses to correct refractive errors of the patient that have a significant impact on the correct assessment of the position of the test target. Thus, it is possible to measure eye deviation and / or vertical and horizontal viewing angles (including the strabismus angle).

[0040] In another preferred variant, each side arm on which the opto-mechanical module is mounted also has at least one vertical guide rail that is perpendicular to the horizontal guide rail and is embedded in the integrated housing. The horizontal guide rail and the vertical guide rail together enable the module to move independently in the horizontal and vertical directions relative to the left and right eyes.

[0041] In another preferred variant, each opto-mechanical module may have its own integrated screen, which can better control the cyclic display of the test target and allows the complete segmentation of the visual fields of the left and right eyes, and no additional cover is required.

[0042] The present invention also lies in providing a method for automatically measuring the strabismus angle using the above device, which method uses the measurement of the observer's interpupillary distance and the geometric distortion model of the visual field. In this method, first, the magnitudes of the vertical and horizontal distortions caused by the lens system used in front of the observer's eyes are determined. The lens system includes additional corrective lenses of spherical or cylindrical surfaces and enables a screen at an infinite distance to be observed. Then, the lens system is adjusted according to the observer's individual refractive error, for example, by placing trial lenses adapted to their individual refractive correction in front of the eyes. Further, through the movement of the servo drive and the use of the alternate line-of-sight closing system, the position of the optical axis of the optomechanical module is centered relative to the left and right eye pupils, so as to obtain information on the actual horizontal pupil distance of the observer and determine the positions of the fixation points to be placed in front of each eye on the screen, preferably at the mutual distance corresponding to the interpupillary distance on the screen. Then, during the alternate cycle of the line-of-sight closing system to close the line of sight of one eye, an image pattern is displayed on the screen surface at a fixed position directly in front of one eye, and another image pattern is displayed at a variable position relative to the fixed position directly in front of the other eye, where the variable position is determined according to the intensity and direction of the adjustment movement of the pupil recorded by the camera when the line of sight is opened by the line-of-sight closing system in each cycle. After the pupil movement stops and the image pattern is set on the natural axes of the patient's binocular fields of view, the final variable position of the pattern is corrected by the vertical and horizontal distortion values introduced by the lens system, which uses the geometric distortion model of the visual field. Finally, according to the corrected position and the distance relative to the screen, the vertical and horizontal viewing angles of the image pattern are determined.

[0043] Particularly preferably, the parameters of the lens system are changed, such as selecting trial lenses according to the actual distance from the screen to force viewing the screen at a close distance and moving the fixation points of the left and right eyes towards the symmetry axis of the device to force viewing the screen at a close distance.

[0044] In a preferred variant, in each cycle, the variable position of the image pattern is determined according to the intensity and direction of the adjustment movement of the pupil of the eye being examined, where the intensity and direction of the pupil adjustment movement are recorded by the camera at the moment when its line of sight is closed and exactly at the moment when the other eye starts to directly view the non-moving image pattern.

[0045] Preferably, the graphic pattern represents the same three-dimensional object, and the visualization of the three-dimensional object on the screen respectively considers the geometric transformations of the left and right eyes and produces the effect of stereoscopically observing a real three-dimensional entity.

[0046] Preferably, additional background images, such as mountain views and / or starry skies, can also be displayed on the screen just before starting the measurement and during the measurement process to enhance the observer's spatial impression, facilitate the binocular adjustment and switching, and direct the gaze towards an infinite distance.

[0047] Preferably, the optical barrel with the lens system and / or the screen is mounted on an additional rail and driven by a computer-controlled servo drive, whose movement direction is perpendicular to the screen, can change the focus of the image, and can be adjusted according to the diopter of the eye.

[0048] Preferably, the camera has an additional optical module and a structured light projection module, which can project onto the retina of the eye, observe the image of the light through the camera, and automatically measure the refractive error. The measurement results in turn enable the optomechanical module to automatically adjust according to the refractive error of the eye before measuring the eye deviation angle and / or the vertical and horizontal viewing angles. For example, the device according to the present invention can alternately cover the two eyes as in a traditional examination, and perform periodic tests on a static graphic object in front of one eye being gazed at, while the movement of the graphic object for the other eye is proportional to the intensity of the pupil adjustment movement recorded in the image when the line of sight is switched on by an appropriate camera.

[0049] The design of the device of the present invention enables the patient to observe the screen while continuously recording the images of the two pupils through the camera system. Each successive movement of the graphic pattern is automatically calculated based on two basic pieces of information: the individual pupil distance in the vertical and horizontal directions, and the intensity of the adjustment movement in the vertical and horizontal directions of the examined eye at the last recorded visual switch. The device does not perform fixed cyclic operations repeatedly, but dynamically selects the pattern position according to the intensity of the patient's eye movement. The cooperation with the patient depends only on their ability to track and focus on the graphic patterns displayed at different positions on the screen. The moment when the adjustment action stops is equivalent to the position of the graphic pattern stabilizing, and a well-cooperating patient may finish after about ten seconds or so. The final position of the visual target, combined with the visual field distortion model and the individual refractive error and pupil distance data, can determine the deviation angle of the patient's strabismus.

[0050] Like the traditional method, the device of the present invention examines the strabismus angles at far and near distances by appropriately adjusting the lens system parameters and / or appropriately setting the screen position. Similarly, at any time when an examination is performed on the device, the vision of one of the patient's eyes is always in a closed state, which causes an image fusion fragmentation effect, which is crucial for accurate measurement.

[0051] When used for typical medical diagnosis, the undoubted advantage of the present invention is that measurements can be repeatedly carried out under stable and reproducible conditions, and the position of the patient's head can be kept unchanged during the examination, which is particularly important for patients with poor cooperation ability and pediatric patients. In addition, the examination can be carried out faster and without the participation of other medical staff (holding the child's head when calculating the vertical or diagonal deviation coexisting with the horizontal, holding an additional prism rod). According to the solution of the present invention, the measurement results can be partially or completely unaffected by the experience and participation of the researcher. The patient only needs to focus on the selected pattern. Using the device of the present invention can also make the strabismus surgery achieve better and more accurate results, because the measurement result of the strabismus angle is the basis for correctly diagnosing the type of strabismus, the degree of muscle deviation and the range of deviation, and is also the basis for planning the technical scope of the extraocular muscle surgery.

[0052] When used for non-medical diagnosis, the advantage of the present invention is undoubtedly that it can be used to anthropomorphize devices for creating virtual or augmented reality, such as using properly designed goggles. These devices can be used to create virtual workspaces, virtual operation panels for controlling machines, or 3D graphic demonstrations for entertainment purposes, etc. Anthropomorphization means adjustment according to the individual anatomical characteristics of the visual organs, which can be translated into long-term comfortable use of these devices without adverse side effects such as fatigue, headache or dizziness. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The solution proposed by the present invention is described in detail in the examples of implementation and application as well as in the drawings, wherein,

[0054] Figures 1a and 1b show schematic diagrams of the operation of the device and its two variant structures (basic and equipped with vertical guide rails),

[0055] Figure 2 show the calibration of the optical axis spacing,

[0056] Figure 3 show the concept of the field of view calibration,

[0057] Figure 4 are schematic diagrams of the pupil distance measurement when the left eye line of sight is closed (a) and when the right eye line of sight is closed (b),

[0058] Figure 5 is the measurement cycle of the strabismus angle of the right fixation eye at a short distance, where (a) is when the right eye line of sight is closed and (b) is after the right eye line of sight is opened. DETAILED DESCRIPTION OF THE INVENTION

[0059] Example 1

[0060] As shown in FIG. 1, the device for measuring eye deviation and / or vertical and horizontal viewing angles includes the following components integrated in the housing 15: a screen 1 for displaying an image pattern, which can be based on any technology, a computing unit 4 (such as a personal computer), an operation panel 3 fixedly connected to the head stabilizer housing 17, and two symmetrically arranged embedded opto-mechanical modules. Each opto-mechanical module includes the following fittings fixed to the element 12: a camera 2 operating in the near-infrared band and connected to the computer 4 for image acquisition and analysis, a line-of-sight closing system 6 (a partial occlusion 6a of the screen, or a cover plate 6b) controlled by the computer 4, an optical barrel 5 for mounting a replaceable test lens 8, an illuminator 11 (such as a light-emitting diode operating in the near-infrared band), and a mounting element 12 movably mounted on the guide rails 16 so that the entire module can move precisely along these guide rails. In a variant of the device (as shown in FIG. 1b), on each side arm 12 for mounting the opto-mechanical module, at least one vertical guide rail 28 perpendicular to the horizontal guide rail 16 and embedded in the integrated housing 15 can also be provided. The horizontal guide rail 16 and the vertical guide rail 28 together enable the optical module to move independently in the horizontal and vertical directions relative to the left and right eyes. The two mounting elements 12 are each moved independently of each other relative to each other on the horizontal axis by a servo drive 9 and on the vertical axis by a servo drive 29, and are respectively controlled by the computer 4 and the drive elements 10, 30 (such as lead screws) to jointly achieve precise determination of the distance between the principal optical axis of the camera 2 and the lens 8. The illuminator 11 is fixedly mounted in such a way as to illuminate the entire pupil of the eye while not causing light reflection on the surface of the lens 8, thereby hindering the camera 2 from observing the pupil. The opto-mechanical module should be constructed to allow the distance between the axes of the lenses 8 to be movable within a certain range to be adjusted to the typical distance D between human pupils. The screen 1 is arranged perpendicular to the axis of the lens 8 and is kept at a certain distance from the optical barrel 5 to cover as much of the eye's field of view as possible. The selection mirror 7 is arranged between the lens 8 and the screen 1 such that both pupil images in the infrared band can be reflected onto the camera 2, but at the same time continuous visual observation of the screen 1 can be carried out. In another variant (as shown in FIG. 1b), one selection mirror 7 can be divided into two and symmetrically attached to each opto-mechanical module respectively. In the variant shown in FIG. 1a, the field of view can be closed by the occluding portion 6a of the screen 1. In contrast, in an alternative variant (as shown in FIG. 1b), in order to close the field of view of a specified eye, a cover plate 6b (such as an LCD) can be used to shield the left and right eyes respectively, and this cover plate 6b can be connected to the side arm 12. The cover plate can be connected such that any part of the screen 1 is invisible in the field of view of the shielded eye.

[0061] In the computer 4, there is software installed to control the operation of the servo drive 9, software for analyzing and adjusting the intensity and direction of eye movement, which controls the display of the moving image pattern 13 of the eye under examination and the still image pattern 14 of the other eye, and software for controlling the operation of the occluding portion 6a of the screen 1 (as shown in Fig. 1a) and / or the cover plate 6b (as shown in Fig. 1b). The graphic patterns 13 and 14 represent the same object, which is small in size and has a shape convenient for visual fixation, and can be a planar graphic, such as a vector or a raster. In an alternative, the graphic patterns 13 and 14 represent the same three-dimensional object, and the geometric transformation thereof with respect to the left and right eyes respectively can achieve the effect of stereoscopic observation of a real three-dimensional object.

[0062] The calibration of the device is divided into two stages, including the calibration of the spacing of the opto-mechanical module and the calibration of the field of view with respect to the viewing angle. As Figure 2 shown, the first stage includes finding the relationship between the actual spacing L of the optical axes of the optical barrels 5 and the movement of the servo drive 9 / drive element 10. For this purpose, an image 18 of a distance standard needs to be recorded, which is composed of at least two pairs of planar markers 20 placed at distances corresponding to typical minimum and maximum pupil distances, where the left camera 2 only observes the left markers and the right camera 2 only observes the right markers. For each pair of markers 20, the spacing of the cameras 2 is set such that on the image 19 in the cameras 2, the markers are exactly in the middle of the width direction of these images, and the position of the servo drive 9 is recorded. By recording the positions of the drive 9 corresponding to all reference distances 20, a linear model of this relationship can be established, and its parameters can be stored in the computer hard disk 4.

[0063] As Figure 3 shown, in the second stage of calibration, it includes determining the mathematical dependence of the position of the farthest point that can be seen on the screen from the actual viewing angle, thereby determining the effective measurement area 21 and simultaneously determining the field of view. For this purpose, after using test lenses 5 with a refractive power in the range of -10 diopters to +10 diopters, a mathematically significant change in the angular size of the eye within the measurement area 21 is determined, and then based on the known distance m between the screen 1 and the position where the test lens 8 is installed, and the distances by and bx of the extreme points of the field of view relative to the point p, the limiting angles α and β of the point p relative to the extreme points of the field of view are determined based on trigonometry. The correlation between the viewing angles of the extreme points of the measurement area on the screen 1 and the refractive power of the installed test lens 8 can create a mathematical model, which enables the correction of the determined viewing angles for any point within the measurement area except the extreme points, and the viewing angles of these points will increase or decrease significantly due to the operation of the test lens 8. The parameters of this model can be saved in the computer hard disk 4. The calibration system can be used to measure the strabismus angle.

[0064] Detection instructions:

[0065] At the start of the detection, the patient correctly leans their head on the contour-stabilizing bracket 17, and then the position of the contour-stabilizing bracket 17 can be adjusted so that the left and right pupils are respectively within the field of view of the left and right cameras 2, with the head remaining stationary.

[0066] In the first stage of the measurement, the distance between the pupils is measured. As Figure 4 shown, the left eye line of sight is blocked by the left eye cover plate 6b to close the left eye's line of sight, and a graphic pattern 24 is displayed at a distance of +33 mm from the center p of the screen 1 in front of the right bare eye, and the patient's line of sight is focused on this pattern. As Figure 4 shown in a), the image 22 of the right pupil is recorded by the camera 2, and the software in the computer 4 determines its position relative to the image center and, on this basis, determines the movement direction of the drive element 10. The opto-mechanical module on the right side is automatically arranged together with the mounting element 12 equipped with the camera 2 and the lens 8 so that the pupil is located in the middle of the width direction of the image 22. The position of the servo drive 9 is stored in the computer hard disk 4. Similarly, after opening the left eye line of sight and closing the right eye line of sight, a dot pattern 25 is displayed at a distance of -33 mm from the center p of the screen 1 in front of the left bare eye. As Figure 4 shown in b), then the image 23 of the left pupil is recorded, and then the software aligns the pupil on this image by moving the element 12 and records the second position of the servo drive 9. According to the two positions recorded by the servo drive 9 and the recorded data from the device calibration process, the pupil distance D of the patient is determined and stored in the computer hard disk 4 for further examination.

[0067] In the second stage of the measurement, as Figure 5As shown, the strabismus angle of the left eye at a short distance is measured while the right eye is always focused on the graphic at the center p of the screen 1. Before starting the examination, a trial lens 8 with a diopter individually selected for the patient is placed in the optical barrel 5 so that, due to the pattern being fixed on the screen 1, a natural visual effect up to approximately 300 mm is obtained. Then, a cycle begins in which the line of sight of the left eye is blocked by the cover plate 6b to break the patient's fusion of the images, and the graphic pattern 26 is displayed at the center p of the screen 1 on which the patient's line of sight is focused. The camera 2 records the position of the closed left-eye pupil in the image 23 and saves this position on the computer hard disk 4. Then the cover plate 6b of the left eye is opened while the cover plate 6b of the right eye is closed, and the patient focuses the line of sight again on the dot pattern 26 displayed at the center p of the screen 1. The position of the left-eye pupil after the line of sight is opened in the image 23 is recorded again, and then the software calculates the vector v of the difference between this position and the position recorded before the left eye was opened. Based on this difference, a vector v' is determined, which is a scaled version of the vector v and represents the value by which the dot pattern 26 has moved to a new position 27 on the plane of the screen 1, and the cycle thus ends. In the new cycle, when the left-eye line of sight is opened, the dot pattern is displayed at the new position 27 determined in the previous cycle. Similarly, when the left-eye vision is turned on, a displacement vector v is determined in the left-eye pupil image 23 for calculating the position of the pattern in the next cycle. The ratio between the vectors v and v' is determined experimentally so that in subsequent cycles, the adjustment eye movement of the opened eye does not increase. The cycle is repeated until the pupil displacement vector v of the opened left eye reaches a set minimum value (e.g., the minimum value expressed in image pixels), so that the software can detect the moment when the left-eye adjustment movement stops. The final position of the dot pattern 27 determined and saved in the computer 4 can be corrected according to a known calibration model of the dependence between the viewing angle and the diopter of the trial lens used, and converted into the actual strabismus angles, namely the vertical β and the horizontal α. The measurement process and the measurement results with pupil movement preview can be visualized on the operation panel 3.

[0068] Example 2

[0069] The scheme is the same as in Example 1, but on the calibration device, after measuring the pupil distance D, a trial lens 8 with a diopter individually selected for the patient is placed in the optical barrel 5 so that, due to the pattern being fixed on the screen 1, a natural visual effect up to infinity is obtained. Then, the strabismus angle at a long distance is measured, and the fixed position of the graphic pattern 26 for the right eye displayed on the screen 1 is always shifted to the right by half of the measured patient pupil distance D relative to the center p of the screen 1.

[0070] Example 3

[0071] The solution is the same as in Example 2, but the measurement of the squint angle is for the right eye, while the left eye is always focused on the stationary dot pattern 26 on screen 1, which is shifted to the left by half of the pupil distance D relative to the screen center p.

[0072] Among the optimal variables - for each examination - it is conceivable that images and / or backgrounds are also displayed on screen 1 just before the start of the measurement and during the measurement, to enhance the observer's sense of space and facilitate relaxation of accommodation.

[0073] Example 4

[0074] The solution is the same as in Example 1, but with the system having guides 16 and 28 applied according to Figure 1b, the centering adjustment of the fixed lens system is carried out simultaneously in the horizontal and vertical directions, and the position difference between a pair of drivers 9 and a pair of drivers 29 is additionally considered when calculating the pupil distance.

[0075] Example 5

[0076] The solution is the same as in Example 1, but instead of using a single non - movable screen 1, in this example, two independent screens 1b are used for the left and right eyes, and are respectively fixedly connected to the left and right arms 12. This solution for near and far measurements can ensure that the positions of the graphic patterns 13 and 14 always correspond to the centers of the screens 1b, where the centers of the screens 1b are calibrated relative to the axis of the optical barrel 5. The solution is shown in Figure 6. The advantage of this solution is also that each opto - mechanical module can be integrated with the display 1b in a sealed housing.

[0077] Example 6

[0078] Same as the solution in Example 5, but in each opto - mechanical module, a movable optical barrel 5 with a lens system 8b and / or a movable screen 1b is used instead of the replaceable trial lens 8. The movable optical barrel 5 is mounted on additional guides 31 and / or 32 and is driven by servo drivers 33 and / or 34 controlled by the computer 4. Its movement direction is perpendicular to the screen 1b, at the point where the image sharpness can be changed, and is adjusted according to the refractive error of the eye. The opto - mechanical system of this solution is shown in Figure 6.

[0079] Example 7

[0080] The solution is the same as in Example 6, but the camera can have an additional optical module 35 and a structured - light projection module 36, capable of projecting onto the retina and observing the image of this light through the camera 2 to automatically measure refractive errors. In turn, the measurement results can automatically adjust the opto - mechanical module to adapt to the refractive error of the eye before checking the squint angle. The solution is shown in Figure 7.

Claims

1. An apparatus for automatically measuring eye deviation and / or vertical and horizontal viewing angles, comprising an opto-mechanical system cooperating with an image recording and display device, characterized in that, the opto-mechanical system has a screen (1) placed in an integrated housing (15), and in front of the screen (1) there are two symmetrically embedded opto-mechanical modules mounted on side arms (12), the side arms (12) being movably embedded in horizontal guide rails (16) arranged side by side and perpendicular to the side arms (12), and being driven along the horizontal guide rails (16) by a servo drive (9) and a drive element (10), wherein each opto-mechanical module has a camera (2) operating in the invisible spectrum, an optical barrel (5) for fixing a lens system (8), a line-of-sight closing system (6), and a pupil illuminator (11) operating in the invisible spectrum, wherein the screen (1) is placed perpendicular to the axis of the lens system (8) and is located at a position allowing the screen (1) to be keenly observed and covering as large an eye field of view as possible, furthermore, a selection element (7) is provided between the lens system (8) and the screen (1) such that both pupil images in the invisible spectrum field of view can be reflected to the camera (2), but at the same time allowing the screen (1) to be continuously observed, the pupil illuminator (11) is fixedly mounted on the side arm (12) in such a way as to illuminate the entire pupil of the eye while avoiding the reflection of light on the lens surface (8) being displayed in the image of the camera (2), moreover, the screen (1), the camera (2), the line-of-sight closing system (6), the servo drive (9) and the drive element (10) are all connected to and controlled by a computer (4).

2. The device according to claim 1, wherein The integrated housing (15) has a fixedly mounted head stabilizer (17) and / or has a contour shape allowing the face of the person to be examined to be placed closely against it.

3. The device according to claim 1 or 2, characterized in that, Each opto-mechanical module has the ability to change the parameters of the lens system and / or has a handle for additional trial lenses.

4. The device according to claim 1, 2 or 3, characterized in that, Each side arm (12) on which the opto-mechanical module is mounted also has at least one vertical guide rail (28) perpendicular to the horizontal guide rail (16) and embedded in the integrated housing (15), and preferably the opto-mechanical system has two symmetrically mounted selection mirrors (7).

5. The device according to any one of claims 1 to 4, characterized in that Each opto-mechanical module has its own integrated screen (1).

6. The device according to any one of claims 1-5, characterized in that, The optical barrel (5) with the lens system (8) and / or the screen (1) is mounted on additional guide rails (31 and / or 32) and is driven by servo drives (33 and / or 34) controlled by the computer (4).

7. The device according to any one of claims 1-5, characterized in that, The camera (2) has an additional optical module (35) and a structured light projection module (36) such that projection can be carried out on the retina, and the camera (2) can observe the image of the light and realize the automatic measurement of refractive error.

8. A method for automatically measuring eye deviation and / or vertical and horizontal viewing angles, which uses the device according to claims 1 to 5. The method uses the measurement of the observer's interpupillary distance and the geometric distortion model of the visual field, and is characterized in that, First, at each point in the actual visual field, the magnitudes of the vertical and horizontal distortions caused by the lens system used in front of the observer's eyes are determined. The lens system includes additional correction lenses that are spherical or cylindrical, and the lens system enables the screen (1) at an infinite distance to be observed. Then, the lens system is adjusted according to the observer's individual refractive error. Then, through the movement of the servo driver (9) and the use of the alternating line-of-sight closing system (6), the position of the optical axis module relative to the left and right eye pupils is centered, so as to obtain information on the actual horizontal pupil distance of the observer and determine the position of the fixation points to be placed in front of each eye on the screen (1). Subsequently, during the alternating cycle of the line-of-sight closing system (6) to close the line of sight of one eye, an image pattern (14) is displayed on the surface of the screen (1) at a fixed position directly in front of one eye, and an image pattern (13) is displayed at a variable position relative to the fixed position directly in front of the other eye. The variable position is determined in each cycle according to the intensity and direction of the adjustment movement v of the pupil recorded by the camera when the line-of-sight closing system (6) opens the line of sight. And the final variable position of the image pattern (13) obtained after the pupil movement stops is corrected by the vertical and horizontal distortion values introduced by the lens system, and the lens system uses the geometric distortion model of the visual field. Finally, according to the corrected position (13) and the distance relative to the screen (1), the vertical and horizontal viewing angles of the image pattern are determined.

9. The method according to claim 8, wherein Change the parameters of the lens system to move the fixation points of the left and right eyes along the symmetry axis of the device to force the screen to be observed at a close distance.

10. The method according to claim 8 or 9, characterized in that, In each cycle, the variable position of the image pattern (13) is determined according to the intensity and direction of the pupil adjustment movement recorded by the camera when the line-of-sight closing system (6) switches its line of sight, and exactly at the moment when the other eye starts to fixate on a non-moving image pattern.

11. The method according to any one of claims 8, 9 or 10, characterized in that, The graphic patterns (13 and 14) represent the same three-dimensional object. The visualization of the three-dimensional object on the screen respectively considers the geometric transformations of the left and right eyes, producing the effect of stereoscopically observing a real three-dimensional entity.

12. The method according to any one of claims 8-11, characterized in that, Before and during the measurement, an image or background is also displayed on the screen (1) to enhance the observer's spatial impression.

Images