Apparatus and method for automatic measurement of ocular deviation and / or vertical and horizontal viewing angles - Patents.com

Abstract

A device for the automatic measurement of ocular deviation and / or vertical and horizontal viewing angles, comprising an opto-mechanical system cooperating with an image recording device and a display device, comprising a screen (1) arranged in an integrated housing (15) in front of which two symmetrically embedded opto-mechanical modules are mounted on side arms (12) which are movably embedded in parallel horizontal guideways (16) arranged perpendicularly to the side arms (12) and driven along these guideways by servo drives (9) and drive elements (10), each opto-mechanical module comprising a camera (2) operating in the invisible light spectrum, an optical tube (5) fixing a lens system (8), a visual switch-off system (6) and a pupil illuminator (11) operating in the invisible light spectrum. a screen (1) arranged perpendicular to the axis of the lens system (8) and at a distance allowing clear observation of the screen and covering the largest possible part of the field of view, a selectivity element (7) arranged between the lens system (8) and the screen (1) allowing reflection of both pupil images within the field of view of the invisible light spectrum towards the camera (2) but at the same time allowing continuous visual observation of the screen, an illuminator (11) permanently mounted on the side arm (12) so as to illuminate the entire pupil of the eye and at the same time not cause light reflections on the lens surface (8) visible in the image from the camera (2), and the screen (1), the camera (2), the visual switch-off system (6), the servo drive (9) and the driving element (10) being connected and controlled by a computer (4).

Description

[Technical field]

[0001] The object of the present invention is a method and device for automatic measurement of ocular deviation and / or vertical and horizontal visual angles, comprising a screen and a movable camera, a mirror and corrective lenses that automatically adjust to the individual eye distance, using the techniques of alternating periodic projection of graphic patterns on the screen and synchronized eye covering, analysing and recording the accommodative eye movements resulting from the movement of these patterns, dynamically determining a new position of the patterns based on the last recorded direction of the accommodative movement of the exposed eye, and finally calculating, for example, vertical and horizontal strabismus angles based on the last registered graphic position pattern on the screen after the cessation of the accommodative movement and on information about the patient's individual interpupillary distance and on visual field distortions caused by the patient's refractive lenses. [Background technology]

[0002] In ophthalmologists' and orthoptists' offices, the time-consuming alternating unilateral "cover test" using prism strips is commonly used to assess the actual value of the strabismus angle. This test can be unreliable and prone to errors due to the subjective visual assessment of eye movements performed by the examiner, depending on the examiner's skill and experience. This test is time-consuming and requires good cooperation with the patient, requiring the help of an additional person in cases of complex strabismus and / or in patients who have difficulty in coordinating with the doctor and / or optometrist.

[0003] A commonly known device for measuring strabismus angles is the optical-mechanical synoptophore. In its basic form, this device consists of two rotating optical modules that are placed near the patient's eyes and are used for the projection and observation of stationary images. The structure of the images allows them to be combined into one image by the patient by appropriate positioning of the optical modules and the synoptophore arms. By progressive rotation of the optical modules, the images are alternately erased, forcing the patient's eye movements to accommodate. The optometrist evaluates the strabismus angle based on a visual assessment of the accommodative movements and the current rotation angle of the optical modules, read from a scale or a digital encoder. The synoptophore is a device that is complex to use and requires extensive experience of the examiner-optometrist, and the test results depend on the patient's subjective visual impression.

[0004] The solution of CN101433456A (Chinese Patent Publication No. 101433456) discloses an intelligent synoptophore used to diagnose the type and degree of strabismus, equipped with a camera, an LCD screen and eye movement detection software to facilitate the optometrist's work. In the synoptophore, the position of the image is changed mechanically by an electric motor. Such a solution does not allow for a proper calibration of the camera's optics, i.e. a way to convert the intensity of the eye movement into the angle of the drive position, in this case the angle of the stepper motor, that properly positions the optical module.

[0005] CN105942966A (Chinese Patent Publication No. 105942966A) discloses a strabismus self-detection system based on a digital synoptophore, which improves the autonomy of the device's operation and its effectiveness in detecting and diagnosing strabismus. As with the solution in CN101433456A (Chinese Patent Publication No. 101433456A), the inability to calibrate the camera's optics leads to inaccurate measurement results. Moreover, the device is not used to measure the angle of strabismus, but only to detect strabismus, which therefore does not allow for accurate diagnosis.

[0006] A commonly used method for assessing strabismus is the observation of the position of the point light reflex on the pupil plane. This method is used by some automated devices. There are also many techniques described in the scientific literature that measure eye position and movement by analyzing the position and shape of the pupil in camera images.

[0007] The solution of WO2011021936A1 (International Publication No. WO2011 / 021936) discloses an apparatus and a method for automatically determining the strabismus angle by performing a reflex test. The apparatus requires directing at least one visible light beam to the patient's eye and focusing the eye thereon, then using at least one imaging device to analyze the reflected light to detect the fixating eye and perform a reflex test on both eyes to estimate the strabismus angle. The reflex test consists in applying at least two light sources in known alternating positions and measuring the position of their reflections on the cornea of ​​both eyes. The recorded reflexes are used to obtain the coordinates of the centers of both corneas and to estimate the coordinates of the center of the pupil, which are further used to estimate the strabismus angle. For the fixating eye, an angle is calculated between the optical axis of the eye passing through the center of the cornea and the center of the pupil, and the visual axis passing through the center of the cornea and the center of the field of the eye. This angle is then converted to the strabismus angle.

[0008] The solution of RU2669734C1 (Russian Patent Specification No. 2669734) shows a system for calculating the patient's strabismus angle with a relatively low relative error equal to Δα = 0.4 °. The measurement process described in this solution is non-autonomous and requires a lot of operator involvement. For each patient, it is necessary to carry out a calibration process by applying measuring lines to the patient's face in order to match the number of pixels in the image to the actual distance. For the measurement, a camera and a light source are used, which the patient looks at, and the patient's head is fixed on the forehead-chin support. An image is recorded in which the distance between the vertical lines passing through the outer and inner canthus of the fixating eye is measured, the distance between the center of the pupil and the glare from the light source on the strabismus eye, then the radius of curvature of the sclera and the strabismus angle are calculated using the formulas shown in the solution.

[0009] In the prior art, from CN110575132A (Chinese Patent Publication No. 110575132), a method is also known for calculating the degree of strabismus based on an eye photograph, using an artificial intelligence algorithm, namely deep learning in a neural network. In this solution, the image of the pupil and the corneal light reflection point in the image of the pupil are analyzed, and based on their positions, it is determined whether there is strabismus and, if so, its degree. From the ratio of the shift distance between the corneal light reflection point and the center of the pupil to the radius of the pupil, the degree of strabismus can be calculated. This solution only discloses a measurement method, but does not present the structure of an execution device used for recording and image analysis, and the measurement is based on subjective ophthalmography.

[0010] Another publication US2014268051A1 (US 2014 / 0268051) describes a method and apparatus for detecting strabismus in eye images recorded by a camera using the reflection of a light source on the eye. The subject looks at a target shifted from the light source at a known distance ranging from 5 cm to 10 cm. The shifted target provides a focus for the subject's gaze, and the subject can be instructed to look at (and / or reflexively focus on) the target while capturing the image. By knowing the relative position of the accommodation subject, the light source, and the target, reference data can be determined, which can be compared to data determined from the captured image to detect strabismus. The reference data represents the expected reflex shift distance in an eye without strabismus. The eye image recording device can be a camera, a smartphone, a laptop, an ophthalmoscope, and / or any other device capable of capturing images and having computing capabilities (processor). This solution does not describe the determination of the strabismus angle, nor does it describe how to calibrate the device and obtain reference data from which a threshold value defining the boundary between healthy and strabismus-affected individuals can be determined.

[0011] Observation of the position of the spot light reflex on the pupil plane can also be used for exercises aimed at reducing the strabismus angle. From the description in CN112807200A (Chinese Patent Publication No. 112807200), a device for the treatment of strabismus is known, in which the degree of strabismus is gradually reduced by performing visual training. The device has at least one camera, two LED light sources working together in the near infrared band, a polarizing filter for each eye individually, and one display. The camera is used to detect the position of the eye on the image. The near infrared light source provides the illumination that is received by the near infrared camera and gives rise to the corneal reflex as a reference point for calculating the eye movements. The device does not determine the strabismus angle and cannot automatically adjust to the individual anatomical characteristics of the patient.

[0012] Yet another solution, CN112336301A (Chinese Patent Publication No. 112336301), presents an apparatus for measuring the strabismus angle with filters covering the eyes alternately, in which the spatial position of the eye axis is determined by a stereoscopic vision system based on the pupil position and the corneal reflection. These data are used for an initial individual calibration of the relationship between the coordinates of the point at which the eye fixates on the screen and the movement of the pupil on the image in the entire display surface of the fixation target. Several points at known positions on the screen are used for the initial calibration. In the next stage of the one-point calibration, the individual kappa angle of each patient is determined, which determines the deviation of the geometric axis of the eye from the actual visual axis. Then, for any position of the fixation target and the calibration model. The apparatus according to the present specification helps to clarify the type of strabismus and the tendency of the direction of strabismus. This description does not disclose detailed information on how to determine the strabismus angle other than the analysis of the rotation of the iris of the eye and / or the calculation of the angle between the visual axis of the uncovered eye and the visual axis of the covered eye, which is equivalent to the use of a prism of the appropriate magnification. The axes must coincide in the absence of strabismus. It is not indicated whether the method of determining the position of the fixation target during the test is manual or automatic and on what basis it is performed. The description indicates the possibility of automating the device and obtaining similar results. It is not disclosed whether the device takes into account the significant influence of individual refractive errors on the test results and how effectively the image fusion of the patient is blocked.

[0013] Methods based on the analysis of the reflection at the pupil plane, the reflection from the cornea and deeper layers, or based on the shape of the pupil on the image, even if the kappa angle is estimated, are unreliable because they do not take into account the actual light path from the observed object to the macula on the retina or the various (often far from ideal) anatomical structures of the eye. Both of these methods provide only an initial presumptive diagnosis indicating the presence and type of strabismus.

[0014] The device known from the description in EP 2403260 A2 is a so-called 3D spectacles, the principle of which is to use electronically controlled liquid crystal panels to cover the eyes alternately and to synchronously display different images on a screen for the left and right eye in order to obtain the impression of spatial vision. Alternatively, polarized spectacles are used, where the images on the screen must also be appropriately polarized for the left and right eye. Similar spectacles are used for fusion training in patients diagnosed with strabismus.

[0015] CN104799998A (Chinese Patent Publication No. 104799998) presents an optical device for correcting strabismus based on 3D glasses imaging, in which the patient himself changes the image display position by a button so as to experience stereoscopic vision. The device is not used to measure the strabismus angle and make an accurate diagnosis.

[0016] From the solutions US2016143527A1 (US 2016 / 0143527) and US9572488B2 (US 9,572,488), goggles are known that have an integrated IR camera that is used to observe the pupil movements and an LCD screen for covering the eyes alternately. These make it possible to carry out an automated Hess test, i.e. only the evaluation of eye movements. The measuring device and the measuring method described provide an objective and repeatable measurement of eye movements.

[0017] Virtual reality (VR) goggles with integrated eye-tracking systems are widely available. These solutions are used for visualization, multimedia or entertainment purposes, to control virtual interfaces or in virtual and augmented reality technologies.

[0018] The solution according to the description of CN112107416A presents an apparatus for visual imaging with strabismus correction, based on VR goggles. A module for acquiring video information is mounted at the front of the body, and two image display modules and an image data processing module are mounted inside the goggles. Real-time video information about the external environment can be processed so that the vision of the strabismus patient is not hindered and the strabismus patient can comfortably assimilate the environment. The image transformation is based on the recorded eye movements and the results of another medical examination. This solution does not disclose details of the system calibration and how to transform the image into the patient's strabismus angle, and is not a diagnostic device.

[0019] On the other hand, the descriptions in CN111820860A (Chinese Patent Application Publication No. 111820860) and WO2020184775A1 (International Publication No. 2020 / 184775) present a similar solution for measuring the strabismus angle, based on the display of stereoscopic images (e.g. in VR goggles with a system for recording eye position and / or eye movement). The computer controls the position of the indicator displayed on the screen so that it can be visually followed while the left and right images of the VR glasses are alternately closed and / or blocked. A camera is used to take a picture of the pupil while closing one of the images, and a computer is used to simultaneously evaluate the movement of both pupils and determine a new pointer shift based on the analysis of the strabismus movement. The pointer movement is made until the pupil movement stops, and the last position of the pointer is used to determine the strabismus angle. These publications show that the device does not depend on the subjectivity of the subject and the measurement results are accurate. However, both solutions omit aspects of the field calibration with respect to individual anatomical features, in particular the interpupillary distance and the eye distance from the screen, which may significantly affect the measurement results when the variations are small and the eye distance from the screen is short. Also, these publications do not disclose whether a possible calibration makes it possible to take into account the patient's refractive error and the distortion in the patient's field of view introduced by the lenses, which significantly affects the degree of convergence and the final result of the angle measurement.

[0020] From CN109288493A, an apparatus and method are known for diagnosing strabismus using a graphic pattern on a screen, an infrared and / or visible light camera, a mechanically movable eye cover, and a head support to which a prism bar is attached. The apparatus uses two independent screens to display images and perform tests for a distance of 6 meters and a near distance of 0.33 meters. The solution does not reveal the degree of automation of this measurement. According to the description, the apparatus performs an initial strabismus presence / absence test, evaluates its direction, and then a prism with an estimated power obtained in a qualitative experiment is placed on a prism frame immediately in front of the patient's eye. The apparatus automatically covers the eye and records the movement of the center of the pupil in the image. The apparatus omits the problem of measuring the strabismus angle, as well as the technique for calibrating the position and field of view.

[0021] From the description in WO2017123086A1 (International Publication No. 2017 / 123086), a method and a computer system for determining the strabismus angle are also known. The method consists of the steps of positioning the patient in front of an eye-tracking device and in front of any image display device at various distances of 0.3 to 5 meters for near and far vision testing, displaying small graphic elements on a screen with one and / or nine main visual directions, measuring the gaze of the person's eyes by means of the eye-tracking device by means of a computer, and calculating the strabismus angle between the eyes by calculating the difference between the horizontal and vertical gaze directions. The method of selecting the gaze direction is not explicitly stated in detail. The device can use an infrared filter and two infrared cameras equipped with an illuminator to observe the hidden strabismus, each of these infrared cameras observing both eyes in real time. The publication also indicates the possibility of using corneal reflexes and models of the eye to evaluate the shape of the eye and the position of the eye axis in space. The advantage of this solution is the independent observation of eye movements and head movements, which makes the examination easier in pediatric patients. This solution also allows the calibration of the device without the patient's involvement and ensures that the measurements are adjusted to the interpupillary distance, omitting the technique of correcting refractive errors, which are important during the examination.

[0022] Yet another solution known from KR101825830B1 (Korean Patent Specification No. 101825830) presents a system and method for measuring the strabismus angle using a cover test and eye movement analysis during the observation of a graphic pattern displayed on a screen (e.g. mobile phone, tablet, LCD screen). The test can be performed for long and short fixation distances (30 cm to 1 m) even in people with visual impairments, but the solution does not describe the impact of this deficiency on the method and the effect of the measurements. The cover can be glasses with blinds that are moved manually by the patient and / or worn on the head, which can further have a module for recognizing the position of the pupils and the interpupillary distance. The determined interpupillary distance is related to the position of the pattern displayed on the screen. The device calculates the strabismus angle based on successive photographs of both eyes and recognizes the moment of cessation of the accommodation movement. During the test, the eye follows the template moving on the screen, but the algorithm for planning their position (points P2, P3) and whether it is an automatic or manual process is not described. The device shown is not of one-piece construction and there is no known calibration procedure for any viewing direction and any visual impairment. The determined deviation angle of the eye (θ angle) depends on the position of the template on the screen, at which no accommodative movement of the eye occurs, but this solution does not take into account other important factors that affect the prism diopter power of the calculated prism, such as corrective lenses.

[0023] From the description in US2015265146A1 (US2015 / 0265146), a device for diagnosing and quantifying the degree of strabismus is also known. The device includes a beam, a video camera, a light source generating a Purkinje reflex, and a computer. The patient stares at a target at a known angle (e.g., -30°, 0°, +30°) while the video camera records the patient's eye. The images are sent to a computer that analyzes each image frame. The pupillary and Purkinje reflexes are identified. The described method is effective, but requires the examiner to be a well-trained and experienced operator. The patient's head is not fixed in a fixed position relative to the video camera, and the patient holds the head immobile without the use of any external device. The described device is therefore not suitable for use and / or is difficult to use when measuring strabismus in children. The device can be used both for strabismus screening and as a quantitative tool for surgical planning, reducing the number of surgeries required. In this method, the strabismus angle is calculated by linear regression using the Hirschberg ratio, which means that the method described is not exact.

[0024] From the solution of CN107898429A (Chinese Patent Publication No. 107898429) a solution is known that allows to quickly carry out a screening test for strabismus with its identification, i.e. whether there is recessive and / or manifest strabismus, horizontal and / or vertical strabismus. The subject looks at an eye chart placed at a distance of 33 cm and / or 5 m, and the image is recorded by a thermal imaging camera. This is a type of test based on the principle of covering the eyes. The video recording recorded while covering the eyes is transferred to a computer. To obtain the appropriate result of the screening test, the tables contained in the patent specification are used. This solution does not allow for an accurate diagnosis, and does not reveal the possibilities and principles of calibration of the optical system. Summary of the Invention [Problem to be solved by the invention]

[0025] According to the inventor's knowledge, there is no method or device known in the prior art that allows accurate, fully automatic measurement of eye deviation and / or vertical and horizontal visual angles, takes into account during the measurement the significant correction of the individual interpupillary distance and distortions introduced by an additional lens adapted to the patient's individual refractive error, and operates on the basis of the patient's observation of patterns displayed on a screen while alternatingly and periodically switching off the vision of one and / or the other eye, the position of these patterns being dynamically determined on the basis of an analysis of the current pupil deviation from the fixation position recorded on the camera image.

[0026] The term "patient" includes both persons diagnosed for medical purposes and anyone for whom the individual characteristics of their visual system need to be measured in order to best match them with stereoscopic imaging devices, e.g. interfaces to virtual reality and augmented reality, and to ensure that these devices are easier to use or operate.

[0027] The terms "switching on vision" and "switching off vision" should be understood as the use of any technical means that partially and / or completely blocks the access of light to the eye, resulting in the absence of a fixation object in the visual field of the eye. These terms do not apply to the suppression of vision due to, for example, long-term diseases and dominance of one eye over the other.

[0028] The aim of the present invention is to propose a solution based on the actual path of the light rays to the eye position on the visual axis, avoiding the need to estimate the position of this axis relative to the geometrical axis of the eye, as is the case in many of the solutions mentioned above.

[0029] Routinely, a person with strabismus, without using an appropriate prism correction, switches vision between the eyes and / or selects one dominant eye, which results in alternating accommodative eye movements when trying to focus on a presented object. After applying a conventional prism correction, alternating viewing of a presented object should not produce accommodative eye movements in the patient. Similarly, accommodative movements disappear in synoptophore testing as a result of appropriate positioning of the optomechanical module and the image displayed thereon, and / or by selecting the appropriate prism during the test using a conventional prism bar.

[0030] Mechanical synoptophores and / or prism bars are dynamically moved on the screen surface based on the analysis of the ocular accommodative movements, switched off synchronously and / or replaced by images that are covered alternately separately for each eye, so that the patient regains the impression of spatial binocular vision and the accommodative movements stop. Switching off the vision can be achieved by using mechanical and / or electronic covers or by using separate viewing areas on the screen that can be switched off. Also, if the image movement is related to the lens correction of the patient's own refractive error and related to the spacing of the patient's individual eyes, it is possible to accurately determine the angle between the axes of both eyes. [Means for solving the problem]

[0031] The solution of the present invention thus largely mimics the traditional cover test using a prism bar, but it can be fully automated and does not have the drawbacks of this and other previously presented methods, nor is it based on unreliable methods based on the analysis of light reflections in anterior eye structures or on the analysis of the shape of eye structures.

[0032] The device for automatic measurement of ocular deviation and / or vertical and horizontal viewing angles, comprising an opto-mechanical system cooperating with an image recording device and a display device, is characterized in that it has a screen arranged in an integrated housing. In front of the screen are arranged two symmetrically embedded opto-mechanical modules (constituting the opto-mechanical system) mounted on side arms. These modules are attached to the side arms. The side arms are movably embedded on parallel horizontal guideways arranged perpendicular to the side arms and driven along these guideways by servo drives and drive elements (e.g. toothed belts or lead screws). Every opto-mechanical module has a camera operating in an invisible light spectrum (e.g. near infrared), a system for switching off the vision (e.g. mechanical cover), an optical cylinder for fixing the lens system and a pupil illuminator operating in a light spectrum invisible to the human eye. The screen is arranged perpendicular to the axis of the lens system at a distance that allows a clear observation of the screen and covers the largest possible part of the eye's field of view. Furthermore, a selective element is placed between the optical tube and the screen, for example a glass coated with a selective filter or beam splitter, which allows both pupil images in the invisible light spectrum to be reflected towards the camera, but at the same time allows continuous visual observation of the screen. The illuminator is mounted in such a way that it illuminates the entire pupil of the eye and at the same time does not cause light reflections on the lens surfaces visible in the camera image. What is important is that the screen, the camera, the visual switch-off system, the servo drive and the driving elements are connected and controlled by a computer.

[0033] Particularly preferably, the integral housing has a permanently attached head stabilizer (e.g. in the form of a stabilizing frame) and / or a suitable shape of the housing to allow firm fixation of the subject's face while at the same time minimizing the amount of ambient light impinging on the retina.

[0034] It may also be advantageous to modify the parameters of the lens system, for example by changing the focal length of the lens system, the axial movement of the lens, the screen movement, and / or the movement of both of these elements relative to the eye, and / or by installing additional trial lenses to correct the patient's refractive errors that significantly affect the accurate assessment of the position of the optotype chart and thus the measurements of vertical and horizontal visual angles, including ocular deviation and / or strabismus.

[0035] In another preferred variation, each of the side arms to which the optomechanical modules are attached further includes at least one vertical guideway that is perpendicular to the horizontal guideway and embedded in the integral housing, the horizontal and vertical guideways together allowing the modules to move horizontally and vertically independently for the left and right eyes.

[0036] In another preferred variant, each optomechanical module may have its own integrated screen, which allows greater control over the periodic display of the eye chart and allows complete separation of the left and right eye fields of view, eliminating the need for additional covers.

[0037] The essence of the invention is also a method for automatically measuring the automatic strabismus angle using a device. The method uses measurements of the observer's interpupillary distance and a model of the geometric distortion of the visual field. In this method, first the magnitude of the vertical and horizontal distortion resulting from the application of a lens system in front of the observer's eyes, including additional corrective lenses, i.e. spherical and / or cylindrical lenses, is determined, allowing the viewing of the screen at infinity. The lens system is adapted to the patient's individual refractive error, for example by placing trial lenses adapted to the patient's individual refractive error in front of the patient's eyes. Then, by the movement of the servo drives and using a system that alternately switches off the vision, the main axis of the optomechanical module is centered on the position of the pupils of the left and right eyes, so as to obtain information about the observer's actual horizontal interpupillary distance and to determine on the screen the position of the fixation point located in front of each eye, preferably at a mutual distance on the screen that corresponds to the interpupillary distance. Then, during alternating periodic switching off of the vision of one eye, an image pattern is displayed on the screen surface at a fixed position straight ahead for one eye and at a variable position relative to the fixation point straight ahead for the other eye, the variable position being determined at each cycle based on the strength and direction of the pupil accommodation movement recorded by the camera at the moment of switching on the vision. After the pupil movement stops and the graphic pattern is set to the natural visual axis of both eyes of the patient, the final change position of the pattern is corrected by the values ​​of the vertical and horizontal distortions introduced by the lens system using a model of the geometric distortion of the visual field. Finally, based on the knowledge of the corrected position and the distance from the screen, the vertical and horizontal viewing angles of the graphic pattern are determined.

[0038] Very preferably, the parameters of the lens system are altered, e.g. trial lenses are selected in order to view the screen at a closer distance depending on the actual distance from the screen, and the fixation points of the left and right eyes are moved towards the axis of symmetry of the device in order to view the screen at a closer distance.

[0039] A variant is also advantageous if the variable position of the pattern is determined in each cycle based on the intensity and direction of the accommodation movement of the pupil of the examined eye registered by the camera at the moment when vision is switched off, precisely at the moment when the other eye begins to fixate straight ahead on a stationary graphical pattern.

[0040] Preferably, the graphical patterns represent the same three-dimensional object, the visualization of which on the screen takes into account geometric transformations separately for the left and right eye, and is envisaged to produce the effect of stereoscopic viewing of a real three-dimensional solid.

[0041] It is also preferably provided that immediately before and during the measurement, additional images are displayed on the screen in the background (e.g. a mountainous landscape and / or a starry sky) to enhance the observer's impression of spatiality and to facilitate switching off binocular accommodation and looking to infinity.

[0042] Preferably, the optical cylinder with the lens system and / or the screen is mounted on an additional guideway and driven by a computer-controlled servo drive, the movement of which is perpendicular to the screen, making it possible to change the focus of the image and adjust it to the refractive error of the eye.

[0043] Preferably, the camera has an additional optical module and a structured light projection module, allowing projection onto the retina of the eye, observation of this light image by the camera and automatic measurement of the refractive error. The measurement results allow automatic adjustment of the optomechanical module to the refractive error of the eye before testing the deviation angle of the eye and / or the vertical and horizontal viewing angles. The device of the invention makes it possible, for example, to cover the eyes alternately as in a conventional test and to carry out periodic tests with one eye fixating on a stationary graphic object placed in front of the eye, while at the same time the graphic object for the other eye moves in proportion to the intensity of the pupil accommodation movement in the image recorded by the appropriate camera when switching on the vision.

[0044] The design of the device of the invention allows the patient to observe the screen and at the same time allows the continuous recording of images of both pupils by the camera system. Each successive movement of the graphic pattern is automatically calculated based on two essential pieces of information: the individual interpupillary distance in the vertical and horizontal directions and the strength of the last recorded accommodative movement in the vertical and horizontal directions at the moment of switching on the vision of the examined eye. The device does not perform repetitive fixed operating cycles, but dynamically selects the pattern position based on the strength of the patient's eye movements. The cooperation with the patient is important in that he is able to track the graphic pattern displayed at various positions on the screen and focus his eyes on it. The moment of cessation of the accommodative movement corresponds to the stabilization of the position of the graphic pattern, and in the case of a patient with good cooperation, the accommodative movement may end after a dozen or so seconds. The final position of the visual field chart in conjunction with the model of visual field distortion and the data on the individual refractive error and interpupillary distance allows the deviation angle of the patient's strabismus to be determined.

[0045] The device of the present invention allows the testing of far and near strabismus angles by appropriate adjustment of the parameters of the lens system and / or appropriate setting of the screen position, as in the conventional method. Similarly, at any point during the test in the device, the vision of one of the patient's eyes is always switched off, which creates an image fusion blocking effect that is important for accurate measurements.

[0046] When used in typical medical diagnostics, a clear advantage of the invention is the possibility to perform repeated measurements in a stable and repeatable condition, with a fixed position of the patient's head during the examination, which is particularly important in pediatric patients, where cooperation is difficult. Moreover, the examination can be performed much faster and without the involvement of additional medical personnel (holding the child's head, holding an additional prism bar when calculating the vertical or oblique deviations coexisting with the horizontal deviation). The solution of the invention allows the results to be obtained partially or completely, regardless of the experience and involvement of the researcher during the measurement. The patient is only asked to focus on the selected pattern. The use of the device of the invention can also lead to better and more accurate results of strabological surgery, since the measurements of the strabismus angle are the basis for making an accurate diagnosis of the type of strabismus, the degree of muscle deviation and the extent of this deviation, but also, based on these measurements, the extent of the surgical technique to be adopted for the extraocular muscles is planned.

[0047] When used in non-medical diagnostics, a clear advantage of the invention is that it can be used to anthropomorphize the setup of devices used to create virtual or augmented reality, for example using appropriately designed goggles. Such devices can be used, for example, to create virtual workspaces, virtual operator panels for controlling machines, or 3D graphics presentations for entertainment purposes. Anthropomorphization refers to the matching of the individual anatomical characteristics of the visual apparatus, which can lead to long-term comfortable use of these devices without adverse side effects such as fatigue, headaches, or dizziness. [Brief description of the drawings]

[0048] [Figure 1a] 1 shows a schematic diagram of the operation of the device of the invention with a vertical guideway and its structure. [Figure 1b] 1 shows a schematic diagram of the operation of the device of the invention with a vertical guideway and its structure. [Diagram 2] 1 shows the calibration of the optical axis spacing. [Diagram 3] 1 illustrates a concept for calibrating the field of view. [Figure 4] 1 shows diagrammatically the measurement of interpupillary distance when the left eye vision is switched off and when the right eye vision is switched off. [Diagram 5] 1 shows strabismus angle measurement cycles for near distance for the right fixating eye when right eye vision is switched off and after right eye vision is switched on. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] Working Example The solution of the invention is disclosed in detail in the examples and applications as well as in the drawings, in which Fig. 1a and Fig. 1b show a schematic diagram of the operation of the device and its structure in its basic form and in two variants with vertical guideways, Fig. 2 shows the calibration of the optical axis distance, Fig. 3 shows the concept for calibrating the visual field, Fig. 4 shows a schematic diagram of the measurement of the interpupillary distance when (a) the left eye vision is switched off and when (b) the right eye vision is switched off, and Fig. 5 shows the strabismus angle measurement cycle for the near distance of the right fixating eye when (a) the right eye vision is switched off and after (b) the right eye vision is switched on.

[0050] Example 1 According to Fig. 1, the device for measuring ocular deviation and / or vertical and horizontal visual angles consists of a screen 1 of any technology for displaying image patterns, a calculation unit 4 (e.g. a PC computer), an operator panel 3 permanently attached to the head stabilizer housing 17, and two symmetrically made and embedded opto-mechanical modules, integrated in one housing 15. Each opto-mechanical module consists of subassemblies fixed to the element 12, namely a camera 2 operating in the near infrared band and connected to the computer 4 for image acquisition and analysis, a visual switch-off system 6 (blackout of a part 6a or of a cover 6b of the screen) controlled by the computer 4, an optical tube 5 fitted with an exchangeable trial lens 8, an illuminator 11 (e.g. an LED) operating in the near infrared band, and a mounting element 12 movably mounted on the guideway 16 so that the whole module can be moved precisely along the guideway 16. In a variant of the device (shown in FIG. 1b), each of the side arms 12 on which the optomechanical modules are mounted may comprise at least one vertical guideway 28, perpendicular to the horizontal guideway 16 and embedded in the integral housing 15. The horizontal guideway 16 and the vertical guideway 28 together allow the module to move horizontally and vertically independently for the left and right eye. Both mounting elements 12 move independently relative to each other by servo drives 9 for the horizontal and 29 for the vertical axes, respectively, controlled by the computer 4, and by drive elements 10, 30 (e.g. lead screws), which together allow for the accurate determination of the distance between the main optical axis of the camera 2 and the trial lens 8. The illuminator 11 is mounted non-removably so as to illuminate the entire pupil of the eye and at the same time not to cause light reflections on the surface of the lens 8 that would interfere with the observation of the pupil by the camera 2. The structure of the optomechanical modules must allow for a range of movement such that the distance between the axes of the lenses 8 can be adjusted to the typical distance D between the pupils of humans. The screen 1 is positioned perpendicular to the axis of the trial lens 8 and at a distance from the optical cylinder 5 so as to cover as much of the eye's field of view as possible.Between the lens 8 and the screen 1, a selective mirror 7 is arranged, which is able to reflect both pupil images in the infrared band towards the camera 2, but at the same time allowing a continuous visual observation of the screen 1. In an alternative variant (as in FIG. 1b), the single selective mirror 7 can be divided into two, which are symmetrically mounted separately on each opto-mechanical module. In contrast to the variant of FIG. 1a, in which the vision is switched off by blacking out a part 6a of the screen 1, in an alternative variant (as in FIG. 1b), it is planned to use covers 6b (e.g. LCD) mounted on arms 12, separately for the right and left eye, to switch off the vision of a given eye. The covers are mounted in such a way that no part of the screen 1 is in the field of view of the shielded eye.

[0051] The computer 4 is implemented with software for controlling the operation of the servo drive 9, software for analyzing the strength and direction of the eye's accommodation movement and controlling the display of a moving image pattern 13 for the examined eye and a stationary image pattern 14 for the other eye, as well as software for controlling the blackout (as shown in FIG. 1a) and / or cover 6b operation (as shown in FIG. 1b) of the portion 6a of the screen 1. The graphic patterns 13, 14 represent the same object of small size and shape that facilitates fixation, e.g. flat figures such as vectors or rasters. Alternatively, the graphic patterns 13, 14 represent the same three-dimensional object where separate geometric transformations for the left and right eyes cause the effect of stereoscopic observation of a real three-dimensional volume.

[0052] The calibration of the device is two-stage, including the calibration of the spacing of the optomechanical modules and the calibration of the field of view relative to the viewing angle. According to Fig. 2, the first stage is to find the relationship between the actual spacing L of the optical axes of the optical tube 5 and the movement of the servo drive 9 and the drive element 10. For this purpose, images of a distance standard 18 consisting of at least two pairs of flat markers 20 placed at distances corresponding to typical minimum and maximum interpupillary distances are registered, the left camera 2 observes only the left marker and the right camera 2 observes only the right marker. For each pair of markers 20, the spacing of the cameras 2 is set so that on the images 19 from the cameras 2 the markers are exactly in the middle of the width of these images and the position of the servo drive 9 is recorded. The positions of the drives 9 recorded for all reference distances 20 allow the creation of a linear model of this relationship, the parameters of which are stored on the computer hard drive 4.

[0053] According to FIG. 3, the second stage of the calibration is to determine the mathematical dependence of their position from the actual visual field angle of the farthest points visible on the screen, and thus the active measurement area 21 and at the same time the visual field. For this purpose, the mathematically evident change of the eye in the angular size of the measurement area 21 is determined after using a trial lens 5 with a refractive power ranging from -10 diopters to +10 diopters, then the limit angles α and β are determined from trigonometry for the extreme points of visual field distant from the point p by bx and by, respectively, taking into account the known distance m of the screen 1 from the place where the trial lens 8 is attached. A mathematical model is created, which makes it possible to correct the determined visual field angle for any point of the measurement area, other than the extreme points, which have obviously increased or decreased as a result of the operation of the trial lens 8. The parameters of the model are saved on the hard drive 4 of the computer. Using the calibrated system, the strabismus angle can be measured.

[0054] Test description At the start of the examination, the patient places his / her head on a suitably contoured stabilization frame 17, the position of which must be adjusted so that the left and right pupils are within the field of view of the left and right cameras 2, respectively, and the head remains motionless.

[0055] In the first stage of the measurement, the interpupillary distance is measured. According to FIG. 4, the vision of the left eye is switched off by blocking the left cover 6b and a figure pattern 24 is displayed in front of the exposed right eye at a distance of +33 mm from the center p of the screen 1, on which the patient's vision is focused. According to FIG. 4(a), an image 22 of the right pupil is registered by the camera 2 and the software of the computer 4 determines its position relative to the center of this image and, on this basis, determines the direction of movement of the drive element 10. The right opto-mechanical module, together with the mounting element 12 and the camera 2 and the trial lens 8, is automatically set so that the pupil is in the middle of the width of the image 22. The position of the servo drive 9 is saved in the computer hard drive 4. Similarly, after switching on the vision of the left eye and switching off the vision of the right eye, a dot pattern 25 is displayed in front of the left eye at a distance of -33 mm from the center p of the screen 1. Next, according to Fig. 4(b), the image 23 of the left pupil is registered and then the software performs a centering of the pupil on this image by moving the element 12 and a second position of the servo drive 9 is recorded. Based on both recorded positions of the servo drive 9 and on the recorded data from the device calibration procedure, the interpupillary distance D of the patient is determined and stored in the computer hard drive 4, which is necessary for further examinations.

[0056] According to FIG. 5, in the second stage of the measurement, the strabismus angle for near distance is measured for the left eye, while the right eye is always fixed on a graphic pattern located in the center p of the screen 1. Before the examination, a trial lens 8 is placed in the optical tube 5 of an individually selected refractive power for the patient, and as a result of fixing the pattern on the screen 1, the effect of natural vision is obtained up to a distance of typically 300 mm. Then, in order to block the fusion of the patient's images, a cycle begins in which the vision of the left eye is switched off by the cover 6b, and a graphic pattern 26 is displayed in the center p of the screen 1, on which the patient's vision is focused. The camera 2 registers the position of the pupil of the switched off left eye on the image 23 and saves this position on the computer hard drive 4. Then the cover 6b of the left eye is opened and at the same time the cover 6b of the right eye is closed and the patient again focuses his eye on the dot pattern 26 displayed in the center p of the screen 1. The left eye pupil position after switching on the left eye vision in the image 23 is recorded again, then the software calculates a vector v for the difference between this position and the position recorded before switching on the left eye. Based on this difference, a vector v' is determined which is a proportional rescaling of the vector v and indicates the value of the movement of the dot pattern 26 to a new position 27 on the plane of the screen 1, and the cycle ends. In the new cycle, when the left eye vision is switched on, the dot pattern is displayed in the new position 27 determined in the previous cycle. Similarly, in the left eye pupil image 23, a shift vector v is determined when its vision is switched on, which is used to calculate the position of the pattern in the next cycle. The ratio between the vectors v and v' is experimentally determined so that in the next cycle the accommodation movement of the eye switched on does not increase. This cycle is repeated until the pupil shift vector v of the switched on left eye reaches a set minimum value, for example expressed in image pixels, and thus the moment of cessation of the accommodation movement of the left eye is detected by the software. The final positions of the dot pattern 27 determined and stored in the computer 4 are corrected based on a known calibration model that depends on the field of view and the refractive power of the trial lens used and converted into the actual strabismus angles, i.e. vertical β and horizontal α.The measurement progress and measurement results with a preview of the pupil movement are visualized on the operator panel 3.

[0057] Example 2 This solution is similar to that of example 1, but after measurement of the interpupillary distance D on a calibrated device, a trial lens 8 with an individually selected refractive power for the patient is placed in the optical tube 5 and the effect of natural vision up to infinity is obtained as a result of fixing a pattern on the screen 1. The fixation position of the graphic pattern 26 displayed on the screen 1 for the right eye is then constantly shifted to the right with respect to the center p of the screen 1 by half the measured distance D between the patient's pupils, while the strabismus angle versus distance is measured.

[0058] A similar solution to that of embodiment 2, but while the measurement of the strabismus angle is performed for the right eye, the left eye always fixates on a stationary dot pattern 26 on the screen 1 shifted to the left by half the interpupillary distance D with respect to its center p. Example 3

[0059] In an optimal variant, it is envisaged that for each test, an image and / or a background is also displayed on the screen 1 immediately before and during the measurement, enhancing the observer's impression of spatiality and facilitating accommodative relaxation.

[0060] Example 4 A similar solution to that of embodiment 1, but the centering of the lens system is carried out simultaneously in the horizontal and vertical directions according to the application system of the guideways 16, 28 of FIG. 1b, and the interpupillary distance is calculated taking into account additionally the difference in the positions of the pair of drives 9 and the pair of drives 29.

[0061] Example 5 A similar solution to that of embodiment 1, but instead of a single immovable screen 1, two independent screens 1b are used for the left and right eye, permanently connected to the left and right arms 12, respectively. Such a solution for near and far distance measurements makes it possible to always determine the position of the graphic standards 13, 14 relative to the center of the screen 1b, which is once calibrated relative to the axis of the optical tube 5. This solution is shown in FIG. 6. The advantage of this solution is also that the respective opto-mechanical modules with the displays 1b can be integrated in one sealed housing.

[0062] Example 6 A similar solution to that of embodiment 5, but in each opto-mechanical module, instead of an exchangeable trial lens 8, a movable optical barrel 5 with a lens system 8b and / or a movable screen 1b is used, mounted on additional guideways 31 and / or 32 and driven by servo drives 33 and / or 34 controlled by computer 4, the movement of which is perpendicular to the screen 1b, allowing a change of the point of image sharpness and its adjustment to the refractive errors of the eye. One opto-mechanical system of this solution is shown in Figure 6.

[0063] Example 7 A similar solution to that of example 6, but the camera may have an additional optical module 35 and a structured light projection module 36, which allow projection onto the retina, observation of this light image by the camera 2, and automatic measurement of the refractive error. The measurement results allow an automatic adjustment of the optomechanical module to the refractive error of the eye before testing the strabismus angle. This solution is shown in Figure 7.

Claims

1. An apparatus for automatic measurement of eye deviation and / or vertical and horizontal observation angles, comprising an optical mechanical system in cooperation with an image recording device and display device, having a screen (1) disposed within an integrated housing (15), in front of which two symmetrically embedded optical mechanical modules are mounted on side arms (12), the side arms (12) being movably embedded in parallel horizontal guideways (16) positioned perpendicular to the side arms (12) and driven along these guideways by a servo drive (9) and drive element (10), each optical mechanical module having a camera (2) operating in the invisible light spectrum, an optical tube (5) fixing a lens system (8), a visual switch-off system (6), and a pupil illuminator (11) operating in the invisible light spectrum, the screen (1) The apparatus is characterized in that a selectivity element (7) is positioned perpendicular to the axis of the lens system (8) and at a distance that allows for clear observation of the screen and covers the largest possible portion of the field of view, and a selectivity element (7) is positioned between the lens system (8) and the screen (1) to allow for the reflection of both pupil images within the field of view of the invisible light spectrum toward the camera (2), while simultaneously allowing for continuous visual observation of the screen, and the illuminator (11) is non-removably mounted on the side arm (12) to illuminate the entire pupil of the eye while simultaneously preventing light reflection on the lens surface (8) visible in the image from the camera (2), and the screen (1), camera (2), visual switch-off system (6), servo drive (9), and drive element (10) are connected and controlled by a computer (4).

2. The apparatus according to claim 1, characterized in that the integrated housing (15) has a head stabilizer (17) that is not removable and / or has a contour shape that can firmly fix the face of the person being examined.

3. The apparatus according to claim 1 or 2, wherein each of the optical mechanical modules has the ability to change the parameters of the lens system and / or has a handle for additional trial lenses.

4. The apparatus according to claim 1 or 2, wherein each of the side arms (12) to which the optical mechanical module is attached is perpendicular to the horizontal guideway (16) and has at least one vertical guideway (28) embedded in the integrated housing, and further preferably has two symmetrically mounted selectivity mirrors (7).

5. The apparatus according to claim 1 or 2, characterized in that each optical mechanical module has its own integrated screen (1).

6. The apparatus according to claim 1 or 2, characterized in that the optical tube (5) having the lens system (8) and / or the screen (1) are mounted on additional guideways (31) and / or guideways (32) and driven by servo drives (33) and / or servo drives (34) controlled from the computer (4).

7. The apparatus according to claim 1 or 2, wherein the camera (2) has an additional optical module (35) and a structured light projection module (36) that enable projection onto the retina, observation of the image of this light by the camera (2), and automatic measurement of refractive errors.

8. A method for automatic measurement of ocular deviation and / or vertical and horizontal field angles using the apparatus according to claim 1, which uses a measurement of the observer's interpupillary distance and a model of the geometric distortion of the field of view, wherein first, the magnitude of vertical and horizontal distortion resulting from the use of a lens system in front of the observer's eyes, which includes additional spherical or cylindrical corrective lenses that enable observation of the screen (1) at infinity, is determined at each point in the actual field of view, the lens system is then adjusted for the individual refractive error of the observer, and then, by the movement of a servo drive (9), the principal axis of the optical machine module is centered with respect to the positions of the pupils of the left and right eyes using an alternating visual switch-off system (6), thereby obtaining information about the observer's actual horizontal interpupillary distance, determining the position of fixation points placed in front of each eye on the screen (1), and then, A method characterized in that, between alternating periodic switching of the vision of one eye to off by a system (6), an image pattern (14) is displayed on the surface of the screen (1) at a fixation position directly in front of one eye, and an image pattern (13) is displayed at a variable position relative to a fixation point directly in front of the other eye, the variable position being determined in each cycle based on the intensity and direction of pupillary adjustment movement v registered by the camera at the moment the vision of that eye is switched on by the system (6), the final variable position of the pattern (13) obtained after the pupillary movement has stopped is corrected by values ​​of vertical and horizontal distortion introduced by the lens system using a model of geometric distortion of the field of view, and finally, the vertical and horizontal field of view angles of the image pattern are determined based on knowledge of the corrected position (13) and the distance from the screen (1).

9. The method according to claim 8, characterized in that the parameters of the lens system are changed and the fixation points of the left and right eyes are moved toward the axis of symmetry of the device in order to view the screen at close range.

10. The method according to claim 8 or 9, characterized in that the variable position of the image pattern (13) is determined in each cycle based on the intensity and direction of pupillary accommodation movement registered by the camera at the moment when the system (6) switches its vision off, more precisely at the moment when the other eye begins to fixate on the stationary image pattern.

11. The method according to claim 8 or 9, characterized in that the geometric patterns (13) and (14) represent the same three-dimensional object, and the visualization thereof on the screen takes into account separate geometric transformations for the left eye and the right eye, thereby providing the effect of observing an actual three-dimensional object in three dimensions.

12. The method according to claim 8 or 9, characterized in that images and / or backgrounds that enhance the observer's impression of spatiality are also displayed on the screen (1) immediately before and during the measurement.

Images