Analysis of eye movement in real 3D space in direction and depth

Abstract

The invention relates to a method for processing data representative of a person's binocular motor skills, the method comprising the following steps: - stimulation of a person's binocular motor skills by means of a binocular motor stimulation device (21) configured to specifically stimulate saccades, vergences or a combination of both or a reading test (22); physical stimuli in real 3D space viewed with both eyes naturally (without artifice); - acquisition during said stimulation of the movement of the right eye (OD) and the left eye (OS) of a person (P) and, where appropriate, of a stimulation signal from the binocular motor stimulation device; the method comprising the following steps implemented in a processing unit (3);- determination from the movement of the left eye (OS) and the right eye (RO), of an effective trajectory (Tr1) of the eyes in response to each stimulus, an effective trajectory corresponding to a saccade and / or a vergence movement of the eyes. Figure for the abbreviation: Fig. 1;

Description

Title of the invention: Analysis of eye movement in 3D real space in direction and depth

[0001] GENERAL TECHNICAL FIELD,

[0002] The invention relates to the field of processing data representative of a person's binocular motor skills, the binocular motor skills having been stimulated by means of a visual test, for example by means of a device dedicated to the stimulation of binocular motor skills or by means of a reading test. And the invention applies in particular to the diagnosis of pathologies having a link with binocular motor skills. It also applies to research on normal development or aging, and finally, to work ergonomics applications, and to the reading or exploration of texts or images. STATE OF THE ART

[0003] Binocular tests, and in particular those aimed at testing binocular motor skills, are often used to detect various neurological pathologies.

[0004] Indeed, binocular motor disorders can reflect different binocular pathologies but especially neurological ones.

[0005] There is therefore a need to have methods for testing binocular motor skills

[0006] in order to be able to effectively detect neurological pathologies, that is to say which are as little subjective and dependent on the practitioner as possible. PRESENTATION OF THE INVENTION

[0007] The invention meets this need.

[0008] To this end, the invention proposes a method for processing data representative of the binocular motor skills of a person, the method comprising the following steps:

[0009] - stimulation of the binocular motor skills of a person by means of a device binocular motor stimulation configured to specifically stimulate saccades, vergences, or a combination of both, or a text or image reading test:

[0010] - acquisition during said stimulation of the movement of the right eye and the eye left of a person and, where appropriate, a stimulation signal from the binocular motor stimulation device; the method comprising the following steps implemented in a processing unit;

[0011] - determination from the movement of the left eye and the right eye, of a tra effective jectory of the eyes in response to each stimulation, an effective trajectory corresponding to a saccade and / or a vergence movement of the eyes;

[0012] - determination, for each stimulation of a trajectory representative of the eyes;

[0013] - comparison of each effective trajectory with the corresponding representative trajectory laying in such a way as to eliminate the erroneous effective trajectories furthest from the effective trajectory and thus obtain trajectories retained for each stimulation;

[0014] - processing of each trajectory retained so as to obtain parameters of saccade and / or vergence, the parameters being characteristic of a possible pathology of a person.

[0015] The method according to the invention is advantageously supplemented by the following characteristics, taken alone or in any of their technically possible combinations:

[0016] - the determination consists of processing all the effective trajectories for a sti given mulation so as to obtain a trajectory representative of this stimulation;

[0017] - the method comprises a step of displaying an image of the stimulation device on which the trajectories of eye movements are represented;

[0018] - the effective trajectory corresponding to a saccade is obtained by calculating a conjugate signal defined by the average of the position of the left eye with the position of the right eye;

[0019] - the effective trajectory corresponding to a vergence is obtained by calculating a unconjugated signal defined by the difference between the position of the left eye and the position of the right eye;

[0020] - the movement of the right eye and the left eye are acquired with targets presented in 3D real space, the method comprising a step of transforming the movement of the right eye and the left eye into degrees;

[0021] - a saccade parameter is the maximum speed of the saccade, the average speed;

[0022] - a saccade parameter is the amplitude of a saccade, the amplitude being defined between the start of the saccade and the end of the saccade, the start of the saccade being defined by the instant at which the saccade has a speed x% higher than the maximum speed of the saccade, the end of the saccade being defined by the instant at which the saccade has a speed x% lower than the maximum speed, x being between 5 and 15;

[0023] - the visual test consists of subjecting the person to a first visual stimulus or to the audiovisual stimulus and then subjecting it to a second visual or audiovisual stimulus located at a different location from the first visual or audiovisual stimulus, a saccade parameter being a latency defined by the duration between the instant of activation of the second visual stimulus and the start of the trajectory of the eyes to pass from the first visual or audiovisual stimulus to the second visual or audiovisual stimulus; these stimuli being physical, presented in real space, and seen by the person naturally with both eyes (without known artifices e.g. stereovision glasses, virtual reality 3D screens, or other process creating an artificial vision of depth)

[0024] - a saccade parameter is the duration of the saccade defined by the duration between the end of eye movement and the onset of eye movement;

[0025] - a saccade parameter is the amplitude of the difference between the two eyes between the start of saccade and end of saccade;

[0026] - a saccade parameter is one of the disconjugation parameters: obtained on the signal basis of the difference between the position of the left and right eyes;

[0027] - a disconjugation parameter, is one of the following parameters:

[0028] . amplitude of the disconjugation expressed in degrees of the defined saccade: amplitude of the difference between the two eyes between the start and the end of the saccade;

[0029] . drift 1 expressed in degrees: amplitude of the dis-conjugation between the end of the saccade and up to 80 ms after the end of the saccade;

[0030] . drift 2 expressed in degrees: amplitude of the dis-conjugation between the end of the saccade and up to 160 ms after the end of the saccade;

[0031] - a vergence parameter is the amplitude of a vergence, the amplitude being defined between the start of the vergence and the end of the vergence, the start of the vergence being defined by the instant at which the vergence has a speed x% higher than the maximum speed of the vergence, the end of the vergence being defined by the instant at which the vergence has a speed x% lower than the maximum speed, x being between 5 and 15;

[0032] - the visual or audiovisual test consists of subjecting the person to a first stimulus visual or audiovisual stimulus and then subjecting it to a second visual or audiovisual stimulus located at a different location from the first visual or audiovisual stimulus, a vergence parameter being a latency defined by the duration between the instant of activation of the second visual stimulus and the start of the trajectory of the eyes to pass from the first visual stimulus to the second visual stimulus;

[0033] - a vergence parameter is the duration of the vergence defined by the duration between the end of eye movement and the onset of eye movement;

[0034] - a vergence parameter is the magnitude of the difference between the two eyes between the beginning of the vergence movement and the end of the vergence movement;

[0035] - a vergence parameter is the amplitude of the vergence drift during the 80 ms or 160 ms after the end of the vergence movement;

[0036] - a visual test is a text reading test, the trajectories being pro saccades rightward movements and / or regression saccades, i.e., returns to the previous word. This can also be a test of reading an image.

[0037] With the invention it is therefore possible to test and analyze the movements of the two 3D eyes (in directions and depth: saccades and vergences).

[0038] Furthermore, the stimulations are physical: for example, visual or audiovisual targets anchored at eccentricities and depths on the surface of the stimulation device (REMOBI), or during text reading, or image reading. The person sees naturally with both eyes - that is to say, no process of stereovision glasses, virtual reality, or 3D screen is used. Thus, the person's vision is natural. These are therefore stimulations in real 3D space.

[0039] The invention makes it possible to process data from the movements of the eyes of a person stimulated by visual or audiovisual targets placed in real space at eccentricities and depths as provided in particular by the REMOBI device, or during the reading of text (on a book or screen) or reading of an image on a book or screen. All the stimulations used in the invention are physical and seen naturally with both eyes. Consequently, no method of stereovision glasses, virtual reality, or other artificial vision method is used. PRESENTATION OF FIGURES

[0040] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0041] [fig. 1] [fig.l] illustrates a system for processing data representative of a person's binocular motor skills;

[0042] [fig.2a]

[0043] [fig.2b]

[0044] [fig.2c]

[0045] [fig.2d] figures 2a, 2b, 2c, 2d illustrate methods of stimulating the binocular motor skills of a person;

[0046] [fig.3] [fig.3] illustrates steps of a data processing method represented observations of a person's binocular motor skills;

[0047] [fig.4] [fig.4] illustrates several trajectories of the eyes performing a movement of convergence;

[0048] [fig.5] [fig.5] illustrates an indicator translating the distance between the trajectory theoretical (thick line) and the measured trajectory (thinner line);

[0049] [fig.6] [fig.6] illustrates a trajectory concerning a convergence movement and below, the corresponding speed signal;

[0050] [fig.7] [fig.7] illustrates saccade-type trajectories to the right (top) and to the left (down);

[0051] [fig.8] [fig.8] illustrates vergence type trajectories: convergences (at the top, divergences (bottom);

[0052] [fig.9] [fig.9] illustrates the regular path of the eyes of a reader who does not suffer of no pathology;

[0053] [fig.10] [fig.10] illustrates a complete assessment of a dyspraxic person;

[0054] [fig.lla]

[0055] [fig.l 1b] Figures 11a and 11b illustrate, respectively, an image used for eye movement stimulation with the eye trajectory superimposed and the trajectory followed by the eye movement;

[0056] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION

[0057] In everyday life, subjects constantly make eye movements approximately three times per second to explore the 3D environment. The essential movements are saccades and vergence movements.

[0058] Saccades are rapid movements of refocusing the gaze from one point to another laterally, vertically or both at the same time (we then speak of oblique saccades).

[0059] Vergence movements are movements of the eyes in the opposite direction: to fix a nearby object, the left eye turns to the right and the right eye turns to the left; this convergent movement of the eyes makes it possible to increase the angle of convergence of the axes.

[0060] To fix a distant object the left eye turns to the left, and the right eye turns to the right; this divergent movement makes it possible to reduce the angle of convergence of the two optical axes, by making the optical axes almost parallel.

[0061] Usually, movements combining saccades and vergences are performed together. These movements are performed almost simultaneously, at least for a certain time: in fact, vergence being slower than the saccade, when it is combined with the saccade it accelerates considerably, then continues after the saccade if necessary.

[0062] The concepts of saccade and vergence movement are presented below.

[0063] A saccade corresponds to a change in the position of the gaze. It is expressed by a rotation of the binocular globes allowing a new target to be projected onto the fovea of ​​both retinas. A saccade is very fast (up to 800° / s) and is therefore of very short duration (50 to 150ms). It is the fastest movement that a human being can produce. A saccade normally serves to change the fixation point, therefore to seek information elsewhere in the visual field. It does not, in itself, provide information at the visual level, although the retinas and the visual system still function normally during its occurrence.

[0064] Vergence movements allow the eyes to rotate in opposite directions. They are the only disconjugate binocular movements in the visual system. Vergence movements allow us to see at different distances in depth. The eyes converge to see a closer target and diverge to fixate on a more distant target. This adaptation to distance is achieved through the accommodation triad, or near vision triad (in English, "near triad"), comprising vergence movements (convergence of fusion), accommodation (deformation of the lens) and, to a lesser extent, contraction / relaxation of the pupil. These three components of vision are very closely linked.

[0065] Although these parameters are conventionally used for the study and diagnosis of various pathologies, the Applicant has noticed that there is currently no automatic, rapid analysis of these movements taking into account both eyes, in direction and in depth.

[0066] In relation to [fig.l], a system 1 for processing data representative of the binocular motility of a person P comprises a stimulation part 2, a system 11 for acquiring and recording the eye movements of a person P, in particular, the movements of the right eye OD and the left eye OG of a person. Furthermore, the system comprises a processing unit 3 configured to implement steps of a method for processing data representative of the binocular motility of a person P and which will be described below. Such a method makes it possible in particular to obtain saccade parameters PARAM 1 and / or vergence movements PARAM 2.

[0067] Advantageously, from the saccade parameters PARAM 1 and / or movement parameters of vergences PARAM 2 it is possible to evaluate a person's disorder.

[0068] Visual tests

[0069] The stimulation part 2 advantageously comprises two types of stimulation of the binocular motor skills of a person P. These stimulations have the effect of causing saccades or vergences and movements combining saccades and vergences in the person.

[0070] A first type of stimulation is implemented by means of a device for stimulating binocular motor skills by sensory stimulation means such as diodes and sound diffusion means are arranged along different iso-vergence arcs in front of a person: an iso-vergence arc is such that the vergence angle of the two eyes required to fixate each point on this arc is the same. This device advantageously comprises four iso-vergence arcs. Preferably, the sensory stimulation means are arranged on a flat support. Such a device used for the first type of stimulation is described in patent EP 2 512 395 B1, patent CA 2 784 541 C, patent FR 2 953 711 B1, patent JP 5 671 055 B2, patent US 8 851 669 B2. This device is called the REMOBI device.

[0071] The sensory stimulation means are arranged on arcs at distances of between 20 and 150 cm from a person and between each stimulation means placed on the same arc there is an angle of 10 degrees. The support is advantageously mounted on a height-adjustable foot allowing the device to be positioned appropriately at the face of a person P. The support of the sensory stimulation means is preferably trapezoidal and has dimensions suitable for testing the entire natural range of eye movements (saccades at different depths, iso-vergence arcs, vergences along the median plane, movements combining saccades and vergences) and rehabilitating binocular motor skills in direction (saccades), in depth (vergences) or combining them. The stimulation provided by this type of device is modular; it can be audiovisual (using light diodes and sound means), only sound or only visual.The visual and sound stimulation means constitute targets for the person. Each sensory stimulation means is represented by a voltage so that it is possible to acquire a corresponding output signal allowing the identification of the active targets and, therefore, the type of movement that can be generated by the stimulation.

[0072] The device is advantageously controlled by an on-board microprocessor which allows controlled spatio-temporal activation of the diodes and loudspeakers. Different stimulation protocols, adapted to different types of pathologies, can thus be used and implemented to diagnose and rehabilitate eye movement disorders. These protocols are based on sequences allowing lateral and / or deep eye movements.

[0073] Figures 2a, 2b and 2c illustrate three stimulation modalities using the binocular motor stimulation device. Visual stimulation using diodes is considered, in a non-limiting manner. The diodes are lit one by one, one diode is switched off before lighting the next one so that one diode is lit at a time. In [fig. 2a], a vergence test is illustrated: the diode at position F is initially lit, then those at position T and then T' are lit. In [fig. 2b]: a saccade test is illustrated: the diode at position F is initially lit, then those at position T and then T' are lit; the saccade test can be done, in a non-limiting manner, with targets at 40 cm as illustrated in figure 2B, but also at 20, 70 or 150 cm. In [fig.2c]: a combined movement test is illustrated: the diode at position F is initially lit, then those at position T then T', T” and T'” are lit. The duration of lighting of the diodes is part of the test modalities and depends on the pathologies studied. Other tests use the so-called double target jump paradigm and are used for the rehabilitation of binocular motor skills: the diode at position F is initially lit, then those at position T then T' and 200 ms later the T” is lit; with repetition the brain learns. quickly to program a single accelerated and broad movement aimed at the second position of the target T”. We can also refer to the methods described in document EP 2 512 395 Bl.

[0074] A second type of visual stimulation is that implemented by means of a reading test 22. This stimulation simply consists of having the person P read a text and acquiring and recording the movement of the eyes during reading. The test is advantageously held by the person in a position offering them reading comfort. Also, this reading test includes viewing an image which is "read" by a person P. Also, the test can be of the "bell barrage test" type 23. (see figure 1) such a test consists of recognizing one character among other identical ones. In figure 1, the test 23 includes several letters B among which are arranged numbers 8, the test consists of identifying the 8. The trajectory followed by the eyes will be recorded. An alternative to this test is to position the letter L among several characters representing an 's' symbol.The test consists of identifying the L, again the trajectory of the eyes will be recorded during this identification.

[0075] During the stimulations described above, the person is equipped with a system for acquiring and recording eye movements (see below) in order to be able to acquire and record the movements following the different stimulations or during reading.

[0076] Advantageously, each test on the REMOBI device comprises twenty repetitions in a pseudo-random manner for each target (e.g.: saccades to the left, saccade to the right, convergence or divergence). Also, a typical trajectory can be provided for all saccades to the right during reading.

[0077] System for acquiring and recording the movements of the eyes

[0078] A system for acquiring and recording eye movements 11 makes it possible to measure binocular movement, and more precisely the image of the pupil, constituting the analysis center. It covers the following areas:

[0079] - tracking (the direction) of the gaze of a subject (human being);

[0080] - binocular control, i.e. the use of gaze to activate / validate a function such as clicking on an icon, moving the mouse etc.

[0081] The eye movement acquisition and recording system works advantageously with a videoculograph, namely micro-cameras which focus their objectives on both eyes and record their movements when the person fixes the device for stimulating binocular motor skills 21 or when he is reading a reading test 22.

[0082] In this case, to do this, the micro-cameras capture the contrast between the retina and the pupil using a projection of infrared light, by analyzing the light reflected by the cornea of ​​the human eye. By alternating the contrasting reflections of the pupil (light / dark), it therefore becomes possible "to follow the movement of the eye.

[0083] Such a system is for example an eye tracker from the company Pupil Labs™ which allows not only to have the position of the eyes but also other parameters as well as the video of the eyes and what the person sees. However, only the position of the eyes is useful in what will be described. Another type of eye movement acquisition system is the Powref III from the company PlusOptix™. Such a type of system is placed at a distance from the person, for example in front of the person on the REMOBI support. This system makes it possible to measure the movement of the eyes but also, at a distance, the change in the accommodation of the eyes for and to trace the positions of the eyes but also the trace of the change in the accommodation of the eyes. In this respect, one can refer to the document “HSOA Journal of Clinical Studies and Medical Case Reports”, Kapoula Z, et al., J Clin Stud Med Case Rep 2019, 6: 74. The [fig.2d] illustrates a person in front of the REMOBI device with an eye movement acquisition system placed on the support. The person is subjected to a vergence test according to the methods illustrated in this figure. The vergence movement and the change in accommodation are recorded and illustrated in this figure as well.

[0084] Treatment method (called AIDEAL for "Automatic Intelligent Eye Movement AnaLysis")

[0085] [Fig.3] illustrates steps of a method for processing data representative of a person's binocular motor skills.

[0086] The binocular motor skills of a person P are stimulated El by means of a device 21 for stimulating binocular motor skills or by a test 22 for reading text or images.

[0087] During stimulation 21, acquisition E2 of the movement of the right eye and the left eye is carried out.

[0088] Furthermore, if the binocular motor stimulation device 21 is used, the acquisition E2' of a stimulation signal indicating which sensory stimulation means are activated over time is implemented: which diodes, which loudspeaker if applicable.

[0089] The acquired data relating to eye movement are time-stamped in seconds as is the stimulation signal.

[0090] Thus, at the end of the acquisition steps E2, E2', we obtain E3 data grouped in a matrix comprising nine columns:

[0091] - column 1: time scale corresponding to the signal emitted by the sti device binocular motor skills stimulation (in second);

[0092] - column 2: signal emitted by the binocular motor stimulation device, this signal corresponds to the lighting of the light diodes (in volts);

[0093] - column 3: time scale corresponding to the positions (in seconds);

[0094] - columns 4, 5, 6: position in x, y, z of the right eye (in arbitrary unit);

[0095] - columns 7, 8, 9: position in x, y, z of the left eye (in arbitrary unit).

[0096] It will be understood that if the reading test is used then the first two columns are not fulfilled.

[0097] Advantageously, the data corresponding to the position of the eye in a 3D space of the eye are converted E3' into degrees as is usually expressed. Indeed, the eyes rotate around the vertical or horizontal axis and these rotations are measured in angular degrees.

[0098] From these data, the method comprises a determination E4 of an effective trajectory (Tri) of the eyes in response to each stimulation, an effective trajectory corresponding to a saccade and / or to a vergence movement of the eyes. Indeed, it is assumed that we know which test was used to stimulate a recorded movement.

[0099] In particular, the trajectory corresponding to a saccade is obtained by calculating a conjugate signal defined by the average of the position of the left eye with the position of the right eye.

[0100] Note that the type of movement depends on the test implemented. A saccade test sequence (see [fig.2b]) can only cause saccade movements; a vergence type test (see [fig.2a]) can only cause vergence movements.

[0101] Also, the effective trajectory corresponding to a vergence is obtained by calculating a non-conjugate signal defined by the difference of the position of the left eye with the position of the right eye.

[0102] If the binocular motor stimulation device 21 is used, the different saccades and vergence movements are classified E5 to take into account the location of the sensory stimulation means used when the corresponding eye movements are analyzed. Indeed, to test natural physiological oculomotor performance it is important to unpredictably mix the targets to the left or right of the fixation point (for saccades) or forward or backward for vergences. Thus the person cannot anticipate the direction or depth at which their gaze should move. For the analysis of the properties of eye movements it is important to characterize the parameters separately for each subclass of movements. Indeed, it is possible to have deficits specific to the direction (left vs. right) or to the type of vergence (convergence or divergence).There are even natural asymmetries between different subgroups of movements (e.g., stronger convergence than divergence, or rightward jerks). better than saccades to the left even in the normal population)

[0103] Regarding saccades, a classification of the signals is carried out according to the lit diode (for a diode on the right, conjugate signal of the upward saccade, for a diode on the left of the fixation diode, conjugate signal of the downward saccade). Two data matrices are created (for movements to the right and to the left).

[0104] Regarding the vergence movements, the classification is carried out according to the illuminated diode, for convergence (upward signal) for divergence (downward signal).

[0105] We understand that we obtain a set of Tri trajectories from the acquired signals.

[0106] [Fig.4] illustrates several trajectories of the eyes performing convergence.

[0107] However, certain trajectories may be erroneous. In this respect, the method comprises a processing of the trajectories described below (step E7).

[0108] A set of representative trajectories Tr2 of the eye movement for a given stimulation is calculated (step E71). To do this, all the measured trajectories concerning this stimulation are used. Then (step E72) for each stimulation, the trajectory Tri resulting from the measurement is compared to the representative trajectory Tr2 for this stimulation so as to eliminate the erroneous trajectories and thus obtain retained trajectories Tr.

[0109] In particular, the comparison (step E72) consists of calculating a distance between the actual trajectory and the theoretical trajectory and if the distance is greater than a fixed threshold, the trajectory is eliminated. As a result, only the measurements which correspond to the stimulation considered.

[0110] The elimination of erroneous trajectories is implemented by means of a DTW algorithm (in English, “Dynamic Time Warping”).

[0111] Such an algorithm makes it possible to measure the similarity between two sequences which can vary over time.

[0112] The DTW algorithm is classically exploited in video, audio, computer graphics, bioinformatics and can be applied in any situation where the data can be transformed into a linear representation.

[0113] Generally speaking, the DTW algorithm is a method that searches for an optimal matching between two time series, under certain restrictions. The time series are deformed by non-linear transformation of the time variable, to determine a measure of their similarity, independent of certain non-linear transformations of time. This method of time series alignment is often used in the context of hidden Markov models.

[0114] In the case described here, it is a question of eliminating the trajectories too far from the tra- theoretical jectories.

[0115] [Fig.5] illustrates an indicator translating the distance between the theoretical trajectory (thick line) and the measured trajectory (thinner line). The indicator (61.1331; 85.3046; 123.4698; 140.7682) being for example high, indicates that the measured trajectory is far from the theoretical trajectory. In this example, all cases with an indicator greater than 10, i.e. 5 here, are eliminated.

[0116] For each trajectory, the start and end of the eye movement is detected by calculating the speed of the acquired trajectory signal (the derivative of the instantaneous eye position signal). In particular, the start of the saccade is the point where the speed exceeds 10% of the maximum speed, and the end of the saccade is the moment or where the speed is less than 10% of the maximum speed. Other speed criteria, e.g.: a speed > 45 degrees per second for the start of the saccade and less than 45 degrees per second can be used.

[0117] Then, once the trajectories are well selected, the method comprises a processing step E8 of each trajectory retained Tr so as to obtain saccade and / or vergence parameters, the parameters being characteristic of a possible pathology of a person.

[0118] Each saccade and vergence parameter is described below.

[0119] Before describing the parameters, we note that the processing of the data relating to stimulation by the reading test is similar to that for saccades. Indeed, during reading the eyes make a succession of saccades followed by fixation, progressively from left to right, then a large saccade to the left and downwards to go to the next line.

[0120] Jerky parameters

[0121] - Detection of the start of the stimulation signal (the lighting of the target diode of the device binocular motor stimulation) using signal speed. This target signal is used to measure saccade latency (see below);

[0122] - Latency (in ms) is the time between the target diode turning on and the start of the saccade (when stimulation is performed using the binocular motor stimulation device);

[0123] - Amplitude: difference in degrees between the end of the saccade and the beginning of the saccade. The start of the saccade is defined by the instant for which the saccade has a speed greater than x% of the maximum speed of the saccade, the end of the saccade being defined by the instant for which the saccade has a speed less than x% of the maximum speed, x being between 5 and 15, preferably 10. It is noted that it is possible to set other criteria than the x% of maximum speed, such as for example a speed criterion adjusted according to the amplitude of the saccades studied: for example for large saccades (10, or 20 degrees) a speed greater or less than x% of the maximum speed. less than 45 degrees per / sec allows the beginning and end of the saccade to be discerned with good precision;

[0124] - Duration (ms): the time in msec between the start and the end of the movement;

[0125] - Maximum speed (degree / s): maximum value of the saccade speed signal;

[0126] - Average speed (degree / s): amplitude of the saccade in degrees divided by the saccade duration (in seconds);

[0127] - Disconjugation parameters: obtained on the basis of the signal of the difference between left eye position OG - right eye OD:

[0128] - Amplitude of the dis-conjugation (in degrees) of the defined saccade: amplitude of the difference between the two eyes between the start and the end of the saccade (this is equivalent to the difference in the amplitude of the saccade between the two eyes);

[0129] - Drift 1 (in degrees): amplitude of the disconjugation between the end of the saccade and up to 80 ms after the end of the saccade; we take the difference between these two points to measure the amplitude. But we can also average the disconjugation values ​​between all the points going from the end of the saccade up to 80 ms after;

[0130] - Drift 2 (in degrees): amplitude of the disconjugation between the end of the saccade and up to 160 ms after the end of the saccade.

[0131] Parameters of vergence movements

[0132] - Detection of the start of the stimulation signal using the speed of the diode signal of the binocular motor stimulation device. From this signal, the vergence latency is measured (see below);

[0133] - Latency (ms): time (in ms) between the target diode turning on and the start of the vergence (when stimulation is performed using the binocular motor stimulation device);

[0134] - Amplitude: difference in degrees between the end of the vergence (the point where the speed of the vergence falls to less than 5 degrees / sec, and point of the beginning of the movement (point where the speed is greater than 10% of the maximum speed). Depending on the noisy or not quality of the signal of the movements of the eyes we can average five points around this value to be certain that the beginning or the end of the vergence is well identified;

[0135] - Duration (ms): time between the start and the end of the movement considered;

[0136] - Maximum speed (degree / s): maximum value of the speed signal;

[0137] - Average speed (degree / s): amplitude of movement in degrees divided by the duration of movement (in seconds);

[0138] - Drift 1 (degrees): amplitude of the vergence signal during the 80 msec following the end of movement; note that the average can also be considered;

[0139] - Drift 2 (degrees): amplitude of the vergence signal during the following 160 msec the end of the movement; note that the average can also be considered.

[0140] The saccade and vergence parameters can be used alone or in combination. combination. In the case of combined movements, these include a saccade component (conjugate signal, i.e., left eye + right eye / 2) and the vergence component (left eye - right eye).

[0141] In this case, the eye movement data are processed twice: once to process saccades and once to process vergences.

[0142] The parameters calculated for each component are the same as those indicated previously for saccade and vergence. We then obtain the respective parameters relating to saccade and vergence.

[0143] In a complementary manner, it is possible to process the data obtained interdependently. This is called combined analysis. For this, we base ourselves on saccade detection criteria and evaluate the vergence (amplitude, duration, speed,) during the saccade and 80 and 160 msec after the saccade. We then obtain twice as many parameters, namely: right saccades and divergence, left saccade and divergence, right saccade and convergence, left saccade and convergence. These two analyses correspond to two different physiological hypotheses: independent control of two physiological systems of saccades and vergence; hypothesis of interaction and interdependence between the two, the saccade guiding and accelerating the vergence.

[0144] As an illustration, [fig.6] shows a trajectory relating to a convergence and below, the corresponding speed signal.

[0145] [Fig.7] illustrates saccade-type trajectories to the right (top) and to the left (bottom). These trajectories are superimposed at the moment of lighting up a diode on the REMOBI device. The lighting up of the target is indicated in this figure by the horizontal lines placed at 20 degrees to the left, 20 degrees to the right.

[0146] [Fig.8] illustrates vergence type trajectories: convergences (top), divergences (bottom). These trajectories are superimposed at the moment of lighting of a diode on the REMOBI device. The lighting of the target is indicated in this figure by the horizontal lines placed at 9 degrees (convergence) and -6.5 degrees (divergence). Remember that the fixation diode is 40 cm from the person's eyes, for which the required vergence angle is 9 degrees; the convergence target is 20 cm from the eyes for which the required convergence angle is 18 degrees; the amplitude of the required convergence movement is therefore 8 degrees. The divergence target is 150 cm away or the required vergence angle is 3.5 degrees. The amplitude of the required divergence movement is therefore 6.5 degrees.

[0147] In the case of the reading test, saccades are treated in the same way as saccades obtained after stimulation using the binocular motor stimulation device. The only difference is that latency is not measurable since there is no target signal and it is the reader himself who decides when to trigger the next saccade. On the other hand, the fixation duration is measured, namely the duration between saccades. Reading speed is also measured, namely the number of words read per minute. We distinguish between saccades to the right, progression saccades, saccades to the left on the same line (regression saccades) and large saccades to the left returning to the next line.

[0148] [Fig.9] illustrates the regular path of the eyes of a reader who does not suffer from any pathology. In this figure, on the abscissa x we ​​have the time; on the y the conjugate signal of the two eyes in degrees, showing the succession of saccades towards the right followed by fixations fixing the words one after the other, then the large saccade to the left to begin reading the next line

[0149] [Fig. 10] illustrates a complete assessment of a dyspraxic person. Trajectories of saccades and superimposed vergences tested in a standing vs. sitting position.

[0150] For the saccade test, the upper traces are the right saccades acquired in the saccade test; the lower traces are the left saccades acquired in the same test. For the vergence test, the upper traces are the convergences and the lower traces the divergences. Since these tests are carried out in a standing or sitting position, we can see some differences related to the positioning of the body interacting with the traces of the eye movements.

[0151] In the middle are illustrated saccades and fixations when reading four lines of text (left) or one line (right). The blue trace is the horizontal conjugate signal (left eye + right eye / 2). Saccades are the vertical lines and fixations are the horizontal lines. The large vertical lines are the large saccades to the left to fixate the next line of text. The signal with the lowest amplitude is the disconjugation or vergence (left eye - right eye). The peaks of this signal show that at the beginning of each saccade the vergence changes and then towards the end of the saccade it returns to its initial angle. The disconjugation peaks are increased during large saccades.

[0152] Display (called EYESCANART)

[0153] As a complement, the method comprises a step of displaying (step E9) an image of the stimulation device on which the trajectories of the eye movement are represented.

[0154] For example, the image of the REMOBI device can represent the superposition of the trajectories of the eyes following the diodes lit according to the saccade or vergence test. Represent the trajectories either in the space of the REMOBI or as a function of time.

[0155] For example, we can represent the text read by superimposing the trajectory followed by the eyes.

[0156] For example, the displayed image can be represented by superimposing the trajectory followed by the eyes on this image. [Fig.11a] illustrates such a display and [Fig. 11b] illustrates the trajectory followed by the eye movement. It is this trajectory which is transposed onto the image used as stimulation. The color of the tracings changes according to time every 5 seconds (blue, orange, green, red, purple, brown), the operator can also produce several images separately by choosing the number of temporal segmentations desired, e.g. one image every 5 seconds or more).

Claims

Claims

1. Method for processing data representative of the binocular motor skills of a person, the method comprising the following steps: - stimulation (El) of the binocular motor skills of a person by means of a device (21) for stimulating binocular motor skills configured to specifically stimulate saccades, vergences or a combination of both or a text or image reading test (22); - acquisition (E2) during said stimulation of the movement of the right eye (OD) and the left eye (OG) of a person (P) and, where appropriate, of a stimulation signal from the device for stimulating binocular motor skills; the method comprising the following steps implemented in a processing unit (3);- determination (E6) from the movement of the left eye (OG) and the right eye (OD), of an effective trajectory (Tri) of the eyes in response to each stimulation, an effective trajectory corresponding to a saccade and / or a vergence movement of the eyes; - determination (E71), for each stimulation of a representative trajectory (Tr2) of the eyes; - comparison (E72) of each effective trajectory with the corresponding representative trajectory so as to eliminate the erroneous effective trajectories furthest from the representative trajectory and thus obtain retained trajectories (Tr) for each stimulation; - processing (E8) of each retained trajectory (Tr) so as to obtain saccade and / or vergence parameters, the parameters being characteristic of a possible pathology of a person.;

2. Processing method according to claim 1, in which the determination (E71) consists of processing all the effective trajectories for a given stimulation so as to obtain a trajectory representative of this stimulation.

3. Processing method according to one of the preceding claims, comprising a step of displaying (E9) an image of the stimulation device on which the trajectories of the eye movement are represented.

4. Treatment method according to one of claims 1 to 3, in which the determination of an effective trajectory (Tri) for a saccade-type stimulation consists of determining a combined signal defined by the average of the position of the left eye with the position of the right eye.

5. Treatment method according to one of the preceding claims, in which the determination of an effective trajectory (Tri) for a vergence type stimulation consists of determining a non-conjugate signal defined by the difference between the position of the left eye and the position of the right eye.

6. Processing method according to one of the preceding claims, in which the movement of the right eye (OD) and the left eye (OG) are acquired with targets presented in the 3D real space, the method comprising a step (E3') of transforming the movement of the right eye and the left eye into degrees.

7. Method according to one of the preceding claims, in which a saccade parameter (PARAM1) is the maximum speed of the saccade, the average speed.

8. Method according to one of the preceding claims, in which a saccade parameter (PARAM1) is the amplitude of a saccade, the amplitude being defined between the start of the saccade and the end of the saccade, the start of the saccade being defined by the instant for which the saccade has a speed x% higher than the maximum speed of the saccade, the end of the saccade being defined by the instant for which the saccade has a speed x% lower than the maximum speed, x being between 5 and 15.

9. Method according to one of the preceding claims, in which the device (21) for stimulating binocular motor skills is configured to subject the person to a first visual stimulus and then to subject them to a second visual stimulus located at a location different from the first visual stimulus, a saccade parameter (PARAM1) being a latency defined by the duration between the instant of activation of the second visual stimulus and the start of the trajectory of the eyes to pass from the first visual stimulus to the second visual stimulus.

10. Method according to one of the preceding claims, in which a saccade parameter (PARAM1) is the duration of the saccade defined by the duration between the end of the eye movement and the start of the eye movement.

11. Method according to one of the preceding claims, in which a saccade parameter (PARAM1) is the amplitude of the difference between the two eyes between the start of the saccade and the end of the saccade.

12. Method according to one of the preceding claims, in which a saccade parameter (PARAM1) is one of the dis- conjugation: obtained on the basis of the signal of the difference between the position of the left eye and the right eye.

13. Method according to claim 12, in which, a disconjugation parameter, is one of the following parameters: - amplitude of the disconjugation expressed in degrees of the defined saccade: amplitude of the difference between the two eyes between the start and the end of the saccade; - drift 1 expressed in degrees: amplitude of the disconjugation between the end of the saccade and up to 80 ms after the end of the saccade; - drift 2 expressed in degrees: amplitude of the disconjugation between the end of the saccade and up to 160 ms after the end of the saccade.

14. Method according to one of the preceding claims, in which a vergence parameter (PARAM2) is the amplitude of a vergence, the amplitude being defined between the start of the vergence and the end of the vergence, the start of the vergence being defined by the instant for which the vergence has a speed x% higher than the maximum speed of the vergence, the end of the vergence being defined by the instant for which the vergence has a speed x% lower than the maximum speed, x being between 5 and 15.

15. Method according to one of the preceding claims, in which the visual test consists of subjecting the person to a first visual stimulus and then subjecting them to a second visual stimulus located at a place different from the first visual stimulus, a vergence parameter (PARAM2) being a latency defined by the duration between the instant of activation of the second visual stimulus and the start of the trajectory of the eyes to pass from the first visual stimulus to the second visual stimulus.

16. Method according to one of the preceding claims, in which a vergence parameter (PARAM2) is the duration of the vergence defined by the duration between the end of the eye movement and the start of the eye movement.

17. Method according to one of the preceding claims, in which a vergence parameter (PARAM2) is the amplitude of the difference between the two eyes between the start of the vergence movement and the end of the vergence movement.

18. Method according to one of the preceding claims, in which a vergence parameter (PARAM2) is the amplitude of the vergence drift during the 80 ms or 160 ms after the end of the movement of

19. vergence. Method according to one of the preceding claims, in which a visual test is a reading test (22), the trajectories being progressive saccades to the right and / or regression saccades, i.e. returns to the previous word.

Images