CN116115179A - Eye movement examination apparatus - Google Patents

Abstract

The invention discloses an eye movement checking device, which is characterized by comprising a display module; a near infrared image shooting module; an eye movement point calculation module; an average following deviation calculation module; a rapid eye movement total times calculation module; a rapid eye movement total amplitude calculation module; and a smooth following eye movement checking result judging module. The invention has the beneficial effects that: the eye movement data can be accurately recorded, and automatic data statistics and data analysis can be carried out on the eye movement inspection data, so that doctors can be helped to classify eye movement inspection results more objectively and accurately.

Description

Eye movement examination apparatus

Technical Field

The invention relates to the field of medical equipment, in particular to eye movement examination equipment based on a near infrared eye movement technology.

Background

In clinical eye movement examination, smooth follow-up eye movement (smooth pursuit eye movement, SPEM) is one of the important examination contents. Smooth following, also called smooth tracking, steady eye tracking, is a process of following the motion of a smoothly moving object with the eye's line of sight, reflecting the function of the neural conduction path of the vision tracking system.

Methods for recording eye movement data mainly include an electrode method and a near infrared video method. The electrode method is to attach several electrodes around the eyeball, when the eyeball moves, the electric field formed by the potential difference between cornea and retina changes in space phase, so as to generate cornea-retina potential, and the electrode is used to record and draw waveform, so that the trace of eyeball movement can be recorded. The near infrared video method is to shoot an image of an eye through a near infrared camera matched with a near infrared light source, and record the track of eyeball movement through analyzing the change of pupil positions. In recent years, the latter is convenient to use, and an eye movement recording method based on near infrared video is becoming a mainstream technology.

At present, analysis of smooth follow-up eye movement data remains a difficult problem. The conventional method is to simultaneously draw a motion trail graph of a target point and a motion trail graph of an eye moving point, compare the motion trail graph with the motion trail graph of the eye moving point through naked eye observation by a doctor, perform qualitative judgment according to the coincidence degree of the two trail graphs, judge that the coincidence degree is good, judge that the coincidence degree is poor, and judge that the coincidence degree is abnormal. Or further, the condition of poor anastomosis degree is qualitatively subdivided into a plurality of grades such as slight abnormality, serious abnormality and the like according to the error of the anastomosis degree. At present, the method relies on subjective experience, lacks objective and quantitative data, and can be different in judgment results of different people, so that a new doctor cannot easily master the judgment results.

Disclosure of Invention

The purpose of the invention is that: an apparatus for eye movement examination and statistical analysis of outcome data is provided.

In order to achieve the above object, the present invention provides an eye movement examination apparatus, comprising:

the display module can display a visual target, the visual target can move smoothly on the display module, the track of the movement of the visual target is controlled by a program, the position of the visual target at each moment is known, and when the eye moves for examination, the human eyes are required to follow the movement of the visual target point to look;

the near-infrared image shooting module comprises at least one near-infrared camera and at least one near-infrared light source and can continuously shoot images comprising at least one human eye;

the eye movement point calculation module can calculate the eye image shot by the near infrared image shooting module through an image processing algorithm to obtain the coordinates of the eye movement point corresponding to each frame of eye image, and each frame of eye movement point data comprises the frame of image acquisition time and the eye movement point coordinates corresponding to the frame of image;

an average following deviation calculation module for calculating an average following deviation Z; after the test is started, calculating the distance between the eye movement point coordinate and the corresponding time sighting target coordinate in each frame of eye movement point data, accumulating in the test process, obtaining a total deviation distance L after the test is finished, and setting the frame number of the total eye movement point data of the test as M, wherein Z=L/M;

the rapid eye movement total times calculating module is used for calculating the rapid eye movement total times C; after the test is started, sequentially calculating the eye movement speed of each frame of eye movement point data according to a time sequence, defining the distance between the eye movement point coordinates of the current frame of eye movement point data and the eye movement point coordinates of the N-1 frame of eye movement point data as the eye movement distance of the current frame of eye movement point data, setting delta t as the interval time between the image acquisition time of the current frame of eye movement point data and the image acquisition time of the N-1 frame of eye movement point data, and defining the eye movement speed of the current frame of eye movement point data to be equal to the eye movement distance of the current frame of eye movement point data divided by delta t; setting a speed threshold V and a distance threshold D, defining the current frame of eye movement point data as a frame of quick eye movement point data when the eye movement speed of a frame of eye movement point data is greater than V, and defining the current frame of eye movement point data as a frame of slow eye movement point data when the eye movement speed of a frame of eye movement point data is less than or equal to V; if a plurality of frames of continuous rapid eye movement point data exist between two frames of slow eye movement point data, and the sum of the eye movement distances of the rapid eye movement point data is larger than D, marking the rapid eye movement as one time, and marking the sum of the eye movement distances of the rapid eye movement point data as the amplitude of the rapid eye movement at the time; if only one frame of quick eye movement point data exists between two frames of slow eye movement point data, and the eye movement distance of the frame of quick eye movement point data is larger than D, the frame of quick eye movement point data is also recorded as one time of quick eye movement, and the eye movement distance of the frame of quick eye movement point data is recorded as the amplitude of the quick eye movement; after the test is started, the number of rapid eye movements is accumulated, and when the test is finished, the total number of rapid eye movements is obtained, which is called the total number of rapid eye movements C;

the rapid eye movement total amplitude calculation module is used for calculating a rapid eye movement total amplitude F; after the test is started, accumulating the amplitude of each rapid eye movement, and obtaining an accumulated value of the total rapid eye movement amplitude, namely the total rapid eye movement amplitude F, when the test is finished;

a smooth following eye movement checking result judging module, setting a judging threshold PZ of Z, setting a judging threshold PC of C and setting a judging threshold PF of F; when Z > PZ, or C > PC, or F > PF, it is determined that the smooth follow-up eye movement examination result is abnormal.

Preferably, the smooth movement direction of the optotype is a horizontal direction, and the movement speed is uniform along a straight line.

Preferably, the smooth movement of the optotype is in a horizontal direction, moving along a straight line, and the movement speed varies with time as a sine function.

Preferably, the smooth movement direction of the optotype is a vertical direction, and the movement speed is uniform along a straight line.

Preferably, the smooth movement direction of the optotype is a vertical direction, and the movement speed of the optotype is changed along a straight line according to a sine function along with time.

Preferably, the track of smooth movement of the optotype is square, diamond, circular or lissajous curve.

Preferably, the eye movement point coordinates in each frame of the eye movement point data are decomposed into an X component in the horizontal direction and a Y component in the vertical direction, and the optotype coordinates of the corresponding time are also decomposed into an X component in the horizontal direction and a Y component in the vertical direction; z value, C value and F value on the X component and the Y component are calculated respectively.

Preferably, the method further comprises an automatic blink filtering module capable of automatically judging blinks and filtering abnormal eye movement point data during blinks, and fitting the eye movement point data during blinks with the eye movement point data before and after blinks.

Preferably, the automatic blink filtering module calculates the size of the pupil in real time and detects whether the cornea reflection point exists or not; when the pupil area of a certain frame of image is detected to be smaller than the threshold value B compared with the pupil area of the previous frame of image, the event M1 is marked; when the disappearance of the cornea reflection point is detected, recording as an event M2; when the corneal glistening point can be re-detected, it is noted as event M3; when the pupil area recovers to be greater than the threshold B, it is noted as an event M4; when four events of M1, M2, M3, M4 occur sequentially within any consecutive 500ms, it is determined that one blink, and the time between M1 and M4 is recorded as the blink time.

Preferably, a distance threshold W is set, W > D, and if the magnitude of a certain quick eye movement is greater than D and less than or equal to W, defining the quick eye movement as a quick eye movement of a smaller magnitude; if the amplitude of a certain quick eye movement is larger than W, defining the quick eye movement as a quick eye movement with larger amplitude; the total number of the rapid eye movements with smaller amplitude and the total amplitude of the rapid eye movements with smaller amplitude are counted, and the total number of the rapid eye movements with larger amplitude and the total amplitude of the rapid eye movements with larger amplitude are counted.

Preferably, the system further comprises an auxiliary display capable of displaying the eye image, the sighting target coordinates and the eye movement point coordinates in real time.

The invention has the beneficial effects that: the eye movement data can be accurately recorded, and automatic data statistics and data analysis can be carried out on the eye movement inspection data, so that doctors can be helped to classify eye movement inspection results more objectively and accurately.

Drawings

FIG. 1 is a graph of the displacement of a optotype as a function of time (optotype trajectory graph);

FIG. 2 is an eye movement trace diagram of subject A;

FIG. 3 is a diagram of the eye movement trace of subject B;

FIG. 4 is a diagram of eye movement trajectories of subject C;

FIG. 5 is a view of the eye movement trace of a subject's t;

FIG. 6 is a diagram of a subject's eye movement trajectory;

FIG. 7 is a view of the eye movement trace of the subject;

fig. 8 is an eye movement trace diagram of the subject's heptyl.

Detailed Description

The invention will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. Further, it is understood that various changes and modifications may be made by those skilled in the art after reading the teachings of the present invention, and such equivalents are intended to fall within the scope of the claims appended hereto.

The embodiment discloses an eye movement checking device, which comprises a display module, a near infrared image shooting module, an eye movement point calculating module, an average following deviation calculating module, a rapid eye movement total times calculating module, a rapid eye movement total amplitude calculating module and a smooth following eye movement checking result judging module. The system also comprises an electronic computer, wherein the eye movement point calculating module, the average following deviation calculating module, the rapid eye movement total times calculating module, the rapid eye movement total amplitude calculating module and the smooth following eye movement checking result judging module are programs running on the electronic computer. In this embodiment, the display module is a display connected to the electronic computer, and can display the smoothly moving optotype for the examinee to watch. In addition, the embodiment also comprises an auxiliary display which can display the eye image, the sighting target coordinate, the eye movement point coordinate, the statistical analysis of the eye movement checking data and other information of the checked person in real time, so that doctors can check the eye movement checking process and result in real time.

In this embodiment, the near infrared image shooting module includes 1 near infrared camera and 2 near infrared light sources, the 2 near infrared light sources are located at two sides of the near infrared camera, the near infrared camera and the near infrared light sources are placed in the casing and located below the display module, and the near infrared camera is connected with the electronic computer through a USB data line. The eye movement point calculation module is a program running on an electronic computer, and can perform real-time image processing on the eye image shot by the near infrared image shooting module and calculate the eye movement point coordinates in real time. In this embodiment, the near infrared camera in the near infrared image capturing module is configured to capture 100 frames of eye images every second, that is, capture one frame of eye image every 10ms, and accordingly, the eye movement point calculating module calculates the eye movement point coordinates once every 10ms in real time, and the calculated eye movement point coordinates can be displayed on the auxiliary display for the doctor in real time, and meanwhile, the calculated eye movement point coordinates are stored in the database of the computer, so that statistical analysis is facilitated.

In this embodiment, a head fixing support is used to fix the head of the subject during the eye movement examination, so as to obtain a more accurate eye movement point calculation result.

According to different application occasions, only a single-eye image can be shot and eye movement points of the single eye can be calculated, and also double-eye images can be shot and eye movement points of the double eyes can be calculated. The present embodiment is to take images of both eyes and calculate eye movement points of both eyes, and take the average coordinates of the eye movement points of both eyes as eye movement point coordinates.

The basic principle of the image processing algorithm used by the eye movement point calculation module in this embodiment is as follows: because the brightness of the cornea reflecting points shot by the near infrared camera is high, the gray level can reach 255, and the two cornea reflecting points are arranged in pairs and are close to each other. According to the characteristic, the image areas where the left eye and the right eye are located can be found from the whole image shot by the near infrared camera. Setting a gray threshold value higher than the gray level of the pupil and lower than the gray level of surrounding iris and skin areas, wherein the area lower than the gray threshold value is marked as a possible pupil area; then, an area threshold value for eliminating the interference of smaller black objects such as eyelashes is set, so that the accurate area where the pupil is determined. Obtaining coordinates of the left eye pupil center according to the center of the left eye pupil area; and obtaining the central coordinates of the reflecting points of the cornea of the left eye according to the average coordinates of the central coordinates of the two reflecting points of the cornea of the left eye. And subtracting the central coordinate of the reflecting point of the left cornea from the central coordinate of the pupil of the left eye to obtain the pupil cornea vector of the left eye. And the pupil center coordinates of the right eye, the center coordinates of the reflection points of the cornea of the right eye and the pupil cornea vectors of the right eye can be obtained by the same method.

The pupil cornea vector of the left eye of the subject has a one-to-one correspondence with the left eye movement point coordinates on the display, which is called a left eye mapping function; the pupil cornea vector of the right eye has a one-to-one correspondence with the right eye movement point coordinates on the display, which is called a right eye mapping function.

The present embodiment uses 9-point calibration, with the calibration points displayed at 9 points in the center, left, right, up, down, up left, up right, down left, down right of the display, respectively, the positions of the 9 points being known and determined. After the left eye and the right eye are respectively calibrated, a left eye mapping function and a right eye mapping function are obtained. The eye movement point calculation module substitutes a left eye mapping function according to the left eye pupil cornea vector, so that eye movement point coordinates of the left eye can be calculated; and substituting the pupil cornea vector of the right eye into the right eye mapping function to calculate the eye movement point coordinates of the right eye. In this embodiment, the coordinates of the eye movement point are in terms of viewing angle (degrees) with the midpoint of the display as the origin (0, 0), the right side in the horizontal direction as the forward direction of the X axis, and the upward direction in the vertical direction as the forward direction of the Y axis. In other embodiments, the viewing angle may also be scaled to pixels or units of length on the display when the distance between the display and the human eye is known.

In other embodiments, a binocular camera system may be used in the near infrared image capturing module, and the eye movement point calculating module calculates a three-dimensional visual axis through single-point calibration according to a double-sided vision principle, and then calculates an intersection point of the visual axis and a display plane to obtain eye movement point coordinates. The near infrared image shooting module can also select a device with smaller volume to be integrated into the head-mounted equipment.

The detailed procedure for eye movement examination is as follows:

the subject sits in front of the eye movement examination apparatus, places the chin on the head fixing support and the eyes face the display. The near infrared image shooting module is located right below the display. The subject's eyes are 60 cm from the display. The near infrared camera in the near infrared image capturing module is arranged to capture 100 frames of eye images per second, i.e. one frame of eye image per 10ms interval. After the 9-point calibration is finished, the eye movement point calculation module calculates the eye image shot by the near infrared image shooting module through an image processing algorithm to obtain the coordinates of the eye movement point corresponding to each frame of eye image, and each frame of eye movement point data comprises the frame of image acquisition time and the eye movement point coordinates corresponding to the frame of image.

After the test is started, the computer controls the sighting mark on the display to move smoothly, and the smooth moving track is continuous and has no break. The doctor can ask the subject to follow the optotype all the time through the instruction. In this embodiment, the optotype is a black dot. In other embodiments, the optotype may also be a vivid animation, such as a flying butterfly, for infants with difficulty in focusing. In this embodiment, the optotype is first displayed from the midpoint of the display screen, then moves at a constant speed of 8 °/s in the horizontal direction to the right, moves at a constant speed of 8 °/s in the horizontal direction to the left when moving to 10 ° to the right, moves at a constant speed of 8 °/s in the horizontal direction to the right when moving to 10 ° to the left, returns to the midpoint in one cycle, and the time of each cycle is 5 seconds. After 20 seconds, i.e. after the smooth movement of 4 cycles in the horizontal direction, the optotype stops moving and the test ends. The time is taken as the X axis (unit: ms), the displacement of the horizontal movement of the optotype is taken as the Y axis (the middle is 0 point, the right is positive, the left is negative, the unit is the visual angle degree), and a function image of the displacement of the optotype changing along with the time, namely an optotype track diagram, is obtained, and is a triangle wave changing along with the time as shown in fig. 1.

(III) calculating and displaying the eye movement track

In this embodiment, the total movement time of the cursor is 20 seconds, and one eye movement point coordinate can be obtained at intervals of 10ms, and 20000 eye movement point coordinates can be obtained in 20 seconds. Taking the intuitiveness of the eye movement track graph display into consideration, taking time as an X axis, taking the horizontal component of the eye movement point coordinates as a Y axis value, and connecting the horizontal component values of the 20000 eye movement point coordinates to obtain a function image of the horizontal component of the eye movement point coordinates changing along with time, namely the eye movement track graph of the horizontal component changing along with time. In general, when the optotype moves only in the horizontal direction, the vertical direction component of the eye movement point of the subject and the vertical direction component of the coordinate of the optotype do not differ much, and therefore when the optotype moves only in the horizontal direction, the eye movement trajectory graph in which the horizontal component of the coordinate of the eye movement point varies with time can be emphasized and analyzed. Similarly, if the horizontal direction component of the subject's eye movement point and the horizontal direction component of the coordinate of the optotype do not differ much when the optotype is moved only in the vertical direction, the eye movement locus diagram of the vertical component of the coordinate of the eye movement point with time can be emphasized and analyzed. If the optotype moves in both horizontal and vertical directions, for example, the trajectory of the optotype movement is circular, both the horizontal and vertical components of the eye movement trajectory can be displayed and analyzed simultaneously.

(IV) average following deviation calculation

The average following deviation calculation module is a program running on a computer for calculating the average following deviation Z. After the test is started, namely after the optotype starts to move, calculating the distance between the coordinate of the eye movement point in each frame of eye movement point data and the coordinate of the optotype corresponding to the time, accumulating the distance in the test process, obtaining the total deviation distance L after the test is finished, and setting the frame number of the total eye movement point data of the test as M, wherein Z=L/M. In the present embodiment, since the test time is 20 seconds, 100 frames of eye movement point data are obtained per second, and the frame number m=20000 of the total eye movement point data.

(fifth) calculation of total times of quick eye movements

The rapid eye movement total number calculating module is a program running on a computer and is used for calculating the rapid eye movement total number C. After the test is started, sequentially calculating the eye movement speed of each frame of eye movement point data according to a time sequence, defining the eye movement point coordinates of the frame of eye movement point data and the eye movement distance of the eye movement point coordinates of the frame of eye movement point data from the 2 nd frame to the N-1 st frame of eye movement point data, setting the interval time between the image acquisition time of the frame of eye movement point data and the image acquisition time of the N-1 st frame of eye movement point data to deltat, and defining the eye movement speed of the frame of eye movement point data to be equal to the eye movement distance of the frame of eye movement point data divided by deltat, wherein deltat between every two frames is a fixed time value of 10ms in the embodiment; setting a speed threshold V and a distance threshold D, defining the frame of eye movement point data as a frame of quick eye movement point data when the eye movement speed of the frame of eye movement point data is greater than V, and defining the frame of eye movement point data as a frame of slow eye movement point data when the eye movement speed of the frame of eye movement point data is less than or equal to V; if a plurality of frames of continuous rapid eye movement point data exist between two frames of slow eye movement point data, and the sum of the eye movement distances of the eye movement point data is larger than D, marking the rapid eye movement as one time, and marking the sum of the eye movement distances of the rapid eye movement point data as the amplitude of the rapid eye movement at the time; if only one frame of quick eye movement point data exists between two frames of slow eye movement point data, and the eye movement distance of the frame of quick eye movement point data is larger than D, the quick eye movement is recorded as one time, and the eye movement distance of the frame of quick eye movement point data is recorded as the amplitude of the quick eye movement. The first frame of eye movement point data at the beginning of the test may be defined as slow eye movement point data and the last frame at the end of the test may be defined as slow eye movement point data. After the test is started, the number of rapid eye movements is accumulated, and at the end of the test, the total number of rapid eye movements is obtained, which is called the total number of rapid eye movements C.

The velocity threshold V should be set to a value greater than the maximum smooth movement velocity of the optotype point. In this embodiment, the speed at which the viewpoint moves smoothly is 8 °/sec. In view of the effects of image processing measurement noise and intrinsic fine shake of the eye itself, in general, the velocity threshold V should be set to a value greater than the maximum smooth movement velocity of the viewpoint by 10 °/sec or more to prevent erroneous judgment of noise or intrinsic fine shake of the eye itself as rapid eye movement. In the present embodiment, the speed threshold v=30°/second is taken.

The distance threshold D should be set equal to or greater than V times the image acquisition time interval. In the present embodiment, v=30°/second, and the image acquisition time interval=10 ms, so D should be set to a distance threshold value of 0.3 ° or more. The smaller the value set by D, the more likely the calculated number of rapid eye movements is; the larger the value of D is set, the less likely the calculated number of rapid eye movements will be. Considering that the small magnitude of rapid eye movements are not easily recognized by the naked eye, limited by the resolution of the display or the resolution of the printer, in this embodiment, the distance threshold d=2° is taken.

In other embodiments, if the total number of rapid eye movements is divided by the test time, the number of rapid eye movements per unit time, otherwise known as the rapid eye movement frequency, is equivalent to the total number of rapid eye movements being mutually scaleable. Similarly, if the optotype moves smoothly for a plurality of periods, the average rapid eye movement times of each period can be calculated, and the total rapid eye movement times can be converted into each other, so that the method is equivalent.

(six) fast eye movement Total amplitude calculation

The rapid eye movement total amplitude calculation module is a program running on a computer and is used for calculating the rapid eye movement total amplitude F. The amplitude of each rapid eye movement is accumulated after the test is started, and an accumulated value of the total rapid eye movement amplitude is obtained at the end of the test, which is called the total rapid eye movement amplitude.

In other embodiments, if the total rapid eye movement amplitude is divided by the test time, the total rapid eye movement amplitude per unit time can be obtained, which is equivalent to the total rapid eye movement amplitude being mutually scaleable. Similarly, if the optotype moves smoothly for a plurality of periods, the average rapid eye movement amplitude of each period can be calculated, and the total rapid eye movement amplitude and the average rapid eye movement amplitude can be mutually converted, so that the method is equivalent.

(seventh) determination of smooth follow-up eye movement examination result

The smooth following eye movement check result judging module is a program running on a computer, sets a judging threshold PZ of the average following deviation Z, sets a judging threshold PC of the total number of rapid eye movement C, and sets a judging threshold PF of the total rapid eye movement amplitude F. When Z > PZ, or C > PC, or F > PF, it is determined that the smooth follow-up eye movement examination result is abnormal. When Z.ltoreq.PZ, and C.ltoreq.PC, and F.ltoreq.PF, it is judged that the smooth follow eye movement inspection result is within the normal range.

The average tracking deviation Z reflects the average error of the subject smoothly following the eye movement point and the optotype at any time. If the Z value is large, it tends to indicate that the subject cannot follow the punctuation smoothly with greater accuracy. The value of the judgment threshold PZ of the average follow-up deviation Z is generally in the range of 0.5 ° to 2.0 °. If the smooth movement speed of the optotype is higher and the movement track of the optotype is more complex, the PZ can take a larger value; if the smooth movement speed of the optotype is slower and the movement track is simpler, the PZ can take a smaller value. In the present embodiment, PZ is set to 1.2 °.

The total number of rapid eye movements C quantitatively reflects the subject's ability to control the smooth eye movement following speed in terms of number of times. If the number is large, it may be that the subject cannot follow the punctuation smoothly with stability, and the deviation is frequent, and the eye movement trace may appear as a square wave or a step wave, which is often a toothed waveform. The judging threshold PC of the total rapid eye movement times C is related to the test time, the smooth movement speed of the sighting target, the complexity of the sighting target movement track, the speed threshold V and the distance threshold D. When the test time is T seconds, if the smooth movement speed of the optotype is slower, the movement track of the optotype is simpler, the speed threshold V is set higher, the distance threshold D is set higher, and the lowest PC can be set to be T/10 times; if the smooth movement speed of the optotype is faster, the movement track of the optotype is more complex, the speed threshold V is set lower, the distance threshold D is set lower, and the highest PC can be set to be 2T times. In the present embodiment, the PC is set to 16 (times).

The total amplitude F of the rapid eye movements quantitatively reflects the control ability of the subject to smoothly follow the eye movements in amplitude. If the value is large, it is often indicated that the subject cannot smoothly follow the punctuation more stably, and the amplitude of the deviation is large, and the eye movement track tends to have square waves or step waves with large amplitude. The judging threshold value PF of the total fast eye movement amplitude F is related to the test time, the smooth movement speed of the sighting target, the complexity of the sighting target movement track, the speed threshold value V and the distance threshold value D. When the test time is T seconds, if the smooth movement speed of the optotype is slower, the movement track of the optotype is simpler, the speed threshold V is set higher, the distance threshold D is set higher, and the lowest PF can be set to be T/5 (degrees); if the smooth movement speed of the optotype is faster, the movement track of the optotype is more complex, the speed threshold V is set lower, the distance threshold D is set lower, and the PF is set to be 6T (degrees) at the highest. In the present embodiment, the PF is set to 60 °.

In this example, eye movement test data of seven subjects, such as a, b, c, t, e, g, and g, are taken as an example:

FIG. 2 is an eye movement trace diagram of subject A;

FIG. 3 is a diagram of the eye movement trace of subject B;

FIG. 4 is a diagram of eye movement trajectories of subject C;

FIG. 5 is a view of the eye movement trace of a subject's t;

FIG. 6 is a diagram of a subject's eye movement trajectory;

FIG. 7 is a view of the eye movement trace of the subject;

fig. 8 is an eye movement trace diagram of the subject's heptyl.

Where the X-axis is time (in units of ms) and the Y-axis is the horizontal component of the eye movement point coordinates (in units of viewing angle). In order to facilitate comparison of the difference between the eye movement point coordinates and the sighting target coordinates at each moment, the sighting target track diagram is also displayed at the same time, and is triangular wave in the diagram. The smooth follow-up eye movement examination result data table of these seven subjects is shown in the following table:

	z (unit: degree)	C (unit: secondary)	F (unit: degree)
				Subject armor	0.48	0	0
Subject B	0.81	8	25.16
				Subject C	1.68	9	39.03
Subject t	0.67	21	56.41
				The subject is penta	0.89	14	68.52
Subject's dog	1.72	11	75.97
				Subject seven	2.43	25	143.10

In this embodiment, the smooth following eye movement detection result judging module judges that the smooth following eye movement detection results of the first and second subjects are within the normal range according to the judging method described above; the smooth following eye movement examination result of the third subject, the fourth subject, the fifth subject and the seventh subject is abnormal. It can also be seen from the data sheet that among subjects with abnormal smooth follow-up eye movement examination results, there are subjects with only a higher Z value (subject C), only a higher C value (subject t), only a higher F value (subject t), two of the three results (subject t Z, F) and Z, C, F (subject g). From this, it can be seen that the three inspection data of Z, C, F can more comprehensively determine whether the subject smoothly follows the eye movement inspection result.

In addition, during an eye movement examination, such as a prolonged period of time, some subjects may have one or more blinks during the test. In this embodiment, the system further includes an automatic blink filtering module, where the automatic blink filtering module is a program running on a computer, and can filter abnormal eye movement point data during blink, so as to avoid misjudging blink as quick eye movement, and avoid calculation errors of average following deviation caused by eye movement point coordinate deviation caused by blink. The specific method comprises the following steps: when blinking, the pupil of the eye is firstly partially shielded by eyelid, then is totally shielded, then is partially shielded, and finally the pupil is opened to restore the normal size. The duration of blinking is typically within 500ms, based on statistics. According to the image processing algorithm principle used by the eye movement point calculation module, when blinking is started, when two cornea reflection points of the eye are not blocked by eyelid but the pupil is partially blocked, the pupil area is reduced; then when both corneal glints are completely occluded by the eyelid, the eye movement point may not be calculated. The automatic blink filtering algorithm used in the embodiment can calculate the size of the pupil in real time. When the pupil area of a certain frame of image is detected to be smaller than a certain threshold B compared with the pupil area of a previous frame of image, for example, the pupil area is within 90% of the previous frame of image S, the pupil area is marked as an event M1; when two cornea reflection points are detected to disappear, recording as an event M2; when two corneal glints can be re-detected, it is noted as event M3; when the pupil area returns to more than 90% of S, it is noted as event M4. When four events of M1, M2, M3, M4 occur sequentially within any consecutive 500ms, it is determined that one blink, and the time between M1 and M4 is recorded as the blink time. The eye movement point data during the blinking time may disappear or be abnormal, so that linear interpolation can be performed during the blinking time according to the normal eye movement point data of the frame before and the frame after blinking, so as to fit the eye movement point data during blinking.

In this embodiment, the optotype is moved back and forth at a constant speed in the horizontal direction for 4 cycles, the speed is 8 °/s, and the movement range is ±10°. In other embodiments, the number of periods of movement, the speed of movement, the range of movement, the start and end points of movement may be set when the optotype is moving at a uniform horizontal speed. The optotype may be moved horizontally back and forth for one or several cycles or only once, for example from-10 on the left to 10 on the right.

In other embodiments, the speed at which the optotype moves smoothly in the horizontal direction may also vary as a sinusoidal function over time. For example, setting the moving speed v of the optotype as a function of time t, v (t) =asin (ωt), taking the midpoint of the display screen as the origin, and right as the forward direction, the starting position of the optotype being-a/ω (degree), and then starting to move right; the optotype moves fastest at the midpoint with the speed A; the speed of the optotype is 0 when moving to the right a/ω (degrees) and starts to move to the left; the period of the optotype movement is 2 pi/omega (seconds). The number of periods of movement of the optotype, the speed of movement, the range of movement, the start point and the end point of movement can be set. The optotype may be moved back and forth for one or several cycles or only once, for example from left-a/ω (degrees) to right-a/ω (degrees). The smooth movement direction of the optotype can also be in a straight line in the vertical direction, and the movement speed can be uniform or can be changed according to a sine function. The optotype may be moved in the vertical direction for one or several cycles or only once.

The track of smooth movement of the optotype may also be square, or diamond, or circular, or Lissajous curve (Lissajous curve). The optotype may be moved one cycle or several cycles.

In other embodiments, a distance threshold W may be set, where W > D, and if the magnitude of a fast eye movement is greater than W and less than or equal to D, define the fast eye movement as a fast eye movement with a smaller magnitude; if the amplitude of a certain quick eye movement is larger than W, defining the quick eye movement as a quick eye movement with larger amplitude; the total number of the rapid eye movements with smaller amplitude and the total amplitude of the rapid eye movements with smaller amplitude can be counted, and the total number of the rapid eye movements with larger amplitude and the total amplitude of the rapid eye movements with larger amplitude can be counted.

When eye movement examination is performed, effective eye movement time and ineffective eye movement time can be respectively counted, the ineffective eye movement time is blink time, eye closing time and time for looking at an area outside a display screen, the effective eye movement time is total test time minus the ineffective eye movement time, and if the ratio of the effective eye movement time to the total test time is lower than a certain threshold value, for example 80%, a person to be examined is considered not to be attentively matched with eye movement examination, and the person to be examined needs to be done again so as to obtain a meaningful statistical result. For subjects with low comprehension such as infants, if the subjects cannot understand the instruction words of the doctor, the subjects can first perform appropriate smooth follow-up eye movement exercises and then perform formal eye movement examination.

Claims (11)

1. An eye movement examination apparatus, comprising:

the display module can display a visual target, the visual target can move smoothly on the display module, the track of the movement of the visual target is controlled by a program, the position of the visual target at each moment is known, and when the eye moves for examination, the human eyes are required to follow the movement of the visual target point to look;

the near-infrared image shooting module comprises at least one near-infrared camera and at least one near-infrared light source and can continuously shoot images comprising at least one human eye;

the eye movement point calculation module can calculate the eye image shot by the near infrared image shooting module through an image processing algorithm to obtain the coordinates of the eye movement point corresponding to each frame of eye image, and each frame of eye movement point data comprises the frame of image acquisition time and the eye movement point coordinates corresponding to the frame of image;

an average following deviation calculation module for calculating an average following deviation Z; after the test is started, calculating the distance between the eye movement point coordinate and the corresponding time sighting target coordinate in each frame of eye movement point data, accumulating in the test process, obtaining a total deviation distance L after the test is finished, and setting the frame number of the total eye movement point data of the test as M, wherein Z=L/M;

the rapid eye movement total times calculating module is used for calculating the rapid eye movement total times C; after the test is started, sequentially calculating the eye movement speed of each frame of eye movement point data according to a time sequence, defining the distance between the eye movement point coordinates of the current frame of eye movement point data and the eye movement point coordinates of the N-1 frame of eye movement point data as the eye movement distance of the current frame of eye movement point data, setting delta t as the interval time between the image acquisition time of the current frame of eye movement point data and the image acquisition time of the N-1 frame of eye movement point data, and defining the eye movement speed of the current frame of eye movement point data to be equal to the eye movement distance of the current frame of eye movement point data divided by delta t; setting a speed threshold V and a distance threshold D, defining the current frame of eye movement point data as a frame of quick eye movement point data when the eye movement speed of a frame of eye movement point data is greater than V, and defining the current frame of eye movement point data as a frame of slow eye movement point data when the eye movement speed of a frame of eye movement point data is less than or equal to V; if a plurality of frames of continuous rapid eye movement point data exist between two frames of slow eye movement point data, and the sum of the eye movement distances of the rapid eye movement point data is larger than D, marking the rapid eye movement as one time, and marking the sum of the eye movement distances of the rapid eye movement point data as the amplitude of the rapid eye movement at the time; if only one frame of quick eye movement point data exists between two frames of slow eye movement point data, and the eye movement distance of the frame of quick eye movement point data is larger than D, the frame of quick eye movement point data is also recorded as one time of quick eye movement, and the eye movement distance of the frame of quick eye movement point data is recorded as the amplitude of the quick eye movement; after the test is started, the number of rapid eye movements is accumulated, and when the test is finished, the total number of rapid eye movements is obtained, which is called the total number of rapid eye movements C;

the rapid eye movement total amplitude calculation module is used for calculating a rapid eye movement total amplitude F; after the test is started, accumulating the amplitude of each rapid eye movement, and obtaining an accumulated value of the total rapid eye movement amplitude, namely the total rapid eye movement amplitude F, when the test is finished;

a smooth following eye movement checking result judging module, setting a judging threshold PZ of Z, setting a judging threshold PC of C and setting a judging threshold PF of F; when Z > PZ, or C > PC, or F > PF, it is determined that the smooth follow-up eye movement examination result is abnormal.

2. The eye movement checking apparatus according to claim 1, wherein the smooth moving direction of the optotype is a horizontal direction, and the moving speed is a uniform speed along a straight line.

3. The eye movement checking apparatus according to claim 1, wherein the smooth moving direction of the optotype is a horizontal direction, and moves along a straight line, and the moving speed thereof varies as a sine function with time.

4. The eye movement checking apparatus according to claim 1, wherein the smooth moving direction of the optotype is a vertical direction, and the moving speed is a uniform speed along a straight line.

5. The eye movement checking apparatus according to claim 1, wherein the smooth moving direction of the optotype is a vertical direction, and moves along a straight line, and the moving speed thereof varies as a sine function with time.

6. The eye movement examination apparatus according to claim 1, wherein the track of smooth movement of the optotype is square, diamond, circular or lissajous curve.

7. The eye movement inspection apparatus according to claim 1, wherein the eye movement point coordinates in each frame of the eye movement point data are decomposed into an X component in a horizontal direction and a Y component in a vertical direction, and the optotype coordinates of the corresponding time are also decomposed into the X component in the horizontal direction and the Y component in the vertical direction; z value, C value and F value on the X component and the Y component are calculated respectively.

8. The eye movement examination apparatus of claim 1, further comprising an automatic blink filtering module capable of automatically judging blinks and filtering out abnormal eye movement point data during blinks, fitting eye movement point data during blinks to eye movement point data before and after blinks.

9. The eye movement examination apparatus of claim 8, wherein the automatic blink filtering module calculates the size of the pupil in real time and detects the presence or absence of a corneal glint point; when the pupil area of a certain frame of image is detected to be smaller than the threshold value B compared with the pupil area of the previous frame of image, the event M1 is marked; when the disappearance of the cornea reflection point is detected, recording as an event M2; when the corneal glistening point can be re-detected, it is noted as event M3; when the pupil area recovers to be greater than the threshold B, it is noted as an event M4; when four events of M1, M2, M3, M4 occur sequentially within any consecutive 500ms, it is determined that one blink, and the time between M1 and M4 is recorded as the blink time.

10. The eye movement examination apparatus according to claim 1, wherein a distance threshold W is set, W > D, and if the magnitude of a certain quick eye movement is greater than D and less than or equal to W, the quick eye movement is defined as a quick eye movement of a smaller magnitude; if the amplitude of a certain quick eye movement is larger than W, defining the quick eye movement as a quick eye movement with larger amplitude; the total number of the rapid eye movements with smaller amplitude and the total amplitude of the rapid eye movements with smaller amplitude are counted, and the total number of the rapid eye movements with larger amplitude and the total amplitude of the rapid eye movements with larger amplitude are counted.

11. The eye movement examination apparatus according to claim 1, further comprising an auxiliary display capable of displaying the eye image, the optotype coordinates, the eye movement point coordinates in real time.

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