Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
  • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
  • A61B3/113—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for determining or recording eye movement

Definitions

• the invention relates to a device for controlling the eye movements of a living being.
• MMHAITH Infrared television recording and measurement of ocular behavior in the human in ant
• American Psychologist, 1969, 24, 279-283 concerning the illumination of the eye in infrared light
• J. MERCHANT and R. MORISETTE Remote measurement of eye direction allowing subject motion over one cubic foot of space
• IEEE Transactions on Biomedical Engineering, 1974, 2, 79-95 concerning the principle known as "bright pupil” .
• a person skilled in the art has therefore developed a device operating on the principle set out above, in order to follow the ocular movements of an eye, then to analyze them.
• the eye of a living being who sits on a suitable support, is illuminated by a parallel infrared light beam, and observes a stimulation image displayed by a video monitor connected to management means such as a microcomputer.
• management means such as a microcomputer.
• the image displayed allows you to test part of the eye activity of the eye, for the specific problems that we want to study.
• the beam of infrared light reflected on the eye then contains information concerning the direction of fixation of the eye. It is detected by a camera whose optical axis coincides with the axis of the reflected infrared parallel light beam, which camera delivers images of the eye which are digitized by an electronic video card and then stored in a memory. management resources.
• calculation processing means calculate the coordinates of the center of the corneal point with reference to the coordinates of the center of the pupil.
• the object of the present invention is to improve the situation, by providing solutions to these problems.
• a first object of the invention is to allow the automated and rapid positioning of the eyes of the living being examined, in the examination position, without external assistance.
• a second object of the invention is to authorize the study of both eyes simultaneously.
• a third object of the invention is to make available, in the same device, and in a fully automated form, all of the known visual examinations.
• a fourth object of the invention is to allow the processing and analysis of the data of a visual examination, in real time and simultaneously for both eyes, and to consequently supply an examination report authorizing the a series of other visual examinations, if necessary.
• a fifth object of the invention is to authorize the optimization of the examination parameters as a function in particular of the age of the subject, and this regardless of his age.
• the calculation processing means are capable of calculating, upon receipt of a digitized image, the positions of the center of the pupil and its outline with reference to a template. They also control the step-by-step movement of the support, in order to optimally position at least one eye in the axis of a camera, as a function of a comparison between the positions of the outline of the pupil and those of the template.
• Said processing means are capable of interrupting the movement of the support, on which the living being examined is located, when the outline of the pupil is entirely contained in the template.
• the mass memory is capable of storing data relating to a plurality of basic visual examinations of variable parameters, and of tests for adjusting the positioning of the eye, each consisting of a selected suite of visual stimulation images.
• the processing means carry out an adjustment test, called “calibration”, to calculate a correction factor, specific to each eye, on a correspondence coordinated with the corneal point / direction of fixation performed for each image of the eye acquired by the camera. They then correct each response of the eye to a stimulation image according to the correction factor.
• the processing means further comprise means for recording and analyzing the voice of the living being, as well as a time delay for measuring, if necessary, the time taken by said be alive to respond vocally to an image of stimulation.
• the support also comprises means for connecting a helmet provided with electrodes to the processing means, which electrodes collect- slow electrical signals emitted by retinal cells of the living being towards the occipital lobes of his brain, following the observation, by at least one eye, of a stimulation image.
• the electrical signals are then correlated to the stimulation images by the processing means.
• the device comprises two calibrated infrared light sources and two charge transfer cameras.
• Each infrared light source is capable of delivering a reference light beam intended to be reflected on an eye of the living being, then detected by the camera whose axis is coincident with the axis of the reference light beam, which camera provides images of the eye.
• the processing means are able to process, in parallel, and in real time, the images of the eyes provided by the two cameras, and to associate a direction of fixation, for each eye, with a stimulation image. .
• FIG. 4 schematically illustrates the elements of the device allowing the acquisition of the images of the eye, as well as the optical paths of the different light beams;
• Figure 5 shows schematically the coding, in the form of a logic voltage threshold, of a digitized eye image;
• FIG. 6 shows the image of the eye displayed by the master video monitor after processing, as well as an example of coding on 16 bits of information relating to this image of the eye;
• FIG. 7 shows the grid used during the calibration procedure to make a correction in real time of the position of the corneal point
• FIG. 8 shows the grid used during the calibration procedure, to make a delayed-time correction of the position of the corneal point
• FIG. 10 is a screenshot of the parameter sheet of a given exam
• FIG. 11 shows three copies of screens corresponding to stimulation images displayed on the slave video monitor, and each belonging to a given examination;
• FIG. 12 is a double graph of the evolution of the coordinates of the corneal point over time
• FIG. 13 shows schematically the processing, in real time, by the device, of the data of an examination
• FIG. 14 shows schematically the processing, in deferred time, by the device, of the data of an examination.
• the purpose of the device is to automatically examine the eye movements of a living being, which requires precise positioning.
• the device consists of two separate but connected parts.
• the first part comprises a support 12 intended to receive, in a preferably seated position, a living being. This part will be described later.
• the second part comprises, housed in a frame 1, elements intended either to ensure the management of the device and the visual examinations which it offers, or to process the data delivered by these visual examinations.
• a microcomputer 2 provided with a mass memory 3, capable of storing data relating to all the basic visual examinations offered by the device, as well as adjustment tests.
• This microcomputer is further connected, on the one hand, to a master video monitor 4, authorizing the display of images and information concerning the management of examinations and, on the other hand, to a microprocessor 5, by a first bus 6 preferably chosen according to ISA or CENTRONIX standards.
• the microprocessor 5 is able to process the data delivered by an examination. It is also connected to a first electronic input / output control card 7, thanks to a second input / output bus 8.
• This control card 7 allows the microprocessor 5 to interact with all of the elements constituting the device according to the invention.
• This control card 7 is also connected in parallel to a second electronic video image digitization card 9, a slave video monitor 10, an electrical power regulation unit 11, and the support 12 for being alive. .
• Each visual examination consists of a succession of so-called stimulation images intended to be displayed on the screen of the slave video monitor 10.
• the digitization card 9 is also connected to two infrared charge transfer cameras (CCD for Coupled Charge Device) 13-1 and 13-2. Its function is to digitize the images of the eyes of the living being examined, acquired by the two cameras 13-1 and 13-2.
• CCD Coupled Charge Device
• control unit 11 is further connected to three light sources, including two infrared 14-1 and 14-2 each delivering a reference light beam at 950 nanometers, each intended to illuminate an eye 30-i of the living being examined, and a cold source 15 of neon type intended to illuminate the whole of the room in which the device is installed.
• This source 15 is adjustable in intensity by the microcomputer 2.
• the box 11 is also connected to the support 12.
• control card 7 is also connected to a photodiode 16 to measure the ambient infrared radiation, a rangefinder 17, the diode 18 of which emits at 500 nanometers, to measure the distance between the living being placed on the support, the device, as well as three sensors 18-1 to 18-3 for controlling the position of the support 12 in the three directions (X, Y, Z) defining the space, and a monitoring unit 19 for monitoring the all of the elements described above.
• FIG. 3 describes in detail the first part of the device, and in particular the support 12.
• This is the only element of the device not integrated into the frame 1. It comprises on the one hand a backrest 20 in which is housed a connection box 21 intended to connect a headset 22 provided with electrodes 23, to the electronic card for controlling the inputs / outputs 7.
• D on the other hand, it comprises a plate 24 connected to the backrest 20, and resting on a first displacement unit 25-1 allowing its translation parallel to the ground (axis X).
• This first control box 25-1 is fixed to the end of a leg 26, which is also fixed to a second displacement box 25-2 allowing its translation along a vertical support axis 27 (perpendicular Z axis to the X axis).
• This axis 27 is fixed on a third displacement housing 25-3 allowing the translation of the support on the ground 28, in a direction Y perpendicular to the directions X and Z.
• connection of the support 12 with the power regulation unit 11 allows the latter to manage the positioning speed of said support 12. Two speeds are provided, a fast and a slow.
• Each displacement unit 25 consists of a stepping motor, and an endless screw provided with stops. They are also connected respectively to one of the position sensors 18-1 to 18-3, which supply the microprocessor 5 with data relating to the position of the support 12 relative to the stops of the displacement boxes 25.
• the support 12 is able to be positioned very precisely in the three directions of space, so that the eyes of the living being seated on the support 12 are optimally placed in the examination position in a eye area 29.
• FIG. 4 describes the device making it possible to route the light beams up to the eye area 29, which defines two sub-areas 29-1 and 29-2 intended to materialize the respective location of the left eye 30-1 and that of the right eye 30-2.
• two infrared light sources 14-1 and 14-2 are provided, each consisting of eight light-emitting diodes, emitting a light beam at 950 nanometers.
• Each beam is treated on its own channel, the two channels being made up of identical elements.
• a source S delivers a beam of infrared light towards a first lens 31-1 which focuses it on a diffuser 32-1, which gives it a diameter of about 10 centimeters.
• the beam thus diffused is diaphragmed 33-1 then transformed into a parallel beam by a second lens 34-1.
• the parallel beam can then be filtered by filters 35-1 and 36-1 in order to eliminate the spectral components respectively less than 900 nanometers and greater than 1200 nanometers, which can be dangerous for the eye.
• the beam thus treated 37-1 is reflected by a first semi-transparent mirror 38-1, which is oriented so that said beam 37-1 arrives in the sub-area for the eye 29-1 corresponding to it.
• the eye 30-1 Before reflecting on the eye 30-1, it passes through a second semi-transparent mirror 39, common to the two channels, which is oriented so that the slave video monitor 10 can transmit, exactly in the axis of the beam processed from reference 37-1 and of the camera 13-1, the stimulation image which it displays on its screen at the level of the zone for eyes 29.
• the treated beam 37-1 is then reflected on the stimulated eye 29-1 by the stimulation image, and is responsible for information concerning said stimulated eye 29-1.
• the beam containing information 47-1 departs in the direction strictly opposite to the treated reference beam 37-1, crosses the two semi-transparent mirrors 39 and 38-1 then arrives at the camera 13-1 which is exactly in the axis of the beam 40-1, which allows it to acquire at least one image of the 29-1 eye stimulated.
• the acquired images are then digitized by the digitization card 9 and then processed by the microprocessor 5.
• the latter then transmits to the master video monitor 4 the images of the two stimulated eyes, with reference to templates 41-1 and 41-2 stored in mass memory 3.
• Each image of the eye acquired by a camera 13-i consists of an image of the pupil 41-i and a corneal point 42-i, according to the now well-known principle of corneal reflection.
• the images delivered by the 13-i camera include all the gray levels between white and black.
• the images thus digitized are filtered by the microprocessor 5, so as to keep only three levels (at least) unambiguously interpretable, and characterized by their own voltage, as shown diagrammatically in FIG. 5: the white bright (1 volt) for the corneal point 42-i, light gray (0.5 volt) for the pupil 41-i and black (0 volt) for the rest of the field.
• the microprocessor 5 can then determine the positions of the contour of the pupil 41-i, which it compares to those of the template 40-i stored in the mass memory 3. When the contour of the pupil 41-i is entirely contained in the template 40-i, the eye 30-i is considered by the microprocessor 5 as being in the examination position, in the sub-area for eyes 29-i.
• This template 40-i is chosen so that the image of the eye remains included therein despite head movements of ⁇ 15 °.
• Said microprocessor 5 can then calculate the positions of the centers of the pupil 41-i and of the corneal point 42-i, then reference the center of the corneal point 42-i relative to the center of the pupil 41-i previously calculated.
• the image is then retained for further processing if it meets the following requirements: horizontal and vertical diameter of the pupil 41-i sufficiently large, and corneal point 42-i of correct shape.
• the XP and YP coordinates of the center of the pupil are determined over all of the horizontal and vertical lines inscribable in the pupil, by averaging the X and Y coordinates of the midpoints of the respectively horizontal lines. and vertical. An identical calculation is carried out for the coordinates XS, YS of the center of the corneal point 42-i.
• a value is assigned to XV and YV, according to predefined criteria, when XP and YP, or XS and YS cannot be calculated, to preserve the possibility of an analysis of the causes of unsatisfactory results. Knowing the coordinates of a corneal point 42-i with reference to those of the center of the pupil 41-i must be perfectly accurate if one wishes to know precisely the direction of gaze fixation and correlate it to a stimulation image. However, AMSLATER and J.
• FINDLAY have shown ("The corneal reflexion technique and the visual preference method: sources of error", Journal of experimental Child Psychology, 1975, 20, 240-247) that by systematically reporting the position of the corneal point 42-i to that of the center of the pupil 41-i, whatever the direction of the gaze, an error is made due to the exact non-coincidence of the center of rotation of the eye 30-i and the center of the corneal diopter.
• A.BULLINGER and JLKAUFMANN showed ("Technique of recording and analysis of ocular movements", Perception, 1977, 6, 345-353) that the error made was all the more important that the direction of the gaze moved away from the central point of the eye 30-i. However, they demonstrated that this problem could be solved by performing a calibration on a limited number of test points.
• This calibration is carried out before starting a basic visual examination, then restarted before any new examination to eliminate the risk of significant movements of the head between examinations. It is performed for both eyes simultaneously.
• the objective of the calibration is to calculate a correction factor on the preliminary reading of the coordinates of the corneal point 42-i.
• the calibration procedure used by the device is carried out by means of a positioning adjustment test stored in the mass memory 3. It consists of presenting successively to the living being, on the slave monitor 10, five stimulation images generally, or only two in the case of a newborn, to lighten the calibration phase in the latter case. On each image is placed a single point of reference, the five points materializing the center and the four corners of a grid limiting a visual field of ⁇ 15 °. Each image remains displayed on the screen of the slave video monitor 10 for one second.
• Two levels of correction are authorized depending on whether the analysis of the visual examination is carried out in real time or in deferred time.
• the real-time correction refers to the diagram in Figure 7, where the calibration grid is a square materialized by a grid (X, Y) of step 5 e . Two vectors V0 and VI are also shown.
• V0 (VOx, VOy) is the vector obtained when the living being fixes the central point.
• VI (Vlx, Vly) is the vector obtained when the living being fixes any point on the screen of the slave monitor 10.
• the correction in deferred time refers to FIG. 8, which is valid for the right eye 30-2.
• the objective of this second correction is to provide a very precise correction factor when reprocessing archived data, either in mass memory 3, or on a magnetic tape or a removable floppy disk, and without the constraint of the time of appearance of an image (of the order of 40 milliseconds).
• V'ix ⁇ Vlx ⁇ VOx
• the position of the gaze in Y is a function of the two directions X and Y, as indicated below.
• Vx Vlx - VOx
• Vy Vly - VOy, the ordinate of a point E with coordinates (Ex, Ey) belonging to the line d corresponding to the abscissa of V is given by:
• the calibration of the left eye 30-1 is obtained by using the symmetry of the trapezoid of FIG. 6, relative to the vertical axis AB.
• the operator installs the living being on the support 12, which has been automatically positioned in a reference position at the end of the previous examination. Then, he settles on his seat 43 and begins to dialogue with the microcomputer 2 thanks to a keyboard with keys 44.
• the management of the device is carried out under "Windows" environment. This environment was chosen for its user-friendliness and for its widespread use. However, under Windows, it is not yet possible to work in timeshare, or multitasking, on 32 bits. However, the device is designed for real-time processing of the images of the eyes 30 acquired via the cameras 13.
• the Applicant has chosen a microcomputer 2, PC compatible, provided with an i486DX processor operating at least at 33MHz, and assisted by a microprocessor 5, at least to ensure the calculation part.
• This microprocessor 5 will for example be that manufactured by the company SIEMENS under the reference No. 166.
• the Applicant has chosen to couple the digitization card 9 to a VESA BUS type memory bus interface.
• the device informed of the start of the examination energizes its elements.
• the two infrared light sources 14-1 and 14-2 then each deliver a reference light beam, which is processed by the optical elements described above, then reflected towards a sub-area for the eye 29-i , by the semi-transparent mirror 38-i associated with its optical path.
• the screen of the master video monitor 4 then delivers two images each composed of a template 40-i and an image acquired by one of the cameras 13-i, which image does not represent the eye 30-i, if the living being is not in an optimal position for examination.
• the operator controls the vertical positioning of the support, which is done by means of the displacement unit 25-2, so that the images of the eyes 30 provided by the cameras 13 appear at least in part at 'interior of the two templates 40.
• the microcomputer 2 gives the order to the microprocessor 5 to perform the comparai ⁇ sound between the positions of the contour of the two pupils 41-1 and 41-2 and those of the two templates 40-1 and 40-2 respectively. If the contours are fully included in the templates 40, the eyes 30 of the living being are in an optimal position and the examination can begin. On the other hand, if this is not the case, the microprocessor 5 calculates by how many steps it will have to move each displacement unit 25-i so that the two eyes 30 are facing the eye areas 29. In the event of If this fails, this comparison procedure begins again. If necessary, the microcomputer 2 uses the range finder 17 to know precisely the distance between the eyes 30 of the living being and said device.
• the microcomputer 2 controls the photodiode 16 to measure the infrared light intensity reflected on the face of the living being.
• the photodiode 16 is connected to an electronic circuit which can trigger an alarm at the level of the master video monitor 4, if a chosen intensity threshold is exceeded. If this threshold is exceeded, the microcomputer 2 is able to command the control unit 11 to adjust the intensity of the infrared light sources 14, so that this intensity is less than said threshold.
• the microcomputer 2 controls the calibration procedure described above, then offers the operator on the screen of the master video monitor 4 a choice of basic visual examinations from which the operator can select an adapted examination. to the living being examined.
• These examinations constitute a database which can be supplemented later by loading a floppy disk, or a magnetic tape, into the microcomputer 2, which is provided for this purpose with at least three slots on the front allowing accept a 5 inch floppy disk, a 3.5 inch, or 5 inch hard drive, and a 3.5 inch external format magnetic cartridge reader / writer.
• the device provided with its database, managed under Windows environment, therefore allows the selection by icon bars of a particular examination adapted to the living being examined, which that it is, since each exam is configured.
• the microcomputer 2 displays on the screen of the master video monitor 4 the menu presenting the adjustable parameters of said visual examination.
• An example of a menu for adjusting the parameters of a given examination is shown in the screenshot of FIG. 10.
• the size of the objects to be displayed on the screen of the slave video monitor 10 will be adjusted, as well as their speed and their direction of travel.
• Three stimulation images, extracted from basic visual examinations, intended to test the peripheral detection of the eyes, are given by way of example in FIG. 11.
• the library of visual examinations which constitutes the database, offers the following examinations:
• the proposed examinations can be classified into three groups of methods, which relate to visual activity or oculomotility.
• the first group concerns behavioral methods. Many of them have already been automated, but for the study of a single eye, which prohibits binocular examinations. They mainly include the preferential gaze technique, which is particularly suitable for children under the age of four, and the so-called visual target tracking technique. These two techniques are obviously proposed by the device in monocular or binocular examination.
• the second group concerns the subjective methods, which call for an active collaboration of the living being examined. In children, they are generally usable after 30 months. These methods are not subject to automation, since they generally require either a voice response or a manual indication on a twin image of that displayed on the slave video monitor 10.
• the device is provided with a voice module composed of a voice recorder 45 coupled to an electronic voice synthesis card 46 which can recognize a certain number of keywords with reference to the stimulation images displayed on the screen of the slave video monitor 10. Furthermore, the device is able to measure the reaction time, called "integration time", which elapses between the display of a stimulation image and a voice response emitted by the being alive examined following the observation of said image.
• integration time the reaction time
• the operator asks the living being examined to read aloud the characters displayed on the screen of the slave monitor 10.
• the voice module will transcribe the words or letters sent by the living being examined, and compare them to the content of the displayed image.
• the analysis of the examination is carried out character after character, image of stimulation after image of stimulation, by a true / false comparison. Depending on the examination parameters chosen by the operator and the number of correct answers, the microcomputer 2 then assigns an examination mark.
• the third group concerns objective methods. They bring together the techniques of visual evoked potential (EPI) and the electroretinogram.
• the visual evoked potential is an electrical cortex response to light stimulation.
• the excitation of the retinal cells causes a discharge of action potentials, which are transmitted through the optical pathways to the occipital cortex of the living being examined.
• These signals are then collected by the electrodes 23 placed on the scalp, facing the two occipital lobes.
• the electrodes 23 are fixed inside the adjustable helmet 22, and connected to the connection box 21 housed in the backrest 20 of the support 12.
• the connection box is also connected to an acquisition circuit. and digital processing of complex analog signals of low amplitude, which circuit is coupled to a library of mathematical programs, such as Fourier transforms, stored in mass memory 3.
• the device will only provide a statement of brain activity induced by stimulation images, and not an analysis of brain activity. This, as well as the report, must be made at the end of the examination by the operator.
• the visual evoked potential is a low voltag signal masked by the electroencephalogram, which constitutes background noise. It is therefore necessary to extract the signal of the visual evocation potential from this background noise.
• the electroretinogram represents the potential for overall activity of the retinal tissues induced by light stimulation. This technique requires prior pupil dilation as well as corneal anesthesia. As with visual evoked potential techniques, the living being examined is equipped with a helmet 22 provided with electrodes 23. The stimulation is carried out using a specific display. of stimulation images on the screen of the slave video monitor 10. This makes it possible to obtain stimulation in full field which uniformly illuminates the retina.
• the microcomputer 2 controls the display, on the screen of the slave video monitor 10, of the first image of stimulation of said examination.
• the camera or cameras 13-i have the time to acquire several images of the eye or eyes 30-i examined.
• the procedure for acquiring each image and calculating the coordinates of the associated corneal point 42-i, with reference to the center of the pupil 41-i, have been described previously. It then remains at the microcomputer 2, in the event of real-time processing, to correct the coordinates of the corneal points 42-i with the correction factor calculated during calibration, and to deduce from these corrected coordinates the direction of fixation of the gaze, common to the images of the eye or the eyes, in order to correlate them with the stimulation image displayed.
• the procedure is repeated for all stimulation images of the visual examination carried out.
• the measured fixing directions are then grouped together on a graph, like that of FIG. 12. This makes it possible to follow, over time, the movement of the eyes 30 in the two directions X and Y defining the screen of the slave video monitor 10.
• microsaccades of gaze adjustment which can be linked to microdisplacements either of the gaze or of the living being examined, or else to the imprecision on the calculation of coordinates of the corneal point 42-i;
• the microprocessor 5 is provided with a filter which allows it to keep, for analysis, only the saccades and the fixings.
• the microprocessor 5 is able to correlate this information with the positions of the patterns of the stimulation images successively displayed.
• the microcomputer 2 is then able to deliver an account of the visual examination carried out, after weighting of the results by a coefficient depending on the examination parameters initially chosen, with reference to a correspondence table examination parameters / coefficient, stored in mass memory 3.
• This report is displayed on the screen of the master video monitor 4. It can also be printed by a printer 47 connected to the microcomputer 2, on the operator's order, which can select this option in a menu managed by the Windows environment, at the end of the exam.
• the data of the examination and the report are also stored in mass memory 3. This data can also be transferred either on diskette or on magnetic tape, after selection of options in a menu managed by the Windows environment. (Registered trademark), at the end of the exam.
• the deferred time calibration procedure will be applied directly to the coordinates of the corneal points 42-i, then data processing, identical to that performed in real time, will be done.
• the processing of data, in deferred time is automatic when the visual examination calls for eye movement monitoring coupled with vocal participation by the living being examined. This will be the case, for example, for Monoyer type exams.
• deferred processing is made compulsory because the microcomputer 2 cannot manage at the same time (less than 40 ms), both the voice synthesis, the voice response times, and the determination of the fixation directions, and correlate this information to the stimulation images.
• the operator may, depending on the results of this first examination, decide to carry out one or more other visual examinations. If he decides to carry out a second examination, he must then repeat the entire procedure described above, including the calibration, but nevertheless without affecting the positioning of the support 12.
• the device delivers at the end of the examination a report according to the examination parameters chosen by the operator at the start of said examination, in all objectivity.
• the system cannot be limited to the prevention of visual pathologies. It can be used in many situations, such as in functional exploration centers, or in occupational health centers to determine whether a given job corresponds to a given person, or even in experimental offices. tise to detect possible post-accident simulations, but also for an eye control intended for example for piloting objects in real time.

Landscapes

• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Heart & Thoracic Surgery (AREA)
• Molecular Biology (AREA)
• Biophysics (AREA)
• Ophthalmology & Optometry (AREA)
• Biomedical Technology (AREA)
• Human Computer Interaction (AREA)
• Medical Informatics (AREA)
• Physics & Mathematics (AREA)
• Surgery (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Eye Examination Apparatus (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9463406

Family Applications (1)

Country Status (4)

Cited By (5)

Families Citing this family (3)

Citations (2)

• 1994
  • 1994-05-20 FR FR9406205A patent/FR2719988B1/fr not_active Expired - Fee Related
• 1995
  • 1995-05-15 JP JP7530091A patent/JPH10500340A/ja active Pending
  • 1995-05-15 EP EP95920142A patent/EP0759722A1/de not_active Withdrawn
  • 1995-05-15 WO PCT/FR1995/000627 patent/WO1995031927A1/fr not_active Application Discontinuation

Patent Citations (2)

Non-Patent Citations (4)

Also Published As

Similar Documents

Legal Events