WO2025051943A1

WO2025051943A1 - Device and method for obtaining dynamic measurements of eye optical surfaces

Info

Publication number: WO2025051943A1
Application number: PCT/EP2024/074970
Authority: WO
Inventors: Fernando MARTÍN-PALOMINO SAHAGÚN; Rafael RAMOS DÍAZ; Darío RUIZ RODRÍGUEZ
Original assignee: Aura Innovative Robotics SL
Current assignee: Aura Innovative Robotics SL
Priority date: 2023-09-08
Filing date: 2024-09-06
Publication date: 2025-03-13
Anticipated expiration: 2026-03-08

Abstract

The invention relates to a device (1) for obtaining dynamic measurements of eye optical surfaces, characterized in that it comprises a visual stimulus generator (2), a viewer unit (9), an illumination unit (4), an imaging system (6), an optical deflection element (7) arranged between the visual stimulus generator (2) and the viewer unit (9), and a processor (8).

Description

DEVICE AND METHOD FOR OBTAINING DYNAMIC MEASUREMENTS

OF EYE OPTICAL SURFACES

FILED OF THE INVENTION

The present invention relates to the technical field of bioengineering and biomedical devices.

In particular, the invention relates to a device for measurement of eye(s) movements of a subject in order to determine possible abnormalities of a variety of disorders within and outside of the visual system, including disorders of the visual system's nerves and the nervous system. More specifically the present invention operates in the field of systems for the diagnosis of neurodegenerative pathologies based on eye-tracking technology and on the analysis of gaze movements and latencies.

BACKGROUND OF THE INVENTION

The neural pathways and brain regions involved in eye movements during ocular fixation and gaze control include the cerebrum, brainstem and cerebellum, and abnormal eye movements can indicate the presence of neurodegeneration. In some patients, oculomotor signs are key to making a diagnosis. Careful clinical examination of eye movements in patients with neurodegenerative disorders is, therefore, an invaluable adjunct to neurological and cognitive assessments. Laboratory recordings of eye movements can provide valuable information about disease severity, progression or regression in neurodegenerative disease, and hold particular promise for objective evaluation of the efficacy of putative neuroprotective and neurorestorative therapies. For example, aspects of saccade performance can be tested to probe both motor and cognitive aspects of oculomotor behavior.

Thus, the abnormality of eye movements may be a sign of an alteration of nervous system, and they have been described in diseases such as dementias (Alzheimer's, frontotemporal dementia), Parkinson's disease, parkinsonism, schizophrenia, obsessive compulsive disorder, anxiety, depression, bipolar disorder, multiple sclerosis, ataxia, ADHD (attention deficit hyperactivity disorder), autism, Tourette's syndrome, dyslexia and dizziness ("Eye movements in patients with neurodegenerative disorders". T. J. Anderson and M. R. MacAskill (2013) Nature Reviews, Neurology, pp. 1 -12; "Diagnosing Stroke in Acute Vertigo: The HINTS Family of Eye Movement Tests and the Future of the Eye EGG". D. E. Newman-Toker, I.S. Curthoys and G. M.l. Halmagyi (2015) Seminar of Neurology Vol. 35. Num 5, pp. 506-21 ; and "Ocular motor disorders" (2014) A. W. and C.J. Lueck. Current Opinion in Neurology. Vol 27, pp. 75- 82.)

In general, conventional medical systems for determination of abnormality of eye movements include one or more data storage devices storing a plurality of computer-readable instructions. The instructions are configured to be executed by one or more processors to perform a plurality of method steps which include causing at least one display device to generate a plurality of graphics configured to stimulate a voluntary or an involuntary eye function of at least one eye of a subject. The method steps also include causing at least one sensor of the device to sense an eye movement of the at least one eye relative to a starting position.

In general terms, the medical analysis data includes a plurality of benchmark parameters associated with a plurality of eye characteristic categories such as gain, latency, delay etc. The medical analysis data also includes a plurality of parameter deviation thresholds associated with a plurality of the eye characteristic categories. The examination output also includes an abnormality resource if at least one of deviations associated with one of the eye characteristic categories is greater than the parameter deviation threshold associated with the eye characteristic category. Also, the examination output includes a diagnostic resource. The diagnostic resource includes a plurality of possible diagnoses indicative of a plurality of disorders associated with one or more of the eye characteristic categories.

Therefore, there is a need for eye movement recordings useful for objective and precise identification of disease status and monitoring of disease progression, thereby enabling cognitive as well as motor impairments associated with neurodegeneration to be detected. Notably, to accurately relate eye movements with diseases of the nervous system, not only the precise positioning of the eyes but also a rapid acquisition of their movements is required.

In the state of the art, many devices can be found for measuring eye movements and to assist in the diagnosis of these diseases through analysis of data obtained. Thus, for example, in US 2013 0027665 patent application, a device for eye tracking movement is described. The device comprises an image acquisition module disposed to take a single image of both eyes and an optical means for data transmission. In the devices disclosed in this patent application, the image of both eyes is formed by combining several images of each eye, taken through several different optical paths. In addition, the camera must remain fixed and be located about 20 degrees of visual field system of the patient, in order to avoid distortion. However, it would be desirable to provide a device capable, not only of following the eye movements of both eyes, but also of following only one of them and that could be able, preferably, to follow movements of the right and left eye independently.

EP 1 088 511 , for example, describes an ophthalmologic device which has a positioning unit for orientation of the measuring unit with respect to the eye to be examined. For this purpose, a detection unit which determines the relative position of the measurement unit with respect to the eye and monitors this position during measurement is provided. The determined measurement values are stored or rejected depending on the eye position determined by the detection unit. In this way, only measurements that were recorded when the eye was accurately positioned are processed and stored. On the one hand, this approach is disadvantageous since the measurement unit of the ophthalmologic device must be roughly oriented by the user by means of a joystick at the start of the examination. On the other hand, the system is not configured to obtain dynamic measurements of the movements of an eye in response to visual stimulus for diagnosis of disorders of the nervous system.

An automatically aligning optometric measurement device and the method for its use are described in U.S. Pat. No. 6,145,990. This approach has means for projecting a light mark on the eye, means for evaluating corneal reflex images, and means for controlling the actuating drives for exact positioning of the optometric measurement device. Positioning is carried out in all three coordinate directions for the first eye and then for the second eye based on the position of two light marks relative to one another, these light marks being generated from the corneal reflex image. However, the system is not configured for analyzing the response of the eye to the display a plurality of graphics configured to stimulate a voluntary or an involuntary eye function of diagnosis of disease of the nervous system.

In order to reliably determine if the eye movements of a subject are altered or not, it is appropriate to assess the greatest number of different movements. At the same time, many of these eye movements are subtle, high speed and difficult to quantify, especially saccadic movement. Therefore, there is a need of precision instruments and automatically process of data analysis for this specific purpose.

The eye movements of people with neurological disease differ significantly from those of healthy people. In addition, eye movements among people with seemingly similar but different neurological diseases can also be different from each other. Because of the importance of accurate diagnosis of neurological diseases, a need exists for better methods of evaluating such differences. The eyes do not stay perfectly still during visual fixation. Fixational eye movements and saccadic intrusions continuously change the position of the gaze. Microsaccades are rapid, small-magnitude involuntary saccades that occur several times each second during fixation; microsaccades counteract visual fading and generate strong neural transients in the early visual system. Microsaccades may also drive perceptual flips in binocular rivalry. Microsaccade rates and directions are moreover modulated by attention, and thus generate rich spatio-temporal dynamics. Further, fixational eye movements as a whole enhance fine spatial acuity. The most common type of saccadic intrusion is referred to as a square wave jerk (SWJ). SWJs are characterized by one small horizontal saccadic movement that moves the eye away from the fixation target, followed by a corrective saccade towards the target shortly thereafter. SWJs are prevalent in some neurological diseases such as progressive supranuclear palsy (PSP). However, they are also common in normal healthy subjects and in patients with Parkinson's disease (PO). Patients with PSP and those with early stages of PO often appear to present similarly. It would be beneficial to be able to differentially diagnose one disease from the other in a non-invasive manner. Thus, it would be desirable to provide means for reducing sources of optical interference during the dynamic measurement of eye movements upon display of images to a subject, which may represent an obstacle to reliably analyze, often minor and rapid, eye responses.

US 2016/0106315 A1 discloses a system and method for use of a mobile device to capture one or more images of one or more eyes of a user in a period before, during or after conducting one or more tests involving the eyes, vision or eye movements of the user. A position, motion, pattern or other characteristic of the position motion or movement of one or more eyes may be evaluated in each of such images and comparisons of such positions, motions or movements in the various images may be made as part of a diagnostic effort for various medical conditions. US2014221869A1 discloses a method and apparatus including identifying a plurality of at least partially repetitive eye movements of a person, the eye movements defined by a first predominantly horizontal saccadic movement that moves the eye away from a fixation target followed by a corrective saccadic movement towards the target shortly thereafter, measuring a vertical component associated with the plurality of eye movements and comparing the vertical component with a predetermined threshold value. However, none of these devices provide means for stable positioning of the eyes of the subject and a precise acquisition of the eye movements for reliable diagnosis. Therefore, there is a need of devices that simplify and accelerate the examination of a subject suspected of suffering from a disease by performing a plurality of visual tests, providing an accurate determination of the dynamic positional data of an eye. Also, there is a need for devices which minimize interferences of the optical data acquisition process, thereby resulting in a significant reduction of capturing errors and improving the interpretation of acquired data for proper diagnosis.

BRIEF DESCRIPTION OF THE INVENTION

The present invention overcomes the drawbacks and problems of the state of the art by providing, in a first aspect, a device for obtaining dynamic measurements of eye optical surfaces, characterized in that it comprises: a visual stimulus generator, configured to display visual stimuli of visible light towards at least one eye optical region,

- a viewer unit for the subject viewing through it the visual stimulus generator, configured to spatially and opaquely confine the at least one eye optical region,

- an illumination unit for illuminating the at least one eye optical region, configured to illuminate with near infrared light,

- an imaging system, configured for capturing images of near infrared light,

- an optical deflection element arranged between the visual stimulus generator and the viewer unit, the optical deflection element being configured to deflect near infrared light generated by the illumination unit towards the at least one eye optical region and to deflect near infrared light reflected by the at least one eye optical region optical region towards the imaging system, and

- a processor, configured to control the display of a sequence of a plurality of visual stimuli by the visual stimulus generator, capture images of the near infrared light reflected by the at least one optical region (9a) acquired by the imaging system upon display of the plurality of visual stimuli displayed by the visual stimulus generator in a timely dependent manner, and analyze said images of the near infrared light to determine the coordinates of position, in a timely dependent manner, of the oculomotor movements of the at least one eye optical region in response to the visual stimuli displayed by the visual stimulus generator. In another aspect, the invention relates to a method for obtaining dynamic measurements of eye optical surfaces, characterized in that it comprises the steps of: displaying, by means of a visual stimulus generator, a sequence of a plurality of visual stimulus of visible light towards at least one optical region spatially and opaquely confined in a viewer unit, illuminating the at least one eye optical region by means of an illumination unit configured to illuminate with near infrared light, deflecting, by means of an optical deflection element, near infrared light generated by the illumination unit towards the at least one optical region, deflecting, by means of the optical deflection element, near infrared light reflected by the at least one defined optical region towards an imaging system, acquiring, by means of the imaging system, at least one image of the deflected near infrared light, processing, by means of a processor, of the at least one image acquired by the imaging system comprising analyzing the at least one image to determine the coordinates of position, in a timely dependent manner, of oculomotor movements of the at least one eye optical region in response to the visual stimuli displayed by the visual stimulus generator, and determining a variance between the measured oculomotor movements of the at least one optical region and data indicative of normative values.

In another aspect, the invention relates to a use of the device according to the invention, wherein said use is selected from the group consisting of use for the evaluation, classification, and follow-up of a test subject with or without pathologies or for determining the threshold value indicative of the onset of one selected from the group consisting of following pathologies: Alzheimer's disease, Frontotemporal Dementia, Mild Cognitive Impairment, Parkinson's Disease, Parkinsonisms, Progressive Supranuclear Palsy, Multiple System Atrophy, Corticobasal Degeneration, Lewy Body Dementia, Minimal Hepatic Encephalopathy, Early - Minimal Hepatic Encephalopathy, thereby improving predictability in the diagnosis of said pathologies and enabling the determination of a suitable treatment for said pathologies. DESCRIPTION OF THE INVENTION

In order to solve the drawbacks and bridge the gaps mentioned in the state of the art, the following device for obtaining dynamic measurements of eye optical surfaces (eye tracking), and the method of use thereof, are described.

The present invention provides a system for carrying out a simple diagnostic test, capable of measuring, in a quantitative manner, perceptive thresholds, latencies, response amplitudes and easily measurable functional deficits, like visual-motor coordination (saccades tied to perceptive thresholds), easy-to-use even for the general practitioner and, above all, low cost for a widespread use through the biomedical practice. For this purpose, the system described hereinbelow is capable both of generating visual stimuli that are quantitatively characterized, and of recording the visual and motor responses in an accurate manner and free of interferences.

Stimuli may be, for example, bright green circles with a total outer diameter of 0.5° of visual angle. Each stimulus may be designed with a small white center cross on which to focus. Thus, it can be achieved a high contrast to enhance their perception. Preferably, stimuli may be displayed individually for 1500 milliseconds on a black background.

In the sense of the present invention, eye tracking refers to the group of methods used to monitor oculomotor behavior, including gaze direction, spatiotemporal aspects of saccadic movements, smooth tracking, and fixational eye movements. The device according to the invention collects, by means of the camera, a video of the movement of the eyes in front of the stimuli projected on the patient's screen. The complete video is transmitted to the computer. The device according to the invention is advantageous to aid in the diagnosis of diseases of the central nervous system and minimal encephalopathy by tracking eye movements. The system also comprises of a capture hardware, responsible for taking images of the eye, and a software that allows the capture of images during the presentation of visual stimuli and the subsequent processing and visualization of the data obtained.

Device

In a first aspect, the invention relates to a device for obtaining dynamic measurements of eye optical surfaces, characterized in that it comprises: - a visual stimulus generator, configured to display visual stimuli of visible light towards at least one eye optical region,

- an illumination unit for illuminating the at least one eye optical region, configured to illuminate with near infrared light, i.e. light in the electromagnetic spectrum from about 780 nm to about 2500 nm,

- an imaging system, configured for capturing images of near infrared light,

- an optical deflection element arranged between the visual stimulus generator and the viewer unit, the optical deflection element being configured to deflect near infrared light generated by the illumination unit towards the at least one eye optical region and to deflect near infrared light reflected by the at least one eye optical region towards the imaging system, and

- a processor, configured to control the display of a sequence of a plurality of visual stimuli by the visual stimulus generator, capture images of the near infrared light reflected by the at least one optical region (9a) acquired by the imaging system upon display of the plurality of visual stimuli displayed by the visual stimulus generator in a timely dependent manner, and analyze said images of the near infrared light to determine the coordinates of position, in a timely dependent manner, of the oculomotor movements of the at least one eye optical region in response to the visual stimuli displayed by the visual stimulus generator.

According to the invention, the viewer unit spatially and opaquely confines the at least one eye optical region. Thus, the movements of the at least one eye optical region can be measured with higher accuracy and precision, since the reflection of near infrared light by the at least one eye optical region towards the imaging system remains isolated from external light interferences.

It is advantageous to obtain accurate measurements of the eye while avoiding optical interferences, which in turn allow a highly precise acquisition of images of the eye of a test subject. This precision is of particular importance by the performance of visual tests which involve subtle and rapid eye movements, so that this information may be properly related to a disorder, in particular, a neurological disorder. The optical deflection element is also advantageous because it allows the physical separation of optical/visual data, i.e. visible light from infrared light, which provides an accurate measurement of the dynamic movements of the eyes.

The accuracy and precision that can be obtained according to the invention is above the normal values of the commercially available eye trackers, which report values of 0,5° and 0,005° for accuracy and precision.

Preferably, according to the invention, the visual stimulus generator is configured to display the visual stimuli of visible light horizontally in an axis of display of the visual stimulus generator. It is contemplated that the optical deflection element may be arranged inclined with respect to the axis of display of the visual stimulus generator, an angle of incidence within the range of [35°, 55°], preferably, of [40°, 50°], more preferably the angle of incidence is 45°.

More preferably, the imaging system and the illumination unit are configured to, respectively, acquire images and generate near infrared light, vertically and perpendicularly to the axis of display of the visual stimulus generator.

In a preferred embodiment according to the invention, the imaging system is a high-speed imaging system, comprising at least one high-speed camera, configured to capture images at a frame rate greater than or equal to 100 fps, preferably, to 300 fps.

In one embodiment of the invention, the imaging system is configured to acquire images vertically in an axis perpendicular to the axis of display of the visual stimulus generator, and the imaging system is arranged to be horizontally displaceable. According to the invention, a high-speed infrared camera is provided to record oculomotor movements. This camera is placed on a rail that allows horizontal displacement to focus on the dominant right or left eye. In addition, to improve accuracy, the camera is installed as close as possible to the position of the eye. The camera and the optical deflection element (also hot mirror) are placed at a fixed distance independent of the patient. The camera is also equipped with a filter that allows only infrared light to pass through. This arrangement is advantageous since it allows a precise positioning of the imaging system to acquire accurate images of the dynamic movements of one or the other eye. In another embodiment of the invention, the imaging system comprises at least one high-speed infrared camera comprising at least one optical filter configured to only allow deflected near infrared light striking the imaging system. In some embodiments, the camera is a high-speed camera, configured to capture images at a frame rate greater than or equal to 100 fps, preferably, to 300 fps. For example, it may be used a camera with a dynamic range of 10 bit with a resolution 720x540 (0.4 MP) and a frame rate of 539 fps. In some embodiments, the optical filter has a useful range of 845-1100 nm with a cut-on wavelength 50% T of 830nm.

In another embodiment of the invention, the illumination unit comprises at least one near infrared light emitting diode (LED), preferably at least two near infrared light emitting diodes (LEDs). External conditions such as artificial light can considerably decrease the resolution of the images. For this reason, near infrared (NIR) illumination is advantageously used while recording the eye. Nevertheless, the room illumination as well as the noise and temperature must be homogeneous so as not to distract the patient. The illumination system is based on two light-emitting diodes installed inside the camera compartment. These diodes are used not only for illumination, but also for gaze estimation. The corneal reflection, generally called glints, is widely used to correct slight head movements. Such flares must be within the pupil or iris area to be able to be detected. For estimation purposes, averaging their position reduces the error. It is worth noting that the light intensity is controlled by software using a light controller. It is also important to note that this intensity is at most 100 mA. This intensity is limited to ensure compliance with the photobiological safety condition, UNE-EN 62471. In addition, the lighting system complies with the radiance and irradiance values necessary to be considered a risk-free system according to I EC 62471-2. In some embodiments, for example, the LEDs are infrared (IR) with a radiant Intensity (le) Min @ If 80mW/sr @ 100mA at a wavelength of 950 nm oriented in top view.

In another embodiment of the invention, the illumination unit is integrally housed with the imaging system, wherein the illumination unit and the imaging system are arranged vertically in the same beam path. In another embodiment of the invention, the illumination unit is configured to illuminate vertically in an axis perpendicular to the axis of display of visual stimulus by the visual stimulus generator.

In another embodiment of the invention, the device further comprises a light controller configured to control the light intensity generated by the illumination unit, wherein the light controller is configured to control the illumination unit to generate a maximum light intensity of 100mA. In a preferred embodiment, the light intensity is controlled by software using a light controller, wherein this intensity is at most 100 mA.

Preferably, the optical deflection element is arranged at a preferred angle of 45° with respect to the test subject's direction of gaze, wherein the imaging system and the optical deflection element are arranged vertically in a perpendicular axis to the test subject's direction of gaze.

In another embodiment of the invention, the optical deflection element is configured to allow visible light emitted by the visual stimulus generator pass through undeflected towards the at least one eye optical region. In a preferred embodiment of the invention, the optical deflection element is a dichroic mirror. According to the invention, the optical deflection element or “hot mirror” is located in front of the patient's eyes at a preferred angle of 45° to the chin rest. The use of this component makes it possible to capture images as if the camera were located directly in front of the examined eye but leaving the field of view unobstructed. The reason is that the NIR light emitted by the aforementioned light sources is reflected by the hot mirror and captured by the camera. The position and orientation of the camera perpendicular to the patient's visual axis depends mainly on this reflection. This arrangement provides a precise dynamic measurement of the eye movement, without optical interferences, which in turn increases the diagnostic value of the test. In some embodiments the hot mirror is a dichroic filter with dielectric coating. In some embodiments, the hot mirror is 101 .0 x 127.0 mm in size and 3.30 mm thick with a wavelength range 400-1125 nm.

According to the invention, the hot mirror is placed at preferred angle of 45° with respect to the patient's direction of gaze, whereas the camera is placed perpendicular to the patient's direction of gaze. In some embodiments, the distance between the hot mirror and the test subject is, preferably in the range of [40, 70] mm, more preferably 50 ± 5 mm, and the distance between the camera and the hot mirror is, preferably in the range of [45, 80] mm, more preferably 70 ± 5 mm.

In another embodiment of the invention, the processor analyzes near infrared light output from the optical deflection element to determine horizontal and vertical biases of the near infrared light reflected by the at least one eye optical region to determine the coordinates of position of the at least one optical region.

In another embodiment of the invention, the processor is configured to: calibrate the imaging system, calculate the position of the imaging system in space, determine the position of the at least one optical region relative to the imaging system, synchronize the generation of a sequence of a plurality of visual stimulus of visible light displayed by means of the visual stimulus generator with the imaging of near infrared light reflected by the at least one optical region by means of the imaging system, and process, store, analyze and display image data in a timely dependent manner corresponding to sequential measurements of the two-dimensional information of the at least one optical region acquired by the imaging system.

In some embodiments, the processor is a computer, for example, a personal computer (PC).

In another embodiment of the invention, the at least one optical region is spatially confined by a viewer unit.

In another embodiment of the invention, the device according further comprises a housing, wherein the housing comprises a first support structure integrally holding the viewer unit, the imaging system, the optical deflection element, the illumination unit, the light controller, a camera position adjustment unit, a chin support portion, for supporting the chin of the subject, handgrips; a second support structure integrally holding the visual stimulus generator, connections to peripheral devices, and a basis structure integrally holding the processor, wherein said first support structure and second support structure are attached to said basis structure at opposite ends. The housing serves, inter alia, the purpose of isolating the illumination unit and the imaging system from the interaction with visible light for accurate acquisition of images.

In some a preferred embodiment, a forehead and chin rest are used to immobilize the patient's head. The use of these elements is based on their ability to minimize head movement which, in turn, ensures accurate data acquisition. In addition, the forehead and chin support can be adjusted to adapt to different head anatomies. Such adaptability aims to provide maximum comfort for patients.

In another embodiment of the invention, the central portion of the visual stimulus generator is horizontally aligned with the viewer unit in a beam path. In another embodiment of the invention, the chin support portion is arranged to be displaceable in a vertical axis for fixedly supporting a subject's head in position with the viewer unit.

In another embodiment of the invention, said beam path corresponds to the position and orientation of a subject's visual axis, wherein the at least one optical region corresponds to the pupil or iris of the subject.

In some embodiments, the visual stimulus generator is a monitor, a computer screen or similar, for example, with a monitor size of, preferably in the range of [20, 24]”, more preferably of 22”at minimum 60Hz. In some embodiments, the distance between the monitor and the patient's forehead support is, preferably in the range of [50, 75] mm, more preferably 60 cm ±3cm. This arrangement provides advantages visual response from the test subject, which in turn increase accurate measurement and reliable diagnosis.

In another embodiment of the invention, the imaging system is a high-speed infrared camera configured to record oculomotor movements of the test subject. In another embodiment of the invention, the high-speed infrared camera is configured to measure, in time and in the two spatial coordinates, at least one of a spatial pupil or iris movement of the test subject in response to the visual stimulus displayed by the visual stimulus generator.

In another embodiment of the invention, the near infrared light generated by the illumination unit is deflected by the optical deflection element towards the pupil or iris of the subject, wherein the near infrared light is reflected by the test subject within the pupil or iris area.

In some embodiments, the device further comprises a monitor, screen or display for the operator or clinician.

According to the invention, the device is advantageous for the identification and diagnosis of a plurality of pathologies, including but not restricted to: Alzheimer's disease, Frontotemporal Dementia, Mild Cognitive Impairment, Parkinson's Disease, Parkinsonisms, Progressive Supranuclear Palsy, Multiple System Atrophy, Corticobasal Degeneration, Lewy Body Dementia, Minimal Hepatic Encephalopathy, Early - Minimal Hepatic Encephalopathy. Method

In another aspect, the invention relates to a method for obtaining dynamic measurements of eye optical surfaces, characterized in that it comprises the steps of: displaying, by means of a visual stimulus generator, a sequence of a plurality of visual stimulus of visible light towards at least one optical region spatially and opaquely confined in a viewer unit, illuminating the at least one eye optical region by means of an illumination unit configured to illuminate with near infrared light, deflecting, by means of an optical deflection element, near infrared light generated by the illumination unit towards the at least one optical region, deflecting, by means of the optical deflection element, near infrared light reflected by the at least one defined optical region towards an imaging system, acquiring, by means of the imaging system, at least one image of the deflected near infrared light, processing, by means of a processor, of the at least one image acquired by the imaging system comprising analyzing the at least one image to determine the coordinates of position, in a timely dependent manner, of oculomotor movements of the at least one eye optical region in response to the visual stimuli displayed by the visual stimulus generator, and determining a variance between the measured oculomotor movements of the at least one optical region and data indicative of normative values.

In one embodiment, the at least one optical region is the pupil or iris of a test subject's eye.

In another embodiments, the method according to the invention comprises the use of a device according to the invention.

According to the invention, functional analysis of performed by means of a capture software, whose main objective is to record the eye movement of a subject when viewing a stimulus on a computer screen or monitor. Also, this software calculates the location of the pupil during this recording in coordinates of the International System of Units (ISU). The software contains an algorithm for the analysis of the data collected by the capture software and its evaluation for diagnostic support. According to the invention, the capture software is installed on the processor of the device. The general objective of this software is to record the eye movement of a subject when viewing a stimulus on a screen of the device of the invention. From the recording, and following the classic methodology of computer vision techniques, the image is processed, and the location of the pupil is calculated according to the ISU.

For this purpose, the Capture software has the following goals: a) Identify the subject to be tested in the form of ID and age. b) Identify the medical test to be performed on the subject (by means of test identification number). c) Visualize the pupil in the viewing area of the technician interface: patient positioning, manual adjustment of chin rest degrees, manual adjustment of hot mirror, switching on the illumination system, manual adjustment of camera position, manual brightness and contrast controls (structured environment). d) Correct pupil detection in the viewing area of the technician interface: manual adjustment of camera focus. e) Display visual stimuli on patient interface according to the medical test selected from the technician interface. f) Capture and save on the computer hard disk all the frames coming from the camera during the test performance. g) Process the saved images following the classical computer vision methodology. h) Verify the quality of the recording considering the main objective of the application: by means of image segmentation technique, recognize the pupil in at least 70% of the processed frames. i) Obtain the location of the pupil (position, velocity and acceleration) in ISU from the frames considered valid. j) Display the coordinates (x,y) of the test performed. k) Deactivate the illumination system. l) Generate a file with the pupil localization data, for example a csv file. m) Manage the communication with the cloud service. n) Upload the data file to the cloud sector corresponding to the device unit or synchronize databases with the cloud.

The device and method are configured, by means to the capture software, to advantageously perform different tests, including but not restricted to: - CC9: 9-point calibration test.

- TSVH: Horizontal visual saccade test.

- TSVV: Vertical visual saccade test.

- TASVH: Horizontal visual antisaccade test.

- TASVVV: Test of vertical visual saccades.

- TSMH: Horizontal memory saccade test.

- TSMVV: Test of vertical memory saccades.

- TASMH: Horizontal memory antisaccade test.

- TASMV: Test of vertical memory saccades.

- TCMS: Counterbalanced saccade test.

- TIFN: Still image test (N is the number of image: 1 to 10).

- TFIX: Fixation test.

- TPL: Pupil light test.

- TSLSH: Slow sinusoidal horizontal tracking test.

- TSLSV: Vertical sinusoidal slow tracking test.

- TSLSD1 : Diagonal sinusoidal slow tracking test 1.

- TSLSD2: Diagonal sinusoidal slow tracking test 2.

- TSLSC: Circular sinusoidal slow tracking test.

- TSLLH: Horizontal linear slow tracking test.

- TSLLV: Test of vertical linear slow tracking.

- TSLLS: Sinusoidal linear slow tracking test.

- TOPTHL: Left horizontal optokinetic test.

- TOPTHR: Right horizontal optokinetic test.

- TOPTVU: Test of optokinetics vertical up.

- TOPTVD: Test of optokinetics vertical down.

Use of the device

In another aspect, the invention relates to a use of the device according to the invention, wherein the at least one eye optical region is the pupil or iris of a test subject's eye, wherein said use is selected from the group consisting of use for the evaluation, classification, and follow-up of a test subject with or without pathologies or for determining the threshold value indicative of the onset of one selected from the group consisting of following pathologies: Alzheimer's disease, Frontotemporal Dementia, Mild Cognitive Impairment, Parkinson's Disease, Parkinsonisms, Progressive Supranuclear Palsy, Multiple System Atrophy, Corticobasal Degeneration, Lewy Body Dementia, Minimal Hepatic Encephalopathy, Early - Minimal Hepatic Encephalopathy, thereby improving predictability in the diagnosis of said pathologies and enabling the determination of a suitable treatment for said pathologies.

In use, the height of the chin rest, the mirror and the camera (position and focus) is adjusted so that the eye is centered on the video and focused so that the pupil is as defined as possible. The contrast and brightness can also be varied in the sliders that appear below the video shown in the patient's screen or monitor, so that the pupil and glints (“a small flash of light, especially a reflected one”) are defined and easily identifiable. A good practice here is to check that the software is able to recognize the pupil consistently and unambiguously. If everything works correctly, the software will draw, in each frame, the ellipse that comes closest to the pupil outline. It should be checked that this ellipse is formed correctly, and for different positions of the patient's gaze.

The various tests that make up a study are usually grouped into blocks, at the beginning of each of which a calibration is given. Calibration allows the system to match the position of the pupil on the video to the point on the patient's screen at which the patient is looking. It is therefore important that, once the calibration is performed, the patient does not rearrange or move excessively until the end of the test block. The blocks contain the calibration and one or two tests.

Calibration (modeling of the patient's eye):

Calibration points will start to appear on the patient's screen or monitor. The first one is located in the upper left corner. Once the patient is looking at the stimulus on the screen, the patient presses a key to proceed. Then, different frames will be analyzed, and the pupil positions associated with this first point will be recorded. Immediately afterwards, the stimulus will move to the next point. When the patient is looking at the new stimulus position, the space bar may be pressed again. Repeating this process, the calibration of the 9 points is recorded. As the pupil positions are recorded, they are added to the graph in this window.

Test

Then, pressing a key, the next test will start or, once this one is finished, it will advance to the next one in case there are more tests programmed for that block. It should be noted that the infrared LED will automatically turn off after 5 minutes of light emission. The user must coordinate with the software to perform the calibrations and each test in less than 5 minutes, starting the infrared emission at the beginning of each cycle. Once the block is finished, it automatically advances to the next one. It will wait for the test quality level check to finish. Aspects such as whether the calibration has been performed consistently, or that the activity in the tests does not deviate too far from that expected, are checked. The progress of this analysis can be seen in the progress bars (for each test and overall). At the end of this process, by means of various graphs, the patient's eye positions versus the desired positions are shown.

Data processing and reporting

Once the anonymized data is properly stored, it is available for processing. The data is extracted from the files containing the eye movement of each test and analyze them with the analyzer software. The first step is to determine whether the data is sufficient for a complete analysis based on the patient's age, the pathologies suggested by the physician. If so, the data will be analyzed, and a report will be prepared. In negative case, a message will be sent to the physician with the detected incidences so that the physician can take the decisions he/she considers appropriate. Once the report has been prepared, a message will be sent to the physician to indicate that the data analysis report is available and can be downloaded.

Data visualization

The equipment provides a comprehensive set of tools for analyzing refined data. This data is showcased visually, and depending on the kind of test, it might use line, scatter, or color diagrams. A significant aspect of viewing this data is the capability to revisit the eye movements recorded through video previews. Different methods, such as playback options or mouse engagement with charts through actions like clicking or dragging specific segments, can execute this. “Reviewing the video footage allows for multiple visual inspections of the actual events, making it possible to spot minor irregularities, like small eye twitches that might move the eye but don't touch the edges of the pupil or the sides of the cornea”.

Safety Classification

The device according to invention fulfills a series of safety/technical requirement as follows:

• According to EN 55032:2015 the device has been classified within Group 1 Class B. • According to EN 60601-1:2006 + AC:2010 + A1 :2013 the device is classified as Class I Equipment.

• According to standard 60601-1-2:2015 the device has been subjected to the relevant immunity tests for professional healthcare environments.

• According to EN 62471 :2008 the device is classified as Exempt from Risk in terms of photobiological safety, i.e. it does not cause thermal damage to the retina, cornea or skin due to infrared illumination.

• According to Regulation 2017/745 concerning Medical Devices, the device is classified as Class Ila in accordance with Regulation 10 of Annex VIII.

Visual tests

The device according to the invention is advantageously configured to perform, but not restricted to, following tests:

• Visual saccades: saccade test. The patient should look at the points displayed on the screen. These are displayed on a single axis depending on the variant (horizontal or vertical). A central point appears first and then changes randomly to a different position and side. Two saccades are generated for each position and side. In horizontal the positions are 5 degrees, 10 degrees and 20 degrees and in vertical 5 and 10 degrees, the time that each point appears with "Recording Time" in milliseconds can be modified.

• Visual antisaccades: Antisaccades test. It is the same test as the previous one, but the patient instead of looking at the dot must look at the opposite place to where the stimulus appears. In detail, starting from a stimulus point that appears in the center of the screen for 1.5 seconds, this stimulus point moves in a horizontal or vertical direction (depending on the variant of the test being performed) at a certain distance from the center, remains there for 1.5 seconds and returns to the center. This execution is repeated for a given time. The amplitudes to which the point can move are defined, but the direction of displacement (left or right/up or down) is random, as is the amplitude from among the possible ones. The amplitudes are 5°, 10° and 20° horizontally and 5° and 12° vertically. The objective is for the patient to look to the opposite side to the stimulus point, at an equal amplitude.

• Memory saccades: Memory saccades test. It is similar to the saccade test, the stimulus is shown in the center and then to one of the sides, the next repetition the stimulus is shown in the center and then disappears, at this point the patient must remember where he had looked before and fixate on that point. The time that each point appears with "Recording Time" in milliseconds can be changed. In detail, the test starts with a stimulus dot in the center of the screen that after 1.5 seconds moves horizontally or vertically (depending on the type of test being performed) in a random manner in terms of the direction and amplitude of the movement, remains for 1.5 seconds, returns to the center of the screen and remains for 1.5 seconds, disappears for 1.5 seconds and reappears in the center of the screen to start again. The amplitudes to which the point can move are defined, being 5°, 10° and 20° horizontally and 5° and 12° vertically. The aim is for the patient to first track the dot in the same way as in the visual saccade test and, when the stimulus dot disappears, to look again at the position of the last stimulus. When the stimulus reappears in the center of the screen, the patient should look at the dot again. This is intended to test the patient's memory.

• Memory antisaccades: Memory antisaccades test. It is the same test as the previous one, but instead of looking at the dot, the patient must look at the place opposite to where the stimulus appears. In detail, the test starts with a stimulus dot in the center of the screen which after 1.5 seconds moves horizontally or vertically (depending on the type of test being performed) in a random manner in terms of the direction and amplitude of the movement, remains for 1.5 seconds, returns to the center of the screen and remains for 1.5 seconds, disappears for 1.5 seconds and reappears in the center of the screen to start again. The amplitudes to which the point can move are defined, being 5°, 10° and 20° horizontally and 5° and 12° vertically. The objective is that the patient first performs a visual antisaccade, in the same way as in the visual antisaccade test and, when the stimulus dot disappears, looks again at the position where the visual antisaccade was performed. When the stimulus reappears in the center of the screen, the patient should look at the dot again. This is intended to test the patient's memory.

• Countermanding saccades: Saccade test where the person's ability to stop a saccade can be analyzed. A series of saccade stimuli are shown on the horizontal axis, which the patient must observe. A "stop signal" can be randomly generated, which consists of the central point reappearing. When the central dot appears, the patient must look at it. These test signals are generated with latencies of 10, 50, 90, 90, 130 and 170. Once they have been generated the test ends.

• Counterbalanced saccades: This type of test consists of a series of stimuli that the patient must observe appearing on the horizontal axis of the screen. Randomly, at a given moment, a stop signal is generated, which means that the stimulus appears at the central point of the screen and the patient must look at it.

• Fixed Image: An image is displayed. The specific image is chosen with the variant. The time the image is displayed can be modified with "Test Duration" in seconds. Fixation: The fixed center point is displayed. The duration of the test can be changed with "Test Duration" in seconds.

• Still image: This type of test consists of showing an image on the screen, of the 10 possible ones, and the patient must look at it for an estimated time that can be configured.

• Fixation test: In this test a stimulus is shown in the center of the screen for a certain configurable time, by default 15 seconds. The patient is instructed to stare at the point for the duration of the test.

• Pupil Light: Pupillary reflex test. The display is completely illuminated and switched off at regular intervals. The patient must look at a central point for the results to be valid. The number of repetitions and time per repetition can be specified. The number of times the screen is illuminated and turned off is configurable, as is the duration of the illumination-off set.

• Slow tracking; This type of test consists of showing a slowly moving stimulus on the screen. The type of movement of the dot is varied, as well as its speed, which can be linear or sinusoidal. A linear velocity means that the dot moves at the same speed all the time. On the other hand, a sinusoidal velocity indicates that the point is varying its velocity from an intermediate velocity, increasing and decreasing it.

- Within the linear variant, the motion of the point has several options: horizontal trajectory, vertical trajectory or sinusoidal trajectory.

- Within the sinusoidal variant, the movement of the point has several options: horizontal path, vertical path, a path on one diagonal of the screen (diagonal 1), a path on the other diagonal of the screen (diagonal 2) or a circular path.

By default, 3 complete cycles of 8 seconds period each are performed in the test, although the number of cycles and the period is configurable.

The objective of the test is for the patient to follow the dot with the gaze.

• Linear Smooth Pursuit: Slow tracking test with fixed speed. A dot is shown moving at a constant speed across the screen. You can choose whether it is performed horizontally, vertically or with a sinusoidal trajectory. By modifying "Laps", the number of repetitions of the pattern is chosen and with "Period" the time it takes to perform each repetition is specified in seconds.

• Sinusoidal Smooth Pursuit: Slow tracking test with sinusoidal velocity. In this case the point moves at a variable speed following a sinusoidal reference. Variants allow the trajectories to be performed horizontally, vertically, two diagonals and a circumference. The number of repetitions and the time per repetition can be specified. • Optokinetic: Optokinetic test. It consists of displaying alternating black and white bands moving across the screen at constant speed. The direction and direction of displacement can be chosen. The duration of the test can be modified with "Test Duration" in seconds.

Beyond the direction, all these tests have some specific features that can be customized. For example, the time of saccade in a saccade-based test, regardless of its type: pro, anti or memory. In fixation, the test duration in seconds. In fixed image test, the duration in seconds and the image to be presented. In pupillary light reflex, the time between black and white changes. Finally, in smooth pursuit, the animation speed in hertz.

The device according to the invention is advantageously configured to determine, by means of the above mentioned tests, a plurality of pathologies with high sensitivity and specificity.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a perspective side view of one embodiment of the device according to the invention without housing.

Figure 2 shows a perspective side/back view of one embodiment of the device according to the invention with housing.

Figure 3 shows a schematic top view of one embodiment of the device according to the invention indicating a first beam path (pointed at by two thick arrows) and dimensions in mm (thin arrows).

Figure 4 shows a schematic sagittal view of one embodiment of the device according to the invention, indicating a first beam path and a second beam path (thick arrows) and dimensions in mm (thin arrows).

Figure 5A shows a schematic representation of an embodiment of the optical deflection element according to the invention (VIS: visible light; IR: infrared light); Figure 5B shows a front view (test subjects’ view) of one embodiment of the device according to the invention with housing.

Figure 6A shows a graph depicting the ratio between the amplitude of the stimulus signal (straight lines) and the amplitude of the signal generated by the patient's response (Gain). Figure 6B shows a graph depicting the measurement of time from the change of the stimulus signal (straight lines) to the starting point of the patient's response (Delay). Figure 7A shows a graph depicting the measurement that starts from the change of the stimulus signal (straight lines) until the establishment of the patient's response signal that occurs when it enters the establishment margin of 3% (Latency); Figure 7B shows a graph depicting the measurement that starts from the change of the stimulus signal (straight lines) to the point at which the maximum peak of the signal of the patient's response occurs (Maximum peak time).

PREFERRED EMBODIMENT OF THE INVENTION

A specific embodiment of the invention is described below as an illustrative and non-limiting example with reference to the accompanying figures.

In Figure 1 , one embodiment of the device 1 according to the invention is shown without housing 10. The device 1 comprises a visual stimulus generator 2 in form of a monitor or computer screen having a central portion 2a. The visual stimulus generator 2 is supported by the second support structure 10b. The viewer unit 9, which confines the eye optical region 9a to be tested is provided opposite to the visual stimulus generator 2. As it can be seen in the figures, in a preferred embodiment the viewer unit 9 is in the form of googles. The googles confines spatially and opaquely the optical region 9a, laterally surrounding it. Likewise, as it can be seen in the figures, in a preferred embodiment the housing 10 is configured to spatially and opaquely confine a space between the at least one eye optical region 9a and the optical deflection element 7 and between the optical deflection element 7 and the imaging system 6.

In use, the test subject places the eye(s) (eye optical region 9a) within the viewer unit 9 so that the test subject can observe the visual stimulus displayed by the visual stimulus generator 2. The illumination unit 4, the high-speed imaging system 6 and the optical filter 6b are housed together and can be moved as one unit, whereas the camera position adjustment unit 6c is provided for adjusting the position of the illumination unit 4, the high-speed imaging system 6 and the optical filter 6b. A chin support portion 11 , and chin support position adjustment 11a are provided to allow stably placing the test subject's head at the viewer unit 9. Handgrips 12 are provided to allow the subject remaining stable while on use of the device. The illumination unit 4, high-speed imaging system 6, optical filter 6b, viewer unit 9, chin support portion 11 , chin support position adjustment 11a, handgrips 12 are supported by the first support structure 10a. A processor 8 is provided supported by a basis structure 10c. The first support structure 10a and the second support structure 10b are fixedly connected to opposite ends of the basis structure 10c. The device 1 is provided with connections to peripheral devices 13 such as operator's monitor, mouse, keyboard, etc.

For the eye tracking, the subject should sit facing the device, resting his/her head on it, and looking through the viewer unit at the visual stimulus generator 2 screen. This screen is set at a uniform distance from the eye being examined. Within this arrangement, the person can view the displayed stimulus, and his/her eye movements can be recorded in a raw video format. This recording is subsequently analyzed for comprehensive data findings.

In Figure 2, one embodiment of the device 1 according to the invention is shown with housing. The device 1 comprises a visual stimulus generator 2 provided opposite to viewer unit 9 and eye optical region 9a (test subject's eye(s)) so that the images generated by visual stimulus generator 2 are displayed in a first beam path 3 directed to the optical region 9a. The optical deflection element 7 is provided at a preferred angle of 45° to the first beam path 3 and the optical region 9a, adjacent to the viewer unit 9 and opposite to the visual stimulus generator 2. The device 1 corresponds with the device in Figure 1, however, provided with a housing which covers most elements of the device 1 except the viewer unit 9, optical region 9a, visual stimulus generator 2, camera position adjustment unit 6c, handgrips 12, and connections to peripheral devices 13. The housing 10 is integrally provided supporting/covering the first support structure 10a, second support structure 10b and basis structure 10c.

In Figure 3, a schematic top view of one embodiment of the device 1 according to the invention is shown. The first beam path 3 is shown as a dotted line visually connecting the central portion 2a of the visual stimulus generator 2, optical deflection element 7, viewer unit 9 and optical region 9a. Dimensions of the device 1 are shown in millimeter (thin arrows).

In Figure 4, a schematic sagittal view of one embodiment of the device 1 according to the invention is shown. The first beam path 3 is shown as a thick arrow visually connecting visual stimulus generator 2 and the viewer unit 9. Perpendicular to the first beam path 3, the second beam path 5 is shown as a thick arrow which optically connects the optical deflection element 7 to the illumination unit 4 and high-speed imaging system 6, which are comprised as a unit that can be moved together, horizontally. The housing 10, which covers/supports the first support structure 10a, second support structure 10b, basis structure 10c, is shown. Dimensions of the device 1 are shown in millimeter (thin arrows). In Figure 5A, a schematic representation of an embodiment of the optical deflection element 7 in form of a dichroic mirror 7a according to the invention is shown (VIS: visible light; IR: infrared light). It shows that, placed at a preferred angle of 45°, visible light in a striking beam path is allowed to pass through the dichroic mirror 7a, whereas infrared light is reflected perpendicularly to the beam path of visible light.

In Figure 5B, a front view corresponding to test subjects’ view, of one embodiment of the device 1 according to the invention with housing is shown. The visual stimulus generator 2 is shown opposite to the viewer unit 9, eye optical region 9a in the same visual path. The chin support portion 11, chin support position adjustment 11a, and chin support portion holder 11b are provided to vertically adjust the position of the test subject's head. The housing 10 is provided with the basis structure 10c supported by bottom support legs 14.

In Figure 6A, a graph for obtaining the gain in a test performed by means of the device according to the invention is depicted. In detail, the graph shows the ratio between the amplitude of the stimulus signal (straight lines) and that of the signal generated by the patient's response (curve). In the patient’s response, the measurement starts at the first (left) cross and ends at the median of the values between the end point of the slope (second (middle) cross) and the starting point of the next stimulus (third (right) cross).

In Figure 6B, a graph to obtain the delay in a test performed by means of the device according to the invention is depicted. In detail, the graph shows the measurement of time from the change of the stimulus signal (from high to low level in the curve) to the starting point of the patient's response (cross).

In Figure 7A, a graph to obtain the latency in a test performed by means of the device according to the invention is depicted. In detail, the graph shows the measurement that starts from the change of the stimulus signal (straight line) until the establishment of the patient's response (curve) signal (second (middle) cross) that occurs when it enters the establishment margin of 3%. If, for example, the stimulus value is 200, the corresponding range would comprise the values of ±3% of this value (from 194 to 206). The range starts to be evaluated from the first (left) cross and ends at the third (right) cross.

In Figure 7B, a graph for obtaining the maximum peak time in a test performed by means of the device according to the invention is shown. In detail, the graph shows the measurement that starts from the change of the stimulus signal (straight line) to where the maximum peak of the signal (second cross) of the patient's response (curve) occurs. The evaluation band is between the first and third cross.

The above results confirm the provision of a device which allows a simplified and rapid examination of a subject suspected of suffering from a disease by performing a plurality of visual tests, providing an accurate determination of the dynamic positional data of an eye. The device according to the invention, thus, is advantageous in minimizing interferences of the optical data acquisition process, thereby resulting in a significant reduction of capturing errors and improving the interpretation of acquired data for proper diagnosis.

LIST OF NUMERICAL REFERENCES USED IN THE FIGURES device (1) visual stimulus generator (2) central portion (2a) of the visual stimulus generator (2) first beam path (3) illumination unit (4) near infrared light emitting diode (LED) (4a) light controller (4b) second beam path (5) high-speed imaging system (6) high-speed infrared camera (6a) optical filter (6b) camera position adjustment unit (6c) optical deflection element (7) dichroic mirror (7a) processor (8) viewer unit (9) eye optical region (9a) housing (10) first support structure (10a) second support structure (10b) basis structure (10c) chin support portion (11) chin support position adjustment (11a) chin support portion holder (11b) handgrips (12) connections to peripheral devices (13) bottom support legs (14)

Claims

1. A device (1) for obtaining dynamic measurements of eye optical surfaces of a subject, characterized in that it comprises:

- a visual stimulus generator (2), configured to display visual stimuli of visible light towards at least one eye optical region (9a),

- a viewer unit (9) for the subject viewing through it the visual stimulus generator (2), configured to spatially and opaquely confine the at least one eye optical region (9a),

- an illumination unit (4) for illuminating the at least one eye optical region (9a), configured to illuminate with near infrared light ,

- an imaging system (6), configured for capturing images of near infrared light ,

- an optical deflection element (7) arranged between the visual stimulus generator (2) and the viewer unit (9), the optical deflection element (7) being configured to deflect near infrared light generated by the illumination unit (4) towards the at least one eye optical region (9a) and to deflect near infrared light reflected by the at least one eye optical region (9a) towards the imaging system, and a processor (8), configured to control the display of a sequence of a plurality of visual stimuli by the visual stimulus generator (2), capture images of the near infrared light reflected by the at least one optical region (9a) acquired by the imaging system (6) upon display of the plurality of visual stimuli displayed by the visual stimulus generator (2) in a timely dependent manner, and analyze said images of the near infrared light to determine the coordinates of position, in a timely dependent manner, of the oculomotor movements of the at least one eye optical region (9a) in response to the visual stimuli displayed by the visual stimulus generator (2).

2. Device according to claim 1 , characterized in that: the visual stimulus generator (2) is configured to display the visual stimuli of visible light horizontally in an axis of display of the visual stimulus generator (2), and the optical deflection element is arranged inclined with respect to the axis of display of the visual stimulus generator (2), an angle of incidence within the range of [35°, 55°], preferably, of [40°, 50°], more preferably the angle of incidence is 45°.

3. Device according to claim 2, characterized in that the imaging system (6) and/or the illumination unit (4) are configured to, respectively, acquire images and generate near infrared light, vertically and perpendicularly to the axis of display of the visual stimulus generator (2).

4. Device according to any preceding claim, characterized in that the imaging system (6) is arranged to be horizontally displaceable.

5. Device according to any preceding claim, characterized in that the illumination unit (4) is integrally housed with the imaging system (6).

6. Device according to any preceding claim, characterized in that the imaging system (6) is a high speed imaging system, comprising at least one high-speed camera (6a), configured to capture images at a frame rate greater than or equal to 100 fps, preferably, to 300 fps.

7. Device according to any preceding claim, characterized in that the imaging system (6) comprises at least one optical filter (6b) configured to only allow deflected near infrared light striking the imaging system (6).

8. Device according to any preceding claim, characterized in that the illumination unit (4) comprises at least one near infrared light emitting diode (LED) (4a), preferably at least two near infrared light emitting diodes (LEDs).

9. Device according to any preceding claim, characterized in that it further comprises a light controller (4b) for controlling the light intensity generated by the illumination unit (4), being configured to control the illumination unit (4) to generate a maximum light intensity of 100 mA.

10. Device according to any preceding claim, characterized in that the optical deflection element (7) is configured to allow visible light emitted by the visual stimulus generator (2) pass through undeflected towards the at least one optical region (9a).

11. Device according to any preceding claim, characterized in that the optical deflection element (7) is a dichroic mirror (7a).

12. Device according to any preceding claim, characterized in that the at least one eye optical region (9a) corresponds to the pupil or iris of the subject.

13. Device according to any preceding claim, characterized in that the viewer unit (9) is in the form of googles.

14. Device according to any preceding claim, characterized in that it further comprises a housing (10), wherein the housing is configured to spatially and opaquely confine a space between the at least one eye optical region (9a) and the optical deflection element (7) and between the optical deflection element (7) and the imaging system (6).

15. Device according to any preceding claim, characterized in that it further comprises a chin support portion (11 ) for supporting the chin of the subject.

16. Device according to claim 15, characterized in that the chin support portion (11) is arranged to be displaceable in a vertical axis for fixedly supporting a subject's head in position with the viewer unit (9).

17. A method for obtaining dynamic measurements of eye optical surfaces, characterized in that it comprises the steps of: displaying, by means of a visual stimulus generator (2), a sequence of a plurality of visual stimulus of visible light towards at least one optical region (9a) spatially and opaquely confined in a viewer unit (9), illuminating the at least one eye optical region (9a) by means of an illumination unit (4) configured to illuminate with near infrared light, deflecting, by means of an optical deflection element (7), near infrared light generated by the illumination unit (4) towards the at least one optical region (9a), deflecting, by means of the optical deflection element (7), near infrared light reflected by the at least one defined optical region (9a) towards an imaging system (6), acquiring, by means of the imaging system (6), at least one image of the deflected near infrared light, processing, by means of a processor (8), of the at least one image acquired by the imaging system (6) comprising analyzing the at least one image to determine the coordinates of position, in a timely dependent manner, of oculomotor movements of the at least one eye optical region (9a) in response to the visual stimuli displayed by the visual stimulus generator (2), and determining a variance between the measured oculomotor movements of the at least one optical region (9a) and data indicative of normative values.

18. Use of the device according to any one of claims 1 to 16, wherein said use is selected from the group consisting of use for the evaluation, classification, and follow-up of a subject with or without pathologies or for determining the threshold value indicative of the onset of one selected from the group consisting of following pathologies: Alzheimer's disease, Frontotemporal Dementia, Mild Cognitive Impairment, Parkinson's Disease, Parkinsonisms, Progressive Supranuclear Palsy, Multiple System Atrophy, Corticobasal Degeneration, Lewy Body Dementia, Minimal Hepatic Encephalopathy, Early - Minimal Hepatic Encephalopathy, thereby improving predictability in the diagnosis of said pathologies and enabling the determination of a suitable treatment for said pathologies.