System and method for measuring eye movement and/or eye position and postural sway of a subject

• US 10,342,473 B1
• Filed: 11/10/2017
• Issued: 07/09/2019
• Est. Priority Date: 04/17/2015
• Status: Active Grant

• Current Assignee: Bertec Corporation
• Original Assignee: Bertec Corporation
• Inventors: Berme, Necip, Barnes, Scott Zerkle
• Primary Examiner(s): Eiseman, Lynsey C
• Assistant Examiner(s): Steinberg, Amanda L
• Application Number:
  US15/809,705
• Time in Patent Office: 606 Days
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 3/113 for determining or recording eye movement
• CPC Class Codes: A61B 3/14 Arrangements specially adapted for eye photography apparatus or arrangements for taking photographs per se G03B
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0077 Devices for viewing the surface of the body, e.g. camera, magnifying lens
• CPC Class Codes: A61B 5/1036 Measuring load distribution, e.g. podologic studies
• CPC Class Codes: A61B 5/1114 Tracking parts of the body
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1124 Determining motor skills
• CPC Class Codes: A61B 5/1128 using image analysis A61B5/1127 takes precedence
• CPC Class Codes: A61B 5/163 by tracking eye movement, gaze, or pupil change
• CPC Class Codes: A61B 5/398 Electrooculography [EOG], e.g. detecting nystagmus; Electroretinography [ERG]
• CPC Class Codes: A61B 5/4023 Evaluating sense of balance
• CPC Class Codes: A61B 5/4076 Diagnosing or monitoring particular conditions of the nervous system A61B5/4821, A61B5/4824 take precedence
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61B 5/7445 Display arrangements, e.g. multiple display units
• CPC Class Codes: A61B 8/10 Eye inspection

Abstract

A method for measuring the gaze direction and postural sway of a subject is disclosed herein. The system generally includes an eye movement tracking device, a head position detection device, a postural sway detection device, and a data processing device operatively coupled to the eye movement tracking device, the head position detection device, and the postural sway detection device. During the execution of the method, the eye movement and/or eye position of the subject is measured using the eye movement tracking device, the position of the head of the subject is measured using the head position detection device, and the postural sway of the subject is measured using the postural sway detection device. A method for measuring the eye movement and/or eye position and postural sway of a subject during a balance test and/or a concussion screening test and a method for assessment of a subject are also disclosed herein.

Claims

1. A method for concurrently measuring the gaze direction and postural sway of a subject, the method comprising the steps of:

providing an eye movement tracking device configured to track eye movement and/or eye position of the subject while the subject performs a balance test and/or a concussion screening test, the eye movement tracking device being configured to output one or more first signals that are representative of the detected eye movement and/or eye position of the subject, the eye movement tracking device comprising at least one of the following;

(i) a video camera, (ii) an infrared sensor, (iii) an ultrasonic sensor, and (iv) an electrooculographic sensor;

providing a head position detection device, the head position detection device configured to detect a position of a head of the subject and output one or more second signals that are representative of the detected position of the head of the subject, the head position detection device comprising one or more inertial measurement units;

providing a postural sway detection device, the postural sway detection device configured to detect a postural sway of the subject while the subject performs the balance test and/or the concussion screening test, the postural sway detection device being configured to output one or more third signals that are representative of the detected postural sway of the subject, the postural sway detection device comprising a force or balance plate;

providing a data processing device operatively coupled to the eye movement tracking device, the head position detection device, and the postural sway detection device, the data processing device configured to receive the one or more first signals that are representative of the detected eye movement and/or eye position of the subject, the one or more second signals that are representative of the detected position of the head of the subject, and the one or more third signals that are representative of the detected postural sway of the subject, the data processing device further configured to determine one or more gaze directions of the subject using the one or more first signals and the one or more second signals, and to determine a postural sway of the subject using the one or more third signals;

positioning the subject in an upright position on a surface;

positioning the eye movement tracking device on the subject or on an object proximate to the subject;

positioning the head position detection device on a head of the subject or on an object proximate to the head of the subject;

instructing the subject to displace his or her head back and forth in an oscillatory manner over a prescribed range;

measuring eye movement and/or eye position of the subject using the eye movement tracking device that comprises at least one of the following;

(i) the video camera, (ii) the infrared sensor, (iii) the ultrasonic sensor, and (iv) the electrooculographic sensor, and measuring head position of the subject using the head position detection device that comprises the one or more inertial measurement units while a portion of the body of the subject is displaced by the subject, and outputting the one or more first signals that are representative of the detected eye movement and/or eye position of the subject from the eye movement tracking device and outputting the one or more second signals that are representative of the detected position of the head of the subject from the head position detection device;

measuring the postural sway of the subject using the postural sway detection device that comprises the force or balance plate while measuring the eye movement and/or eye position of the subject and the position of the head of the subject, and outputting the one or more third signals that are representative of the postural sway of the subject from the postural sway detection device;

determining, by using the data processing device, gaze direction data for the subject from the one or more first signals output by the eye movement tracking device and the one or more second signals output by the head position detection device, wherein determining the gaze direction data for the subject comprises computing the gaze direction of the subject based upon the detected position of the head of the subject and the detected eye position of the subject;

determining, by using the data processing device, postural sway data for the subject from the one or more third signals output by the postural sway detection device;

determining whether the subject is displacing his or her head over the prescribed range by comparing the head position determined by using the head position detection device to a predetermined head displacement range;

determining, by using the data processing device, one or more gaze direction deviation values based upon the gaze direction data determined for the subject, the one or more gaze direction deviation values quantifying instances during the balance test and/or the concussion screening test where the subject is unable to follow a particular target with his or her eyes;

determining, by using the data processing device, a balance sway score for the subject based upon the postural sway data determined for the subject, the balance sway score comprising at least one of;

(i) a maximum sway of the center-of-pressure of the subject, (ii) a maximum sway of the center-of-gravity of the subject, and (iii) a confidence area for a path of the center of pressure of the subject; and

computing, by using the data processing device, an adjusted balance sway score for the subject by adjusting the balance sway score determined for the subject by a numerical factor proportionate to the one or more gaze direction deviation values.

2. The method according to claim 1, wherein the force or balance plate includes:

a force receiving component having a top surface for receiving at least one portion of the body of the subject; and

at least one force transducer disposed underneath the force receiving component, and the at least one force transducer supporting the force receiving component, the at least one force transducer configured to sense one or more measured quantities and output the one or more third signals, the one or more third signals being representative of forces and/or moments being applied to the top surface of the force receiving component of the force measurement assembly by the subject, and the at least one force transducer comprising a pylon-type force transducer or a force transducer beam.

3. The method according to claim 1, wherein the step of positioning the eye movement tracking device on the subject or on an object proximate to the subject further comprises positioning the eye movement tracking device on glasses or goggles worn by the subject during the performance of the balance test and/or the concussion screening test.

4. The method according to claim 1, wherein the one or more inertial measurement units include an accelerometer configured to detect linear acceleration and a gyroscope configured to detect angular velocity;

and

wherein the step of measuring the head position of the subject using the head position detection device further comprises measuring the head position of the subject using the accelerometer and the gyroscope of the one or more inertial measurement units, and the detected position of the head of the subject is determined by the data processing device based upon the linear acceleration detected by the accelerometer and the angular velocity detected by the gyroscope.

5. A method for concurrently measuring the head position and postural sway of a subject, the method comprising the steps of:

providing a head position measurement device configured to measure a position of a head of the subject while the subject performs a balance test and/or a concussion screening test, the head position measurement device comprising one or more inertial measurement units, the head position measurement device being configured to output one or more first signals that are representative of the detected head position of the subject;

providing a postural sway detection device, the postural sway detection device configured to detect a postural sway of the subject while the subject performs the balance test and/or the concussion screening test, the postural sway detection device being configured to output one or more second signals that are representative of the detected postural sway of the subject;

providing a data processing device operatively coupled to the postural sway detection device and head position measurement device, the data processing device configured to receive the one or more second signals that are representative of the detected postural sway of the subject, the data processing device further configured to determine the postural sway of the subject using the one or more second signals, the data processing device further configured to receive the one or more first signals that are representative of the detected position of the head of the subject from the head position measurement device, and to determine a head angular position of the subject from the one or more first signals output by the head position measurement device;

positioning the subject in an upright position on a surface;

instructing the subject to displace his or her head back and forth in an oscillatory manner over a prescribed angular range;

measuring the position of the head of the subject using the head position measurement device that comprises the one or more inertial measurement units;

measuring the postural sway of the subject using the postural sway detection device while measuring the position of the head of the subject, and outputting the one or more second signals that are representative of the postural sway of the subject from the postural sway detection device;

determining, by using the head position measurement device, an angular position of the head of the subject from the one or more first signals output by the head position measurement device as the subject displaces his or her head over the prescribed angular range, wherein determining the head angular position of the subject further comprises determining, by using the data processing device, the angular position of the head of the subject as the subject displaces his or her head over the prescribed angular range at a speed of rotation based on beats per minute of a metronome;

determining, by using the data processing device, postural sway data for the subject from the one or more second signals output by the postural sway detection device; and

determining whether the subject is displacing his or her head over the prescribed angular range by comparing the angular position of the head of the subject determined by using the head position measurement device to a predetermined head displacement range.

6. The method according to claim 5, wherein the postural sway detection device comprises a force or balance plate;

and

wherein the step of measuring the postural sway of the subject using the postural sway detection device further comprises measuring the postural sway of the subject using the force or balance plate.

7. The method according to claim 5, wherein the one or more inertial measurement units include an accelerometer configured to detect linear acceleration and a gyroscope configured to detect angular velocity;

and

wherein the step of measuring the position of the head of the subject using the head position measurement device further comprises measuring the position of the head of the subject using the accelerometer and the gyroscope of the one or more inertial measurement units, and the position of the head of the subject is determined by the data processing device based upon the linear acceleration detected by the accelerometer and the angular velocity detected by the gyroscope.

8. The method according to claim 5, wherein the the force or balance plate includes:

a force receiving component having a top surface for receiving at least one portion of the body of the subject; and

at least one force transducer disposed underneath the force receiving component, and the at least one force transducer supporting the force receiving component, the at least one force transducer configured to sense one or more measured quantities and output the one or more second signals, the one or more second signals being representative of forces and/or moments being applied to the top surface of the force receiving component of the force measurement assembly by the subject, and the at least one force transducer comprising a pylon-type force transducer or a force transducer beam.

9. A method for assessment of a subject, the method comprising the steps of:

providing a measurement assembly configured to receive a subject thereon, the measurement assembly including;

a surface for receiving at least one portion of a body of a subject, and

at least one measurement device, the at least one measurement device configured to sense one or more measured quantities and output one or more first signals that are generated based upon the subject'"'"'s contact with the surface;

providing an eye movement tracking device configured to track eye movement and/or eye position of the subject while the subject performs one or more tasks and/or tests, the eye movement tracking device being configured to output one or more second signals that are representative of the detected eye movement and/or eye position of the subject, the eye movement tracking device comprising at least one of the following;

(i) a video camera, (ii) an infrared sensor, (iii) an ultrasonic sensor, and (iv) an electrooculographic sensor;

providing a head position measurement device configured to measure a position of a head of the subject while the subject performs the one or more tasks and/or tests and to output one or more third signals, the head position measurement device being in the form of one or more inertial measurement units, the one or more inertial measurement units comprising an accelerometer configured to detect linear acceleration and a gyroscope configured to detect angular velocity;

providing a data processing device operatively coupled to the at least one measurement device of the measurement assembly, the eye movement tracking device, and the one or more inertial measurement units;

positioning the subject on the measurement assembly;

instructing the subject to perform a first task, which involves one or more changes in eye position by the subject, and a second task, which comprises one or more detectable movements on the surface of the measurement assembly, the first task comprises a first neurocognitive task and the second task comprises a second motor or muscular task;

sensing, by utilizing the at least one measurement device, one or more measured quantities and outputting one or more first signals that are generated based upon the one or more detectable movements on the surface of the measurement assembly;

measuring the eye movement and/or eye position of the subject using the eye movement tracking device that comprises at least one of the following;

(i) the video camera, (ii) the infrared sensor, (iii) the ultrasonic sensor, and (iv) the electrooculographic sensor, and measuring the position of the head of the subject using the one or more inertial measurement units while the subject performs the first neurocognitive task, and outputting the one or more second signals that are representative of the detected eye movement and/or eye position of the subject from the eye movement tracking device and outputting the one or more third signals that are representative of the detected position of the head of the subject from the one or more inertial measurement units;

receiving, at the data processing device, the one or more first signals that are generated based upon the one or more detectable movements of the subject on the surface of the measurement assembly, the one or more second signals that are representative of the detected eye movement and/or eye position of the subject, and the one or more third signals that are representative of the detected position of the head of the subject;

computing, by using the data processing device, one or more numerical values from the one or more first signals outputted by the at least one measurement device;

determining, by using the data processing device, one or more changes in eye position of the subject from the one or more second signals output by the eye movement tracking device and one or more changes in the position of the head of the subject from the one or more third signals output by the one or more inertial measurement units;

quantitatively determining, by using the data processing device, a subject'"'"'s performance during the first neurocognitive task and the second motor or muscular task, the assessment of the subject'"'"'s performance of the first neurocognitive task being based at least partially upon the one or more changes in eye position of the subject and one or more changes in the position of the head of the subject, the assessment of the subject'"'"'s performance of the second motor or muscular task being based at least partially upon the one or more numerical values, the subject'"'"'s performance of the first neurocognitive task being quantitatively expressed in terms of one or more first performance values and the subject'"'"'s performance of the second motor or muscular task being quantitatively expressed in terms of one or more second performance values, the one or more first performance values for assessing the subject'"'"'s performance of the first neurocognitive task comprising one or more of the following;

(i) an eye pursuit performance parameter specifying an amount that one or more eyes of the subject lag behind an intended target, (ii) an eye velocity of one or more eyes of the subject, (iii) an eye pursuit performance ratio of eye velocity to target velocity for the subject, (iii) an accuracy parameter specifying an accuracy of one or more eyes of the subject, and (iv) an eye latency parameter specifying a time for the subject to initiate eye movements, and the one or more second performance values for assessing the subject'"'"'s performance of the second motor or muscular task comprise one or more of the following;

(i) a maximum sway range of the center of pressure of a force vector applied by the subject on the measurement assembly, (ii) a maximum sway range of the center of gravity of the subject, and (iii) a confidence area for a path of the subject'"'"'s center of pressure; and

assessing, by using the data processing device, one or more medical conditions of the subject by mathematically combining the one or more first performance values for the first neurocognitive task with the one or more second performance values for the second motor or muscular task to obtain an overall combined score for assessing the one or more medical conditions of the subject.

10. The method according to claim 9, wherein the first neurocognitive task comprises reading one or more passages on a visual display device, and wherein the second motor or muscular task comprises maintaining a substantially stationary, upright position on the surface of the measurement assembly.

11. The method according to claim 9, wherein the one or more medical conditions of the subject assessed by using the data processing device comprise one or more of the following:

(i) a traumatic brain injury or concussion, (ii) a neurological disorder or disease, and (iii) a muscular disorder or disease.

12. The method according to claim 9, wherein the measurement assembly comprises one of a force measurement assembly, a pressure measurement assembly, and a contact or timing measurement assembly;

and

wherein the at least one measurement device comprises one of a force transducer, a pressure transducer, and a contact or timing switch.