Method of Precision Eye-Tracking Through Use of Iris Edge Based Landmarks in Eye Geometry

Abstract

In the field of eye tracking, greater accuracy or resolution in monitoring movement of the eye can be gained by digitizing the eye, and tracking the movement of a landmark with fixed size and a fixed location relative to the eye's local coordinate system. The edge of the iris can be used as such a fixed landmark. Through the location and or establishment of at least a portion of the outer edge of the iris and/or an iris center point, both large and small scale eye movements, including but not limited to micro-tremors, can be traced with a higher degree of accuracy. This will aid in the diagnosis of diseases, assessing state of consciousness, and defining brainstem death.

Claims

1 . A method of identifying at least one landmark in the eye comprising the steps of: digitizing an image of the eye; and identifying at least a portion of the edge of the iris from the digitized image of the eye. 2 . The method of claim 1 further including the steps of calculating a geometric center of the iris based upon the edge of the iris. 3 . A method of eye tracking comprising the steps of: digitizing an image of the eye; identifying at least a portion of the edge of the iris from the digitized image of the eye; establishing at least one fixed landmark based upon the identified portion of the edge of the iris; and tracking the movement of the at least one landmark over time. 4 . The method of claim 3 further including the steps of calculating a geometric center of the iris based upon the identified edge of the iris, wherein the geometric center of the iris is one said landmark.
RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Patent Application No. 61/043,349, filed Apr. 8, 2008, entitled “Method of Precision Eye-tracking Through Use of Iris Edge Based Landmarks in Eye Geometry” BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention pertains generally to eye tracking technologies, and more particularly to precision eye tracking through use of relative iris edge based landmarks in eye geometry. [0004] 2. Background Information [0005] In addition to the eyes being the “gateway to the soul” (Herman Melville), a subject's eyes are an incredibly sensitive bio-indicator that can be utilized for many functions. [0006] Eye movement is the voluntary or involuntary movement of the eyes, helping in acquiring, fixating and tracking visual stimuli. In addition, rapid eye movement (REM) occurs during REM sleep. [0007] “Eye tracking is the process of measuring either the point of gaze (“where we are looking”) or the motion of an eye relative to the head. An eye tracker is a device for measuring eye positions and eye movements. Eye trackers are used in a wide array of applications including research in numerous fields, medical diagnosis, psychology, in cognitive linguistics and even in advertising and product design. There are a number of methods for measuring eye movements. The most popular variant is a non-invasive technique that uses video images from which the eye position is extracted. Other methods use search coils or are based on the electro-oculogram. The non-invasive technique for recording eye position relative to the head using a camera to record eye position relative to the head is also known as video oculography or VOG. VOG systems are used by Vestibular Researchers, Ophthalmologist, Otolaryngologists, Physical Therapists, Neurologists, Audiologists, Balance Clinicians, Neurophysiologists, Physiologists, Neuroscientists, Occupational Therapists, and others. [0008] The most widely used current designs are video-based eye trackers. A camera focuses on one or both eyes and records their movement as the subject viewer will often look at some kind of stimulus. Most modern eye-trackers use contrast to locate the center of the pupil. Image processing software is utilized to interpret the images to provide objective data of eye position. This type of image processing software is described in “A GEOMETRIC BASIS FOR MEASUREMENT OF THREE-DIMENSIONAL EYE POSITION USING IMAGE PROCESSING” Vision Res. Volume 36. No. 3, Moore et al., pp 445-459, 1996, which is incorporated herein by reference. In general, most eye tracking devices digitize an image of the, define the pupil using the high contrast difference between the pupil and the rest of the eye, and then define the center of the pupil by approximating a circle of the same size or calculating the centroid of the pupil itself. For relatively large-scale eye movements, such as saccades and nystagmus, this method is appropriate despite of the fact that the pupil changes in size and, to a lesser degree, shape. [0009] Accurate eye position recording and monitoring in three dimensions (3D-yaw, pitch and torsion rotation about line of sight) is a significant clinical diagnostic tool in the field of vestibular disorders such as vertigo and other neurological disorders. [0010] There is a need for greater precision in eye tracking systems. SUMMARY OF THE INVENTION [0011] In the field of eye tracking, greater accuracy or resolution in monitoring the movement of the eye can be gained by digitizing the eye, and tracking the movement of a landmark with fixed size and a fixed location relative to the eye's local coordinate system. At least a portion of the edge of the iris can be used as such a fixed landmark, or simply landmark. Further, by defining at least a portion of the edge of the iris, possibly even calculating its center (or other fixed landmark relative to the calculated iris edge), and tracking a portion of the edge and/or the center over time, both large and small scale eye movements, including but not limited to micro-tremors, can be traced with a higher degree of accuracy. This will aid in the diagnosis of diseases, assessing state of consciousness, and defining brainstem death. [0012] These and other objects of the present invention will be clarified in the following description which is taken together with the attached figures in which like reference numerals represent like elements throughout. BRIEF DESCRIPTION OF THE DRAWINGS [0013] FIG. 1 is a schematic view of an image of a subject's eye; [0014] FIG. 2 is a schematic view of an image of the subject's eye of FIG. 1 illustrating a representative change in pupil size and shape; [0015] FIG. 3 is a schematic representation of a relative location marker in accordance with one aspect of the present invention; and [0016] FIG. 4 is a schematic representation of portions of calculating a geometric center of an iris in accordance with one aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0017] A complete understanding of the invention will be obtained from the following description when taken in connection with the accompanying drawing figures, wherein like reference characters identify like parts throughout. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting. [0018] As discussed above, most eye tracking devices digitize an image of the, define the pupil using the high contrast difference between the pupil and the rest of the eye, and then define the center of the pupil by approximating a circle of the same size or calculating the centroid of the pupil itself. For relatively large-scale eye movements, such as saccades and nystagmus, this method is appropriate despite of the fact that the pupil changes in size and, to a lesser degree, shape. However, greater accuracy or even resolution in monitoring the movement of the eye can be gained by digitizing the eye, and tracking the movement of a landmark with fixed size and a fixed location relative to the eye's local coordinate system. The edge of the iris can be used as such a fixed landmark. The present invention provides that by defining or establishing at least a portion of the outer edge of the iris both large and small scale eye movements, including but not limited to micro-tremors, can be traced with a higher degree of accuracy. This will aid in the diagnosis of diseases, assessing state of consciousness, and defining brainstem death. [0019] The term landmark within the meaning of the present application will reference a perceptible or visible artifact that is fixed relative to the local co-ordinate system of the eye. The eye defines a local co-ordinate system, often represented with an axis “through” the center of the pupil generally along a gaze path and two perpendicular axes thereto. It does not matter where the local co-ordinate system is established within the eye, rather that the artifact is fixed in such a local system such that it is a landmark or a fixed landmark. In other words the landmarks will move with the eye. [0020] The concepts of the present invention can be explained in connection with FIGS. 1-2 . In these figures the wide variation in the pupil size (and shape) will illustrate that the pupil monitoring methods results in a certain amount of error. The pupil center is established typically by approximating the shape as a circle, and, the center of the circle (the assumed center of the eye), in theory remains unchanged as the circle expands in diameter. Due to changes in pupil diameter. However these are merely approximations that lead to noise in the system that prevents the system from identifying small eye movements, such as micro-tremors. [0021] The present invention utilized at least a portion of the outer edge of the iris as a landmark for tracking eye movement. As shown in FIG. 3 , the iris outer segment, namely the lower outer quadrant, can be used as a landmark and this segment viewed to determine eye movement. The representation in FIG. 3 illustrates that the eye position has not moved from FIG. 1-2 even though the pupil diameter and shape has changed between these two representations. [0022] The image processing for establishing the outer iris edge is substantially the same as for pupil edge detection, and is the same as general edge detection in image processing as known in the art. The term iris edge is intended to be broad enough to cover various formulations of finding such an image border. For example, in some edge recognition programs, an image will convert the color of different pixels to ranges or even to merely 0 and 1 depending upon a fixed threshold. In order to distinguish between noise and other eye artifacts (eye vessel), the edge detection algorithm may select find the first 1 in a row and verify that the next 2-5 pixels are also 1 before calculating that it is an edge, or may look at the surrounding X pixel values before calculating that the iris edge has been found. The term iris edge will define the edge of the iris within the scope of image edge detection algorithms. [0023] The present invention contemplates detecting the outer iris edge and utilizing at least a portion of this as a landmark for eye tracking. The length of the segment that is utilized can be varied and the quadrant shape is merely an illustration. In some applications a single or distinct iris edge point will be a sufficient landmark to track. A plurality of edge points at different locations or of edge segments at different locations could also be utilized as eye landmarks within the scope of the present invention. [0024] A further aspect of the present invention is to utilize the iris edge to define a center of the iris and to use the center of the iris as an eye tracking landmark. [0025] The center of the iris landmark would be at the centroid of the iris area. The centroid of an area is very similar to the center of mass of a body. The centroid is calculated using only the geometry of the figure. The general function for calculating the centroid of a geometrically complex cross section is most easily applied when the figure is divided into known simple geometries and then applying the formula: [0000] x _ = ∑ x i _  A i ∑ A i y _ = ∑ y i _  A i ∑ A i [0026] The distance from the y-axis to the centroid is x [0027] The distance from the x-axis to the centroid is y [0028] The coordinates of the centroid are ( x , y ). [0029] This calculation of a centroid of the iris is represented in FIG. 4 in schematic fashion. One further aspect is that to calculate the iris centroid the full shape of the iris must be used. Thus the present invention contemplates looking for discontinuities along the originally presumed iris edge, which could be indicative of the lid cutting across the iris portion. In this case the full iris will need to be approximated between the points of discontinuity based upon the general shape of the remaining iris portions. The methods of interpolating between the discontinuities based upon the remaining portions of the iris edge are believed to be well understood. [0030] A further iris based landmark would be a centroid of an iris segment such as a quadrant shown in FIG. 3 . Calculating the centroid of the pie shaped quadrant follows the same formula above and only needs the iris edge for that segment in order for this point to be calculated. [0031] In summary the key feature of the present invention is the use of the iris edge as a basis for establishing landmarks for eye tracking. The iris edge may be used itself as a landmark or collection of landmarks in the form of a single iris edge point, as a single iris edge segment, as a collection of points or segments of the iris edge and combinations of iris edge points and iris edge segments. Further the iris edge may be used to calculate an iris center point, or other distinct point that is used as a landmark for eye tracking, and these can be used individually or in combination with each other. The landmarks that are calculated from the iris edge may be used in combination with the landmarks formed by the iris edge itself. [0032] Further the iris based landmarks (which includes the landmarks formed by the iris itself) of the present invention can be used with known prior art landmarks to improve the prior art tracking methodologies. For example, the present invention can use both pupil center and iris based landmarks to track the eye position. It is believed that the iris edge based landmarks will provide for more precision in eye tracking methodologies and open up greater diagnostic possibilities accordingly. [0033] Although the present invention has been described above by reference to an embodiment of the invention, the present invention is not limited to the embodiments described above. Modifications and variations of the embodiment described above will occur to those skilled in the art, in light of the above teachings without departing from the spirit of the present invention The present invention, therefore, to be limited only as indicated by the scope of the claims appended hereto and equivalents thereto.

Description

Topics

Download Full PDF Version (Non-Commercial Use)

Patent Citations (99)

    Publication numberPublication dateAssigneeTitle
    US-6609523-B1August 26, 2003Philip F. AnthonyComputer based business model for a statistical method for the diagnosis and treatment of BPPV
    US-6796947-B2September 28, 2004Canadian Space AgencyMethod for evaluating vestibular response
    US-5687020-ANovember 11, 1997Samsung Electronics Co., Ltd.Image projector using acousto-optic tunable filter
    US-6629935-B1October 07, 2003The University Of QueenslandMethod and apparatus for diagnosis of a mood disorder or predisposition therefor
    US-4320768-AMarch 23, 1982Georgetown University Medical CenterComputerized electro-oculographic (CEOG) system
    US-2005216243-A1September 29, 2005Simon Graham, Richard Mraz, Konstantine Zakzanis, Lee Jang HComputer-simulated virtual reality environments for evaluation of neurobehavioral performance
    US-5838420-ANovember 17, 1998Bid Instruments LimitedMethod and apparatus for ocular motility testing
    US-6800062-B2October 05, 2004Epley Research, L.L.C.Comprehensive vertigo management
    US-4084182-AApril 11, 1978Laser Video, Inc.Multi-beam modulator and method for light beam displays
    US-6162186-ADecember 19, 2000Beth Israel Deaconess Medical CenterNon-invasive method for diagnosing alzheimer's disease in a patient
    US-6634749-B1October 21, 2003Leica Microsystems (Schweiz) AgEye tracking system
    US-4309608-AJanuary 05, 1982The United States Of America As Represented By The Secretary Of The ArmyFlightline goggle tester
    US-6631989-B2October 14, 2003West Virginia UniversityNon-invasive ocular assessment method and associated apparatus
    US-6542081-B2April 01, 2003William C. TorchSystem and method for monitoring eye movement
    US-6271915-B1August 07, 2001Autonomous Technologies CorporationObjective measurement and correction of optical systems using wavefront analysis
    US-5365941-ANovember 22, 1994Atr Auditory And Visual Perception Research LaboratoriesApparatus for detecting small involuntary movement
    US-5983128-ANovember 09, 1999Centre National De La Recherche ScientifiqueDevice for examining a subject and, in particular, determining his or her vestibular evoked potentials
    US-5368041-ANovember 29, 1994Aspect Medical Systems, Inc.Monitor and method for acquiring and processing electrical signals relating to bodily functions
    US-5481622-AJanuary 02, 1996Rensselaer Polytechnic InstituteEye tracking apparatus and method employing grayscale threshold values
    US-6748275-B2June 08, 2004Respironics, Inc.Vestibular stimulation system and method
    US-5381804-AJanuary 17, 1995Aspect Medical Systems, Inc.Monitor and method for acquiring and processing electrical signals relating to bodily functions
    US-5714967-AFebruary 03, 1998Olympus Optical Co., Ltd.Head-mounted or face-mounted image display apparatus with an increased exit pupil
    US-5305746-AApril 26, 1994Aspect Medical Systems, Inc.Disposable, pre-gelled, self-prepping electrode
    US-5345281-ASeptember 06, 1994John Taboada, William RobinsonEye tracking system and method
    US-5410376-AApril 25, 1995Pulse Medical InstrumentsEye tracking method and apparatus
    US-5130838-AJuly 14, 1992Pioneer Electronic CorporationLaser projection type display unit
    US-6524581-B1February 25, 2003The Children's Medical Center CorporationPrevention and treatment of retinal ischemia and edema
    US-4474186-AOctober 02, 1984Georgetown UniversityComputerized electro-oculographic (CEOG) system with feedback control of stimuli
    US-6113237-ASeptember 05, 2000Ober; Jan Krzysztof, Ober; Jan JakubAdaptable eye movement measurement device
    US-6231187-B1May 15, 2001Queen's University At KingstonMethod and apparatus for detecting eye movement
    US-5792069-AAugust 11, 1998Aspect Medical Systems, Inc.Method and system for the extraction of cardiac artifacts from EEG signals
    US-5980513-ANovember 09, 1999Autonomous Technologies Corp.Laser beam delivery and eye tracking system
    US-6247813-B1June 19, 2001Iritech, Inc.Iris identification system and method of identifying a person through iris recognition
    US-6024707-AFebruary 15, 2000Beth Israel Deaconess Medical CenterNon-invasive method for diagnosing Alzheimer's disease in a patient
    US-6077237-AJune 20, 2000Adaboy, Inc.Headset for vestibular stimulation in virtual environments
    US-5458117-AOctober 17, 1995Aspect Medical Systems, Inc.Cerebral biopotential analysis system and method
    US-4852988-AAugust 01, 1989Applied Science LaboratoriesVisor and camera providing a parallax-free field-of-view image for a head-mounted eye movement measurement system
    US-6669341-B2December 30, 2003Metrologic Instruments, Inc.Ophthalmic instrument having wavefront sensor with multiple imaging devices that simultaneously capture multiple images of an array of spots produced by a lenslet array
    US-3612642-AOctober 12, 1971Bulova Watch Co IncA high-velocity optical scanner including a torsional fork supporting two reflectors
    US-5704369-AJanuary 06, 1998Beth Israel Hospital Association, Inc.Non-invasive method for diagnosing Alzeheimer's disease in a patient
    US-7019778-B1March 28, 2006Eastman Kodak CompanyCustomizing a digital camera
    US-4863259-ASeptember 05, 1989Schneider Michael B, Lloyd Stephen RRapid eye movement sleep state detector
    US-6367932-B1April 09, 2002Bid Instruments LimitedApparatus and method for visual field testing
    US-6637883-B1October 28, 2003Vishwas V. Tengshe, Hemant V. Tengshe, Venkatesh G. TengsheGaze tracking system and method
    US-4006974-AFebruary 08, 1977Resnick Sam LEyeglass structure
    US-5943116-AAugust 24, 1999Johns Hopkins UniversitySystem for imaging an ocular fundus semi-automatically at high resolution and wide field
    US-5813404-ASeptember 29, 1998Aspect Medical Systems, Inc.Electrode connector system
    US-6402320-B1June 11, 2002Childrens Hospital Los AngelesMethods and apparatus for measuring visual acuity in preverbal children
    US-6213943-B1April 10, 2001Marcio Marc AbreuApparatus for signal transmission and detection using a contact device for physical measurement on the eye
    US-5892566-AApril 06, 1999Bullwinkel; Paul E.Fiber optic eye-tracking system
    US-6568808-B2May 27, 2003Alcon Universal Ltd.Eye tracker control system and method
    US-6456261-B1September 24, 2002Evan Y. W. ZhangHead/helmet mounted passive and active infrared imaging system with/without parallax
    US-6943754-B2September 13, 2005The Boeing CompanyGaze tracking system, eye-tracking assembly and an associated method of calibration
    US-2005278004-A1December 15, 2005Steinert Roger F, Overbeck James WLaser system for vision correction
    US-5491492-AFebruary 13, 1996Biocontrol Systems, Inc.Method and apparatus for eye tracking for convergence and strabismus measurement
    US-6299308-B1October 09, 2001Cybernet Systems CorporationLow-cost non-imaging eye tracker system for computer control
    US-5821521-AOctober 13, 1998Symbol Technologies, Inc.Optical scanning assembly with flexible diaphragm
    US-4836219-AJune 06, 1989President & Fellows Of Harvard CollegeElectronic sleep monitor headgear
    US-2006039583-A1February 23, 2006Stefan Bickert, Ulrich Gunther, Paul Hing, Jurgen WieserMethod for recording a charcteristic of at least one object
    US-5098426-AMarch 24, 1992Phoenix Laser Systems, Inc.Method and apparatus for precision laser surgery
    US-6033073-AMarch 07, 2000Potapova; Olga, Mikhaylenok; Yevgeniy (Eugueni) L., Voronina; OlgaVisual training system and apparatus for vision correction, especially for various forms of strabismus ("crossed" eyes)
    US-6032072-AFebruary 29, 2000Aspect Medical Systems, Inc.Method for enhancing and separating biopotential signals
    US-5652756-AJuly 29, 1997Hughes ElectronicsGlass fiber laser system using U-doped crystal Q-switch
    US-2005110950-A1May 26, 2005Thorpe William P., Plant Charles P.Saccadic motion sensing
    US-5942954-AAugust 24, 1999Massachusetts Institute Of TechnologyApparatus and method for measuring vestibular ocular reflex function
    US-2007140531-A1June 21, 2007Honeywell International Inc.standoff iris recognition system
    US-5070883-ADecember 10, 1991Konan Camera Research Institute Inc.Eye movement analyzing device utilizing pupil center-of-gravity data
    US-6697894-B1February 24, 2004Siemens Dematic Postal Automation, L.P.System, apparatus and method for providing maintenance instructions to a user at a remote location
    US-5320109-AJune 14, 1994Aspect Medical Systems, Inc.Cerebral biopotential analysis system and method
    US-2004181168-A1September 16, 2004Plant Charles P., Denman William T., Mckeown Craig A., Humphries Charles K.Saccadic motion sensing
    US-6090051-AJuly 18, 2000Marshall; Sandra P.Method and apparatus for eye tracking and monitoring pupil dilation to evaluate cognitive activity
    US-6459446-B1October 01, 2002Dynamic Digital Depth Research Pty. Ltd.Eye tracking apparatus
    US-5304112-AApril 19, 1994Theresia A. MrklasStress reduction system and method
    US-2002171805-A1November 21, 2002Odom James V., Smith James E., Craven Robert P.M.Non-invasive ocular assessment method and associated apparatus
    US-6275718-B1August 14, 2001Philip LempertMethod and apparatus for imaging and analysis of ocular tissue
    US-2006098087-A1May 11, 2006Ludwig-Maximilians-UniversitatHousing device for head-worn image recording and method for control of the housing device
    US-2005101877-A1May 12, 2005Miller Steven M., Pettigrew John D.Method and apparatus for diagnosis of a mood disorder or predisposition therefor
    US-5963300-AOctober 05, 1999Amt Technologies, Corp.Ocular biometer
    US-2002027779-A1March 07, 2002Cassarly William J., Schuck Miller H.Image generator having an improved illumination system
    US-RE38668-EDecember 07, 2004The Board Of Trustees Of The Leland Stanford Junior UniversityMethod for inferring metal states from eye movements
    US-4572199-AFebruary 25, 1986University Of New HampshireSystem to determine arterial occlusion and other maladies
    US-6120461-ASeptember 19, 2000The United States Of America As Represented By The Secretary Of The ArmyApparatus for tracking the human eye with a retinal scanning display, and method thereof
    US-6574352-B1June 03, 2003Evans & Sutherland Computer CorporationProcess for anticipation and tracking of eye movement
    US-2005079636-A1April 14, 2005White Keith D., Kuldau John M., Leonard Christiana M., Pettigrew John DouglasMethod and apparatus for diagnosing schizophrenia and schizophrenia subtype
    US-5252999-AOctober 12, 1993Nidek Co., Ltd.Laser apparatus including binocular indirect ophthalmoscope
    US-6652458-B2November 25, 2003The Mclean Hospital CorporationADHD detection by eye saccades
    US-2009198148-A1August 06, 2009Lonky Martin LMethods and techniques to measure, map and correlate ocular micro-movement and ocular micro-tremor (omt) signals with cognitive processing capabilities
    US-6089716-AJuly 18, 2000Lashkari; Kameran, Harooni; MarkElectro-optic binocular indirect ophthalmoscope for stereoscopic observation of retina
    US-6099124-AAugust 08, 2000Hidaji; FaramarzOphthalmological system and method
    US-6467905-B1October 22, 2002John S. Stahl, Mark J. Lehmkuhle, Kelvin Wu, Bennett Curtis BurkeAcquired pendular nystagmus treatment device
    US-6659611-B2December 09, 2003International Business Machines CorporationSystem and method for eye gaze tracking using corneal image mapping
    US-6003991-ADecember 21, 1999Erik Scott ViirreEye examination apparatus and method for remote examination of a patient by a health professional
    US-6032064-AFebruary 29, 2000Aspect Medical Systems, Inc.Electrode array system for measuring electrophysiological signals
    US-2005024586-A1February 03, 2005Sensomotoric Instruments GmbhMultidimensional eye tracking and position measurement system for diagnosis and treatment of the eye
    US-2006167670-A1July 27, 2006Deering Michael FPhoton-based modeling of the human eye and visual perception
    US-2002175880-A1November 28, 2002Melville Charles D., Johnston Richard S.Augmented retinal display with view tracking and data positioning
    US-2002085174-A1July 04, 2002Ciaran Bolger, Arms Steven W., Townsend Christopher P., Smith Kurt R.Method and apparatus for monitoring eye tremor
    US-6551575-B1April 22, 2003Neurosciences Research Foundation, Inc.Methods for identifying compounds for motion sickness, vertigo and other disorders related to balance and the perception of gravity
    US-2003028081-A1February 06, 2003Eastman Kodak CompanyADHD detection by eye saccades

NO-Patent Citations (0)

    Title

Cited By (9)

    Publication numberPublication dateAssigneeTitle
    US-2013169532-A1July 04, 2013Grinbath, LlcSystem and Method of Moving a Cursor Based on Changes in Pupil Position
    US-2015146167-A1May 28, 2015CLearlyVenture LimitedMethod and Device for Improving Visual Performance
    US-8668337-B2March 11, 2014TBI Diagnostics LLCSystem for the physiological evaluation of brain function
    US-8860660-B2October 14, 2014Grinbath, LlcSystem and method of determining pupil center position
    US-9101312-B2August 11, 2015TBI Diagnostics LLCSystem for the physiological evaluation of brain function
    US-9265458-B2February 23, 2016Sync-Think, Inc.Application of smooth pursuit cognitive testing paradigms to clinical drug development
    US-9292086-B2March 22, 2016Grinbath, LlcCorrelating pupil position to gaze location within a scene
    US-9380976-B2July 05, 2016Sync-Think, Inc.Optical neuroinformatics
    US-9788714-B2October 17, 2017Iarmourholdings, Inc.Systems and methods using virtual reality or augmented reality environments for the measurement and/or improvement of human vestibulo-ocular performance