Patent Publication Number: US-2019167097-A1

Title: Eye tracking system with biometric identification

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/786,759 filed on Oct. 18, 2017 entitled, “EYE TRACKING SYSTEM WITH BIOMETRIC IDENTIFICATION,” which claims priority to U.S. Provisional Patent Application Ser. No. 62/410,754, entitled “Apparatus for Biometric Identification Within An Eye-Tracking Apparatus For Neuro-Diagnosis,” filed Oct. 20, 2016, the full disclosure of which is hereby incorporated by reference. 
     This application also hereby incorporates by reference: U.S. Pat. No. 9,642,522; U.S. Patent Application Pub. Nos. 2016/0278716, 2017/0172408 and 2018/0092531; and U.S. Patent Application Ser. No. 62/558,069, titled “Eye Tracking System,” filed Sep. 13, 2017. The above-listed patents and applications may be referred to collectively below as “The Incorporated References.” The above-listed patents and applications, as well as all publications, patent applications, patents and other reference material mentioned in this application, are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     This application is directed to medical devices, systems and methods. More specifically, the application is directed to devices, systems and methods for providing eye tracking and biometric identification. 
     BACKGROUND OF THE INVENTION 
     Many central nervous system injuries and abnormalities can be challenging to diagnose and localize within the nervous system. The assignee of the present application has developed methods and systems that use eye tracking measurement to help diagnose and/or localize a number of different central nervous system injuries and abnormalities, such as but not limited to increased intracranial pressure (ICP), concussion, traumatic brain injury (TBI), reduced or impaired cranial nerve function, and the like. Some of these methods and systems are described in the Incorporated References. 
     BRIEF SUMMARY 
     The present application is directed to a system and method that combines eye tracking capabilities with ocular biometric identification of an individual. Using the system and method, biometric identification may be performed before or during an eye tracking session. Identification of the patient may be performed by a cloud-based biometric service. In various embodiments, the biometric identification component of the system may be incorporated into, or added to, any suitable eye tracking system, such as but not limited to the eye tracking systems described in the Incorporated References. 
     These and other aspects and embodiments are described in greater detail below, in reference to the attached drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  are patient-facing, side, and technician-facing views, respectively, of a system for measuring eye tracking, according to one embodiment; 
         FIG. 2  is side-view diagram of an eye tracking system that includes an ocular capture device for biometric identification, according to one embodiment; and 
         FIG. 3  is a flow diagram, illustrating a method for eye tracking and biometric identification, according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The assignee of the present patent application has developed eye tracking devices, systems and methods that may be used to track the movement of a patient&#39;s pupils over time as they follow a video moving across a screen and measure metrics such as distance traveled over time and the ability to coordinate eye movements. Cranial Nerve III and VI palsies, for example, may be identified using this system and method, which includes at least one computer processor that employs an algorithm to perform diagnostic calculations. These devices, systems and methods are described more fully in the Incorporated References. The present application uses the same technology, method and algorithm to provide a non-invasive eye tracking methodology to measure ICP, and combines that technology and methodology with a device and method for biometric identification of the patient. 
     Referring to  FIGS. 1A-1C , an eye tracking, biometric identification and diagnostic system  10  is illustrated, according to one embodiment. The eye tracking portion of system  10  is described in further detail in U.S. Provisional Patent Application Ser. No. 62/558,069, which was previously incorporated by reference. System  10  is used to track a patient&#39;s eye movement and diagnose one or more eye movement abnormalities. In some embodiments, system  10  includes at least one processor, which may further analyze data related to the eye movement abnormalities to help diagnose and/or localize a neurological injury or abnormality, such as but not limited to increased ICP, concussion, TBI, or reduced or impaired cranial nerve function. In use, a stimulus video is presented on system&#39;s  10  LCD stimulus screen  12 , and the patient&#39;s eye movement is tracked over time by an infrared eye tracking camera  14 . Fixed orientation of the patient&#39;s head, relative to the stimulus screen  12  and camera  14 , is ensured by a head rest assembly  18 , which adjusts to a seated or supine patient. System  10  is operated from a touchscreen interface  26 . System  10  is coupled together via a wheeled chassis  20  suitable for wheeling to the examination location. 
     Chassis  20  includes two main parts: a main column  28  supported by a base  22 , and a head rest assembly  18 . Head rest assembly  18  is supported on an arm  24 , which can be raised and lowered using an electrically-driven elevator in main column  28 , controlled by an up/down button  38  ( FIG. 1C ). Arm  24  moves up and down through a vertical slot  29  ( FIG. 1A ) in main column  28 . Four locking castors  32  in base  22  allow the entire unit to be moved, with base  32  being sized to fit underneath a patient bed or gurney. A handle  30  on main column  28  is used to push and/or pull system  10  into place. 
     In one embodiment, main column  28  houses two computers, a power supply, the elevator mechanism, an isolation transformer, and other electrical parts, none of which is visible in the figures. Operator touchscreen interface  26  (also called “operator console  26 ” herein) is located on main column  28 . 
     Head rest assembly  18  includes a chin rest  34  and a forehead rest  36 , to stabilize the patient&#39;s head, stimulus screen  12 , an optical mirror  16  used to fold the optical path allowing for more compact casing, and a high-speed eye tracking camera  14 . The entire head rest assembly  18  can be rotated in the horizontal plane 90 degrees in either direction, for a total horizontal rotation of 180 degrees, and up to 90 degrees in the vertical direction downward to accommodate supine patients. In one embodiment, there are several discrete positions within the vertical rotation where head rest assembly  18  locks into place. Buttons  40  on the back of head rest assembly  18  activate solenoids, so assembly  18  can be rotated vertically and then locked. 
     A standard 110-volt medical grade cord may provide power to system&#39;s  10  elevator mechanism and a 400-watt power supply. The power supply provides regulated DC power to the computers, as well as the solenoid controls in head rest assembly  18 . 
     System  10  includes two computers, which are housed in main column  28  of chassis  20  and thus not visible in the figures. A camera computer, which may be provided by the same manufacturer as the manufacturer of camera  14 , may run the real-time software for camera  14  under a real-time operating system. It detects eye motion events, such as saccades, blinks, and fixations, and computes the gaze coordinates for each eye at 500 Hz, storing the raw data until it is needed by the application. The application computer may be a small form-factor PC that runs a system application for system  10 . The system application provides the user interface, controls the logic flow, displays the stimulus video, processes the raw data from the camera computer, and stores results in persistent storage. 
     The user interacts with the system application through touchscreen interface  26 . Stimulus screen  12  (the second monitor on system  10 ) displays the stimulus media to the patient. Two built-in speakers provide the audio for the stimulus media. 
     In some embodiments, the processor(s) in system  10  is configured to generate a score describing a patient&#39;s eye tracking ability. For example, in one embodiment, system  10  generates a score ranging from 0-20, where the score is interpreted as a binary classification for eye movement abnormalities, and where anything equal to or greater than 10 is a positive result (abnormality present) and everything below 10 is negative (no abnormality). The system&#39;s  10  operating algorithm identifies eye tracking abnormalities and computes the score. 
     In one embodiment, eye tracking camera  14  is an EyeLink 1000 Plus USB (SR Research, Ottawa, Canada) and is used to capture the eye movements of the patient. Camera  14  captures 500 frames of gaze data per second for each eye, with an average accuracy of 0.25 to 0.5 degrees. The illuminators are infrared, and it uses dark pupil eye tracking, in which the infrared sources are offset from camera  14 . This technique typically provides better results across ethnicities and varied lighting conditions. The gaze tracking ranges up to 32 degrees horizontally and 25 degrees vertically. The distance between the subject&#39;s eyes and the camera is 52 cm. The specifications for camera  14 , as provided by the vendor, are shown in Table 1. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 EyeLink Camera Specifications 
               
            
           
           
               
               
            
               
                 Spec 
                 Description 
               
               
                   
               
               
                 Average accuracy of gaze 
                 Down to 0.15 degrees (0.25 degrees to 0.5 
               
               
                 coordinate data 
                 degrees typical) 
               
               
                 sampling rate 
                 Binocular: 250, 500 hz 
               
               
                 End-to-end sample delay 
                 m &lt; 1.8 msec, sd &lt; 0.6 msec @ 1000 hz 
               
               
                 Blink/occlusion recovery 
                 m &lt; 1.8 msec, sd &lt; 0.6 msec @ 1000 hz 
               
               
                 Spatial resolution 
                 &lt;0.01 degrees rms 
               
               
                 Eye tracking principle 
                 Dark pupil - corneal reflection 
               
               
                 Pupil detection models 
                 Centroid or ellipse fitting 
               
               
                 Pupil size resolution 
                 0.2% of diameter 
               
               
                 Gaze tracking range 
                 32 degrees horizontally, 25 degrees 
               
               
                   
                 vertically 
               
               
                 Allowed head movements 
                 ±25 mm horizontal or vertical6, ±10 
               
               
                 without accuracy reduction 
                 mm depth 
               
               
                 Optimal camera-eye distance 
                 Between 40-70 cm 
               
               
                 Glasses compatibility 
                 The user must remove their glasses to use 
               
               
                   
                 the system 
               
               
                 On-line event parsing 
                 Fixation/saccade/blink/fixation update 
               
               
                 Real-time operator feedback 
                 Eye position cursor or position traces. 
               
               
                   
                 Camera images and tracking status. 
               
               
                   
               
            
           
         
       
     
     Eye Tracking Computer 
     As mentioned above, in one embodiment, camera  14  is driven by a dedicated real-time computer running the QNX operating system. The specifications for this eye tracking computer are shown in Table 2. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 EyeLink Computer Specifications 
               
            
           
           
               
               
            
               
                 Spec 
                 Description 
               
               
                   
               
               
                 Design 
                 Pico form factor; 8-layer SBC 
               
               
                   
                 PCB size: 100 mm × 72 mm 
               
               
                 Embedded CPU 
                 Intel Braswell SoC CPU 
               
               
                 Memory 
                 Onboard 4 GB unbuffered DDR3L 1600 MHz DRAM 
               
               
                 Expansion slot 
                 1 full-size mini-PCIE slot 
               
               
                 Storage 
                 SATA III port 
               
               
                   
                 M.2 M-key 2242 slot 
               
               
                 LAN chip 
                 Integrated with Intel i211 AT PCI-E Gigabit LAN chip 
               
               
                   
                 Support fast Ethernet LAN function of providing 
               
               
                   
                 10/100/1000 Mbps Ethernet data transfer rate 
               
               
                 Audio chip 
                 Realtek ALC662 2-CH HD audio codec integrated 
               
               
                   
                 Audio driver and utility included 
               
               
                 BIOS 
                 64 Mbit flash ROM 
               
               
                 Rear I/O 
                 12 V DC-in power jack 
               
               
                   
                 USB 3.0 port (2) 
               
               
                   
                 Display port 
               
               
                   
                 RJ-45 LAN port 
               
               
                 Internal I/O 
                 2-pin internal 12 V DC-in power connector 
               
               
                   
                 SATA power-out connector 
               
               
                   
                 Front panel audio header 
               
               
                   
                 9-pin USB 2.0 header 
               
               
                   
                 Serial port header (2) 
               
               
                   
                 Front panel header 
               
               
                   
                 LAN LED activity header 
               
               
                   
                 LVDS header 
               
               
                   
                 LVDS inverter 
               
               
                   
               
            
           
         
       
     
     System Application Computer 
     As mentioned above, in one embodiment, the system application runs on a mini-ITX board running Windows 10 Pro, configured as a kiosk device. The specifications are shown in Table 3. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 System Application Computer Specifications 
               
            
           
           
               
               
            
               
                 Spec 
                 Description 
               
               
                   
               
               
                 Design 
                 Mini ITX form factor 
               
               
                 CPU 
                 Intel i7 (speed, etc TBD) 
               
               
                 Chipset 
                 Intel H170 
               
               
                 Memory 
                 16 GB dual channel DDR4 
               
               
                 Expansion slot 
                 PCI Express 3.0 × 16 slot 
               
               
                   
                 Vertical half-size mini-PCI Express slot 
               
               
                 Graphics 
                 Intel HD graphics, dual graphics output, 
               
               
                   
                 DVI/HDMI max resolution to 4K × 2K 
               
               
                 Additional 
                 Invidia GeForce 210, DVI/VGA/DisplayPort max 
               
               
                 graphics 
                 resolution to 2560 × 1600 
               
               
                 Audio 
                 7.1 CH HD audio 
               
               
                 LAN 
                 Intel 1219V (gigabit LAN) 
               
               
                   
                 Realtek RTL8111H (gigabit LAN) 
               
               
                 Rear I/O 
                 PS/2 mouse/keyboard port 
               
               
                   
                 DVI port 
               
               
                   
                 HDMI port 
               
               
                   
                 USB 2.0 ports (2) 
               
               
                   
                 USB 3.0 ports (6) 
               
               
                   
                 RJ-45 LAN ports (2) 
               
               
                   
                 HD audio jack 
               
               
                 Storage 
                 SATA 3 256 GB SSD 
               
               
                 BIOS 
                 128 MB AMI UEFI legal BIOS 
               
               
                 Certifications 
                 FCC, CE, WHQL 
               
               
                   
               
            
           
         
       
     
     Stimulus Display 
     Stimulus screen  12 , according to one embodiment, is used to display a video that may last any suitable length of time, such as 220 seconds in one embodiment. In one embodiment, the only purpose of stimulus screen  12  is to display the visual stimulus. The video may be one of several pre-determined videos. These videos may include music videos, clips from children&#39;s movies, sports clips, talent performances, “reality TV” clips, etc. The choice of videos may be designed to appeal to a broad group of subjects. Users of the device may choose which video to display or may ask the patient which one they would like to watch. Additional media selections may be downloaded via a UBS drive, for example. In one embodiment, the video aperture is square, with each side being approximately ¼ the width of the visible display. The trajectory of the displayed video around stimulus screen  12  follows a predefined discrete path, such as 5 cycles along the perimeter of stimulus screen  12  with a velocity of 10 seconds per side, according to one embodiment. In one embodiment, stimulus screen  12  is an GeChic 1303 monitor, with the specifications shown below in Table 4. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Stimulus Screen Specifications 
               
            
           
           
               
               
               
            
               
                   
                 Spec 
                 Description 
               
               
                   
                   
               
               
                   
                 Aspect ratio 
                 1.78:1 
               
               
                   
                 Maximum resolution 
                 1920 × 1080 
               
               
                   
                 Screen size 
                 13.3 inches 
               
               
                   
                 Display type 
                 LED 
               
               
                   
                 Viewing angle 
                 89°/89°/89°/89° 
               
               
                   
                 Contrast ratio 
                 700:1 
               
               
                   
                 Power input 
                 5 V, 2.0 A 
               
               
                   
                   
               
            
           
         
       
     
     Touchscreen Interface 
     Touchscreen interface  26  (which may also be referred to as an “operator console” or simply “touchscreen”) is used by the technician to interact with the system application. In the pictured embodiment, touchscreen interface  26  includes only a touch screen display, meaning that there is no keyboard or other input device. Of course, alternative embodiments may include a keyboard or other input device(s). In one embodiment, touchscreen interface  26  may be a Mimo UM-1080CH-G, with the specifications set forth below in Table 5. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Touchscreen Interface Specifications 
               
            
           
           
               
               
               
            
               
                   
                 Spec 
                 Description 
               
               
                   
                   
               
               
                   
                 Capacitive touchscreen 
                 Yes 
               
               
                   
                 Maximum resolution 
                 1280 × 800 
               
               
                   
                 Screen size 
                 10.1 inches 
               
               
                   
                 Viewing angle 
                 170° × 170° 
               
               
                   
                 Contrast ratio 
                 800:1 
               
               
                   
                 Power input 
                 6 W 
               
               
                   
                   
               
            
           
         
       
     
     Head Rest Assembly 
     Chin rest  34  and forehead rest  36  are used to stabilize the user&#39;s head and maintain appropriate distance from stimulus screen  12  during eye tracking. Chin rest  34  may be made from the non-toxic, non-hazardous biodegradable plastic Bakelite resin (polyoxybenzylmethylenglycolanhydride), and forehead rest  36  may be constructed from aluminum covered with a thin EPDM (ethylene propylene diene terpolymer) foam pad blended with neoprene and SBR (styrene-butadiene rubber) pad with closed-cell construction, to resist liquid, solid, and gas absorbance. Both surfaces may be wiped using sterile alcohol swabs before and after each use. 
     System Calibration 
     The calibration information below in Table 6 applies to the components of system, according to one embodiment. 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 System Calibration 
               
            
           
           
               
               
            
               
                 Component 
                 Calibration notes 
               
               
                   
               
               
                 Eye tracking 
                 A focus knob on the bottom of the unit adjusts focus. 
               
               
                 camera 14 
                 Once it is set, it generally does not need any adjustment 
               
               
                   
                 unless the knob is accidentally jarred. The user guide 
               
               
                   
                 provides instructions for adjusting focus. Gaze point 
               
               
                   
                 calibration is not required. System 10 uses camera&#39;s 14 
               
               
                   
                 built-in default calibration for calculating gaze points 
               
               
                   
                 from pupil detection and corneal reflection measurements. 
               
               
                 Stimulus 
                 Stimulus display 12 is surrounded by bezels to reduce the 
               
               
                 display 12 
                 size of display 12 to effectively be 4:3 instead of 1.78:1. 
               
               
                   
                 The software uses calibration information stored in the 
               
               
                   
                 device configuration file to determine what part of the 
               
               
                   
                 display is actually visible to the user. The configuration, 
               
               
                   
                 once set, does not change since the bezels and display are 
               
               
                   
                 fixed. These configuration parameters will be set at the 
               
               
                   
                 factory before being shipped to the end user. 
               
               
                 Operator 
                 The aspect ratio will be set when the unit is assembled. 
               
               
                 console 26 
                 No additional calibration by the user is needed. 
               
               
                 Computers 
                 The computers perform a boot sequence upon startup that 
               
               
                   
                 will run diagnostic procedures to ensure correct operation. 
               
               
                   
                 No additional calibration of the computers is necessary. 
               
               
                 Head rest 
                 At assembly time, the head rest assembly 18 rotation 
               
               
                 assembly 18 
                 limits are set and fixed into place. No additional 
               
               
                 rotation 
                 calibration is needed. 
               
               
                 Chin rest 34 
                 The user should use an alcohol wipe before and after 
               
               
                 and forehead 
                 each patient in order to sterilize the parts of the device 
               
               
                 rest 36 
                 that come in contact with the patient. Instructions for 
               
               
                   
                 this are included in the user guide. 
               
               
                 Elevator 
                 At assembly time, the elevator height limits are set and 
               
               
                   
                 fixed into place. No additional calibration is needed. 
               
               
                   
                 The elevator is not expected to require any maintenance 
               
               
                   
                 during the normal lifetime of the device. 
               
               
                 Optical 
                 Dust or dirt may accumulate in the camera/mirror bay 
               
               
                 mirror 16 
                 of head rest assembly 18. User guide instructions provide 
               
               
                   
                 information about how to remove the debris using 
               
               
                   
                 compressed air if needed. 
               
               
                   
               
            
           
         
       
     
     Principle of Operation 
     System  10  measures a patient&#39;s eye tracking while watching a video move around stimulus screen  12  and then analyzes the data from the eye tracking measurements, using an algorithm, to extract clinically relevant eye measures by using temporal assessment. The patient watches a video moving inside an aperture with a set trajectory for 220 seconds (in one embodiment) at a fixed distance from stimulus screen  12 . The position of each pupil is recorded over time elapsed, as the video travels on its time course, enabling detection of impaired ability to move the eyes relative to time and therefore relative to each other. The algorithm inputs are measurements of the individual (left and right) eye-movements, averaged over the 5 cycles that the eyes move while watching the 220-second video that plays in an aperture moving around screen  12 . In one embodiment, the algorithm output is a “BOX Score,” calculated by multiplying multiple constants with different individual parameters, and summing those factors. 
     System Computer Processing Overview 
     Central to the operation of system  10  is how the software processes raw gaze data from the eye tracking camera and calculates a BOX score. An overview of this process is outlined below.
         1. During a tracking, system  10  collects 220 seconds of binocular gaze data at 500 Hz as the patient watches the video stimulus go around screen  12  five times. The trajectory is as follows:
           a. The stimulus starts in the upper left corner and remains stationary for 10 seconds.   b. The stimulus moves around the outer edges of the stimulus screen in a clockwise fashion, taking ten seconds for each side or 40 second for each cycle. The stimulus makes five cycles plus one extra side along the top for a total of 220 seconds.   
           2. The first and last ten seconds of data are discarded.   3. The processing first removes blink data. These data become “NaN&#39;s” (not a number) in the processing and are ignored in all subsequent processing.   4. Next, the gaze data are normalized, and several dozen metrics are computed from the normalized data, which characterize the patient&#39;s tracking. Some of the metrics are conjugate values that evaluate the differences between the left and right eye.   5. The most correlated metrics are then fed into a polynomial formula that produces a BOX score between 0 and 20. Scores less than 10 are considered normal.   6. The algorithm also computes a quality score (1 to 10 with 10 being the best) based on the percentage of NaN&#39;s that were in the raw data.       

     Referring now to  FIG. 2 , a diagrammatic representation of a combined eye tracking and biometric identification system  100  is provided. In this embodiment, system  100  includes an ocular biometric capture device  110 , a stimulus monitor  112 , an eye tracking camera  114 , a central processing unit (CPU)  116 , a chin rest  134 , a forehead rest  136 , and a biometric matching engine and database  120 . Any or all of the details regarding the eye tracking features and components of system  100  may be the same as, or similar to, those described above in relation to system  10  and  FIGS. 1A-1C . During use, the patient&#39;s face is stabilized in chin rest  134  and forehead rest  136 , at a precise distance from stimulus monitor  112 . Eye tracking camera  114  is positioned just below stimulus monitor  112  and captures images from the eyes. Ocular biometric capture device  110  is positioned just above stimulus monitor  112  and captures biometric data from the eyes. In an alternative embodiment, eye tracking camera  114  may be configured to capture ocular biometric data from the patient, thus eliminating the need for a separate ocular capture device  110 . Central processing unit  116  controls the display of the stimulus media, eye tracking camera  114  and ocular biometric capture device  110 . Central processing unit  116  also communicates with cloud-based biometric matching engine and database  120 . 
     Referring now to  FIG. 3 , a flow diagram of a combined eye tracking and biometric identification method  200  is provided. In the illustrated embodiment, biometric identification and eye tracking are shown as if performed in parallel. This may be the case in some embodiments, but according to various embodiments, it is possible to perform biometric identification before, during and/or after eye tracking. In other words, method  200  is not limited to one particular timing or sequence. 
     In the illustrated embodiment, at the beginning of the procedure  201 , two threads of execution are initiated, one that begins an ocular biometric data capture method  202  and one that begins an eye tracking method  212 . Eye tracking method  212  may be the same as, or similar to, the methods described above. In  FIG. 3 , the details of eye tracking method  212  are not illustrated and instead are shown simply as eye-tracking session complete  214 , which is typically signaled by the end of the stimulus video. Biometric method  202  involves capturing an ocular biometric sample and sending it to a cloud-based biometric identification service  204 , for example including matching engine and database  120  ( FIG. 2 ). The service attempts to match the biometric sample with a record in the biometric data  206 . If a match is found  208 , biometric method  202  associates the patient with the current eye-tracking session, and waits until the eye tracking session is complete  214 . If a match is not found  210  and the eye tracking is not complete, another biometric sample is taken  202  and sent to the cloud-based service  204 . This process continues until either a match is found or the eye-tracking session is complete. Sending multiple biometric samples to the cloud-based service decreases the chance of the ultimate result being that no match is found, even though the patient is enrolled. If the eye tracking session completes without a match being found, the patient&#39;s demographic data is requested, linked to the biometric sample(s), and sent to the cloud-based service as a new enrollment  218 . This method  200  is just one embodiment, and variations may be made without departing from the scope of the disclosure. For example, alternative embodiments may include fewer steps, greater numbers of steps and/or different ordering of steps. 
     The foregoing is believed to be a complete and accurate description of various embodiments of a system and method for assessing glaucoma in a patient. The description is of embodiments only, however, and is not meant to limit the scope of the invention set forth in the claims.