Faro An Interactive Interface For Remote Administration Of Clinical Tests Based On Eye Tracking


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A challenging goal today is the use of computer networking and advanced
monitoring technologies to extend human intellectual capabilities in medical decision making. Modern commercial eye trackers
are used in many of research fields, but the improvement of eye tracking technology, in terms of precision on the eye movements capture, has led to consider the eye tracker as a tool for vision analysis, so that its application in medical research, e.g. in ophthalmology, cognitive psychology and in neuroscience has grown considerably. The improvements of the human eye tracker interface become more and more important to allow medical doctors to increase their diagnosis capacity, especially if the interface allows them to remotely administer the clinical tests more appropriate for the problem at hand. In this paper, we propose a client/server eye tracking system that provides an interactive system for monitoring patients eye movements depending on the clinical test administered by the medical doctors. The system supports the retrieval of the gaze information and provides statistics to both medical research and disease diagnosis.

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Faro An Interactive Interface For Remote Administration Of Clinical Tests Based On Eye Tracking

  1. 1. An Interactive Interface for Remote Administration of Clinical Tests Based on Eye Tracking A. Faro, D. Giordano, C. Spampinato, D. De Tommaso, S. Ullo∗ Department of Informatics and Telecommunication Engineering University of Catania, Catania, 95125, Italy Abstract lowing an off-line analysis of the obtained results. In this paper, we propose a client/server eye tracking-based archi- A challenging goal today is the use of computer networking and ad- tecture for handling a medical doctor-patient real-time interaction, vanced monitoring technologies to extend human intellectual capa- both locally and remotely, which requires a very low interaction at bilities in medical decision making. Modern commercial eye track- the patient side and offers a customizable and powerful interface at ers are used in many of research fields, but the improvement of eye the medical doctor (for simplicity doctor) side. For ”customizable” tracking technology, in terms of precision on the eye movements we mean the possibility, given to the doctors, to set-up new tests capture, has led to consider the eye tracker as a tool for vision (not implemented in the platform) according to medical standards analysis, so that its application in medical research, e.g. in oph- and novel tests for discovery hidden aspects of the analyzed dis- thalmology, cognitive psychology and in neuroscience has grown eases. The main challenges of the proposed system are: first, the considerably. The improvements of the human eye tracker inter- opportunity of performing remote visual tests, without the necessity face become more and more important to allow medical doctors to for the doctor and the patient to be in the same place; second, the increase their diagnosis capacity, especially if the interface allows low coupling of the designed architecture permits to perform and them to remotely administer the clinical tests more appropriate for record test sessions and analyze all the collected data and statistics the problem at hand. In this paper, we propose a client/server eye at a different time. But the most important goals are: providing an tracking system that provides an interactive system for monitoring high customizable test tool for the doctor, who can perform stan- patients eye movements depending on the clinical test administered dard tests as well as patient-specific tests, just configuring them by the medical doctors. The system supports the retrieval of the through a friendly graphical interface; and finally obtaining a direct gaze information and provides statistics to both medical research feedback from the patient, through his gaze behavior, without re- and disease diagnosis. quiring a body motion (e.g. pushing a button) or any other explicit stimuli response. Keywords: Eye Tracking, Opthalmology, Neuroscience, Medical The paper is so organized: the next section introduces the topic of Research, Vision Research, Cognitive Psychology gaze data analysis for biomedical applications. Section 3 shows the main features of the modern eye tracking systems, giving more de- tails about the adopted Tobii T60 eye tracker. Section 4 illustrates 1 Introduction the proposed architecture. Finally, in section 5 conclusion and fu- ture work are pointed out. In the last years eye tracking systems have been often used in human-computer interaction research, mainly for evaluating the us- ability of graphical user interfaces [Teiwes et al. 1999], but also in 2 Eye Movements Analysis for Biomedical both e-learning applications, [Asteriadis et al. 2009], and medical Applications field, e.g. in [Nicolaou et al. 2004]. The analysis of eye move- ments and visual attention represents a new field of research, still in Eye movements can be used as a powerful experimental test of the expansion. Modern eye trackers have the advantage of being very brain functions and health conditions, e.g. in [Theeuwes et al. 2009] easy to install and to use and they also achieve unobtrusive eye vi- a hypothesis of the interactions between working memory, attention sion tests, providing a good precision. Commercial eye tracking and eye movements is pointed out. To maintain a clear image of a systems are able to collect a large number of real-time gaze infor- moving target the oculomotor system uses saccadic eye movements mation, e.g. pupil diameter, right and left eye position and their for correcting the position between the eye and the target. For a distance, which are very useful to understand the characteristics of clear vision, saccades must be fast and accurate, so knowledge on human vision and link them to the health status. Indeed, several how saccadic movements work, may support the study of the neu- studies confirm the relationship between eye movements, visual at- ral system and highlight various neurological disorders. In fact, the tention, gaze parameters and many human diseases, involving dif- ocular process of saccades is performed smoothly in healthy pa- ferent areas of ophthalmology as well as neuroscience [Perry and tients but suffers of many documented abnormalities in people af- Zeki 2000] and [Murray et al. 2009]. More in detail, an eye tracker fected by different kinds of disease, including Parkinson’s disease allows researchers to process gaze information for several purposes: [Mannan et al. 2008], Huntington’s disease [Blekher et al. 2009], discovery of pathologies related to eye vision, retrieval of relation- Alzheimer’s dementia [Tippett and Sergio 2006], diabetes, dyslexia ships with new pathologies, ophthalmology training for medical and so on. That’s the reason why the analysis of eye movements students, or simply performing and recording real-time tests, al- and attention assumes a basic role in medical research and diag- ∗ e-mail: nosis. This leads to the importance of having a powerful tool to {afaro, dgiordan, cspampin,ddetom,sullo}@diit.unict.it perform accurate and customizable vision tests, to collect this in- Copyright © 2010 by the Association for Computing Machinery, Inc. formation in a proper manner and to allow researchers to discover Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed possible disorders. Actually, there are many eye movements tests, for commercial advantage and that copies bear this notice and the full citation on the which can be performed with expensive medical tools to highlight first page. Copyrights for components of this work owned by others than ACM must be specific human vision characteristics. Some of the most widely honored. Abstracting with credit is permitted. To copy otherwise, to republish, to post on used tests are: perimetry, visual attention, eye velocity and con- servers, or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from Permissions Dept, ACM Inc., fax +1 (212) 869-0481 or e-mail trast sensitivity. A disorder detected by one of these tests, can be permissions@acm.org. associated to a specific disease. For instance, a low contrast sen- ETRA 2010, Austin, TX, March 22 – 24, 2010. © 2010 ACM 978-1-60558-994-7/10/0003 $10.00 69
  2. 2. sitivity can be a symptom of certain eye conditions or disorders the form of real-time coordinates, and the eyes information coming such as glaucoma, cataracts or diabetic retinopathy, whereas a vi- from Tobii eye tracker. sual field loss can be a symptom of Alzheimer’s disease [Whittaker et al. 2002]. These tests are performed through test-oriented med- ical instruments, which are very expensive and can perform just a specific task. The novel idea of this work, is to carry out all these tests with the help of a single eye tracking system, so that a large amount of additional information can be provided for more effec- tive diagnosis and for medical research improvement. 3 The Proposed Architecture In this paper we propose a system architecture that allows doctors to perform local or remote vision tests on patients, in order to ex- tract useful information in real-time, for a subsequent diagnosis and analysis. This leads to a reduction of costs for performing specific tests and can be used for huge screenings in non specialized medical centers. Indeed, the main peculiarity of the proposed architecture is providing an eye tracking-based system, to be used for a number of customizable vision tests, instead of using multiple specific and Figure 1: The Proposed Architecture. At the doctor’s side the client expensive medical instruments. applications runs, it is connected both to the patient application The proposed architecture, shown in fig. 1, consists of three main and to the TET server of the Tobii T60. At the patient’s side the components: application acts like a server, providing the services to perform cal- • Hardware instrument: a Tobii T60 eye tracker device at the ibration and tests. patient side, connected to a personal computer and another PC at the doctor side; 3.1 The Developed Tool • Management software: a client-server system, based on the eye tracker which allows the remote analysis of gaze informa- In this section the developed tool that implements the above ar- tion; chitecture management software, providing the basic functions for network communication and a number of additional features related • Human operators: the patient, who needs to perform a spe- to vision tests, is described. This system is based on two user inter- cific vision test, a doctor (or a medical operator) who executes faces: the doctor interface, where the tests to be administered can tests and the doctor himself, for the subsequent analysis and be chosen and the monitoring of the patient can be done, and the pa- diagnosis. tient’s interface, where the tests provided by the doctor appear. The client/server communication is implemented via remoting objects, Tobii T60 eye tracker device looks like a simple computer monitor so that the patient side provides a number of services accessible but it provides a camera-based eye tracking system, where sensors through a unique URL. Both client and server processes are written are placed inside the monitor itself. This eye tracker works through in C#, using the DLLs provided by Tobii T60 SDK. a Tobii Eye Tracker (TET) server, which processes the camera im- ages and sensors data for mapping the results over screen coordi- The main features of the proposed system are: nates. In order to communicate to the TET server it is possible to use the available APIs, enclosed into the provided Tobii T60 SDK, • Very low interaction at the patient side, because no knowledge at two different abstraction levels: low level, using Microsoft COM on how the software works is required. The tests handling is objects and high level, using Eye Tracker Components APIs, for all performed by the client at the doctor side. simplifying the applications development. • Configurable and powerful interaction at the doctor side: the The system management software is based on a client/server ar- doctor has a friendly interface for providing standard tests, chitecture where the doctor behaves as a client, which activates a creating new vision tests, monitoring the calibration process number of clinical tests at the other side, and gives directives to the and analyzing the collected results. patient’s on what they have to do. The software at the patient side • On-line and off-line operative modes. plays the server role, publishing all the provided medical tests as remote services. The server runs on the eye tracker system, while After the calibration phase where the system is tuned for the pa- the client usually runs at a different host. At both the doctor and tient, the doctor can choose a test or a sequence of customizable the patient sides a direct communication with the server and the as- clinical tests to be performed by the patient. All the information sociated Tobii eye tracker must be available in order to allow the available at the doctor side, such as pupil size and distance between doctor to monitor the patient’s gaze status in real-time and the pa- the head and the screen (shown in the bottom-right side of fig.2), tient to perform the calibration process and to have a visual feed- helps the doctor in correcting any wrong patient’s position, which back on his/her track status. All these features lead to three distinct can invalidate the calibration and data collection. flows of communication: the first, between the doctor and the pa- tient for sending calibration, tracking and testing commands; the The doctor’s interface consists of two main sections: Control and second, between the patient and the Tobii eye tracker and the third Test sections. In the Control section, the patient’s eyes movements between the doctor and the TET server itself, for retrieving calibra- can be tracked in real-time (right side of the Figure 2) and the cali- tion results, gaze coordinates and other additional information to be bration process can be managed (left side of Figure 2). Once a cali- analyzed. So the client (at the doctor side) may handle everything bration has been done, the client at the doctor side will be connected can be viewed on the patient’s screen and monitors gaze data, in directly to the TET server to retrieve the test results, and visualize 70
  3. 3. them for possibly repeating the tests. After obtaining a correct cal- ibration, customized vision tests can be performed. Currently, the prototype tool provides three vision tests, i.e.: 1) perimetry, 2) eye velocity and contrast sensitivity and 3) visual attention measure- ment. In the Test section, the user can choose the test to carry out, e.g. in Figure 3 a general test to check the visual field and related control information is shown. In particular, a little transparent circle shows to the doctor where the patient is looking in real-time. Figure 4: The Test section of the doctor’s application interface: a perimetry test. The doctor chooses a number of stimuli charac- teristics and shows the stimulus on the patient’s screen just with a mouse click. Figure 2: The Controls section of the doctor’s application graphi- (a) Latency in ms (b) Eye Velocity in m/s cal interface. On the right, a real-time status of patient’s gaze track- ing is shown, while the last calibration process results are shown on the left. (c) Gain Figure 5: Statistic Values for a normal patient Figure 3: The Test section of the doctor’s application interface. (a) Latency in ms (b) Eye Velocity in m/s The doctor can monitor what is happening on the patient’s screen and a number of eye movements parameters, shown on the right. In this case a visual field test is performed. Figure 4 shows the test for the evaluation of perimetry vision. The doctor can provide a light stimulus at any part of the patient’s screen, setting its size, intensity and duration properties via the re- (c) Gain lated menu (left part of fig. 4), available simply with a right mouse click. The transparent red circle shows where the patient is looking Figure 6: Statistic Values for an Alzheimer affected patient in real-time; when the patient matches the stimulus provided by the doctor, a written notification is given to help the doctor to evaluate the patient status. As seen before, no motion or vocal interaction is required for the patient, in fact s/he only looks at the screen and and Gain 0.95 ± 0.26, whereas for the Alzheimer patient the values follows the shown stimuli. were: Latency 258 ± 51 ms, Eye Velocity 375.33 ± 59.78 m/s and Gain 0.86 ± 0.16. These values are compatible with the ones At the end of each test, relevant statistics are available, to give to obtained in neurological research as shown in [Shafiq-Antonacci the doctor a further opportunity to deeply analyze the data or to et al. 2003]. Therefore the proposed system aims at helping med- save them into a datastore for future analysis. For example, in fig. ical doctors in the diseases’ diagnosis, but of course more medical 5 and 6 the latency in ms , the eye velocity in m/s and the gain examinations are needed for the final diagnosis. (amplitude of initial saccade divided by amplitude of the provided As outlined before, one of the main feature of the proposed system stimuli) are shown respectively for a normal patient and for a pa- is the test personalization. Indeed, the doctor can easily choose the tient affected by Alzheimer disease. In detail, we obtained for the features of a specific test. The workflow for the test personalization normal patient, on a set of 30 measurements for each test, the fol- is shown in fig. 7. The doctor has to perform a correct eye tracker lowing values of mean (µ) and standard deviation (σ) (in the form calibration before starting a new test. After that, s/he can configure µ ± σ): Latency 321 ± 103 ms, Eye Velocity 356.45 ± 51.32 m/s and start the chosen test, and monitor what happens at the patient 71
  4. 4. side. new customizable vision tests, based on well-known medical pro- The use of a powerful and accurate software tool to analyze the eye tocols, and improve medical examinations at distance, in order to movements and gaze behavior, leads to a number of advantages, achieve a better adaptation of the application to the doctors’ needs. due to the test costs reduction and the capability of obtaining a pa- It would be also interesting and useful to build a central DBMS tient’s implicit feedback, without requiring any additional stimuli (DataBase Management System) for collecting and retrieving in- response. This last feature deserves a more detailed analysis, since formation coming from several geographically distributed systems, currently used medical tests always require an explicit body motion making the collected data accessible all over the web for the pur- or vocal answer to verify the patient’s health status. Indeed, these pose of improving the medical research. A semantic based system tests need the patient to push a button every time a given event oc- will be included in order to carry out queries such as: ”What is the curs, leading to several problems with patients who have no motion mean and the standard deviation of latency in patients affected by capabilities. In addition, requiring an explicit feedback introduces Alzheimer?”, allowing us to de-identify the database (for privacy unavoidable delays, due to the patient’s capacity of reaction, some- issues) not including names, gender and other sensitive informa- times invalidating test results. The eye trackers allow us to directly tion. Thus, future work will consider the possibility of recording capture the patient’s feedback, thus granting a better accuracy on patient’s examinations for an off-line analysis or simply for facil- health evaluation. itating the patient’s anamnesis. It is envisaged that this work will contribute to a more massive spread of the eye tracking technology into the medical field, providing a better way to discover human diseases and opening new horizons for the documentation of the patients’ medical history. References A STERIADIS , S., T ZOUVELI , P., AND K ARPOUZIS , K. 2009. Es- timation of behavioral user state based on eye gaze and head poseapplication in an e-learning environment. Multimedia Tools and Applications 41, 3, 469–493. B LEKHER , T. M., W EAVER , M. R., AND C AI , X. 2009. Test- retest reliability of saccadic measures in subjects at-risk for Huntington disease. Invest. Ophthalmol. Vis. Sci. (Jun). M ANNAN , S. K., H ODGSON , T. L., H USAIN , M., AND K EN - NARD , C. 2008. Eye movements in visual search indicate im- paired saliency processing in Parkinson’s disease. Prog. Brain Res. 171, 559–562. M URRAY, I. C., F LECK , B. W., AND B RASH , H. M. 2009. 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