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A new tool for monitoring brain function: eye tracking goes beyond assessing attention to measuring central nervous system physiology.

Samadani U - Neural Regen Res (2015)

View Article: PubMed Central - PubMed

Affiliation: Steven and Alexandra Cohen Veterans Center for Post-Traumatic Stress and Traumatic Brain Injury at NYU Langone Medical Center; Departments of Neurosurgery, Psychiatry, Physiology and Neuroscience, New York University School of Medicine, New York; New York Harbor Health Care System, USA.

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Concussion and other forms of brain injury are not always detectable with conventional means such as radiographic imaging... The lack of accurate diagnostics, biomarkers, and outcome measures has a devastating impact... The lack of appropriate classification schemes and objective outcome measures for patients entering clinical trials for concussion and other forms of traumatic brain injury (TBI) contributes to the failure of such trials for therapeutics and prophylactics at great expense to the research and development community and those it hopes to serve, including athletes, students and hapless victims of trauma... Calibration also requires vision and intact functioning of the cranial nerves moving the pupil... It is this latter requirement that has, until the publication of our papers, limited the utility of eye tracking to conditions that do not affect this basic activity... The pupils are tracked over 220 seconds of time for comparison to each other and to a database of control subjects... The technique does not require a trained examiner and is fully automatable... The challenge of working with uncalibrated data is how to determine whether a given eye-movement trace results from an observer's engagement in the task, as opposed to artifact, random eye movements, or deliberate eye movements unrelated to the task... By looking at the eye movement trajectories in the time domain rather than the spatial domain, we can quantify spatiotemporal measures that do not rely on spatial calibration... We showed that recording of subject eye movements during watching of a 220 second music video allows rapid detection of cranial nerve palsies and that these can be tracked through their resolution... Cranial nerve palsies are commonly found in numerous diseases, including trauma, vascular lesions, tumors, diabetes and other endocrinopathies, and infectious and inflammatory pathology among many more... We demonstrated that (1) eye tracking can detect and quantitate the severity of abnormal eye movements within a few hours after concussion (2) that the severity of abnormal eye movements correlates with the severity of concussion symptoms using two different measures as measured by Spearman correlation and (3) that after concussion eye tracking initially worsens then improves towards normal within one month in most patients (Samadani et al., 2015)... The technology we have developed is as passive a task as possible, to limit the impact of volitional factors such as attention and compliance with instructions, which are components of fatigue... When a subject closes the eyes or turns away from the screen, such data (or lack thereof) does not affect analysis results which are only based upon the data that is actually captured... Spatially calibrated eye tracking assessing rigorous optometric measures in cooperative patients demonstrates eye movement abnormalities in patients with post-concussive syndrome relative to uninjured controls (Heitger et al., 2009; Cifu et al., 2015).

No MeSH data available.


Related in: MedlinePlus

Spatial calibration transforms the amount of light reflecting off the cornea and pupil into a constant value regardless of whether the eye has normal motility, thus masking deficits. Without calibration, abnormal motility can be detected.
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Figure 1: Spatial calibration transforms the amount of light reflecting off the cornea and pupil into a constant value regardless of whether the eye has normal motility, thus masking deficits. Without calibration, abnormal motility can be detected.

Mentions: The reason that calibration prevents detection of subtly abnormal eye movements is that if one eye has weakened movement in a particular direction, the camera will interpret the eye's ability to move in the direction of that weakness as the full potential range of motion in that direction due to the calibration process. For example, if during calibration, a person is directed to look at a position but only moves halfway there, the calibration algorithm will mistakenly indicate that movement to the halfway point is actually full movement. Subsequent eye movements to the halfway point will be interpreted as occurring at the full range of normal motion. Thus, though one eye only makes it half-way to the target, while the other eye is fully there, the camera will interpret both eyes as being together when one moves only half the distance as the other (Figure 1). While it is possible to separately track each eye to detect abnormal motility, this is a suboptimalapproach as it requires a dichoic apparatus, if one wishes to compare the pupil positions over time, and a subject capable and willing to endure the calibration process twice.


A new tool for monitoring brain function: eye tracking goes beyond assessing attention to measuring central nervous system physiology.

Samadani U - Neural Regen Res (2015)

Spatial calibration transforms the amount of light reflecting off the cornea and pupil into a constant value regardless of whether the eye has normal motility, thus masking deficits. Without calibration, abnormal motility can be detected.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4590232&req=5

Figure 1: Spatial calibration transforms the amount of light reflecting off the cornea and pupil into a constant value regardless of whether the eye has normal motility, thus masking deficits. Without calibration, abnormal motility can be detected.
Mentions: The reason that calibration prevents detection of subtly abnormal eye movements is that if one eye has weakened movement in a particular direction, the camera will interpret the eye's ability to move in the direction of that weakness as the full potential range of motion in that direction due to the calibration process. For example, if during calibration, a person is directed to look at a position but only moves halfway there, the calibration algorithm will mistakenly indicate that movement to the halfway point is actually full movement. Subsequent eye movements to the halfway point will be interpreted as occurring at the full range of normal motion. Thus, though one eye only makes it half-way to the target, while the other eye is fully there, the camera will interpret both eyes as being together when one moves only half the distance as the other (Figure 1). While it is possible to separately track each eye to detect abnormal motility, this is a suboptimalapproach as it requires a dichoic apparatus, if one wishes to compare the pupil positions over time, and a subject capable and willing to endure the calibration process twice.

View Article: PubMed Central - PubMed

Affiliation: Steven and Alexandra Cohen Veterans Center for Post-Traumatic Stress and Traumatic Brain Injury at NYU Langone Medical Center; Departments of Neurosurgery, Psychiatry, Physiology and Neuroscience, New York University School of Medicine, New York; New York Harbor Health Care System, USA.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

Concussion and other forms of brain injury are not always detectable with conventional means such as radiographic imaging... The lack of accurate diagnostics, biomarkers, and outcome measures has a devastating impact... The lack of appropriate classification schemes and objective outcome measures for patients entering clinical trials for concussion and other forms of traumatic brain injury (TBI) contributes to the failure of such trials for therapeutics and prophylactics at great expense to the research and development community and those it hopes to serve, including athletes, students and hapless victims of trauma... Calibration also requires vision and intact functioning of the cranial nerves moving the pupil... It is this latter requirement that has, until the publication of our papers, limited the utility of eye tracking to conditions that do not affect this basic activity... The pupils are tracked over 220 seconds of time for comparison to each other and to a database of control subjects... The technique does not require a trained examiner and is fully automatable... The challenge of working with uncalibrated data is how to determine whether a given eye-movement trace results from an observer's engagement in the task, as opposed to artifact, random eye movements, or deliberate eye movements unrelated to the task... By looking at the eye movement trajectories in the time domain rather than the spatial domain, we can quantify spatiotemporal measures that do not rely on spatial calibration... We showed that recording of subject eye movements during watching of a 220 second music video allows rapid detection of cranial nerve palsies and that these can be tracked through their resolution... Cranial nerve palsies are commonly found in numerous diseases, including trauma, vascular lesions, tumors, diabetes and other endocrinopathies, and infectious and inflammatory pathology among many more... We demonstrated that (1) eye tracking can detect and quantitate the severity of abnormal eye movements within a few hours after concussion (2) that the severity of abnormal eye movements correlates with the severity of concussion symptoms using two different measures as measured by Spearman correlation and (3) that after concussion eye tracking initially worsens then improves towards normal within one month in most patients (Samadani et al., 2015)... The technology we have developed is as passive a task as possible, to limit the impact of volitional factors such as attention and compliance with instructions, which are components of fatigue... When a subject closes the eyes or turns away from the screen, such data (or lack thereof) does not affect analysis results which are only based upon the data that is actually captured... Spatially calibrated eye tracking assessing rigorous optometric measures in cooperative patients demonstrates eye movement abnormalities in patients with post-concussive syndrome relative to uninjured controls (Heitger et al., 2009; Cifu et al., 2015).

No MeSH data available.


Related in: MedlinePlus